Suspected Appendicitis Child

Suspected Appendicitis Child. Regarding perforated appendicitis, Dillman et al [40] showed subsequent MRI to have similar sensitivity and specificity to CT for diagnosis of perforation in patients with an initially equivocal or nondiagnostic RLQ US. It should be noted, however, that the total number of cases of perforation in this study was small (10 in the MR group and 4 in the CT group).


Suspected Appendicitis Child

Suspected Appendicitis Child. Variant 5: Child. Suspected acute appendicitis with clinical suspicion or initial imaging suggestive of complication (eg, abscess, bowel obstruction). Next imaging study. Complicated appendicitis, generally a result of perforation, occurs at a frequency of approximately 30% in the pediatric population and has implications for clinical care [73]. There is debate in the literature regarding optimal care for patients with perforated appendicitis, which can range from antibiotic therapy with delayed appendectomy to interventional drainage to surgical intervention.


Suspected Appendicitis Child

Suspected Appendicitis Child. Radiography Abdomen Radiographs may identify possible complications of acute appendicitis by identifying bowel obstruction or gross perforation. Radiographs, however, have limited sensitivity and specificity for the diagnosis of acute appendicitis as a cause of the complication [51].


Suspected Appendicitis Child

Suspected Appendicitis Child. US Abdomen RLQ In general, US has been shown to have limited accuracy in the distinction of perforated from nonperforated acute appendicitis [2]. While US can identify RLQ fluid collections/abscesses and dilated bowel loops, the limited field of view may be inadequate to fully assess complications of appendiceal perforation and thereby guide clinical management.


Suspected Appendicitis Child

Suspected Appendicitis Child. US Abdomen The greater anatomic coverage of a full abdominal US (versus an RLQ US) may identify additional findings of complicated acute appendicitis outside of the RLQ, but the small image field of view is still limiting in terms of overall assessment of complications.


Suspected Appendicitis Child

Suspected Appendicitis Child. US Pelvis Focused US of the pelvis is limited in terms of overall assessment of complicated acute appendicitis secondary to its small scope of imaging and field of view.


Suspected Appendicitis Child

Suspected Appendicitis Child. CT Abdomen and Pelvis CT of the abdomen and pelvis with IV contrast, with or without oral contrast, provides a broad field of view for assessment of complications of acute appendicitis, including perforation, abscess, and bowel obstruction. Focused CT will likely be sufficient to characterize complicated appendicitis in the lower abdomen and pelvis; however, the limited coverage may not permit characterization of complications if they extend into the upper abdomen (eg, perisplenic or perihepatic collections). However, this has not been specifically studied.


Suspected Appendicitis Child

Suspected Appendicitis Child. There are no studies that compare unenhanced and contrast-enhanced CT for diagnosis of acute appendicitis. Unenhanced CT may be limited in its ability to characterize complicated appendicitis (eg, perforation and abscess formation) [38,39].


Suspected Appendicitis Child

Suspected Appendicitis Child. MRI Abdomen and Pelvis MRI has not been specifically compared to CT as a modality for assessment of suspected complications of acute appendicitis and the role of IV gadolinium in this setting has not been specifically assessed. Data from a small number (n = 10) of patients with an initially equivocal or nondiagnostic RLQ US suggest MRI performs similarly to CT for the detection of perforated appendicitis [40], but patients with known or suspected perforation were not included in that study, and the ability of MRI to accurately characterize the perforation or other complications has not been studied. The broad field of view provided by MRI of the abdomen and pelvis should allow for assessment of complications of acute appendicitis.


Suspected Appendicitis Child

Suspected Appendicitis Child. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch.acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.


Suspected Appendicitis Child

Suspected Appendicitis Child. For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


Imaging of Facial Trauma Following Primary Survey. aMallinckrodt Institute of Radiology, Saint Louis, Missouri. bPanel Chair, University of Iowa Hospitals and Clinics, Iowa City, Iowa. cPanel Vice-Chair, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts. dFroedtert Memorial Lutheran Hospital Medical College of Wisconsin, Milwaukee, Wisconsin. eEmory University, Atlanta, Georgia; American Association for the Surgery of Trauma. fMontefiore Medical Center, Bronx, New York. gUniversity of Rochester Medical Center, Rochester, New York; American Academy of Otolaryngology-Head and Neck Surgery. hHouston Methodist Hospital, Houston, Texas. iUniversity of Texas Health Science Center, Houston, Texas. jThe University of Texas MD Anderson Cancer Center, Houston, Texas. kUniversity of Illinois at Chicago, Chicago, Illinois; University of Chicago, Chicago, Illinois; American Society of Plastic Surgeons. lNew York University Langone Health, New York, New York. mMetroHealth Medical Center, Cleveland, Ohio. nMayo Clinic Arizona, Phoenix, Arizona. oUniversity of Iowa Carver College of Medicine, Iowa City, Iowa, Primary care physician. pThe University of Texas MD Anderson Cancer Center, Houston, Texas; Commission on Nuclear Medicine and Molecular Imaging. qGeorge Washington University Hospital, Washington, District of Columbia. rUniversity of Colorado Denver, Denver, Colorado. sSpecialty Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia.


Imaging of Facial Trauma Following Primary Survey. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization.


Imaging of Facial Trauma Following Primary Survey. Reprint requests to: publications@acr.org


Imaging of Facial Trauma Following Primary Survey. OR Discussion of Procedures by Variant Variant 1: Tenderness to palpation or contusion or edema over frontal bone. Suspect frontal bone injury. Initial imaging following primary survey. Representing 5% to 15% of all facial fractures, frontal bone fractures are often the result of high-energy blunt trauma, such as motor vehicle collisions, assaults, and significant falls [30]. Thick cortical bone comprises the anterior table of the frontal sinus, allowing it to withstand up to 1,000 kg of force before fracturing, rendering it the sturdiest bone in the face [31]. In contrast, the posterior table of the frontal sinus, separating the sinus from the anterior cranial fossa, is relatively easily fractured secondary to its thin, delicate nature. One-third of injuries are isolated to the anterior table, whereas two-thirds involve both anterior and posterior tables [31]. Injuries along the inferomedial aspect of the frontal sinus and anterior ethmoids may cause occlusion of the nasofrontal duct leading to potential mucocele formation and possibly osteomyelitis [9,15,22,31-33]. Likewise, fractures through the medial aspect of the frontal sinus floor typically involve the cribriform plate and fovea ethmoidalis and may result in cerebrospinal fluid (CSF) leak or chronic sinusitis. Fractures through the lateral part of the frontal sinus floor may involve the orbital roof.


Imaging of Facial Trauma Following Primary Survey. Imaging of Facial Trauma Following Primary Survey CT Maxillofacial Multidetector CT (MDCT) is useful in diagnosing maxillofacial injuries [2,30,31,37-43]. MDCT offers superb delineation of osseous and soft-tissue structures. CT provides high image resolution with thin-section acquisitions allowing for the detection of subtle nondisplaced fractures of the facial skeleton. Also, CT offers multiplanar and 3-D image reconstructions, allowing for better characterization of complex fractures. In particular, many surgeons find the 3-D reformations to be critical in their preoperative planning [13,15,21,39,41,44-46]. CT allows for a faster acquisition time than other modalities such as radiography and MRI. Also, it is less reliant on patient positioning than radiography. CT is typically the first-line of imaging to identify penetrating foreign bodies and the subsequent determination of their trajectory and extent of the injury [47,48]. A novel volume visualization tool, cinematic rendering, is a promising technique to illustrate maxillofacial fractures [41]. CT with IV contrast does not aid in detection of osseous facial injury.


Imaging of Facial Trauma Following Primary Survey. associated cervical spine injuries [19].


Imaging of Facial Trauma Following Primary Survey. Imaging of Facial Trauma Following Primary Survey Radiography Skull CT has replaced radiographs for the initial imaging evaluation of suspected frontal bone injury because radiographs cannot characterize the full extent of fractures, detect nasofrontal duct involvement, and ascertain intracranial pathology [30,59]. Approximately 3% of radiographs that did not detect skull fracture had fractures visible on CT in one study. In the group in which radiographs failed to detect a skull fracture, half of the group eventually developed an epidural hematoma [60]. Radiographs may be useful in identifying and determining the location of foreign bodies in the maxillofacial region [50].


Imaging of Facial Trauma Following Primary Survey. High-velocity maxillofacial trauma and penetrating neck trauma are the most common causes of traumatic vascular injuries. Identification and treatment of these injuries should be swift because irreversible neurologic damage or death may occur. Although blunt cerebrovascular injuries (BCVI) are uncommon in maxillofacial trauma, exclusion of these injuries is necessary when clinical suspicion is present [21]. The excellent negative predictive value and high sensitivity of the revised Denver criteria make them an excellent screening tool for BCVI [61]. Using these criteria, blunt trauma patients with particular signs and symptoms of BCVI or risk factors for BCVI should undergo cerebrovascular imaging. Complex skull fractures or scalp degloving are both risk factors for BCVI, which may occur in frontal injuries. Occult neurovascular injury, carotid-cavernous fistula, or carotid transection can occur with severe facial fractures [62,63]. A penetration trajectory, vessel wall hematoma, infiltration of perivascular fat, or foreign bodies <5 mm from a vessel wall should raise suspicion of vascular injury requiring vascular imaging [64,65]. CT angiography (CTA) has been recommended over digital subtraction angiography for initial vascular evaluation because of its short acquisition time and low complication rate [21,29]. CTA detects almost all clinically relevant blunt cervical arterial injuries [29,66].


Imaging of Facial Trauma Following Primary Survey. As stated above, BCVI, although uncommon in maxillofacial trauma, carries significant morbidity and mortality if not identified and treated early. Therefore, the exclusion of these injuries is necessary in the correct clinical context. Although MR angiography (MRA) is inferior to conventional arteriography, it is considered equivalent to CTA in BCVI. Similar to CTA, MRA does distinguish almost all clinically significant cervical arterial injuries [29,66]. However, MRA without IV contrast in the neck may be limited because of artifacts and limited resolution. Subtle vascular injuries such as wall irregularity and thickening and mild luminal irregularity can be difficult to detect [67]. Also, MRA with or without IV contrast is time-consuming, making it challenging to use in an acute trauma setting. Some debate exists as to whether CTA is superior to MRA in BCVI. One study found CTA to be superior [68], whereas another found them to be equivalent [29,69]. Virtual arteriograms can be created without IV contrast using time-of-flight or phase-contrast sequences. Nevertheless, pseudoaneurysms or subtle stenoses are more easily detected by administering contrast intravenously using 3-D time-of-flight imaging.


Imaging of Facial Trauma Following Primary Survey. Arteriography Cervicocerebral Angiography of the head and neck may logically follow identification of specific bony or soft tissue injuries but is not useful as the initial imaging modality to identify frontal bone injury. Angiography is used as a problem-solving


Imaging of Facial Trauma Following Primary Survey. Imaging of Facial Trauma Following Primary Survey


Imaging of Facial Trauma Following Primary Survey. As stated above, BCVI, although uncommon in maxillofacial trauma, carries significant morbidity and mortality if not identified and treated early. Therefore, the exclusion of these injuries is necessary in the correct clinical context. Despite improvements in CTA and MRA, the reference standard for identifying cervical arterial injury remains arteriography because of its ability to detect low-grade injuries missed on other modalities [29,70-72]. However, CTA or MRA is generally utilized over arteriography currently, secondary to the 1% to 2% risk of meaningful complications such as stroke and dissection [29].


Imaging of Facial Trauma Following Primary Survey. addresses the role of imaging in the setting of head trauma. CT with IV contrast does not aid in detection of head injury.


Imaging of Facial Trauma Following Primary Survey. MRI Maxillofacial There is no relevant literature to support the use of MRI of the face in the initial imaging evaluation of suspected midface injury. However, in patients with cranial nerve deficits not explained or incompletely characterized by CT, MRI can be a useful supplement [31]. In particular, some Le Fort II injuries can disrupt the infraorbital nerve (V2), leading to anesthesia of the upper teeth, gingiva, upper lip, and lateral aspects of the nose [15,32,80]. Zygomatic maxillary complex fractures are often associated with infraorbital nerve (V2) deficits as well [4,79]. In naso-orbital- ethmoid fractures, olfactory nerve injury often occurs. Because of its superior soft-tissue contrast and multiplanar capabilities, MRI may be helpful in the detection of CSF leak from a skull base fracture. High resolution heavily T2-weighted images are useful in the evaluation of the olfactory nerve and for potential CSF leaks. MRI aids in diagnosing the contents that have herniated through a defect in skull base injuries [49]. These skull base injuries can occur in naso-orbital-ethmoid fractures [31]. Also, MRI is superior to CT for detecting small pieces of asphalt, which could occur as facial foreign bodies [50]. MRI with IV contrast is not useful in detection of facial injury.


Imaging of Facial Trauma Following Primary Survey. Imaging of Facial Trauma Following Primary Survey associated cervical spine injuries [19].


Imaging of Facial Trauma Following Primary Survey. Radiography Paranasal Sinuses For injuries of the midface, CT has largely replaced radiographs [15,30]. The limitations with radiographs are primarily related to inaccuracies, especially with small or fine structures, associated with the superimposition of adjacent anatomic structures and the lack of technical skill resulting from disuse and a lack of training [2]. In one study, radiologists missed 12% of maxillofacial fractures on radiographs compared with CT [81]. When combined with an appropriate physical examination, the Waters, Caldwell, and submentovertex views can provide sufficient information to verify the clinical diagnosis of a zygomaticomaxillary complex fracture. Still, both patient positioning and technological experience are essential [15]. Radiographs may be useful in identifying and determining the location of foreign bodies in the maxillofacial region [50].


Imaging of Facial Trauma Following Primary Survey. High-velocity maxillofacial trauma and penetrating neck trauma are the most common causes of traumatic vascular injuries. Identification and treatment of these injuries should be swift because irreversible neurologic damage or death may occur. Occult neurovascular injury, carotid-cavernous fistula, or carotid transection can occur with severe facial fractures [62,63]. Although BCVI are uncommon in maxillofacial trauma, exclusion of these injuries is necessary when clinical suspicion is present [21]. The excellent negative predictive value and high sensitivity of the revised Denver criteria make them an excellent screening tool for BCVI [61]. Using these criteria, blunt trauma patients with particular signs and symptoms of BCVI or risk factors for BCVI should undergo cerebrovascular imaging. Le Fort II and Le Fort III fractures are both risk factors for BCVI. Also, the Eastern Association for the Surgery of Trauma currently recommends screening all patients with Le Fort II or III facial fractures for the presence of BCVI [82]. One study based on an analysis of 4,398 patients recommended screening for BCVI in Le Fort I facial fractures [17]. A penetration trajectory, vessel wall hematoma, infiltration of perivascular fat, or foreign bodies <5 mm from a vessel wall should raise suspicion of vascular injury requiring vascular imaging [64,65]. CTA has been recommended over digital subtraction angiography for initial vascular evaluation because of its short acquisition time and low complication rate [21,29]. CTA detects almost all clinically relevant blunt cervical arterial injuries [29,66].


Imaging of Facial Trauma Following Primary Survey. MRA Head and Neck MRA of the head and neck may logically follow identification of specific bony or soft-tissue injuries but is not useful as the initial imaging modality to identify midface injury. Guidance on the imaging of vascular injuries in


Imaging of Facial Trauma Following Primary Survey. As stated above, BCVI, although uncommon in maxillofacial trauma, carries significant morbidity and mortality if not identified and treated early. Therefore, the exclusion of these injuries is necessary in the correct clinical context. Although MRA is inferior to conventional arteriography, it is considered equivalent to CTA in BCVI. Similar to CTA, MRA does distinguish almost all clinically significant cervical arterial injuries [29,66]. However, MRA without IV contrast in the neck may be limited because of artifacts and limited resolution. Subtle vascular injuries such as wall irregularity and thickening and mild luminal irregularity can be difficult to detect [67]. Also, MRA with or without IV contrast is time-consuming, making it challenging to use in an acute trauma setting. Some debate exists as to whether CTA is superior to MRA in BCVI. One study found CTA to be superior [68], whereas another found them to be equivalent [29,69]. Virtual arteriograms can be created without IV contrast using time-of-flight or phase-contrast sequences. Nevertheless, pseudoaneurysms or subtle stenoses are more easily detected by administering contrast intravenously using 3-D time-of-flight imaging.


Imaging of Facial Trauma Following Primary Survey. Radiography Chest There is no relevant literature to support the use of chest radiography in the initial imaging evaluation of suspected midface injury. However, a chest radiograph may be warranted to exclude tooth aspiration if there is a tooth that is absent [46,83]. A physician or surgeon should remove an avulsed tooth in the airway because of the risk of developing obstructive pneumonia [9].


Imaging of Facial Trauma Following Primary Survey. Imaging of Facial Trauma Following Primary Survey cosmetic deformity and nasal obstruction [32]. In particular, a fracture involving the nasal cartilage may cause a septal hematoma leading to cartilage necrosis or resorption, and if untreated, a subsequent saddle nose deformity.


Imaging of Facial Trauma Following Primary Survey. US Maxillofacial Ultrasound (US) is typically not the first-line imaging test for evaluation of nasal injuries. However, researchers have investigated whether US might be useful in this scenario. Research using US has revealed a very high accuracy with sensitivity ranging from 90% to 100%, a specificity of 98% to 100%, and high predictive values [38,85,86]. This is particularly true of isolated nasal bone fractures [87,88]. According to two reports, US better detects nondepressed fractures of the nasal bridge and anterior septal cartilage deviation than CT [85,86]. A conductor- assisted nasal US technique detected nasal fractures, with 100% sensitivity and 89% specificity, 96% positive predictive value, and 100% negative predictive value [89]. Another study revealed that US is a reliable diagnostic tool for estimating the time of nasal bone fracture [90].


Imaging of Facial Trauma Following Primary Survey. Radiography Paranasal Sinuses Nasal radiographs have limited diagnostic value in the evaluation of nasal trauma. According to several studies, the diagnostic accuracy for radiographs to detect nasal bone fractures ranges from 53% to 82% [91-93]. Radiographs do not considerably alter the diagnosis or management of nasal fractures [94].


Imaging of Facial Trauma Following Primary Survey. CT Head There is no relevant literature to support the use of CT of the head in the initial imaging evaluation of suspected nasal bone injury.


Imaging of Facial Trauma Following Primary Survey. CT Maxillofacial MDCT is useful in diagnosing maxillofacial injuries [2,30,31,37-43]. MDCT offers superb delineation of osseous and soft-tissue structures. CT provides high image resolution with thin-section acquisitions allowing for the detection of subtle nondisplaced fractures of the facial skeleton. Also, CT offers multiplanar and 3-D image reconstructions, allowing for better characterization of complex fractures. In particular, many surgeons find the 3- D reformations afforded by CT to be critical in their preoperative planning [13,15,21,39,41,44-46]. In complex nasal injuries and other associated facial fractures, CT can fully characterize the extent of injuries and detect any additional facial injuries [30]. When compared with radiographs, CT is more sensitive in confirming the clinical suspicion of nasal bone fracture [93]. Several classification systems exist for nasal bone fractures, and one classification system created by Rhee et al [95] relies solely on CT to determine the degree of septal deviation. CT allows for a quicker acquisition time compared with other modalities such as radiography and MRI. Also, it is less reliant on patient positioning than radiography. CT is useful as the first-line of imaging to identify penetrating foreign bodies and the subsequent determination of their trajectory and extent of the injury [47,48]. A novel volume visualization tool, cinematic rendering, is a promising technique to illustrate maxillofacial fractures [41]. CT with IV contrast does not aid in detection of facial injury.


Imaging of Facial Trauma Following Primary Survey. MRI Maxillofacial There is no relevant literature to support the use of MRI of the face in the initial imaging evaluation of suspected nasal bone injury.


Imaging of Facial Trauma Following Primary Survey. Variant 4: Trismus or malocclusion or gingival hemorrhage or mucosal hemorrhage or loose teeth or fractured teeth or displaced teeth. Suspect mandibular injury. Initial imaging following primary survey. Fractures of the mandible comprise a large proportion of facial fractures because it is vulnerable to low-energy forces. In the setting of assaults and ballistic trauma, the mandible is the most common maxillofacial fracture site [6,96]. Mandibular fractures are classified according to the degree of comminution, location, and the presence of displaced fragments [22]. The mandible is a U-shaped bone forming an incomplete ring that articulates with the calvaria via the temporomandibular joints. Secondary to this ring-like configuration, two separate fractures occur in the mandible in approximately 67% of cases [22,31]. Thus, a second fracture must be sought and excluded after the first fracture is detected. A frequent pattern with two distinct fractures is a mandibular angle or subcondylar fracture with a contralateral parasymphyseal fracture. Another critical pattern, a flail mandible, consists of bilateral subcondylar fractures with a symphyseal fracture. In addition to these osseous injuries, fractures of the mandible may damage the inferior alveolar nerve because they extend through the mandibular canal. Beyond the mandible, approximately 20% to 40% of patients with mandibular fractures have further injuries [97].


Imaging of Facial Trauma Following Primary Survey. CT Maxillofacial MDCT is useful in diagnosing maxillofacial injuries [2,30,31,37-43]. MDCT offers superb delineation of osseous and soft-tissue structures. CT provides high image resolution with thin-section acquisitions allowing for the detection of subtle nondisplaced fractures of the facial skeleton. CT is superior to radiography for the evaluation of mandibular fractures [96]. Nearly 100% sensitive with an improved interobserver agreement, CT with multiplanar reformations is proficient in detecting fractures of the mandible [31,99]. This is especially true of posterior mandibular fractures [3,100]. According to one study, more fractures are identified on CT when there is no fracture visible on orthopantomogram (OPG) [99]. CT is beneficial when evaluating ramus or condyle fractures, because the degree of displacement in these areas can be subtle [101]. CT is especially useful in identifying comminution and displacement of mandibular fractures. These are critical findings because they result in a change in surgical management [100,102,103]. Also, CT offers both multiplanar and 3-D image reconstructions, which allow for better characterization of complex fractures. In particular, many surgeons find the 3-D reformations afforded by CT to be critical in their preoperative planning [13,15,21,39,41,44-46]. CT allows for a faster acquisition time than other modalities such as radiography and MRI. Also, it is less reliant on patient positioning than radiography. CT is typically the first-line of imaging to identify penetrating foreign bodies and the subsequent determination of their trajectory and extent of the injury [47,48]. A novel volume visualization tool, cinematic rendering, is a promising technique to illustrate mandibular fractures [41]. CT with IV contrast does not aid in detection of facial injury.


Imaging of Facial Trauma Following Primary Survey. MRI Maxillofacial In rare instances, some reports have advocated for MRI in the acute setting to diagnose temporomandibular joint disc morphology and position in certain condylar fractures [2,104,105]. Also, in patients with cranial nerve deficits not explained or incompletely characterized by CT, MRI can be a useful supplement [31]. In particular, fractures through the mandibular canal may damage the inferior alveolar nerve as it travels through the mandibular canal. Damage to the inferior alveolar nerve may result in anesthesia of the ipsilateral lower lip, chin, anterior tongue, and mandibular teeth. Also, MRI is superior to CT for detecting small pieces of asphalt, which could occur as facial foreign bodies [50]. MRI with IV contrast is not useful in detection of facial injury.


Imaging of Facial Trauma Following Primary Survey. Radiography Mandible In patients with a low clinical suspicion of injury, an OPG (panoramic radiograph) or mandibular series consisting of Towne, bilateral lateral oblique, and lateral views may be obtained to evaluate for mandibular fractures. With a sensitivity of 86% to 92%, OPG has better sensitivity for detecting simple mandibular fractures than a standard 4- view mandibular imaging series [31,101,102,106]. Specifically, an OPG demonstrated a sensitivity of 92% in detecting a mandibular fracture in contrast with 66% with a mandibular series [106]. A mandibular series possess several disadvantages compared with an OPG such as superimposition of osseous structures, difficulty in placing the film perpendicular to the fracture, and presence of confusing spatial relationships. A mandibular series does not require the patient to be upright, remain motionless for an extend period, or cervical spine clearance like an OPG [31]. Although isolated mandibular fractures have often been accurately diagnosed using radiography techniques, notable limitations include fractures of the mandible condyle and subcondylar fractures having anterior


Imaging of Facial Trauma Following Primary Survey. 14 Imaging of Facial Trauma Following Primary Survey


Imaging of Facial Trauma Following Primary Survey. displacement, both of which are more easily demonstrated on CT [107,108]. In addition, an OPG can miss both nondisplaced and minimally displaced anterior fractures when there is overlap with the cervical spine [99,109]. A complex fracture may be mistaken for an isolated fracture if OPG is used initially [42]. An OPG can better visualize dental root fractures compared with CT, particularly when the fracture is located at an angle [31]. The use of OPG and mandibular series radiographs has become less favorable in emergency and trauma care settings [110]. Despite this fact, some authors have used radiographs for creating scoring systems for mandibular fractures for an objective and standardized assessment for the degree of severity of mandibular fractures [111].


Imaging of Facial Trauma Following Primary Survey. associated cervical spine injuries [19].


Imaging of Facial Trauma Following Primary Survey. Imaging of Facial Trauma Following Primary Survey High-velocity maxillofacial trauma and penetrating neck trauma are the most common causes of traumatic vascular injuries. Identification and treatment of these injuries should be swift because irreversible neurologic damage or death may occur. Occult neurovascular injury, carotid-cavernous fistula, or carotid transection can occur with severe facial fractures [62,63]. Although BCVI are uncommon in maxillofacial trauma, exclusion of these injuries is necessary when clinical suspicion is present [21]. The excellent negative predictive value and high sensitivity of the revised Denver criteria make them an excellent screening tool for BCVI [61]. As a risk factor for BCVI, condylar and extracapsular subcondylar fractures should heighten suspicion for concomitant BCVI [9,112]. The data support a force transmission mechanism of injury in addition to direct damage from bony fragments [72,105]. A penetration trajectory, vessel wall hematoma, infiltration of perivascular fat, or foreign bodies <5 mm from a vessel wall should raise suspicion of vascular injury requiring vascular imaging [64,65]. CTA has been recommended over digital subtraction angiography for initial vascular evaluation because of its short acquisition time and low complication rate [21,29]. CTA detects almost all clinically relevant blunt cervical arterial injuries [29,66].


Imaging of Facial Trauma Following Primary Survey. As stated above, BCVI, although uncommon in maxillofacial trauma, carries significant morbidity and mortality if not identified and treated early. Therefore, the exclusion of these injuries is necessary in the correct clinical context. Regarding mandibular injuries, condylar and extracapsular subcondylar fractures should heighten suspicion for concomitant BCVI [9,112]. The data support a force transmission mechanism of injury in addition to direct damage from bony fragments [72,105]. Although MRA is inferior to conventional arteriography, it is considered equivalent to CTA in the setting of BCVI. Similar to CTA, MRA does distinguish almost all clinically significant cervical arterial injuries [29,66]. However, MRA without IV contrast in the neck may be limited because of artifacts and limited resolution. Subtle vascular injuries such as wall irregularity and thickening and mild luminal irregularity can be difficult to detect [67]. Also, MRA with or without IV contrast is time-consuming, making it challenging to use in an acute trauma setting. Some debate exists as to whether CTA is superior to MRA in BCVI. One study found CTA to be superior[68], whereas another found them to be equivalent [29,69]. Virtual arteriograms can be created without IV contrast using time-of-flight or phase-contrast sequences. Nevertheless, pseudoaneurysms or subtle stenoses are more easily detected by administering contrast IV using 3D time-of-flight imaging.


Imaging of Facial Trauma Following Primary Survey. As stated above, BCVI, although uncommon in maxillofacial trauma, carries significant morbidity and mortality if not identified and treated early. Therefore, the exclusion of these injuries is necessary in the correct clinical context. Regarding mandibular injuries, condylar and extracapsular subcondylar fractures should heighten suspicion for concomitant BCVI [9,112]. The data support a force transmission mechanism of injury in addition to direct damage from bony fragments [72,105]. Despite improvements in CTA and MRA, the reference standard for identifying


Imaging of Facial Trauma Following Primary Survey. cervical arterial injury remains arteriography because of its ability to detect low-grade injuries missed on other modalities [29,70-72]. However, CTA or MRA is generally utilized over arteriography currently secondary to the 1% to 2% risk of meaningful complications such as stroke and dissection [29].


Imaging of Facial Trauma Following Primary Survey. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch.acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.


Imaging of Facial Trauma Following Primary Survey. For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


Imaging of Facial Trauma Following Primary Survey. Imaging of Facial Trauma Following Primary Survey


Neck Mass Adenopathy

Neck Mass Adenopathy. The American Academy of Otolaryngology-Head and Neck Surgery recently created clinical guidelines for the evaluation of a neck mass in adults [14], emphasizing the importance of timely diagnosis. They issued a strong recommendation for contrast-enhanced neck CT or contrast-enhanced neck MRI for patients with a neck mass deemed at risk for malignancy. In their treatment flow chart, imaging was considered in parallel with fine-needle aspiration of the palpable mass or node for timing of diagnostic evaluation. Ultrasound (US) was considered an option for initial imaging in suspected thyroid or salivary masses or as an adjunct to expedite sampling.


Neck Mass Adenopathy

Neck Mass Adenopathy. Discussion of Procedures by Variant Variant 1: Nonpulsatile neck mass(es). Not parotid region or thyroid. Initial imaging. Cross-sectional imaging with CT or MRI allows for precise localization of the palpable finding. Both CT and MRI can accurately assess tumors and inflammation, and CT and MRI are considered equally effective studies for clinical oncologic evaluation [14,19].


Neck Mass Adenopathy

Neck Mass Adenopathy. Intravenous (IV) contrast is essential for detecting neck abscesses, especially those that are intramuscular [20-22]. Contrast-enhanced imaging is helpful for identifying nodal necrosis and can help guide the search for primary tumor [23,24]. Contrast also helps to clarify primary tumor within the upper aerodigestive tract and the relationship of neck masses to the major vessels of the neck.


Neck Mass Adenopathy

Neck Mass Adenopathy. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document.


Neck Mass Adenopathy

Neck Mass Adenopathy. Reprint requests to: publications@acr.org


Neck Mass Adenopathy

Neck Mass/Adenopathy

Neck Mass Adenopathy. Neck Mass/Adenopathy


Neck Mass Adenopathy

Neck Mass Adenopathy. CT Neck Contrast-enhanced CT has the advantage of superior spatial resolution and is the preferred initial imaging modality for a palpable nonpulsatile neck mass in an adult, particularly considering the risk of head and neck cancer [14,19,25,26]. The presence and distribution of abnormal lymph nodes may be helpful when refining the differential as a reactive or malignant process and in guiding the search for an unknown primary malignancy [19,27,28]. Dual-phase CT imaging (without and with IV contrast) is not usually necessary. CT performed only without IV contrast may be helpful in some cases.


Neck Mass Adenopathy

Neck Mass Adenopathy. CTA Neck There is no evidence to support the use of CT angiography (CTA) for evaluation of a nonpulsatile neck mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. MRI Neck The primary advantage of MRI is improved soft-tissue intrinsic contrast. Intrinsic T1-hyperintensity and fat suppression techniques can confirm fat-containing lesions in the neck [28]. Diffusion-weighted imaging can identify soft-tissue abscess [34]. Apparent diffusion coefficient values also have been proposed as a discriminator between benign and malignant nodal disease in the neck [34-36] and with intravoxel incoherent motion features for both primary and nodal disease [37]; however, histology is needed to confirm any suspected malignancy [13,14,19]. Motion artifact may be a significant issue, particularly for patients who have difficulty managing secretions that are due to neck disease. MRI performed without IV contrast may be helpful in some cases.


Neck Mass Adenopathy

Neck Mass Adenopathy. MRA Neck There is no evidence to support the use of MR angiography (MRA) for evaluation of a nonpulsatile neck mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. US Neck The overall use of neck US in the United States has lagged behind the use of US in Europe and Southeast Asia, which is due, in part, to greater accessibility of CT and MRI in the United States [38-40]. For discrete cystic lesions of the neck, US may suffice to characterize a lesion prior to definitive management. A few studies suggested that US can distinguish between metastatic and inflammatory neck nodes [41-47]. Although these results are promising, scans are user dependent. US serves as a powerful tool for image-guided sampling [48], which is beyond the scope of this document. Advantages of US include the ability to be performed at the point of care and to expedite sampling [14]; however, US is limited for comprehensive evaluation of the deep spaces of the neck, and for larger, multispatial, and malignant lesions.


Neck Mass Adenopathy

Neck Mass Adenopathy. US may play a future rule in identifying unknown primary mucosal tumors, notably in the oropharynx [49]. Techniques such as US elastography and contrast-enhanced US are being explored for possible future clinical applications [44,45,50-58].


Neck Mass Adenopathy

Neck Mass Adenopathy. FDG-PET/CT Skull Base to Mid-Thigh While there is established literature regarding the use of PET using the tracer fluorine-18-2-fluoro-2-deoxy-D- glucose (FDG)/CT for staging and surveillance of head or neck malignancy, FDG-PET/CT is not an initial imaging study for evaluation of a nonpulsatile neck mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. FDG-PET/MRI Skull Base to Mid-Thigh While there is growing literature regarding the use of FDG-PET/MRI for staging and surveillance of head or neck malignancy, FDG-PET/MRI is not an initial imaging study for evaluation of a nonpulsatile neck mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. Arteriography Cervicocerebral There is no evidence to support the use of catheter angiography for evaluation of a nonpulsatile neck mass.


Neck Mass Adenopathy

Neck Mass/Adenopathy


Neck Mass Adenopathy

Neck Mass Adenopathy. CT Neck Neck CT should be performed with IV contrast. Dual-phase CT imaging (without and with IV contrast) is not usually necessary. CT performed only without IV contrast may be helpful in a small minority of cases. Contrast is useful for distinguishing vessels from lymph nodes and confirming whether a mass is hypervascular as many pulsatile neck masses (especially those in level II or III) are lymph nodes overlying the carotid artery rather than true vascular masses. There is no current literature comparing the efficacy of contrast-enhanced CT to CTA or MRI and MRA for the evaluation of a pulsatile neck mass. Advances in lower dose protocols and reconstruction vary among vendors [32], and all imaging should reflect ALARA practices [33].


Neck Mass Adenopathy

Neck Mass Adenopathy. CTA Neck Although CTA is optimized to visualize the cervical arteries, the soft tissues are usually well characterized. There is no current literature comparing efficacy of contrast-enhanced CT to CTA or MRI and MRA for the evaluation of a pulsatile neck mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. MRI Neck The primary advantage of MRI is improved soft-tissue intrinsic contrast. A noncontrast MRI also serves a role for anatomic definition of a pulsatile neck mass in patients who cannot receive contrast. There is no current literature comparing efficacy of contrast-enhanced CT to CTA or MRI and MRA for the evaluation of a pulsatile neck mass. Arterial phase, time-resolved (4-D) MRI may be useful for evaluation of possible paragangliomas in the head and neck [59-61], but it is not an initial imaging study of a new palpable neck mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. MRA Neck MRA is complementary to MRI in the evaluation of a pulsatile neck mass to achieve anatomic and vascular detail. Time resolved (4-D) contrast-enhanced MRA technique may be useful for characterization of head and neck arteriovenous malformations [62]. There is no current literature comparing efficacy of contrast-enhanced CT to CTA or MRI and MRA for the evaluation of a pulsatile neck mass. The use of contrast for MRA is institution dependent but generally preferred.


Neck Mass Adenopathy

Neck Mass Adenopathy. US Neck US may identify a distinct mass overlying or adjacent to an artery, may confirm vascularity of a lesion, or may be useful to confirm a clinical suspicion of a tortuous artery. The characteristic US appearance of phleboliths may aid in the diagnosis of low-flow vascular malformations [59].


Neck Mass Adenopathy

Neck Mass Adenopathy. FDG-PET/CT Skull Base to Mid-Thigh Patients with suspected recurrent paraganglioma may benefit from additional types of PET imaging beyond the scope of this document [63-65]; however, PET/CT is not an initial imaging study for evaluation of a pulsatile neck mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. FDG-PET/MRI Skull Base to Mid-Thigh Patients with suspected recurrent paraganglioma may benefit from additional types of PET imaging beyond the scope of this document [63-65]; however, PET/MRI is not an initial imaging study for evaluation of a pulsatile neck mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. Arteriography Cervicocerebral Catheter angiography may be used for surgical planning and endovascular treatment or for further characterization of vascular neck lesions identified on US or cross-sectional imaging; however, it is not an initial imaging study for evaluation of a pulsatile neck mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. Variant 3: Parotid region mass(es). Initial imaging. Imaging generally cannot determine if a newly symptomatic or palpable parotid lesion is benign or malignant. However, imaging may help determine whether the mass is arising from within or outside the parotid gland, the characteristics of the mass, and whether additional masses are present [66]. An extraparotid mass usually reflects a lymph node. For an intraparotid lesion, differential considerations include lymph nodes, benign, malignant, inflammatory, and congenital etiologies. Although certain imaging findings often suggest a specific diagnosis for a parotid mass, histologic diagnosis is usually needed to exclude malignancy [26,67-72]. Clinical history and


Neck Mass Adenopathy

Neck Mass/Adenopathy

Neck Mass Adenopathy. Neck Mass/Adenopathy


Neck Mass Adenopathy

Neck Mass Adenopathy. physical examination also influences the workup as numbness, trismus, fixation, and facial weakness may suggest a malignant etiology. Radiologist consultation is essential to achieve appropriate anatomic coverage.


Neck Mass Adenopathy

Neck Mass Adenopathy. CT Neck CT face and/or neck with IV contrast is commonly used to evaluate palpable parotid region abnormalities, usually in the setting of suspected parotid acute inflammation [73]. CT performed only without IV contrast may be helpful in a small number of cases. Bony details (landmarks, erosion, remodeling) and sialoliths are better delineated by CT compared with MRI [74]. Dual phase (without and with IV contrast) is not usually necessary as most sialoliths are not obscured by contrast. A noncontrast CT study is usually not indicated in patients presenting with a neck mass suspected of being a swollen major salivary gland that is due to obstructing sialolith [20]. CT imaging coverage of the entire neck should be considered if full assessment of regional nodes is required. Advances in lower dose protocols and reconstruction vary among vendors [32], and all imaging should reflect ALARA practices [33]. CT perfusion imaging is still a research tool for evaluation of parotid pathology [75,76].


Neck Mass Adenopathy

Neck Mass Adenopathy. CT Neck Parotid Sialography In the absence of acute infection, CT sialography may provide detailed assessment of the parotid ducts if there is a clinical concern for duct obstruction.


Neck Mass Adenopathy

Neck Mass Adenopathy. CTA Neck There is no evidence to support the use of CTA for evaluation of a parotid region mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. MRI Neck Parotid Sialography Noninvasive MRI sialography may provide assessment of the parotid ducts [88] complementary to anatomic MRI of the face or neck, if there is a clinical concern for acute parotitis in the setting of duct obstruction.


Neck Mass Adenopathy

Neck Mass Adenopathy. MRA Neck There is no evidence to support the use of MRA for evaluation of a parotid region mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. US Neck US is adept at localization of parotid versus extraparotid masses [77,89], and identifying features suspicious for malignancy [90]. Deep lobe lesions are generally not as well delineated with US as in the superficial lobe. Much of the published literature focuses on US-guided fine-needle aspiration, and not the diagnostic utility of US. Contrast-enhanced US and US elastography are newer techniques currently being explored for evaluation of salivary pathology [71,91-94].


Neck Mass Adenopathy

Neck Mass Adenopathy. FDG-PET/CT Skull Base to Mid-Thigh While there is established literature regarding the use of FDG-PET/CT for staging and surveillance of parotid malignancy, FDG-PET/CT is not an initial imaging study for evaluation.


Neck Mass Adenopathy

Neck Mass Adenopathy. FDG-PET/MRI Skull Base to Mid-Thigh There is no evidence to support the use of FDG-PET/MRI for evaluation of a new parotid mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. Arteriography Cervicocerebral There is no evidence to support the use of catheter angiography for evaluation of a new parotid mass.


Neck Mass Adenopathy

Neck Mass Adenopathy. Fluoroscopy Sialography Parotid In the absence of acute infection, conventional fluoroscopic parotid sialography may provide detailed assessment of the parotid ducts if there is a clinical concern for duct obstruction.


Neck Mass Adenopathy

Neck Mass/Adenopathy


Neck Mass Adenopathy

Neck Mass Adenopathy. Variant 4: Child. Neck mass(es). Not parotid region or thyroid. Initial imaging. In children who present with neck masses, congenital etiologies should be added to differential diagnostic considerations [6,95] in addition to infectious and malignant etiologies. Clinical examination features and correlation with onset, change in mass size, fluctuance, fever, overlying skin erythema, or recent trauma are important to guiding imaging.


Neck Mass Adenopathy

Neck Mass Adenopathy. CT Neck CT with IV contrast can be performed in children suspected of a having a malignancy or a deep neck infection that may require surgery [21,29,96]. CT has reduced or absent sedation requirements given the shorter examination time. Dual phase (without and with IV contrast) is not usually necessary, as most sialoliths are not obscured by contrast. [20]. CT performed only without IV contrast may be useful in some cases. Advances in lower dose protocols and reconstruction vary among vendors [32], and all imaging should reflect ALARA practices [33].


Neck Mass Adenopathy

Neck Mass Adenopathy. CTA Neck There is no evidence to support the use of CTA for evaluation of a palpable neck mass in a child.


Neck Mass Adenopathy

Neck Mass Adenopathy. MRI Neck MRI of the neck can be performed in children suspected of having a malignancy or a deep neck abscess that may require surgical drainage [21,29,96]. Additionally, in suspected vascular malformation, MRI provides detail of trans-spatial extent and adjacent neurovascular structures [97,98]. The addition of contrast is usually helpful for evaluation of suspected vascular lesions [99]; however, it should be considered on a case-by-case basis as it is not always necessary to achieve diagnosis [100].


Neck Mass Adenopathy

Neck Mass Adenopathy. MRA Neck There is no evidence to support the use of MRA for evaluation of a palpable neck mass in a child, though time- resolved postcontrast MRA could be useful for evaluating venous malformations and other pathology [59]. Contrast may not be necessary for defining arterial anatomy.


Neck Mass Adenopathy

Neck Mass Adenopathy. US Neck In children suspected of having a congenital abnormality, US is useful in differentiating solid from cystic neck lesions and in discriminating high-flow from low-flow vascular malformations [59,101-103]. Color-flow Doppler US is also helpful for characterizing vascular flow in solid lesions [41,104]. US may suffice for evaluation of superficial infection [105].


Neck Mass Adenopathy

Neck Mass Adenopathy. FDG-PET/CT Skull Base to Mid-Thigh There is no evidence to support the use of FDG-PET/CT for evaluation of a palpable neck mass in a child.


Neck Mass Adenopathy

Neck Mass Adenopathy. FDG-PET/MRI Skull Base to Mid-Thigh There is no evidence to support the use of FDG-PET/MRI for evaluation of a palpable neck mass in a child.


Neck Mass Adenopathy

Neck Mass Adenopathy. Arteriography Cervicocerebral There is no evidence to support the use of catheter angiography for evaluation of a palpable neck mass in a child.


Neck Mass Adenopathy

Neck Mass Adenopathy. Summary of Recommendations Variant 1: CT neck with IV contrast or MRI neck without and with IV contrast is usually appropriate for the initial imaging of nonpulsatile neck masses, not parotid region or thyroid. These procedures are equivalent alternatives. Variant 2: CT neck with IV contrast, CTA neck with IV contrast, MRI neck without and with IV contrast, or MRA neck is usually appropriate for the initial imaging of pulsatile neck masses, not parotid region or thyroid. These procedures are equivalent alternatives, although CTA or MRA may be complementary to CT and MRI.


Neck Mass Adenopathy

Neck Mass Adenopathy. Variant 3: CT neck with IV contrast, MRI neck without and with IV contrast, or US neck is usually appropriate for the initial imaging of parotid region masses. These procedures are equivalent alternatives. Variant 4: CT neck with IV contrast, MRI neck without and with IV contrast, US neck, or MRI neck without IV contrast is usually appropriate for the initial imaging in children with neck masses, not parotid region or thyroid. CT and MRI studies may be complementary to US.


Neck Mass Adenopathy

Neck Mass/Adenopathy

Neck Mass Adenopathy. Neck Mass/Adenopathy


Neck Mass Adenopathy

Neck Mass Adenopathy. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch.acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.


Neck Mass Adenopathy

Neck Mass Adenopathy. For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Introduction/Background Incidental liver masses are commonly discovered on imaging performed for other indications. Because the prevalence of benign focal liver lesions in adults is high, with at least one lesion seen in up to 15% of patients, accurate characterization of incidentally detected lesions is an important objective of diagnostic imaging [1].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Benign lesions are very common in the liver, and even in patients with primary malignancy, benign lesions unrelated to the known malignancy can be found in nearly 30% of patients [2]. Common benign liver masses include cysts, hemangiomas, and focal nodular hyperplasia (FNH). Common malignant tumors include metastases and hepatocellular carcinomas (HCCs). Less common liver masses include hepatocellular adenoma, intrahepatic cholangiocarcinoma, fibrolamellar HCC, biliary cystadenoma and cystadenocarcinoma, lymphoma, stromal tumors, and a variety of sarcomas. On occasion, benign lesions and pseudolesions may mimic liver tumors. These mimics include focal fat deposition or sparing, intrahepatic vascular shunts, transient hepatic attenuation/intensity difference, abscess, hematoma, and peliosis hepatis. Patients with cirrhosis are a special patient population in whom certain benign (regenerating nodules), premalignant (dysplastic nodules), malignant (HCC), and nontumorous (confluent hepatic fibrosis) masses as well as pseudolesions (vascular shunts) are more prevalent than in the general population [3].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. For each of the variants in this document, it is assumed that an imaging study has identified a lesion that was not fully characterized by the study that detected it. Prior imaging studies may include ultrasonography (US) with color- flow evaluation, noncontrast or contrast-enhanced multidetector helical CT, or noncontrast or contrast-enhanced MRI.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Management recommendations of incidental liver lesions were addressed in a recent white paper by the ACR Incidental Findings Committee (Management of Incidental Liver Lesions on CT: A White Paper of the ACR Incidental Findings Committee) [4]. The document addressed management guidance for incidental liver lesions detected on CT only. In contrast, this document addresses approaches to characterization of hepatic lesions detected with various modalities and in various clinical scenarios.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. For purposes of increased clarity in this document, we combined the low-risk and average-risk individual into one category using the definitions as stated in the white paper (any age with no known malignancies, hepatic dysfunction, risk factors for HCC, or symptoms attributable to the liver). The definition of a high-risk individual in this document differs from that in the white paper in that we separate those individuals with pre-existing liver disease (cirrhosis and chronic hepatitis B without cirrhosis) from those with a known primary malignancy.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Special Imaging Considerations When considering a definitive diagnosis of liver lesions, the dynamic pattern of lesion enhancement can guide the final diagnosis. Therefore, at least two dynamic imaging phases (ie, dual-phase) are required for characterization of most liver lesions. These phases include hepatic arterial phase and portal venous phase and are applicable to CT,


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. aMontefiore Medical Center, Bronx, New York. bPanel Vice-Chair, Northwestern University, Chicago, Illinois. cPanel Chair, Johns Hopkins University School of Medicine, Baltimore, Maryland. dUniversity of Arizona, Banner University Medical Center, Tucson, Arizona. eDuke University Medical Center, Durham, North Carolina. fUniversity of Texas Health Science Center at Houston and McGovern Medical School, Houston, Texas; American Gastroenterological Association. gInterventional Endoscopy and Pancreatic Diseases, New Haven, Connecticut; American Gastroenterological Association. hUMass Medical School, Worcester, Massachusetts. iUniversity of Florida College of Medicine, Gainesville, Florida. jRush University Medical Center, Chicago, Illinois; American College of Surgeons. kNew York University Medical Center, New York, New York. lStanford University Medical Center, Stanford, California. mUniversity of Alabama Medical Center, Birmingham, Alabama. nUniversity of Alabama Medical Center, Birmingham, Alabama. oJohns Hopkins Bayview Medical Center, Baltimore, Maryland. pUniversity of Illinois College of Medicine, Chicago, Illinois; American College of Physicians. qJohns Hopkins Hospital, Baltimore, Maryland. rSpecialty Chair, Virginia Commonwealth University Medical Center, Richmond, Virginia.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Reprint requests to: publications@acr.org


Liver Lesion Initial Characterization

Liver Lesion-Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. For MRI, extracellular gadolinium-based contrast agents are commonly used in a variety of clinical settings. However, hepatobiliary contrast agents were developed to assist with detection and characterization of liver lesions. Two such agents are available: gadoxetate disodium and gadobenate dimeglumine. Hepatobiliary agents have the advantage of hepatobiliary phase (HBP) in addition to the dynamic postcontrast phases. In the HBP, parenchymal uptake of the contrast agent provides avid enhancement of the liver and therefore the ability to detect nonhepatocellular lesions. Of the two agents, gadoxetate is used more widely for HBP imaging as its HBP occurs approximately 20 minutes after injection as compared with 1 to 2 hours when using gadobenate.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. A positron-emitting radioisotope-labeled somatostatin analogue called Ga-68-DOTATATE utilized in PET/CT is designed to image neuroendocrine tumors (NETs). It offers a higher spatial resolution and considerably shorter imaging times compared with In-111 somatostatin receptor or metaiodobenzylguanidine scintigraphy [8].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Discussion of Procedures by Variant Variant 1: Indeterminate, greater than 1 cm liver lesion on initial imaging with US. Normal liver. No suspicion or evidence of extrahepatic malignancy or underlying liver disease. CT Abdomen In some cases, establishing the benign nature of the lesion, rather than a definitive diagnosis is sufficient. In differentiation between malignant and benign lesions, contrast-enhanced CT is accurate in 74% to 95% of cases [9,10]. Definitive diagnosis can be established on contrast-enhanced CT in 71% of patients, with additional imaging recommended in 10% of patients [11]. For patients with incidental liver lesions, multiphase contrast-enhanced CT has 91% to 95% accuracy for diagnosis of hemangioma, 85% to 93% accuracy for the diagnosis of FNH, and 96% to 99% accuracy for diagnosis of HCC [10,12]. For lesions detected on grayscale US, contrast-enhanced CT has sensitivity of 72% to 91%, specificity of 38% to 82%, positive predictive value (PPV) of 92%, negative predictive value (NPV) of 80%, and accuracy of 80% to 88% for establishing a definitive diagnosis [9,13]. CT of the abdomen with and without IV contrast is not recommended for this clinical scenario because there is no added value for unenhanced images.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. DOTATATE PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of Ga-68-DOTATATE PET/CT in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen There is no relevant literature to support the use of In-111 somatostatin receptor scan with single-photon emission computed tomography (SPECT) or SPECT/CT in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. MRI Abdomen In lesions detected on grayscale US, one study of MRI with and without intravenous (IV) contrast has sensitivity of 82% and specificity of 43% for establishing an exact diagnosis [14]. In another series, MRI with and without IV contrast is able to establish a definitive diagnosis in 95% of liver lesions, which is significantly higher than contrast- enhanced CT [11]. Furthermore, only 1.5% of patients with MRIs require recommendation for further imaging as opposed to 10% with CT [11]. Performance characteristics of MRI depend on the sequences and type of contrast, as well as the lesion itself. A combination of diffusion-weighted imaging (DWI) and HBP allows correct classification of lesions as benign or malignant in 91% of cases and exact characterization in 85% of cases [15]. Gadoxetate-enhanced MRI has an accuracy of 95% to 99% for diagnosis of hemangioma, accuracy of 88% to 99% for the diagnosis of FNH, and accuracy of 97% for diagnosis of HCC in patients with incidentally discovered liver lesions [10,12]. For differentiation between adenoma and FNH, low signal on HBP is 100% specific, 92% sensitive,


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization and 97% accurate for hepatocellular adenoma [16]. However, it should be noted that inflammatory adenoma can mimic FNH on MRI [17]. For the diagnosis of a hemangioma, MRI with extracellular gadolinium contrast has sensitivity of 93%, specificity of 99%, accuracy of 98%, PPV of 96%, and NPV of 99% [18]. Although apparent diffusion coefficient (ADC) values of solid benign lesions are higher than those of the solid malignant lesions, there is a considerable overlap of the ADC values between the two groups [19]. Therefore, in patients without a history of malignancy, the value of DWI for differentiating solid liver masses may be limited.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. There is no relevant literature that has assessed the performance of MRI without IV contrast specifically for this clinical scenario. Therefore, the committee recommendations on the use of MRI without IV contrast are based primarily on expert opinion. In some cases, MRI without IV contrast may be appropriate, particularly if the initial US has a high index of suspicion for the diagnosis of a cyst.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-Guided Biopsy Liver An indeterminate liver lesion detected on US is often further evaluated with a diagnostic CT or MRI prior to biopsy, in order to avoid biopsy of solid benign liver lesions such as hemangiomas or areas of FNH [4].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Percutaneous image-guided biopsy may be necessary to establish the diagnosis, particularly when the imaging features on a CT or MRI examination indicate possibility of malignancy. In some liver lesions, such as lymphoma, histopathologic analysis is the only technique that can make a definitive diagnosis [20]. Various techniques exist for guidance of the biopsy, and US and CT are the most commonly utilized modalities for biopsy guidance. When a biopsy is performed to diagnose or rule out malignancy in indeterminate lesions, the overall technical success rate under grayscale US guidance is 74%, which can be increased to 100% under CEUS guidance [21,22].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. The percentage of tumor cells in the biopsy sample is greater with a higher number of collected biopsy samples [23]. Furthermore, for lesions not seen on grayscale US, the success rate for CEUS-guided biopsy can be as high as 88% to 96% [24,25]. US fusion with CT or MRI, can be used for percutaneous biopsy of lesions with poor sonographic conspicuity, with a 96% technical success rate [25]. Lesions that are isointense on CT can also present a challenge for CT-guided biopsy; however, use of anatomic landmarks or IV contrast can achieve accuracy of 96% to 98% [26].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-guided biopsies carry a risk of postbiopsy bleeding, which may be as high as 9% to 12%, particularly with hypervascular lesions [27,28]. In addition, a very small risk of needle-track seeding exists.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m red blood cell (RBC) scan in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. US Abdomen with Contrast For patients with a lesion on grayscale US, addition of CEUS reduces the number of indeterminate diagnoses from 57% to 6%, and the sensitivity and specificity improve from 49% and 25% at baseline US to 93% and 75% with CEUS, respectively [29]. Furthermore, CEUS can reach a specific diagnosis in 77% to 93% and distinguish benign versus malignant lesions in 89% to 97% of indeterminate liver lesions discovered on grayscale US [9,30-32]. Of the complex cystic lesions found on grayscale US, CEUS correctly categorizes 95% of the malignant cases [33]. CEUS is comparable to CT for establishing a diagnosis for lesions detected on grayscale US, with sensitivity of 94% to 96%, specificity of 75% to 83%, PPV of 92%, NPV of 88%, and accuracy of 88% to 90% [13,14,29]. CEUS can definitively characterize an additional 41% of hemangiomas that are deemed indeterminate on a grayscale US [34].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. For specific diagnoses, CEUS correctly characterizes 89% of areas of focal fat, 80% to 90% of hemangiomas, 87% of complex cysts, 78% of hepatic adenomas, 84% to 94% of FNHs, 86% of abscesses, and 60% of hematomas [14,30,35]. Typical pattern of enhancement on CEUS (eg, centripetal fill in during the arterial phase, hyper- enhanced lesion during venous and late phases) has 88% to 90% sensitivity, 99% specificity, 94% to 95% PPV, 97% to 98% NPV, and 97% accuracy for the diagnosis of hemangiomas [18,36]. In noncirrhotic patients, the hypoechoic pattern in portal and sinusoidal phase (rapid wash-out) or the markedly hypoechoic or anechoic pattern in sinusoidal phase (marked late wash-out) showed a sensitivity, specificity, and accuracy of 97%, 100% and 98%, respectively, for the diagnosis of malignancy [37].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization Variant 2: Indeterminate, greater than 1 cm liver lesion on initial imaging with CT (noncontrast or single- phase) or noncontrast MRI. Normal liver. No suspicion or evidence of extrahepatic malignancy or underlying liver disease. CT Abdomen Contrast-enhanced CT correctly differentiates between malignant and benign lesions in 74% to 95% of lesions [9,10]. For patients with incidental liver lesions, multiphase contrast-enhanced CT has 91% to 95% accuracy for diagnosis of hemangioma, 85% to 93% accuracy for the diagnosis of FNH, and 96% to 99% accuracy for diagnosis of HCC [10,12]. CT of the abdomen with and without IV contrast is not recommended for this clinical scenario because there is no added value for unenhanced images.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT in this clinical scenario.


Liver Lesion Initial Characterization


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen There is no relevant literature to support the use of In-111 somatostatin receptor scan with SPECT or SPECT/CT in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-Guided Biopsy Liver Percutaneous image-guided biopsy may be necessary to establish the diagnosis, particularly when the imaging features on a CT or MRI examination indicate possibility of malignancy. In some liver lesions, such as lymphoma, histopathologic analysis is the only technique that can make a definitive diagnosis [20]. Various techniques exist for guidance of the biopsy, and US and CT are the most commonly utilized modalities for biopsy guidance. When a biopsy is performed to diagnose or rule out malignancy in indeterminate lesions, the overall technical success rate under grayscale US guidance is 74%, which can be increased to 100% under CEUS guidance [21,22].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. US Abdomen Diagnostic accuracy of grayscale US is 41% to 68% for specific diagnosis and 86% for differentiation between malignant and benign lesions [9,29]. US can be helpful in some cases due to its ability to characterize a lesion as a


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization cyst. Doppler evaluation of flow is an integral part of the clinical grayscale US examination. However, none of the reviewed studies specifically compared performance of US examinations with and without the addition of Doppler.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. US Abdomen with Contrast In a small retrospective study of solid indeterminate lesions detected on contrast-enhanced CT in patients without parenchymal liver disease, addition of CEUS improves diagnostic accuracy from 43% to 49% to 89% to 92% [39]. CEUS is able to provide correct diagnosis in 89% of cases and can distinguish between benign and malignant lesions in 97% of cases [9]. In noncirrhotic patients, the hypoechoic pattern in portal and sinusoidal phase (rapid wash-out) or the markedly hypoechoic or anechoic pattern in sinusoidal phase (marked late wash-out) showed a sensitivity, specificity, and accuracy of 97%, 100%, and 98%, respectively, for the diagnosis of malignancy [37].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Variant 3: Indeterminate, greater than 1 cm liver lesion on initial imaging with US. Known history of an extrahepatic malignancy. CT Abdomen In patients with a history of primary malignancy, contrast-enhanced CT can differentiate between metastases and benign lesions with 74% accuracy [40]. Specifically, in patients with a history of colon cancer, lesion characterization on contrast-enhanced CT is correct in 77% of cases [41]. When metastases are suspected based on US, the sensitivity and specificity of contrast-enhanced CT for detection of metastases are 88% and 17%, respectively [42].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. In patients with hypervascular liver metastases, addition of noncontrast CT can improve the confidence level for lesion characterization by 4% to 15%; however, it does not change the diagnostic accuracy [43]. The addition of noncontrast CT can increase sensitivity for breast cancer metastases by 5% to 23% but does not improve sensitivity for melanoma metastases [44]. Sensitivity of noncontrast CT alone is 61% to 100% for breast cancer metastases, 62% to 100% for melanoma metastases, and 17% to 88% for NET metastases [44]. In comparison, contrast- enhanced CT has sensitivity of 77% to 95% for breast cancer metastases, 86% to 100% for melanoma metastases, and 44% to 77% for NET metastases [44,45].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. FDG-PET/CT Skull Base to Mid-Thigh In patients with a history of primary malignancy, FDG-PET/CT can differentiate between malignant and benign lesions with an accuracy of 75% [40]. When metastases are suspected based on US, the sensitivity and specificity of PET/CT in the detection of hepatic metastases is 97% and 75%, respectively, which is higher, compared with contrast-enhanced CT alone with sensitivity and specificity of 88% and 17%, respectively [42].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. DOTATATE PET/CT Skull Base to Mid-Thigh In patients with primary NET, Ga-68-DOTATATE PET/CT demonstrates sensitivity of 80% to 100% and of specificity 82% to 100% [8]. Specifically, Ga-68-DOTATATE PET/CT is more sensitive than FDG-PET/CT, with sensitivities of 72% to 100% versus 54% to 78%, respectively [8]. Ga-68-DOTATATE PET/CT is not used in assessment metastases from primary cancers other than NET.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen Sensitivity of In-111 somatostatin receptor scan with SPECT or SPECT/CT varies depending on the specific histologic type of the primary NET. For example, detection rates are >75% in small-cell-lung cancer and carcinoid metastases and 40% to 75% in insulinoma and medullary thyroid cancers [46].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-Guided Biopsy Liver Percutaneous image-guided biopsy may be necessary to establish the diagnosis, particularly when the imaging features on a CT or MRI examination indicate a possibility of malignancy. In some liver lesions, such as lymphoma, histopathologic analysis is the only technique that can make a definitive diagnosis [20]. Various techniques exist


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization for guidance of the biopsy, where US and CT are the most commonly utilized modalities for biopsy guidance. When a biopsy is performed to diagnose or rule out malignancy in indeterminate lesions, the overall technical success rate under grayscale US guidance is 74%, which can be increased to 100% under CEUS guidance [21,22].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. The percentage of tumor cells in the biopsy sample is greater with a higher number of collected biopsy samples [23]. Furthermore, for lesions not seen on grayscale US, the success rate for CEUS-guided biopsy can be as high as 88% to 96% [24,25]. US fusion with CT or MRI can be used for percutaneous biopsy of lesions with poor sonographic conspicuity with a 96% technical success rate [25]. Lesions which are isointense on CT can also present a challenge for CT-guided biopsy; however, use of anatomic landmarks or IV contrast can achieve accuracy of 96% to 98% [26].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-guided biopsies carry a risk of postbiopsy bleeding, which may be as high as 9% to 12%, particularly with hypervascular lesions [27,28]. In addition, a very small risk of needle-track seeding exists.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. US Abdomen with Contrast Depending on the appearance of the lesion on the initial US, CEUS may be performed for lesion characterization. CEUS can differentiate between malignant and benign lesions in 90% of lesions [48]. Diagnostic accuracy of CEUS for metastases is 83% compared with 76% for MRI with extracellular contrast agent [35]. In noncirrhotic patients, the hypoechoic pattern in portal and sinusoidal phase (rapid wash-out) or the markedly hypoechoic or anechoic pattern in sinusoidal phase (marked late wash-out) showed a sensitivity, specificity, and accuracy of 97%, 100%, and 98%, respectively, for the diagnosis of malignancy [37].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Variant 4: Indeterminate, greater than 1 cm liver lesion on initial imaging with CT (noncontrast or single- phase) or noncontrast MRI. Known history of an extrahepatic malignancy. CT Abdomen In patients with a history of primary malignancy, contrast-enhanced CT can differentiate between metastases and benign lesions with 74% accuracy [40]. Specifically, in patients with a history of colon cancer, lesion characterization on contrast-enhanced CT is correct in 77% of cases [41].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. In patients with hypervascular liver metastases, adding a noncontrast CT phase to a contrast-enhanced CT examination can improve the confidence level for lesion characterization by 4% to 15%; however, it does not change the diagnostic accuracy [43]. The addition of noncontrast CT can increase sensitivity for breast cancer metastases by 5% to 23% but does not improve sensitivity for melanoma metastases [44]. Sensitivity of noncontrast CT alone is 61% to 100% for breast cancer metastases, 62% to 100% for melanoma metastases, and 17% to 88% for NET metastases [44]. In comparison, contrast-enhanced CT has a sensitivity of 77% to 95% for breast cancer metastases, 86% to 100% for melanoma metastases, and 44% to 82% for NET metastases [44,45].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. FDG-PET/CT Skull Base to Mid-Thigh In patients with a history of primary malignancy, FDG-PET/CT can differentiate between malignant and benign lesions with an accuracy of 75% [40]. In patients with a history of primary cancer and indeterminate lesions found by either CT or MRI, FDG-PET/CT has an accuracy of 75% with a high sensitivity of 96% and a limited specificity of 33% [40].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. The sensitivity and specificity of FDG-PET/CT in the detection of hepatic metastases is 97% and 75%, respectively, which is higher compared with contrast-enhanced CT alone (which as a sensitivity and specificity of 88% and 17%, respectively) [42].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. DOTATATE PET/CT Skull Base to Mid-Thigh In patients with primary NET, Ga-68-DOTATATE PET/CT demonstrates sensitivity of 80% to 100% and specificity of 82% to 100% [8]. Specifically, Ga-68-DOTATATE PET/CT is more sensitive than FDG-PET/CT, with sensitivities of 72% to 100% versus 54% to 78%, respectively [8].


Liver Lesion Initial Characterization

Liver Lesion-Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen Sensitivity of a In-111 somatostatin receptor scan with SPECT or SPECT/CT varies depending on the specific histologic type of the primary NET. For example, detection rates are >75% in small-cell-lung cancer and carcinoid metastases and 40% to 75% in insulinoma and medullary thyroid cancers [46].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. MRI Abdomen In patients with a history of primary malignancy, noncontrast MRI can differentiate between malignant and benign lesions with accuracy of 71% [47]. The accuracy increases by between 83% and 91% with the addition of dynamic postcontrast sequences and further increases to 94% with addition of HBP [47,48]. In patients with a history of colon cancer, the lesion characterization on contrast-enhanced MRI is correct in 89% of cases [41]. In patients with suspected colorectal liver metastases, the combination of gadoxetate-enhanced MRI and DWI shows significantly higher accuracy (90% to 93%) for the preoperative detection of small colorectal liver metastases than DWI alone [49]. In patients with known primary cancer, ADC values can help to distinguish between metastasis and benign solid hepatic lesions [50].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-Guided Biopsy Liver Percutaneous image-guided biopsy may be necessary to establish the diagnosis, particularly when the imaging features on a CT or MRI examination indicate possibility of malignancy. In patients with a history of primary malignancy, 91% of biopsies are positive for malignancy, 5% of which can be different from the primary cancer [51]. Up to 6% of biopsies in patients with primary malignancy are nondiagnostic [51].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. In some liver lesions, such as lymphoma, histopathologic analysis is the only technique that can make a definitive diagnosis [20]. Various techniques exist for guidance of the biopsy, and US and CT are the most commonly utilized modalities for biopsy guidance. When a biopsy is performed to diagnose or rule out malignancy in indeterminate lesions, the overall technical success rate under grayscale US guidance is 74%, which can be increased to 100% under CEUS guidance [21,22].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. The percentage of tumor cells in the biopsy sample is greater with a higher number of collected biopsy samples [23]. Furthermore, for lesions not seen on grayscale US, the success rate for CEUS-guided biopsy can be as high as 88% to 96% [24,25]. US fusion with CT or MRI, can be used for percutaneous biopsy of lesions with poor sonographic conspicuity, with a 96% technical success rate [25]. Lesions that are isointense on CT can also present a challenge for CT-guided biopsy; however, use of anatomic landmarks or IV contrast can achieve an accuracy of 96% to 98% [26].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. The image-guided biopsies carry a risk of postbiopsy bleeding that may be as high as 9% to 12%, particularly with hypervascular lesions [27,28]. In addition, a small risk of needle-track seeding exists. In patients with HCC, the rate of seeding is 0.1% to 0.7% [52-54].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario.


Liver Lesion Initial Characterization


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. US Abdomen Grayscale US is able to provide correct diagnosis in 68% of liver lesions [9]. For differentiation between malignant and benign lesions, US is correct in 86% of cases [9].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. US Abdomen with Contrast In noncirrhotic patients, the hypoechoic pattern in portal and sinusoidal phase (rapid wash-out) or the markedly hypoechoic or anechoic pattern in sinusoidal phase (marked late wash-out) showed a sensitivity, specificity, and accuracy of 97%, 100%, and 98%, respectively, for the diagnosis of malignancy [37].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. In a small retrospective study of patients with primary pancreatic adenocarcinoma, CT and CEUS have similar sensitivities for detection of metastases (73% versus 80%, respectively) [2]. However, CEUS is able to more accurately differentiate between an incidental benign lesion (eg, cysts, vascular shunts) from metastases, resulting in fewer false-positive diagnoses and therefore higher PPV (60% versus 92%) [2]. The accuracy of CEUS for diagnosis of metastases is 76% [35].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization Variant 5: Incidental liver lesion, greater than 1 cm on US, noncontrast or single-phase CT, or noncontrast MRI. Known chronic liver disease. Evaluation of liver lesions detected in a patient with chronic liver disease should be performed based on the algorithm set forth by the most recent version of LI-RADS [6,55].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. CT Abdomen The sensitivity of a dual-phase contrast-enhanced CT for diagnosing a small HCC (<2 cm) is 53% [56]. In patients with chronic liver disease, triple-phase contrast-enhanced CT correctly characterizes lesions in 49% to 68% of cases and has a sensitivity of 61% to 73% for lesion detection [57]. Delayed phase wash-out on CT is important in HCC diagnosis [58]. For 1- to 2-cm lesions in patients with cirrhosis detected on screening US, the addition of noncontrast CT to dynamic postcontrast phases (CT without and with IV contrast) does not increase sensitivity or accuracy for HCC [59].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT has a limited role in characterization of liver lesions in patients with parenchymal liver disease [6]. Once the diagnosis of HCC is established, tumor FDG activity may predict microvascular invasion [60].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. DOTATATE PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of Ga-68-DOTATATE PET/CT in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen There is no relevant literature to support the use of In-111 somatostatin receptor scan with SPECT or SPECT/CT in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. MRI with extracellular agents has a sensitivity of 78% to 83% and specificity of 100% [35,61]. Addition of HBP improves sensitivity and accuracy for nodules <2 cm [62]. The sensitivity of MRI with gadoxetate for diagnosing a small HCC (<2 cm) is 76% to 97% [56,63]. Addition of HBP improves detection of HCC and differentiation between HCC and dysplastic nodules [64,65]. Furthermore, addition of HBP improves sensitivity and accuracy for diagnosis of HCC, compared with the dynamic images alone [66,67]. Gadoxetate-enhanced MRI allows for correct characterization of liver lesions in 87% to 91% of cases [63]. However, the HBP on gadoxetate-enhanced MRI can be limited in the setting of poor liver function, and transient hepatic enhancement differences can cause artifacts in the HBP in cirrhotic patients [68,69].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. In patients with chronic liver disease, the mean ADC values in benign solid lesions are higher than those in malignant lesions [70]. In small (<3 cm) lesions, presence of high signal intensity on both T2-weighted imaging and DWI helps differentiate atypical HCCs from dysplastic nodules, with the resultant sensitivity of 80%, specificity of 100%, PPV of 100%, and NPV of 78.3% [71]. For lesions <3 cm in patients with cirrhosis, the sensitivity and accuracy to differentiate the dysplastic nodule from HCC are 46% to 82% and 57% to 75%, respectively [72,73]. The addition of DWI to dynamic sequences improved its ability to distinguish between HCC and dysplastic nodules compared with dynamic sequences alone, with a resultant accuracy of 93% and sensitivity of 97% [73].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-Guided Biopsy Liver Biopsy plays a minor role in establishing the diagnosis of HCC because the imaging criteria of LI-RADS category 5 (definite HCC) can establish such diagnosis with nearly 100% specificity and PPV [6,74]. Biopsy may be necessary if the imaging features of the lesion do not meet the criteria for LI-RADS 5 (definite HCC) category or for molecular analysis to determine clinical trial eligibility or to guide treatment [74]. Overall risk of bleeding for image-guided biopsy can be as high as 12% [27]. An additional risk in biopsy of HCC is a risk of needle-tract seeding, with track seeding incidence being 2.7% overall and 0.1% to 0.9% per year [52-54,75].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization US Abdomen with Contrast For indeterminate liver lesions detected on US, CEUS can provide definitive diagnosis in 77% to 93% of cases and can distinguish between benign and malignant lesions in 89% to 96% of cases [31,32]. The sensitivity of CEUS for diagnosing a small HCC (<2 cm) is 68% compared with 53% for contrast-enhanced CT and 77% for gadolinium- ethoxybenzyl-diethylenetriamine pentaacetic acid MRI in the same study [56]. Diagnostic accuracy of CEUS for HCC is 79% [35].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. On CEUS, HCC typically shows a global arterial hyperenhancement and a delayed contrast wash-out, whereas intrahepatic cholangiocarcinoma shows an initial contrast enhancement primarily at the tumor periphery followed by an early portal-venous contrast wash-out in the tumor center [78]. CEUS can accurately differentiate between intrahepatic cholangiocarcinoma and HCC [79].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. CT of the abdomen with and without IV contrast is not recommended for this clinical scenario because there is no added value for unenhanced images.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. FDG-PET/CT Skull Base to Mid-Thigh In patients with a history of primary malignancy, FDG-PET/CT may be indicated to evaluate for presence of metastases beyond the liver. Current literature does not support the use of FGD-PET/CT specifically to characterize subcentimeter liver lesions due to its limited sensitivity for lesions <1 cm.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. DOTATATE PET/CT Skull Base to Mid-Thigh Ga-68-DOTATATE PET/CT is sensitive for detection of metastases in patients with primary NET; however, there is no relevant literature on assessment of subcentimeter liver lesions.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen In patients with a history of primary NET, In-111 somatostatin receptor scan with SPECT or SPECT/CT can detect liver metastases; however, there is no relevant literature to support the use of this procedure in characterization of subcentimeter liver lesions.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. MRI Abdomen On MRI with gadoxetate, the combination of HBP and DWI has the highest accuracy for detection of subcentimeter liver lesions [15]. ADC values can help differentiate benign versus malignant subcentimeter liver lesions with 92% to 93% accuracy [84].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. There is no relevant literature that has assessed the performance of MRI without IV contrast specifically for this clinical scenario. Therefore, the committee recommendations on the use of MRI without IV contrast are based primarily on expert opinion. In some cases, MRI without IV contrast may be appropriate as it can differentiate between small cysts and solid lesions.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-Guided Biopsy Liver Tissue sampling may be necessary to establish the definitive diagnosis in patients with a history of primary malignancy and indeterminate subcentimeter liver lesions. However, the role of percutaneous biopsy is limited in the evaluation of subcentimeter liver lesions because such lesions are typically difficult to target under image guidance. Furthermore, there is no relevant literature to assess performance of percutaneous biopsy techniques for subcentimeter liver lesions.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario.


Liver Lesion Initial Characterization


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. US Abdomen with Contrast Compared with a baseline grayscale US, CEUS can detect 6.5 times more subcentimeter metastases [9]. For indeterminate liver lesions discovered on grayscale US, CEUS reached a specific diagnosis in 83% of cases and distinguished benign versus malignant in 90% of cases [30]. For the benign diagnoses, CEUS correctly characterized 89% of areas of focal fat, 90% of hemangiomas, 87% of complex cysts, 78% of hepatic adenomas, 90% of FNHs, 86% of abscesses, and 60% of hematomas [30]. CEUS correctly characterized 86% of metastases [30].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Variant 7: Indeterminate, less than 1 cm liver lesion on initial imaging with CT (noncontrast or single-phase) or noncontrast MRI. Known history of an extrahepatic malignancy. CT Abdomen Subcentimeter liver lesions in patients with primary malignancy are seen on contrast-enhanced CT in 13% of patients, and of these, 12% are metastases [82]. Among patients with a history of colorectal and breast cancers, small hepatic lesions were metastatic in 14% and 22% of cases, respectively [82]. Subcentimeter liver lesions in women with breast cancer can be found in 29%, and if no obvious liver metastases are present, 93% to 97% of these subcentimeter liver lesions are benign [85].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. FDG-PET/CT Skull Base to Mid-Thigh In patients with a history of primary malignancy, FDG-PET/CT may be indicated to evaluate for the presence of metastases beyond the liver. There is no relevant literature to support the use of FDG-PET/CT specifically to characterize subcentimeter liver lesions due to its limited sensitivity for lesions <1 cm.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen In patients with a history of primary NET, In-111 somatostatin receptor scan with SPECT or SPECT/CT can detect liver metastases; however, there is no relevant literature on assessment of subcentimeter liver lesions.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. MRI Abdomen For subcentimeter liver lesions detected on CT, the sensitivity, specificity, PPV, and NPV for differentiation of benign from malignant lesions for contrast-enhanced MRI are 83%, 98%, 92%, and 94%, respectively [86]. In patients with a history of colon cancer, MRI has a sensitivity of 60% for detection of subcentimeter metastases [87].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. There is no relevant literature that has assessed the performance of MRI without IV contrast specifically for this clinical scenario. Therefore, the committee recommendations on the use of MRI without IV contrast are based primarily on expert opinion.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-Guided Biopsy Liver Tissue sampling may be necessary to establish the definitive diagnosis in patients with a history of primary malignancy and indeterminate subcentimeter liver lesions. However, the role of percutaneous biopsy is limited in the evaluation of subcentimeter liver lesions because such lesions are typically difficult to target under image guidance. Furthermore, published data are not available to assess performance of percutaneous biopsy techniques for subcentimeter liver lesions.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization US Abdomen In patients with a history of primary malignancy and indeterminate, subcentimeter focal liver lesions on CT, grayscale US is able to prove cystic nature of the lesion in 67% of cases [88].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. US Abdomen with Contrast In patients with a history of primary malignancy and indeterminate, subcentimeter focal liver lesions on CT that were proven to be noncystic on grayscale US, CEUS correctly characterizes 95% of lesions overall, and 98% of metastases [88]. Compared with a baseline dual-phase contrast-enhanced CT, CEUS can detect 6.5 times more subcentimeter metastases [9].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. CT of the abdomen with and without IV contrast is not recommended for this clinical scenario because there is no added value for unenhanced images.