Neuroendocrine Imaging

Neuroendocrine Imaging. MRI Sella MRI using high-resolution pituitary protocols is generally considered the gold standard for imaging the pituitary gland in cases of suspected hormone-secreting adenoma [15]. MRI can directly visualize the pituitary gland on noncontrast sequences. The addition of IV contrast increases the conspicuity of small adenomas, which are typically seen as hypoenhancing lesions [13,74,75]. MRI with IV contrast may only be performed for use in operative guidance, and should not be considered a first-line imaging test. MRI has been used to characterize tissue consistency [76] and has been used to predict response to therapy in cases of acromegaly [77]. Dynamic contrast-enhanced imaging of the pituitary is advocated by some authors for detection of microadenoma [78-80]. Additionally, recent studies have noted an increased sensitivity for spoiled gradient-echo 3-D T1 sequence in the detection of hormone-secreting adenomas [81]. Hormone-secreting pituitary tumors are more commonly microadenomas (<10 mm), highlighting the need for high-resolution, focused field-of-view, and thin-section imaging. MRI may further characterize hemorrhage within adenomas as areas of decreased signal intensity on T2- weighted images [41,60].


Neuroendocrine Imaging

Neuroendocrine Imaging. Venous Sampling Petrosal Sinus Petrosal sinus venous sampling is an invasive study reserved for cases in which a definite excess of pituitary hormone is present, medical management has failed, cross-sectional imaging is negative or equivocal, and surgery is planned [67]. When a significant discrepancy in hormone level, usually adrenal corticotrophic hormone, exists between the petrosal sinus and peripheral blood samples, tumor localization is very accurate [66,68].


Neuroendocrine Imaging

Neuroendocrine Imaging. Radiography Sella There is no relevant literature regarding the use of radiography in the initial evaluation of known or suspected hyperfunctioning pituitary adenoma.


Neuroendocrine Imaging

Neuroendocrine Imaging. Variant 3: Adult. Diabetes insipidus. Initial imaging. Central causes of diabetes insipidus may be associated with abnormalities affecting the pituitary stalk and the hypothalamic-pituitary axis. Mass effect or neoplastic invasion may be present because of germ-line tumors, lymphoma, leukemia, Langerhans cell histiocytosis, metastasis, craniopharyngioma, meningioma, and Rathke cleft cyst, among others [2,15-17]. Inflammatory processes (ie, sarcoid, lymphocytic hypophysitis, granulomatous infiltration) occur in the sellar and suprasellar regions as well. Additionally, an empty sella may be seen with


Neuroendocrine Imaging

Neuroendocrine Imaging

Neuroendocrine Imaging. Neuroendocrine Imaging


Neuroendocrine Imaging

Neuroendocrine Imaging. herniation of the subarachnoid space into the sella turcica; this is usually an incidental finding, close to 30% of patients may demonstrate some hypopituitarism upon testing [19].


Neuroendocrine Imaging

Neuroendocrine Imaging. CT Sella CT can detect solid lesions of the suprasellar cistern and may detect infiltrative lesions of the pituitary stalk but also may miss cystic tumors. Multiplanar reconstructions with thin sections and soft-tissue window settings are crucial to visualize the suprasellar cistern and pituitary stalk. CT with IV contrast helps to visualize the enhancing pituitary stalk and infiltrative lesions of the stalk, though MRI is considered the best first-line study. Dual-phase imaging with and without IV contrast is not indicated as an initial imaging study.


Neuroendocrine Imaging

Neuroendocrine Imaging. CTA Head CTA may be part of operative planning or image guidance; however, CTA is not routinely used for initial evaluation of diabetes insipidus [20].


Neuroendocrine Imaging

Neuroendocrine Imaging. MRA Head There is no relevant literature regarding the use of MRA in the evaluation of diabetes insipidus.


Neuroendocrine Imaging

Neuroendocrine Imaging. MRI Sella MRI with and without IV contrast using high-resolution pituitary or skull base protocols is preferred in the workup of suspected central diabetes insipidus and in the detection of abnormalities of the hypothalamic- neurohypophyseal axis, which may lead to failure of normal antidiuretic hormone release and transport. Thin- section T1-weighted images are used to directly identify typical T1 signal hyperintensity of normal neurosecretory granules; such a signal may be absent from the sella when an ectopic posterior pituitary gland is present or in long-standing diabetes insipidus. Traumatic etiologies, such as stalk transection or postoperative sella, can be characterized using thin-section T2-weighted images. MRI with and without IV contrast is especially useful for the detection and characterization of inflammatory lesions of the stalk and neoplastic invasion [23,82]. MRI with IV contrast may only be performed for use in operative guidance and should not be considered a first- line imaging test.


Neuroendocrine Imaging

Neuroendocrine Imaging. Venous Sampling Petrosal Sinus There is no relevant literature regarding the use of venous sampling in the evaluation of diabetes insipidus.


Neuroendocrine Imaging

Neuroendocrine Imaging. Radiography Sella There is no relevant literature regarding the use of radiography in the evaluation of diabetes insipidus.


Neuroendocrine Imaging

Neuroendocrine Imaging. CT Sella CT may provide useful information in the clinical setting of sudden onset of pituitary dysfunction by identifying a pituitary or suprasellar mass but is less sensitive than MRI for the detection of acute pituitary hemorrhage [16]. MRI is considered the optimal first-line test. Calcification seen on CT may help to clarify complicated cases of craniopharyngioma, which can occasionally be confused with hemorrhagic pituitary adenoma on MRI. While the use of IV contrast may help distinguish hemorrhage from enhancement, dual-phase imaging with and without IV contrast is not indicated as an initial imaging study. As pituitary apoplexy may clinically present with sudden headache and oculomotor palsies; CT may be considered as part of the initial diagnostic evaluation to exclude intracranial hemorrhage or mass lesion, particularly when rapid diagnosis is needed, such as in an emergency department setting.


Neuroendocrine Imaging

Neuroendocrine Imaging. CTA Head CTA may be part of operative planning or image guidance; however, CTA is not routinely used for initial evaluation of pituitary apoplexy [20].


Neuroendocrine Imaging

Neuroendocrine Imaging. MRA Head There is no relevant literature regarding the use of MRA in the evaluation of pituitary apoplexy.


Neuroendocrine Imaging

Neuroendocrine Imaging


Neuroendocrine Imaging

Neuroendocrine Imaging. MRI Sella MRI using high-resolution pituitary protocols is the primary modality for the evaluation of suspected pituitary apoplexy [83]. Tumor enlargement, sellar expansion, and intratumoral hemorrhage are well demonstrated on MRI. Noncontrast imaging is sensitive to the detection of hemorrhage and may show T1 signal hyperintensity, low T2 signal, or a hemorrhage fluid level within the pituitary gland [84]. Not all cases of intrapituitary hemorrhage (ie, subacute/necrotic adenoma) are associated with symptomatic pituitary apoplexy; however, caution is needed in interpreting pituitary hemorrhage in the context of clinical symptoms [85]. While pituitary apoplexy is most commonly caused by hemorrhage into an existing pituitary macroadenoma, other soft-tissue masses may have overlapping imaging features. For example, craniopharyngioma or Rathke cleft cysts can have intrinsic T1-signal hyperintensity that is due to proteinaceous content, and a dermoid or teratoma may show high T1 signal because of fat. Inclusion of T1 fat saturation sequences may aid in differentiation of fat from blood products. Ischemic pituitary apoplexy can be detected on contrast-enhanced MRI in the appropriate clinical context by central nonenhancement of the enlarged pituitary, indicating central tumoral necrosis or ischemia. MRI with IV contrast may only be performed for use in operative guidance and should not be considered a first-line imaging test.


Neuroendocrine Imaging

Neuroendocrine Imaging. Venous Sampling Petrosal Sinus There is no relevant literature regarding the use of venous sampling in the evaluation of pituitary apoplexy.


Neuroendocrine Imaging

Neuroendocrine Imaging. Radiography Sella There is no relevant literature regarding the use of radiography in the evaluation of pituitary apoplexy.


Neuroendocrine Imaging

Neuroendocrine Imaging. Variant 5: Adult. Surveillance postpituitary or sellar mass resection. Delayed surveillance is performed in patients with known subtotal pituitary adenoma resection [86], nonfunctioning pituitary adenomas [87], and postresection of sellar/suprasellar nonadenoma masses guided by tumor pathology and patient symptoms. In the immediate postoperative setting, local complications may be difficult to discern from normal postoperative changes [88,89]. There is variable literature regarding the frequency and duration of routine follow-up for nonfunctioning tumors [90,91]; however, postoperative imaging is often performed >3 months following trans-sphenoidal surgery [88].


Neuroendocrine Imaging

Neuroendocrine Imaging. CT Sella Assessment for tumor growth or suprasellar extension can be performed using CT, although MRI is generally considered superior. Invasion of the skull base by pituitary tumor is an uncommon but important complication that is best characterized preoperatively with CT [95]. CT with IV contrast is not typically needed in the postoperative setting, unless specifically focused on adjacent structures such as the cavernous sinuses. Dual-phase imaging with and without IV contrast is not indicated as an initial imaging study.


Neuroendocrine Imaging

Neuroendocrine Imaging. CTA Head Routine vascular imaging following pituitary surgery is generally not indicated unless there is known or clinical suspicion for a vascular complication.


Neuroendocrine Imaging

Neuroendocrine Imaging. MRA Head Routine vascular imaging following pituitary surgery is generally not indicated unless there is known or clinical suspicion for a vascular complication.


Neuroendocrine Imaging

Neuroendocrine Imaging. MRI Sella MRI using high-resolution pituitary protocols is the most useful tool for diagnostic assessment following pituitary surgery. MRI with and without IV contrast adds additional information when new tumor is suspected in the setting of gross total tumor resection [86], surveillance of smaller known masses [64], and hormone-secreting microadenomas when there is an unexpected hormonal response to medical therapy. In patients with known tumors and normal hormone levels on dopamine agonist therapy, MRI follow-up may be unnecessary [96]. Inclusion of diffusion-weighted imaging may be considered as a tool to differentiate granulation tissue postoperative from residual or recurrent adenoma [97]. Surveillance after resection of nonadenoma sellar/suprasellar masses should be based on the tumor pathology and patient symptoms, generally requiring MRI without and with IV contrast. High-resolution pituitary protocols generally suffice for the assessment of


Neuroendocrine Imaging

Neuroendocrine Imaging

Neuroendocrine Imaging. Neuroendocrine Imaging


Neuroendocrine Imaging

Neuroendocrine Imaging. cavernous sinus involvement or complication. MRI with IV contrast may only be performed for use in operative guidance and should not be considered for routine surveillance.


Neuroendocrine Imaging

Neuroendocrine Imaging. Venous Sampling Petrosal Sinus There is no relevant literature regarding the use of venous sampling in the evaluation of the postoperative sella.


Neuroendocrine Imaging

Neuroendocrine Imaging. Radiography Sella There is no relevant literature regarding the use of radiography in the evaluation of the postoperative sella.


Neuroendocrine Imaging

Neuroendocrine Imaging. Variant 6: Child, males younger than 9 years of age; females younger than 8 years of age. Precocious puberty. Initial imaging. Central causes of precocious puberty are often idiopathic; however, this may be related to intracranial neoplasms, trauma, infection, hydrocephalus, and some syndromes with premature gonadotropin-releasing hormone production that is due to infiltration or extrinsic mass effect [98-103].


Neuroendocrine Imaging

Neuroendocrine Imaging. The appropriateness of imaging in the setting of precocious puberty is debated. Imaging should always follow hormonal studies that suggest a central origin of precocious puberty [104,105]. The age of the child at symptom onset is important, where girls <6 and boys younger <9 are most likely to show a central nervous system abnormality and therefore should be screened with MRI [104,106-108]. For girls 6 to 8 years of age, the likelihood of identifying a central nervous system lesion is lower, estimated between 2% to 7%, and neoplastic in 1% [104,109]. The need for routine central nervous system imaging is controversial and requires careful clinical consideration [107,110].


Neuroendocrine Imaging

Neuroendocrine Imaging. CT Sella CT provides the ability to evaluate the overall size and structure of the sella turcica but offers little in the way of intrasellar and parasellar soft-tissue detail. Larger lesions in the suprasellar cistern can be identified (ie, germinoma, astrocytoma, arachnoid cyst), as well as gross morphological alterations in the configuration and appearance of the ventricles, such as in the setting of hydrocephalus [111]. CT with IV contrast may highlight a solid mass but is rarely indicated as an initial screening examination.


Neuroendocrine Imaging

Neuroendocrine Imaging. CTA Head CTA may be part of operative planning or image guidance; however, CTA is not routinely used for initial evaluation of precocious puberty [20].


Neuroendocrine Imaging

Neuroendocrine Imaging. MRA Head There is no relevant literature regarding the use of MRA in the evaluation of precocious puberty.


Neuroendocrine Imaging

Neuroendocrine Imaging. MRI Sella MRI is the preferred imaging modality to evaluate the hypothalamic-pituitary axis and parasellar regions with its superior depiction of parenchymal tissue [105,112]. Gadolinium-based contrast adds additional benefit in characterizing lesions. Small pituitary lesions, such as adenomas and Rathke cleft cysts, may be occult without postcontrast sequences. Contrast-enhanced MRI also discriminates between nonenhancing hypothalamic hamartoma and an enhancing astrocytoma. MRI with IV contrast may only be performed for use in operative guidance and should not be considered as a first-line imaging test. MRI is able to detect more subtle mass lesions and directly evaluate pituitary morphology, as well as mass effect, upon the hypothalamus. MRI is appropriate, irrespective of age and gender, in patients with precocious puberty and concurrent central nervous system symptoms, such as severe headaches, visual changes, or seizures [107].


Neuroendocrine Imaging

Neuroendocrine Imaging. Congenital abnormalities with imaging manifestations, such as septo-optic dysplasia, are better seen on MRI, although [113] these generally manifest symptomatically earlier in childhood and contrast is generally not needed in these circumstances.


Neuroendocrine Imaging

Neuroendocrine Imaging. Venous Sampling Petrosal Sinus There is no relevant literature regarding the use of venous sampling in the evaluation of precocious puberty.


Neuroendocrine Imaging

Neuroendocrine Imaging. Radiography Sella There is no relevant literature regarding the use of radiography in the evaluation of precocious puberty.


Neuroendocrine Imaging

Neuroendocrine Imaging. 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.


Neuroendocrine Imaging

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


Neuroendocrine Imaging

Neuroendocrine Imaging


Parathyroid Adenoma

Parathyroid Adenoma. Persistent PHPT is defined as failure to achieve normocalcemia within 6 months of initial parathyroidectomy, whereas recurrent PHPT is defined as hypercalcemia occurring after a normocalcemic interval of 6 months or more after parathyroidectomy [2,10]. Parathyroid reoperations are surgically challenging, with lower cure rates than first-


Parathyroid Adenoma

Parathyroid Adenoma. Reprint requests to: publications@acr.org


Parathyroid Adenoma

Parathyroid Adenoma. Parathyroid Adenoma time surgery and higher complication rates. As such, recent international guidelines state that preoperative imaging is essential in the reoperative setting to localize a target parathyroid lesion (or lesions) and to identify postoperative changes from previous parathyroid explorations that can impact a subsequent surgery [10].


Parathyroid Adenoma

Parathyroid Adenoma. Secondary hyperparathyroidism (SHPT) is a failure of calcium homeostasis whereby increased PTH production in response to hypocalcemia (and/or hyperphosphatemia) is unable to correct plasma calcium because of organ failure or reduced calcium availability. This is most commonly due to chronic kidney disease but can also be a result of malabsorption or vitamin D deficiency, among other causes [11]. Rarely, tertiary hyperparathyroidism (THPT) can occur in patients with longstanding SHPT and is characterized by a lack of PTH suppression despite rising serum calcium levels, manifesting as hypercalcemic hyperparathyroidism. This is most commonly encountered following kidney transplantation in patients with longstanding chronic kidney disease [11]. Surgical excision is recommended for medically refractory cases of SHPT and THPT. As these are typically disorders of MGD (ie, parathyroid hyperplasia), the goal of imaging is to identify all eutopic and potential ectopic or supernumerary glands in an attempt to guide the surgical approach [10,12-14].


Parathyroid Adenoma

Parathyroid Adenoma. Discussion of Procedures by Variant Variant 1: Adult or child. Primary hyperparathyroidism. Initial imaging. All patients undergoing imaging in the setting of PHPT should have biochemically proven disease, as imaging has no role in confirming or excluding the diagnosis [2]. As such, assessing the imaging test specificity and negative predictive value is not clinically relevant. Rather, the role of initial imaging in PHPT is to aid in selecting appropriate patients for MIP by accurately identifying and localizing a single parathyroid adenoma; accordingly, these criteria focus on imaging test sensitivity and PPV. Patients with negative or inconclusive imaging results typically remain surgical candidates but will likely require BNE; inconclusive findings on imaging should not preclude surgical referral [2].


Parathyroid Adenoma

Parathyroid Adenoma

Parathyroid Adenoma. Parathyroid Adenoma


Parathyroid Adenoma

Parathyroid Adenoma. Multiple imaging modalities may be utilized in combination during the initial imaging evaluation of PHPT in an attempt to maximize the accuracy and confidence of parathyroid localization via concordant imaging results [2,8,15]. This is supported by multiple studies in the literature showing improved sensitivity and PPV in parathyroid lesion localization with a combination of examinations over each examination in isolation [16-23,25].


Parathyroid Adenoma

Parathyroid Adenoma. CT Neck Neck CT for preoperative localization of PHPT is most commonly performed without and with IV contrast (4-D parathyroid CT) [34]. As such, most published data relate to the performance of CT neck without and with IV contrast; however, there are also some data on the performance of CT neck with IV contrast. There is no relevant literature regarding the use of CT neck without IV contrast in the evaluation of PHPT.


Parathyroid Adenoma

Parathyroid Adenoma. As the initial imaging study, retrospective studies report the overall sensitivity of CT neck without and with IV contrast to range between 62% and 88% [35,36] and the overall PPV to range between 84% and 90% [32,37]. The largest retrospective study (400 patients) reports an overall sensitivity of 79% and PPV of 90% [32]. For single- gland disease, reported sensitivities and PPVs range from 92% to 94% [30,38] and 88% to 92% [38,39], respectively. For MGD, reported sensitivities and PPVs range from 43% to 67% [39,40] and 89% to 100%, respectively [32,39].


Parathyroid Adenoma

Parathyroid Adenoma. A data-driven rationale for the noncontrast CT phase has been provided (eg, differentiation of parathyroid from thyroid tissue): 22% of parathyroid lesions have an enhancement pattern similar to thyroid on arterial and venous phases and therefore may be missed if the noncontrast phase were excluded [30]. However, a few retrospective reports suggest that eliminating the noncontrast CT phase may not adversely affect test performance [41-43]. The largest retrospective study (278 patients) of CT neck with IV contrast (without the noncontrast phase) reports sensitivity of 55% and PPV of 57% among patients with single-gland disease, and sensitivity of 23% and PPV of 19% among patients with MGD [44].


Parathyroid Adenoma

Parathyroid Adenoma. Several studies have directly compared the performance of neck CT without and with IV contrast to ultrasound (US) and to nuclear medicine scans within the same patient population. Most of these studies found the performance of neck CT without and with IV contrast to be superior [29,31,38,40]; however, a prospective study of 91 patients found neck CT without and with IV contrast (58% sensitivity, 88% PPV) to be inferior to dual isotope (sestamibi and I-123) pinhole subtraction scintigraphy (93% sensitivity, 98% PPV) [45].


Parathyroid Adenoma

Parathyroid Adenoma. MRI Neck MRI neck is an emerging technique for PHPT preoperative localization and may be performed without IV contrast, with IV contrast, or without and with IV contrast. Most studies evaluating the performance of MRI neck for preoperative localization in the setting of PHPT are retrospective and include fewer than 50 patients.


Parathyroid Adenoma

Parathyroid Adenoma. As the initial imaging study, the sensitivity of MRI neck without and with IV contrast performed at 1.5T has been reported to be between 64% and 79% [46-48]. In 2 prospective studies performed at 3.0T, the sensitivity of MRI neck without and with IV contrast ranged between 64% and 98%, and the PPV ranged between 67% and 95% [49,50]. A third prospective study of MRI without and with IV contrast performed at 3.0T reported accurate localization of parathyroid adenomas in 92% (34/37) of patients with single-gland disease and 74% (35/47) of patients with MGD [51]. For MRI without IV contrast, the reported sensitivity was 67% at 1.5T [52]. There is no relevant literature regarding the use of 3.0T MRI without IV contrast in the initial imaging evaluation of PHPT.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Dual-Phase Scan Neck Dual-phase Tc-99m sestamibi planar parathyroid scintigraphy is an accepted and traditionally widely utilized method for parathyroid adenoma localization in PHPT. The sensitivity of this method (typically reported as localization to the correct quadrant or to an ectopic location) varies widely in the literature, ranging from 41% to 96% [45,52-63]. A larger retrospective study of 180 patients reported a sensitivity of 79% [58]. A systematic review of 11 studies reported a pooled sensitivity of 76% [17]. Some variability in these results may arise from varied technical parameters of these scans (eg, timing of early and delayed scans, use of pinhole versus parallel collimators, addition of oblique acquisitions, etc).


Parathyroid Adenoma

Parathyroid Adenoma. There is no clear consensus regarding the superiority between sestamibi dual-phase and dual-tracer subtraction planar imaging. One recent study of 63 patients showed greater sensitivity with dual-phase sestamibi (79%) over both dual-tracer (sestamibi and pertechnetate) (69%) and a combined dual-tracer/dual-phase technique (65%) [59]. However, other studies report similar or improved sensitivity of dual-tracer methods (either pertechnetate or I-123, plus sestamibi) over dual-phase sestamibi when utilizing a planar technique [45,54,64,65]. There is a growing


Parathyroid Adenoma

Parathyroid Adenoma


Parathyroid Adenoma

Parathyroid Adenoma. consensus that the addition of single-photon emission CT (SPECT) without or with a coregistered CT (SPECT/CT) improves localization of parathyroid adenomas over a planar dual-phase sestamibi method [59,61,62].


Parathyroid Adenoma

Parathyroid Adenoma. The sensitivity of sestamibi imaging is decreased in the setting of MGD [55,58], concomitant nodular thyroid disease [56,66], small adenomas [53], and mild hypercalcemia [58].


Parathyroid Adenoma

Parathyroid Adenoma. Literature regarding the pediatric population is limited. A retrospective review of 29 patients reported that sestamibi was useful only in older children with a single adenoma in the setting of sporadic PHPT, and added minimal additional information compared with US, with otherwise no utility for sestamibi in neonates or familial PHPT [67].


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Dual-Phase Scan with SPECT or SPECT/CT Neck The addition of SPECT or SPECT/CT to a dual-phase sestamibi scan is more commonly utilized than planar imaging alone. Although there are a number of variations in the timing of the SPECT or SPECT/CT acquisition (ie, early, delayed, or both), it is generally accepted that the improved contrast resolution of SPECT or SPECT/CT over planar imaging provides more precise anatomic localization of parathyroid adenomas [68,69].


Parathyroid Adenoma

Parathyroid Adenoma. The sensitivity of dual-phase sestamibi with SPECT or SPECT/CT is decreased by MGD, uptake masked by retained radionuclide in adjacent thyroid or submandibular gland tissue, and smaller size of the adenoma (within these subsets, sensitivity ranges from 24% to 66%) [71-73].


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and I-123 Thyroid Scan Subtraction scintigraphy of parathyroid glands using a combination of sestamibi and I-123 sodium iodide is a commonly utilized alternative or adjunct to the dual-phase sestamibi technique. The 2009 European Association of Nuclear Medicine parathyroid guidelines expressed a preference for the dual-tracer sestamibi and I-123 technique, citing improved sensitivity for MGD and improved likelihood of distinguishing sestamibi-avid thyroid nodules from parathyroid lesions [15]. A major technical advantage of using I-123 for a subtraction technique is that thyroid and parathyroid images can be acquired simultaneously in a dual-energy window.


Parathyroid Adenoma

Parathyroid Adenoma. Reported sensitivity for dual-tracer sestamibi and I-123 subtraction scintigraphy ranges from 75% to 94% [54,74- 76], including a retrospective review of 2,681 patients revealing a sensitivity of 87% and PPV of 92% [77]. The latter study showed that negative or inconclusive results had a higher association with MGD and lower serum calcium levels.


Parathyroid Adenoma

Parathyroid Adenoma. There is no clear consensus regarding the superiority between dual-tracer subtraction and sestamibi dual-phase planar imaging. One recent study of 63 patients showed greater sensitivity with dual-phase sestamibi (79%) over both dual-tracer (sestamibi and pertechnetate) (69%) and a combined dual-tracer/dual-phase (65%) technique [59]. However, other studies report similar or improved sensitivity of dual-tracer methods (either pertechnetate or I-123, plus sestamibi) over dual-phase sestamibi when utilizing a planar technique [45,54,64,65].


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and I-123 Thyroid Scan with SPECT or SPECT/CT Neck Although there are a number of variations in the timing of the SPECT or SPECT/CT acquisition (ie, early, delayed, or both), it is generally accepted that the improved contrast resolution of SPECT or SPECT/CT over planar imaging provides more precise anatomic localization of parathyroid adenomas [68,69]. However, there are conflicting data in the literature as to what extent the addition of SPECT or SPECT/CT changes the sensitivity of the examination. For example, Bhatt et al [74] evaluated a pinhole protocol, SPECT/CT alone, and a combination of


Parathyroid Adenoma

Parathyroid Adenoma

Parathyroid Adenoma. Parathyroid Adenoma


Parathyroid Adenoma

Parathyroid Adenoma. pinhole/SPECT/CT, revealing sensitivities of 88%, 69%, and 81%, respectively. Other studies have shown superior performance of the combined sestamibi/I-123 plus SPECT/CT protocol with sensitivities ranging from 86% to 95% and PPV from 86% to 100% [45,75,78,79].


Parathyroid Adenoma

Parathyroid Adenoma. The sensitivity and PPV of a sestamibi/I-123 subtraction technique are least negatively impacted by concomitant thyroid disease when SPECT/CT is included in the protocol [75].


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and Pertechnetate Thyroid Scan Subtraction scintigraphy of parathyroid glands using a combination of sestamibi and Tc-99m pertechnetate is a commonly utilized alternative or adjunct to the dual-phase sestamibi technique. Unlike the dual-tracer method with I-123, the pertechnetate method requires 2 separate acquisitions, which prolongs the overall examination time. Although techniques based solely on planar imaging have largely been supplanted by methods with SPECT or SPECT/CT, there are some noteworthy applications of a planar sestamibi and pertechnetate subtraction in recent literature with reported sensitivities ranging from 69% to 79% [59,80]. A meta-analysis including 5 studies utilizing a dual-tracer technique reported sensitivities ranging from 47% to 87%; however, it is unclear which studies relied purely on a subtracted dual-tracer (sestamibi and pertechnetate) planar method and which were performed in combination with a dual-phase sestamibi scan [17]. In a study of 116 patients with PHPT, the addition of pertechnetate subtraction to a dual-phase sestamibi scan increased reader confidence in adenoma localization and changed the final interpretation in 15% of patients from the dual-phase study [81].


Parathyroid Adenoma

Parathyroid Adenoma. MGD decreases the sensitivity of the subtraction sestamibi and pertechnetate scan from 71% to 64% [82].


Parathyroid Adenoma

Parathyroid Adenoma. There is no clear consensus regarding the superiority between dual-tracer subtraction and sestamibi dual-phase planar imaging. One recent study of 63 patients showed greater sensitivity with dual-phase sestamibi (79%) over both dual-tracer (sestamibi and pertechnetate) (69%) and a combined dual-tracer/dual-phase technique (65%) [59]. However, other studies report similar or improved sensitivity of dual-tracer methods (either pertechnetate or I-123, plus sestamibi) over dual-phase sestamibi when utilizing a planar technique [45,54,64,65].


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and Pertechnetate Thyroid Scan with SPECT or SPECT/CT Neck Although there are a number of variations in the timing of the SPECT or SPECT/CT acquisition (ie, early, delayed, or both), it is generally accepted that the greater contrast resolution of SPECT or SPECT/CT over planar imaging provides more precise anatomic localization of parathyroid adenomas [68,69]. The addition of a pertechnetate thyroid scan may further improve localization: in a study of 268 patients, planar pertechnetate subtraction in combination with a dual-phase sestamibi scan with SPECT/CT outperformed the dual-phase sestamibi SPECT/CT alone, increasing sensitivity to 93% and PPV to 96% compared with 88% and 92%, respectively [83].


Parathyroid Adenoma

Parathyroid Adenoma. In patients with concomitant thyroid disease, the addition of CT to a dual-tracer sestamibi and pertechnetate SPECT scan increases sensitivity from 80% to 94% [84].


Parathyroid Adenoma

Parathyroid Adenoma. US Parathyroid US of the parathyroid glands is widely utilized as the initial imaging study in PHPT. Both the American Head and Neck Society Endocrine Surgery Section and the American Association of Endocrine Surgeons deem US to be the preferred initial localization study in patients with PHPT, noting the advantage of concomitant thyroid evaluation [2,8]. A 2012 meta-analysis of 19 studies evaluating US in patients with PHPT revealed a pooled sensitivity of 76% and PPV of 93% [70]. A subsequent 2017 meta-analysis of 12 studies (with few studies also included from the 2012 meta-analysis) revealed a pooled sensitivity of 80% [85]. However, the range of sensitivities reported in the literature varies widely. For example, a study of 604 patients comparing US, scintigraphy, and 4-D CT reported a sensitivity of 59% for US [31], with other smaller studies reporting US sensitivities ranging from 44% to 97% [18,20,58,86-90].


Parathyroid Adenoma

Parathyroid Adenoma. Nonlocalizable adenomas by US are most often due to ectopic or far posterior location, MGD, small adenoma size, and concomitant thyroid disease [58,86,91].


Parathyroid Adenoma

Parathyroid Adenoma. The literature in the pediatric population is limited. In a retrospective review of 29 patients, Alagaratnam et al [67] reported that US in 2 neonates resulted in false-negatives; sensitivity improved in older children to 93%. In a separate study of 16 children, sensitivity of US was 60% [7].


Parathyroid Adenoma

Parathyroid Adenoma. Venous Sampling Parathyroid Parathyroid glands tend to drain ipsilaterally and inferiorly relative to their anatomic location. As such, sampling of PTH levels during selective transvenous catheterization of multiple neck and mediastinal veins can be used to


Parathyroid Adenoma

Parathyroid Adenoma


Parathyroid Adenoma

Parathyroid Adenoma. Variant 2: Adult or child. Primary hyperparathyroidism, recurrent or persistent after parathyroid surgery. Initial imaging. All patients undergoing imaging in the setting of recurrent or persistent PHPT should have biochemically proven disease, as imaging has no role in confirming or excluding the diagnosis [2,10]. As such, assessing the imaging test specificity and negative predictive value is not clinically relevant. Rather, the role of initial imaging in recurrent or persistent PHPT is to accurately identify and localize a parathyroid lesion (or lesions) and identify postoperative changes from previous parathyroid explorations which can impact a subsequent surgery. Accordingly, these criteria focus on imaging test sensitivity and PPV.


Parathyroid Adenoma

Parathyroid Adenoma. Multiple imaging modalities may be utilized in combination during the initial imaging evaluation of recurrent or persistent PHPT after prior surgery in an attempt to maximize the accuracy and confidence of parathyroid localization via concordant imaging results [10,15].


Parathyroid Adenoma

Parathyroid Adenoma. CT Neck Neck CT in the evaluation of recurrent or persistent PHPT after prior surgery is most commonly performed without and with IV contrast (4-D parathyroid CT) [34], which is reflected in the published data regarding the performance of neck CT for parathyroid localization in the setting of prior failed surgery. There is no literature regarding the use of CT neck with IV contrast specifically limited to patients with recurrent or persistent PHPT. Additionally, there is no relevant literature regarding the use of CT neck without IV contrast in the evaluation of PHPT.


Parathyroid Adenoma

Parathyroid Adenoma. In the setting of recurrent or persistent PHPT, retrospective studies report the sensitivity of CT neck without and with IV contrast to range between 50% and 91% and the PPV to range between 69% and 100% [29,36,40,97].


Parathyroid Adenoma

Parathyroid Adenoma. There is no relevant literature regarding the use of MRI without IV contrast in the evaluation of recurrent or persistent PHPT.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Dual-Phase Scan Neck There is no relevant literature regarding the use of planar sestamibi dual-phase scans in the evaluation of recurrent or persistent PHPT after prior surgery.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Dual-Phase Scan with SPECT or SPECT/CT Neck There are limited data regarding the use of sestamibi dual-phase scans with SPECT or SPECT/CT in the setting of prior surgery:


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and I-123 Thyroid Scan There is no relevant literature regarding the use of planar sestamibi and I-123 scans in the evaluation of recurrent or persistent PHPT after prior surgery.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and Pertechnetate Thyroid Scan There is no relevant literature regarding the use of planar sestamibi and pertechnetate scans in the evaluation of recurrent or persistent PHPT after prior surgery.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and Pertechnetate Thyroid Scan with SPECT or SPECT/CT Neck There is no relevant literature regarding the use of sestamibi and pertechnetate scans with SPECT or SPECT/CT in the evaluation of recurrent or persistent PHPT after prior surgery.


Parathyroid Adenoma

Parathyroid Adenoma. Venous Sampling Parathyroid Parathyroid glands tend to drain ipsilaterally and inferiorly relative to their anatomic location. As such, sampling of PTH levels during selective transvenous catheterization of multiple neck and mediastinal veins can be used to infer the laterality and regional location of parathyroid lesions [8,92,93]. Because of its invasive technique, selective parathyroid venous sampling is typically reserved for reoperative surgical candidates with recurrent or persistent PHPT after noninvasive examinations (eg, US, sestamibi, CT, etc) yield nonlocalizing, equivocal, or discordant results [96,102].


Parathyroid Adenoma

Parathyroid Adenoma. Although parathyroid venous sampling has been in use since the 1990s [102], there are few pertinent studies within the last 10 years, and nearly all evaluate patients who have had prior nonlocalizing examinations, as this is the


Parathyroid Adenoma

Parathyroid Adenoma

Parathyroid Adenoma. Parathyroid Adenoma


Parathyroid Adenoma

Parathyroid Adenoma. subset of patients for whom this examination is typically reserved. These studies are retrospective and each evaluated fewer than 40 patients, reporting sensitivities ranging from 40% to 93% [92,93,97,103-105].


Parathyroid Adenoma

Parathyroid Adenoma. There is a potential for false regionalization and/or lateralization of parathyroid lesions due to congenitally variant venous anatomy or alteration of regional venous drainage secondary to previous surgical interventions [93]. As with many invasive vascular procedures, venous sampling is potentially associated with serious but uncommon complications [10].


Parathyroid Adenoma

Parathyroid Adenoma. Variant 3: Adult or child. Secondary hyperparathyroidism. Initial imaging. All patients undergoing imaging in the setting of SHPT should have biochemically proven disease, as imaging has no role in confirming or excluding the diagnosis [11]. As such, assessing the imaging test specificity and negative predictive value is not clinically relevant. Rather, as SHPT is typically a disorder of MGD and is therefore treated with BNE, the role of initial imaging is to accurately identify all eutopic and potential ectopic or supernumerary glands in an attempt to decrease surgical failure rates [12-14]; accordingly, these criteria focus on imaging test sensitivity and PPV.


Parathyroid Adenoma

Parathyroid Adenoma. It is possible that multiple imaging modalities may be utilized in combination during the initial imaging evaluation of SHPT in an attempt to maximize the accuracy and confidence of parathyroid localization via concordant imaging results. This is supported by limited literature specific to SHPT [12] and otherwise inferred from data regarding PHPT [16-23] showing improved sensitivity and PPV in parathyroid lesion localization with a combination of examinations over each examination in isolation.


Parathyroid Adenoma

Parathyroid Adenoma. MRI Neck There is no relevant literature regarding the use of MRI neck performed without IV contrast, with IV contrast, or without and with IV contrast in the evaluation of SHPT.


Parathyroid Adenoma

Parathyroid Adenoma


Parathyroid Adenoma

Parathyroid Adenoma. neoplasia; patients with SHPT comprised 55% of the cohort. On a per-lesion basis, the reported sensitivity of sestamibi dual-phase scans with SPECT in detecting ectopic glands was 29% [110].


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and I-123 Thyroid Scan There is no relevant literature regarding the use of planar sestamibi scan and I-123 thyroid scan in the evaluation of SHPT.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and Pertechnetate Thyroid Scan There is no relevant literature regarding the use of planar sestamibi scan and pertechnetate thyroid scan in the evaluation of SHPT.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and Pertechnetate Thyroid Scan with SPECT or SPECT/CT Neck There is no relevant literature regarding the use of sestamibi scan and pertechnetate thyroid scan with SPECT or SPECT/CT in the evaluation of SHPT.


Parathyroid Adenoma

Parathyroid Adenoma. Venous Sampling Parathyroid There is no relevant literature regarding the use of venous sampling in the evaluation of SHPT.


Parathyroid Adenoma

Parathyroid Adenoma. Variant 4: Adult or child. Tertiary hyperparathyroidism. Initial imaging. All patients undergoing imaging in the setting of THPT should have biochemically proven disease, as imaging has no role in confirming or excluding the diagnosis [11]. As such, assessing the imaging test specificity and negative predictive value is not clinically relevant. THPT is typically a disorder of MGD in which the role of initial imaging is to accurately identify all eutopic and potential ectopic or supernumerary glands in an attempt to guide the surgical approach [12-14]; accordingly, these criteria focus on imaging test sensitivity and PPV.


Parathyroid Adenoma

Parathyroid Adenoma. It is possible that multiple imaging modalities may be utilized in combination during the initial imaging evaluation of THPT in an attempt to maximize the accuracy and confidence of parathyroid via concordant imaging results. This is inferred from data regarding PHPT [16-23] and SHPT [12] showing improved sensitivity and PPV in parathyroid lesion localization with a combination of examinations over each examination in isolation.


Parathyroid Adenoma

Parathyroid Adenoma. CT Neck There is no relevant literature regarding the use of CT neck in the evaluation of THPT.


Parathyroid Adenoma

Parathyroid Adenoma. MRI Neck There is no relevant literature regarding the use of MRI neck performed without IV contrast, with IV contrast, or without and with IV contrast in the evaluation of THPT.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Dual-Phase Scan Neck There is no relevant literature regarding the use of planar sestamibi dual-phase scan neck in the evaluation of THPT.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and I-123 Thyroid Scan There is no relevant literature regarding the use of planar sestamibi scan and I-123 thyroid scan in the evaluation of THPT.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and I-123 Thyroid Scan with SPECT or SPECT/CT Neck There is no relevant literature regarding the use of sestamibi scan and I-123 thyroid scan with SPECT or SPECT/CT in the evaluation of THPT.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and Pertechnetate Thyroid Scan There is no relevant literature regarding the use of planar sestamibi scan and pertechnetate thyroid scan in the evaluation of THPT.


Parathyroid Adenoma

Parathyroid Adenoma. Sestamibi Scan and Pertechnetate Thyroid Scan with SPECT or SPECT/CT Neck There is no relevant literature regarding the use of sestamibi scan and pertechnetate thyroid scan with SPECT or SPECT/CT in the evaluation of THPT.


Parathyroid Adenoma

Parathyroid Adenoma. Venous Sampling Parathyroid Because of its invasive technique, selective parathyroid venous sampling is typically reserved for reoperative surgical candidates with recurrent or persistent PHPT after noninvasive examinations (eg, US, sestamibi, CT, etc) yield nonlocalizing, equivocal, or discordant results [96]. Otherwise, there are limited data regarding the use of selective venous sampling in the initial evaluation of THPT:


Parathyroid Adenoma

Parathyroid Adenoma. 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.


Parathyroid Adenoma

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


Parathyroid Adenoma

Parathyroid Adenoma

Parathyroid Adenoma. Parathyroid Adenoma


Acute Respiratory Illness in Immunocompromised Patients. ARI constitutes a group of signs and symptoms that develop over a brief interval (hours to weeks), some of which are constitutional (eg, fever, chills, weight loss), and some of which are organ specific (eg, cough, shortness of in complications encountered in breath, chest pain). The respiratory system is frequently involved immunocompromised states. in immunosuppressed patients, and many progress along a rapid and potentially fatal course [1,2]. Noninfectious causes should also be considered when an immunocompromised patient presents with ARI, including such entities as pulmonary edema, drug-induced lung disease, atelectasis, malignancy, radiation-induced lung disease, pulmonary hemorrhage, diffuse alveolar damage, organizing pneumonia, lung transplant rejection, and pulmonary thromboembolic disease [2].


Acute Respiratory Illness in Immunocompromised Patients. Discussion of Procedures by Variant Variant 1: Acute respiratory illness in immunocompromised patients. Cough, dyspnea, chest pain, or fever. Initial imaging. Radiography Chest Chest radiography is the initial imaging modality of choice for the diagnostic assessment of immunocompromised patients presenting with ARI [3]. The chest radiograph typically shows the presence and extent of pulmonary infection, although radiographs can be normal in up to 10% of patients with proven disease [4]. The pattern and distribution of abnormalities on the chest radiograph, along with changes on serial radiographic examinations, can aid in formulating a differential diagnosis. Chest radiographs may also show the presence of complications of infectious pneumonia, such as empyema or abscess [3,5]. The well-known limitations of chest radiography; however, are the lack of specificity with regard to specific pathogens and overall low sensitivity for detecting subtle abnormalities in immunocompromised patients with symptomatic disease [1].


Acute Respiratory Illness in Immunocompromised Patients. aResearch Author, University of Southern California Keck School of Medicine, Los Angeles, California. bUniversity of Southern California, Los Angeles, California. cPanel Chair, University of Chicago, Chicago, Illinois. dMassachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. eStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. fThe University of Texas MD Anderson Cancer Center, Houston, Texas. gThe University of Texas MD Anderson Cancer Center, Houston, Texas. hUniversity of Kentucky, Lexington, Kentucky. iMayo Clinic, Rochester, Minnesota. jVanderbilt University Medical Center, Nashville, Tennessee, American College of Chest Physicians. kMayo Clinic Florida, Jacksonville, Florida. lDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. mUniversity of Kansas Medical Center, Kansas City, Kansas. nSpecialty Chair, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.


Acute Respiratory Illness in Immunocompromised Patients. 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.


Acute Respiratory Illness in Immunocompromised Patients. Reprint requests to: publications@acr.org


Acute Respiratory Illness in Immunocompromised Patients. Variant 2: Acute respiratory illness in immunocompromised patients. Normal, equivocal, or nonspecific chest radiograph. Next imaging study. CT Chest Chest radiographs in immunocompromised patients with ARI may be equivocal or even normal despite a high suspicion for pulmonary disease [1]. In this setting, chest CT has been shown to confer a distinct improvement in sensitivity for detecting subtle parenchymal abnormalities [4]. In one study, CT performed in febrile neutropenic patients with normal chest radiographs showed pneumonia in 60% of cases at least 5 days before the abnormalities became visible on chest radiographs [6]. In another study in patients with pulmonary tuberculosis, 11% of HIV-positive patients had normal chest radiographs [7]. Similarly, up to one-third of patients infected with Pneumocystis jirovecii may have normal chest radiographs [8]. In addition, because of its superior spatial resolution and cross-sectional display of findings, CT provides enhanced characterization of pulmonary parenchymal abnormalities, which is often helpful in formulating a differential diagnosis.


Acute Respiratory Illness in Immunocompromised Patients. MRI Chest CT is preferable to MRI in immunocompromised patients with ARI who have normal, equivocal, or nonspecific chest radiographs. CT remains superior to MRI in the detection and characterization of pulmonary parenchymal infection [9,10]. However, MRI can be considered as an alternative imaging modality, albeit less sensitive. Moreover, once a diagnosis of infection has been established, MRI can be used as a reasonable alternative to CT for follow-up of parenchymal disease [10-12].


Acute Respiratory Illness in Immunocompromised Patients. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature regarding the use of FDG-PET/CT in the evaluation of immunocompromised patients with ARI who have normal, equivocal, or nonspecific chest radiographs. Therefore, FDG-PET/CT should be rarely utilized in this clinical scenario. Furthermore, many pulmonary infections typically have high FDG uptake and, thus, may be mistaken for malignancy [13].


Acute Respiratory Illness in Immunocompromised Patients. Variant 3: Acute respiratory illness in immunocompromised patients. Abnormal chest radiograph, multiple, diffuse, or confluent opacities. Next imaging study. CT Chest Further investigation with CT is warranted in immunocompromised patients with ARI who have chest radiographs showing multiple, diffuse, or confluent opacities. In this patient population, multiple or diffuse opacities or nodules have a higher probability of representing an atypical opportunistic infection rather than community-acquired bacterial pneumonia [4,14]. CT provides enhanced characterization of pulmonary parenchymal abnormalities that are due to its superior spatial resolution and cross-sectional display of findings. Consequently, certain infections can be identified on CT with a higher degree of confidence than on radiographs


ARI in Immunocompromised Patients

Acute Respiratory Illness in Immunocompromised Patients. ARI in Immunocompromised Patients


Acute Respiratory Illness in Immunocompromised Patients. [15-17]. Common CT patterns of disease in patients with ARI include pulmonary nodules, tree-in-bud pattern, lung consolidation, and ground-glass opacities [4]. These patterns have been described in the literature to represent the appearances of a number of pulmonary infections in the immunocompromised host, including P. jirovecii [8,15,16], invasive pulmonary aspergillosis [15,17-20], mucormycosis [21,22], candidiasis [22,23], cytomegalovirus pneumonia [15,24,25], human metapneumovirus [26-28], and mycobacterial pneumonias [29- 32]. CT shows the detailed morphology of parenchymal opacities, as well as the pattern and distribution of disease. For example, in febrile patients having undergone recent stem cell transplantation, the ability of CT to detect halos of ground-glass opacity around pulmonary nodules is helpful in making the early presumptive diagnosis of invasive aspergillosis, thus prompting initiation of empiric antifungal therapy with improved prognosis [17,19]. Furthermore, CT may show the presence of infection complications, such as empyema or abscess that may not be visible on radiographs.


Acute Respiratory Illness in Immunocompromised Patients. MRI Chest CT is preferable to MRI in immunocompromised patients with ARI who have chest radiographs showing multiple, diffuse, or confluent opacities. CT remains superior to MRI in the detection and characterization of pulmonary parenchymal infection [9,10]. However, when the aerated parenchyma is replaced by consolidation, nodules, or masses, MRI can be considered as an alternative imaging modality, albeit less sensitive. Recent studies have shown that MRI can be used for the diagnosis of pulmonary infection [9,12,33]. Newer pulse sequences on 3T scanners may further enhance the diagnostic performance of MRI [11,34,35]. Therefore, as technology continues to improve, MRI represents a promising imaging modality for the workup of immunocompromised patients with abnormal chest radiographs. Moreover, once a diagnosis of infection has been established, MRI can be used as a reasonable alternative to CT for follow-up of parenchymal disease [10-12].


Acute Respiratory Illness in Immunocompromised Patients. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature regarding the use of FDG-PET/CT in the evaluation of immunocompromised patients with ARI who have chest radiographs showing multiple, diffuse, or confluent opacities. Therefore, FDG- PET/CT should be rarely utilized in this clinical scenario. Furthermore, many pulmonary infections typically cause high FDG uptake and, thus, may be mistaken for malignancy [13].


Acute Respiratory Illness in Immunocompromised Patients. Image-Guided Transthoracic Needle Biopsy Image-guided transthoracic needle biopsy may play a role in the identification of the specific organism(s) producing pulmonary parenchymal abnormalities in certain clinical scenarios of immunocompromised patients with ARI. Though the diagnostic yield of transthoracic biopsy in detecting infections is significantly less than in detecting malignancies, the underlying pathogen is identified a significant minority of the time, which allows for prompt and appropriate treatment of the infection in these vulnerable patients [36,37]. Transthoracic biopsy demonstrates the greatest value in the diagnosis of fungal infections, even in the presence of normal sputum and blood cultures [36,38,39]. Even if chest radiography reveals the parenchymal opacities, CT should typically still be performed prior to contemplating transthoracic needle biopsy, as certain lesions may be more amenable to bronchoscopic biopsy if they are in close proximity to the airways. If a CT-guided transthoracic biopsy is planned, the interventionalist can also use the preprocedural CT to determine the optimal patient position and biopsy route.


Acute Respiratory Illness in Immunocompromised Patients. Variant 4: Acute respiratory illness in immunocompromised patients. Abnormal chest radiograph, noninfectious disease suspected. Next imaging study. CT Chest Further investigation with CT is warranted in immunocompromised patients with ARI who have chest radiographs suspected. Immunosuppressed patients are susceptible to a variety of noninfectious pulmonary diseases. Because of its superior spatial resolution and cross-sectional display of findings, CT provides enhanced characterization of pulmonary parenchymal abnormalities, which may assist in formulating a differential diagnosis. Noninfectious causes of ARI in immunocompromised hosts include pulmonary edema, drug-induced lung disease, atelectasis, malignancy (including post-transplant lymphoproliferative disorder), radiation-induced lung disease, pulmonary hemorrhage, diffuse alveolar damage, organizing pneumonia, lung transplant rejection, graft-versus-host disease, and pulmonary thromboembolic disease [2]. For example, many chemotherapeutic and immunomodulatory agents may result in pulmonary toxicity [40]. CT is more sensitive than chest radiography in detecting drug-induced lung injury from agents such as bleomycin, busulfan, carmustine, and cyclophosphamide [40,41]. In patients with a history of pulmonary malignancy, recurrence of the primary tumor or development of lung metastases should always be considered when chest radiography shows nodular opacities; similarly, metastases from an


ARI in Immunocompromised Patients


Acute Respiratory Illness in Immunocompromised Patients. extrathoracic primary often manifest as nodules. An organizing pneumonia pattern of lung injury is a well-known complication in immunocompromised patients, particularly as a manifestation of lung transplant rejection and chronic graft-versus-host disease following allogeneic hematopoietic stem cell transplantation [42-44]. Finally, both malignancy and its treatment are risk factors for deep venous thrombosis, which may lead to pulmonary thromboemboli and pulmonary infarcts [45].


Acute Respiratory Illness in Immunocompromised Patients. MRI Chest There is no relevant literature regarding the use of MRI in the evaluation of immunocompromised patients with ARI, abnormal chest radiographs, and suspicion of noninfectious disease. However, there may be certain clinical scenarios in which MRI can be used as a reasonable alternative to CT. Given that MRI can characterize infectious consolidations, nodules, and masses, it may depict similar findings in noninfectious conditions.


Acute Respiratory Illness in Immunocompromised Patients. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT may occasionally be beneficial in the evaluation of immunocompromised patients with ARI, chest radiographs showing pulmonary parenchymal opacities, and clinical suspicion of noninfectious disease. In patients with a history of pulmonary malignancy, recurrence of the primary tumor or development of lung metastases should always be considered when chest radiography shows nodular opacities; similarly, metastases from an extrathoracic primary often manifest as nodules. However, FDG-PET/CT should be interpreted cautiously, as many pulmonary infections typically cause high FDG uptake and, thus, may be mistaken for malignancy [13]. Certain immunodeficient conditions, such as HIV/AIDS, render patients extremely susceptible to both malignancies and opportunistic infections. AIDS-defining malignancies that may manifest in the lungs include Kaposi sarcoma and non-Hodgkin lymphoma. With regard to these neoplasms, FDG-PET/CT may assist in the specific diagnosis, staging or restaging of disease, and monitoring of therapeutic response [46]. FDG- PET/CT is also an accurate diagnostic modality for the staging and follow-up of patients with post-transplant lymphoproliferative disorder [47]. For these and other clinical scenarios, FDG-PET/CT provides diagnostic information without requiring intravenous (IV) contrast and may be advantageous in patients with renal compromise that is due to chronic immunosuppressive therapy [47].


Acute Respiratory Illness in Immunocompromised Patients. Image-Guided Transthoracic Needle Biopsy Image-guided transthoracic needle biopsy may play a role in the diagnosis of pulmonary disease in immunocompromised patients with ARI, chest radiographs showing pulmonary parenchymal abnormalities, and clinical suspicion of noninfectious disease. In a study of patients with known hematologic malignancy and undiagnosed parenchymal lesions, CT-guided transthoracic biopsy yielded a diagnosis of malignancy 63% of the time [48]. Malignancy may also be diagnosed in patients without a history of neoplastic disease, occurring in 10% of HIV patients with solitary pulmonary nodules [49]. Even in patients for whom infection is the primary diagnostic consideration lung cancer and post-transplant lymphoproliferative disorder, may occasionally be diagnosed [36,50]. Even if chest radiography shows the parenchymal opacities, CT should typically still be performed prior to contemplating transthoracic needle biopsy, as certain lesions may be more amenable to bronchoscopic biopsy if they are in close proximity to the airways. If a CT-guided transthoracic biopsy is planned, the interventionalist can also use the preprocedural CT to determine the optimal patient position and biopsy route.


Acute Respiratory Illness in Immunocompromised Patients. ARI in Immunocompromised Patients 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 rating round tabulations for each recommendation.


Acute Respiratory Illness in Immunocompromised Patients. For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


Plexopathy

Plexopathy. aThe Ohio State University Wexner Medical Center, Columbus, Ohio. bResearch Author, The Ohio State University Wexner Medical Center, Columbus, Ohio. cPanel Chair, University of Utah, Salt Lake City, Utah. dPanel Chair, Mayo Clinic, Jacksonville, Florida. ePanel Vice-Chair, Wake Forest University School of Medicine, Winston Salem, North Carolina. fPanel Vice-Chair, Mallinckrodt Institute of Radiology, Saint Louis, Missouri. gUniversity of Pittsburgh Medical Center, Pittsburgh, Pennsylvania. hJames J. Peters VA Medical Center, Bronx, New York; American Academy of Orthopaedic Surgeons. iMontefiore Medical Center, Bronx, New York. jUniversity of Utah Health, Salt Lake City, Utah. kMayo Clinic, Rochester, Minnesota. lThomas Jefferson University Hospital, Philadelphia, Pennsylvania. mUniversity of California Los Angeles, Los Angeles, California; American Academy of Neurology. nUniversity of Michigan, Ann Arbor, Michigan. oJacobi Medical Center, Bronx, New York. pUniversity of California San Francisco, San Francisco, California. qIndiana University School of Medicine, Indianapolis, Indiana; American College of Physicians. rDuke University, Durham, North Carolina; Neurosurgery expert. sUniversity of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado. tSpecialty Chair, University of Kentucky, Lexington, Kentucky. uSpecialty Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia.


Plexopathy

Plexopathy. 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.


Plexopathy

Plexopathy. Reprint requests to: publications@acr.org


Plexopathy

Plexopathy. Plexopathy plexus imaging [15-20]. Research also continues regarding the use and possible advantages of higher field strength [21] in regards to spatial resolution and contrast [4], volumetric sequences [22], and diffusion tensor imaging [6,23- 26]. Imaging at 1.5T may be beneficial to reduce artifact if metal is present in the area of clinical concern.


Plexopathy

Plexopathy. Primary tumors of the brachial plexus are most commonly benign peripheral nerve sheath schwannomas and neurofibromas, which can be sporadic or can be associated with neurofibromatosis type 2 and type 1, respectively. Malignant peripheral nerve sheath tumors of the brachial plexus are rare and occur more frequently in patients with neurofibromatosis type 1. The most common non-neurogenic primary tumors of the brachial plexus are desmoid tumors and lipomas [27]. Lymphoma can involve the plexus either because of local encasement or nerve infiltration. Extrinsic tumors can directly invade or metastasize to the brachial plexus [29], most commonly due to lung and breast cancer, respectively. Superior sulcus tumors of the lung (Pancoast tumors) often directly invade the lower trunk of the brachial plexus and can be associated with Horner syndrome and pain along the ulnar nerve distribution. Variant 5 describes brachial plexopathy in the setting of a known malignancy or post-treatment syndrome; however, plexopathy can be the first clinical presentation of neoplastic disease.


Plexopathy

Plexopathy. Systemic, inflammatory, and/or immune-mediated processes that involve the brachial plexus include Parsonage- Turner syndrome (ie, neuralgic amyotrophy or brachial plexitis) [30-32], chronic inflammatory neuropathies (eg, chronic inflammatory demyelinating polyradiculoneuropathy, multifocal motor neuropathy, Lewis-Sumner syndrome) [15,33-38], hereditary neuropathies (eg, Charcot-Marie-Tooth syndrome) [39], sarcoidosis [27], and infection [40-42]. The diagnosis of these disorders is typically based on clinical and electrodiagnostic evaluation, as the imaging features can overlap considerably.


Plexopathy

Plexopathy. CT Myelography Cervical Spine There is no relevant literature regarding the use of CT myelography of the cervical spine in the evaluation of nontraumatic brachial plexopathy. Myelography is not routinely performed for the evaluation of nontraumatic plexopathy because it does not directly evaluate the plexus lateral to the neural foramina.


Plexopathy

Plexopathy. CT Neck There is no relevant literature regarding the use of neck CT in the evaluation of nontraumatic brachial plexopathy. CT offers the next highest level of anatomic visualization of the brachial plexus after MRI and can evaluate for adjacent soft-tissue lesions or tumors that may involve the plexus [43]. CT with IV contrast can be useful for detecting and characterizing soft-tissue masses and tumors, which are in the differential diagnosis of nontraumatic brachial plexopathy and therefore may provide additional information over CT without IV contrast in this setting [43].


Plexopathy

Plexopathy. Plexopathy CT Cervical Spine There is no relevant literature regarding the use of CT cervical spine in the evaluation of nontraumatic brachial plexopathy. CT cervical spine cannot visualize the preganglionic nerve roots and does not fully evaluate the postganglionic brachial plexus because of the narrow field of view and limited soft-tissue contrast resolution relative to MRI.


Plexopathy

Plexopathy. FDG-PET/CT Whole Body There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT in the evaluation of nontraumatic brachial plexopathy in the absence of a known malignancy.


Plexopathy

Plexopathy. MRI Brachial Plexus Brachial plexus MRI has been shown to be useful in evaluating nontraumatic brachial plexopathy because of its superior soft-tissue contrast and good spatial resolution, providing detailed definition of intraneural anatomy as well as localizing pathologic lesions in conditions in which electrodiagnostic and physical findings are nonspecific [6,9,10,27]. Tagliafico et al [44] in a blinded, retrospective review studied 157 patients who underwent brachial plexus MRI found an overall sensitivity of 81%, specificity of 91%, positive predictive value of 82%, negative predictive value of 91%, and accuracy of 88% when compared with the reference standard of surgical findings and clinical follow-up. Du et al [45] in a retrospective review studied 191 patients and found that the brachial plexus MRI provided additional information beyond that of clinical evaluation and electrodiagnostic studies in 45% of patients. Hilgenfeld et al [46] in a blinded, retrospective review studied 36 patients and found that brachial plexus MRI could reliably differentiate compressive from noncompressive plexopathy in all patients. MRI with and without IV contrast can be useful for detecting and characterizing several of the etiologies in the differential diagnosis of nontraumatic brachial plexopathy and may provide additional information over MRI without IV contrast in this setting [47].


Plexopathy

Plexopathy. US Neck There is no relevant literature to support the use of ultrasound (US) as the primary imaging modality for patients with nontraumatic brachial plexopathy in whom clinical and electrodiagnostic evaluation has been inconclusive. US may be a useful supplemental test in selected centers [50]. US has been described as an adjunctive tool for assessment of nerve enlargement in patients with a clinically diagnosed neuropathy [30,35,39,51-55]. US can be very useful for image-guided therapy, including regional anesthesia, which is beyond the scope of this topic.


Plexopathy

Plexopathy. Variant 2: Lumbosacral plexopathy, acute or chronic, nontraumatic. No known malignancy. Initial imaging. This variant encompasses nontraumatic lumbosacral plexopathy occurring in patients without a history of systemic malignancy or post-treatment syndrome. The differential diagnosis for nontraumatic lumbosacral plexopathy includes entrapment, inflammatory, autoimmune, hereditary, ischemic, and idiopathic etiologies that tend to affect the plexus diffusely, as well as neoplasms or extrinsic compressive lesions that focally involve the plexus [2-4,7,8].


Plexopathy

Plexopathy. Entrapment neuropathies are a common cause of lumbosacral plexopathy and can result from spinal or extraspinal compression [3]. The clinical and electrodiagnostic features of lumbosacral plexopathy and radiculopathy often overlap, and imaging can help localize the site of nerve compression [1]. In some cases, lumbosacral plexus MRI can detect spinal causes of nerve root compression that may not be detected on a lumbar spine MRI, such as a lateral disc herniation that compresses the distal nerve root lateral to the neural foramen [3]. Lumbosacral plexus MRI may also detect signal abnormalities in the nerve root and plexus distal to the site of spinal neural compression, which may provide additional evidence of the symptomatic nerve root compression level [56]. A commonly described cause of extraspinal nerve entrapment is the piriformis syndrome, in which the sciatic nerve can be compressed by


Plexopathy

Plexopathy. Plexopathy the piriformis muscle due to either the anatomic variation or an associated fibrous band [7,8,57]. Imaging can be useful for detecting nerve abnormalities and/or neuromuscular variants associated with extraspinal nerve compression and can help guide treatment with surgery, interventional, or noninvasive therapy.


Plexopathy

Plexopathy. Primary tumors of the lumbosacral plexus are most commonly benign peripheral nerve sheath schwannomas and neurofibromas, which can be sporadic or can be associated with neurofibromatosis. Malignant peripheral nerve sheath tumors of the lumbosacral plexus are rare and occur more frequently in patients with neurofibromatosis [7]. Other primary malignant or metastatic tumors can also involve the lumbosacral plexus [4]. Variant 6 describes lumbosacral plexopathy in the setting of a known malignancy or post-treatment syndrome; however, plexopathy can be the first clinical presentation of neoplastic disease. Non-neoplastic masses involving the lumbosacral plexus can include hematoma, abscess, aneurysm, amyloidosis [4], and endometriosis [58].


Plexopathy

Plexopathy. CT Myelography Lumbar Spine There is no relevant literature to support the use of CT myelography of the lumbar spine in the evaluation of nontraumatic lumbosacral plexopathy. Myelography is not routinely performed for the evaluation of nontraumatic plexopathy as it does not evaluate the plexus lateral to the neural foramina.


Plexopathy

Plexopathy. CT Abdomen and Pelvis There is no relevant literature to support the use of abdominal and pelvic CT in the evaluation of nontraumatic lumbosacral plexopathy. CT offers the next highest level of anatomic visualization of the lumbosacral plexus after MRI, and can evaluate for adjacent soft-tissue lesions or tumors that may involve the plexus. CT with IV contrast can be useful for detecting and characterizing soft-tissue masses and tumors, which are in the differential diagnosis of nontraumatic lumbosacral plexopathy and therefore may provide additional information over CT without IV contrast in this setting.


Plexopathy

Plexopathy. CT Lumbar Spine There is no relevant literature regarding the use of CT lumbar spine in the evaluation of nontraumatic lumbosacral plexopathy. CT lumbar spine cannot visualize the preganglionic nerve roots and does not fully evaluate the postganglionic lumbosacral plexus because of its narrow field of view and limited soft-tissue contrast resolution relative to MRI.


Plexopathy

Plexopathy. FDG-PET/CT Whole Body There is no relevant literature to support the use of FDG-PET/CT in the evaluation of nontraumatic lumbosacral plexopathy in the absence of a known malignancy.


Plexopathy

Plexopathy. MRI Lumbosacral Plexus Lumbosacral plexus MRI is useful in evaluating nontraumatic lumbosacral plexopathy because of its superior soft- tissue contrast and good spatial resolution, providing good definition of intraneural anatomy as well as localizing pathologic lesions in conditions where electrodiagnostic and physical findings are nonspecific [1-4,7,8,61]. The clinical diagnosis of plexopathy can be challenging, and it may be unclear whether neurologic signs and symptoms


Plexopathy

Plexopathy

Plexopathy. Plexopathy


Plexopathy

Plexopathy. localize to a single nerve root (radiculopathy) or to the lumbosacral plexus (plexopathy) because of the considerable overlap in these clinical presentations [1]. For this reason, literature evaluating the diagnostic performance of lumbosacral plexus MRI often includes patients who present with radiculopathy as well as plexopathy. Dessouky et al [62], in a retrospective review, analyzed 202 patients who received MRI of lumbosacral plexus for the evaluation of radiculopathy (57%), pelvic pain (28%), or groin pain (15%) and found that 71% of patients had a change in management resulting from MRI findings. Zhang et al [63] in a retrospective review of 137 patients who received MRI lumbosacral plexus with diffusion-weighted neurography for a clinical diagnosis of sciatica found either nerve root compression or abnormal intraneural signal in the nerves in all patients. Chazen et al [56] in a retrospective review of 64 patients with radiculopathy symptoms who underwent lumbosacral plexus MRI and electromyography found abnormal intraneural signal in 45% of lumbosacral plexus MRI examinations and a statistically significant correlation between nerve signal abnormality on MRI and findings of active radiculopathy on electromyography. Petrasic et al [64] in retrospective review of 23 patients presenting with chronic pelvic pain and/or dysfunction and clinically suspected chronic cauda equina syndrome who underwent MRI lumbosacral plexus found that 78% of patients had a change in diagnosis and 81% had a change in management from the MRI findings. MRI with and without IV contrast can be useful for detecting and characterizing several of the etiologies in the differential diagnosis of nontraumatic lumbosacral plexopathy and may provide additional information over MRI without IV contrast in this setting.


Plexopathy

Plexopathy. MRI Pelvis There is no relevant literature to support the use of MRI of the pelvis (without dedicated plexus imaging) in the evaluation of nontraumatic lumbosacral plexopathy.


Plexopathy

Plexopathy. CT Myelography Cervical Spine CT myelography provides high-resolution imaging capable of detecting traumatic cervical nerve root avulsions and pseudomeningocele formation and can evaluate for other spinal traumatic injuries, such as fracture, hematoma, or cerebrospinal fluid leak [70]. However, CT myelography can only evaluate for preganglionic nerve root injury and does not directly visualize the postganglionic brachial plexus. Therefore, MRI brachial plexus is preferred over CT myelography cervical spine as the first-line imaging test to evaluate for postganglionic brachial plexus injury. CT myelography performed to assess for cervical nerve root avulsion injury should be ideally delayed until approximately 1 month after the initial trauma to allow time for resolution of hemorrhage and formation of a pseudomeningocele [28,68].


Plexopathy

Plexopathy. FDG-PET/CT Whole Body There is no relevant literature to support the use of FDG-PET/CT in the evaluation of traumatic brachial plexopathy.


Plexopathy

Plexopathy. MRI Brachial Plexus Brachial plexus MRI is considered superior to CT in the evaluation of traumatic brachial plexopathy because of its inherently better soft-tissue contrast and good spatial resolution [6,9,10,27]. MRI can identify traumatic nerve root avulsions, which are crucial to detect in order to plan surgical reconstruction and determine prognosis [66]. Wade et al [71] studied 29 consecutive patients requiring brachial plexus exploration following trauma and found that brachial plexus MRI had a diagnostic accuracy of 79% for detecting C5 to T1 nerve root avulsion and that pseudomeningocele as a surrogate marker for root avulsion had a diagnostic accuracy of 68%. MRI can also directly assess the postganglionic brachial plexus and can confirm whether nerve integrity is maintained, differentiating minor stretching injuries from complete nerve disruptions [66]. Tagliafico et al [44], in a blinded retrospective review, studied 38 patients who received brachial plexus MRI for traumatic plexopathy and found a sensitivity of 84%, specificity 91%, positive predictive value of 91%, negative predictive value of 83%, and accuracy of 87% when compared to the reference standard of surgical findings and clinical follow-up. Fuzari et al [69] performed a systematic review of 3 articles reporting diagnostic accuracy of MRI for traumatic brachial plexus injury and found that the studies lacked methodological rigor, thus concluding that more rigorous research should be conducted in this area. Research is ongoing into new MRI sequences that might improve evaluation of traumatic brachial plexopathy, but these are not routinely performed outside of a research setting. For example, diffusion tensor imaging and tractography have been under investigation and show promise in the evaluation of nerve injury and disruption of nerve microstructure [69].


Plexopathy

Plexopathy. Brachial plexus MRI can also delineate other post-traumatic complications that may contribute to symptoms of plexopathy, such as regional soft-tissue hematoma, traumatic neuromas, and scarring. In the post-treatment setting following surgical nerve repair, brachial plexus MRI can be used to study the repaired nerve, assess for complications, and assess for secondary signs of neuropathy, such as degenerative muscular atrophy [72]. MRI with IV contrast usually does not provide significant additional information over MRI without IV contrast for the initial imaging of traumatic brachial plexopathy, though the addition of contrast can help differentiate between vascular structures and nerves.


Plexopathy

Plexopathy. Plexopathy IV contrast usually does not provide significant additional information over MRI without IV contrast for the initial imaging of traumatic brachial plexopathy.


Plexopathy

Plexopathy. Another cause of indirect traumatic injury to the lumbosacral plexus is avulsion fractures at muscular attachment sites, which can cause traumatic edema, hematoma, or inflammation that compresses the adjacent nerve [8]. This can be seen with avulsions of the hamstrings at the ischial tuberosity (injuring sciatic or pudendal nerve), adductor muscles at the inferior pubic symphysis (injuring obturator nerve), or gluteal muscles at the greater trochanter (injuring superior or inferior gluteal nerves) [8]. Similar to avulsion fractures, tendinopathy of the major muscular attachments can also result in local soft-tissue swelling and inflammation that can involve adjacent nerves [3,8]. Iatrogenic injury to the lumbosacral plexus or terminal branches can also occur after childbirth or surgery, such as total hip arthroplasty, gynecologic, or genitourinary surgery [2].


Plexopathy

Plexopathy. CT Myelography Lumbar Spine CT myelography provides high-resolution imaging of the thecal sac capable of detecting traumatic nerve root avulsion or pseudomeningocele. However, CT myelography can only evaluate for preganglionic nerve root injury and does not directly visualize the postganglionic lumbosacral plexus. Therefore, MRI lumbosacral plexus is superior to CT myelography lumbar spine in the evaluation of postganglionic lumbosacral plexus injury. CT myelography performed to assess for preganglionic lumbosacral nerve root injury should be ideally delayed until approximately 1 month after the initial trauma to allow time for resolution of hemorrhage and formation of a pseudomeningocele.


Plexopathy

Plexopathy. CT Abdomen and Pelvis There is no relevant literature to support the use of CT abdomen and pelvis in the evaluation of traumatic lumbosacral plexopathy. However, this test is often used in the setting of major blunt trauma (in which lumbosacral plexus injuries are most common), and can detect many of the associated findings such as pelvic fractures or hematomas. The role of imaging in the setting of major blunt trauma is addressed in the ACR Appropriateness


Plexopathy

Plexopathy. FDG-PET/CT Whole Body There is no relevant literature to support the use of FDG-PET/CT in the evaluation of traumatic lumbosacral plexopathy.


Plexopathy

Plexopathy. MRI Lumbosacral Plexus Lumbosacral plexus MRI has been shown to be superior to CT in the evaluation of traumatic lumbosacral plexopathy because of its inherently better soft-tissue contrast and good spatial resolution. MRI can directly assess the postganglionic lumbosacral plexus and can confirm whether nerve integrity is maintained, differentiating minor stretching injuries from complete nerve disruptions [4]. Lumbosacral plexus MRI can also delineate other post- traumatic complications that may contribute to symptoms of plexopathy, such as regional soft-tissue hematoma, edema, inflammation, avulsion fracture, tendinopathy, traumatic neuromas, and scarring [8]. MRI to assess the extent of injury should be ideally delayed until approximately 1 month after the initial trauma to allow time for resolution of hemorrhage and edema that can obscure the lumbosacral plexus acutely. MRI with and without IV contrast usually does not provide significant additional information over MRI without IV contrast for the initial imaging of acute traumatic lumbosacral plexopathy, though the addition of contrast can help differentiate between vascular structures and nerves.


Plexopathy

Plexopathy. Plexopathy Variant 5: Brachial plexopathy, known malignancy or post-treatment syndrome. Initial imaging. This variant encompasses brachial plexopathy occurring in the setting of a known malignancy or a post-treatment syndrome occurring months to years after radiation treatment for a regional malignancy.


Plexopathy

Plexopathy. In addition, patients can develop brachial plexopathy in the months to years after radiation treatment for regional malignancy, which could be due to recurrent tumor or postradiation injury. Imaging can be helpful in differentiating radiation plexopathy from recurrent malignancy [20,79-81], for which management differs significantly.


Plexopathy

Plexopathy. CT Myelography Cervical Spine There is no relevant literature to support the use of CT myelography for evaluation of brachial plexopathy in the setting of known malignancy or post-treatment syndrome. CT myelography provides high-resolution imaging of the thecal sac capable of detecting thecal sac compression or intradural masses; however, it does not directly visualize the postganglionic brachial plexus.


Plexopathy

Plexopathy. CT Cervical Spine There is no relevant literature regarding the use of CT cervical spine in the evaluation of brachial plexopathy in the setting of known malignancy or post-treatment syndrome. CT cervical spine cannot visualize the preganglionic nerve roots and does not fully evaluate the postganglionic brachial plexus because of its narrow field of view and limited soft-tissue contrast resolution relative to MRI.


Plexopathy

Plexopathy

Plexopathy. Plexopathy


Plexopathy

Plexopathy. MRI Brachial Plexus Brachial plexus is considered an optimal imaging modality to evaluate brachial plexopathy in the setting of known malignancy or post-treatment syndrome because of its superior soft-tissue contrast and good spatial resolution [6,9,10,27]. Extrinsic compression, direct tumor invasion, or metastasis to the brachial plexus can be demonstrated on MRI brachial plexus. Perineural tumor spread or lymphoma infiltrating the plexus [76] can also be visualized on MRI. In the post-treatment setting, MRI can help differentiate radiation plexopathy from neoplastic plexopathy [20,79,80]. Research is ongoing into new MRI sequences that might improve evaluation of neoplastic brachial plexopathy, but these are not routinely performed outside of a research setting. For example, Yuh et al [20] in a retrospective review of 23 patients who underwent brachial plexus MRI with diffusion-weighted imaging for evaluation of a mass-like or infiltrative lesion found that apparent diffusion coefficient values were significantly different between malignant tumors and postradiation changes or benign tumors. MRI with and without IV contrast can provide additional information over MRI without IV contrast in the setting of malignancy or post-treatment syndromes, as it can improve delineation of tumor margins and/or fibrosis [5,6,9,10,27].


Plexopathy

Plexopathy. MRI Cervical Spine There is no relevant literature to support the use of MRI of the cervical spine (without dedicated plexus imaging) for evaluation of brachial plexopathy in the setting of known malignancy or post-treatment syndrome. However, MRI cervical spine may be complementary in this clinical scenario because it can better assess for cervical spinal metastases with extraosseous extension of tumor into the neural foramina and epidural space that can compress the brachial plexus nerve roots or spinal cord. In the post-treatment setting, radiation injury or tumor recurrence involving the intradural nerve roots would also be better evaluated with cervical spine MRI. MRI with and without IV contrast can provide additional information over MRI without IV contrast in the setting of malignancy or post- treatment syndromes, as it can improve delineation of tumor margins and/or fibrosis.


Plexopathy

Plexopathy. US Neck US neck is typically not the first-line imaging test for evaluation of brachial plexopathy in the setting of a known malignancy or post-treatment syndrome, and is generally not useful as the primary imaging modality in this clinical scenario. Researchers have investigated whether US might be useful as a supplemental test to evaluate malignant involvement or radiation-induced plexopathy of the brachial plexus [50,83]. Kultur et al [81] in a prospective analysis of 23 patients receiving radiation therapy for breast cancer found statistically significant differences between the ipsilateral and contralateral brachial plexus on shear wave elastography; however, this technique is not routinely used outside of research settings.


Plexopathy

Plexopathy. Variant 6: Lumbosacral plexopathy, known malignancy or post-treatment syndrome. Initial imaging. This variant encompasses lumbosacral plexopathy occurring in the setting of a known malignancy or a post- treatment syndrome occurring months to years after radiation treatment for a regional malignancy.


Plexopathy

Plexopathy. In addition, patients can develop lumbosacral plexopathy in the months to years after radiation treatment for regional malignancy, which could be due to recurrent tumor or postradiation injury. Imaging can be helpful in differentiating radiation plexopathy from recurrent malignancy [20], for which management differs significantly.


Plexopathy

Plexopathy. CT Myelography Lumbar Spine There is no relevant literature to support the use of CT myelography for evaluation of lumbosacral plexopathy in the setting of known malignancy or post-treatment syndrome. CT myelography provides high-resolution imaging of the thecal sac capable of detecting thecal sac compression or intradural masses; however, it does not directly visualize the postganglionic lumbosacral plexus.


Plexopathy

Plexopathy. CT Lumbar Spine There is no relevant literature regarding the use of CT lumbar spine in the evaluation of lumbosacral plexopathy in the setting of known malignancy or post-treatment syndrome. CT lumbar spine cannot visualize the preganglionic nerve roots and does not fully evaluate the postganglionic lumbosacral plexus because of its narrow field of view and limited soft-tissue contrast resolution relative to MRI.


Plexopathy

Plexopathy. MRI Lumbar Spine There is no relevant literature to support the use of MRI of the lumbar spine (without dedicated plexus imaging) for evaluation of lumbosacral plexopathy in the setting of known malignancy or post-treatment syndrome. However, lumbar spine MRI may be complementary in this clinical scenario because it can better assess for lumbosacral spinal metastases with extraosseous extension of tumor into the neural foramina and epidural space that can compress the lumbosacral plexus nerve roots [3,7]. In the post-treatment setting, radiation injury or tumor


Plexopathy

Plexopathy. recurrence involving the intradural nerve roots would also be better evaluated with lumbar spine MRI. MRI with and without IV contrast can provide additional information over MRI without IV contrast in the setting of malignancy or post-treatment syndromes, as it can improve delineation of tumor margins and/or fibrosis.


Plexopathy

Plexopathy. MRI Lumbosacral Plexus Lumbosacral plexus MRI is considered an optimal imaging modality to evaluate lumbosacral plexopathy in the setting of known malignancy or post-treatment syndrome because of its superior soft-tissue contrast and good spatial resolution [2-4,7,8]. Extrinsic compression or tumor infiltration of the lumbosacral plexus can be well demonstrated on lumbosacral plexus MRI. Perineural tumor spread along the lumbosacral plexus [84,85] or lymphoma infiltrating the plexus [76] can also be visualized on MRI. MRI with and without IV contrast can provide additional information over MRI without IV contrast in the setting of malignancy or post-treatment syndromes, as it can improve delineation of tumor margins and/or fibrosis.


Plexopathy

Plexopathy. 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.


Plexopathy

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


Noncerebral Vasculitis

Noncerebral Vasculitis. Introduction/Background Idiopathic vasculitis is a noninfectious inflammation of the vessels that can lead to serious health consequences. It can be a primary inflammatory process or a secondary process because of an underlying disease. Historically, it has been categorized based on whether inflammation is restricted to blood vessels of particular size as large-vessel vasculitis (LVV), medium-vessel vasculitis (MVV), small-vessel vasculitis, and variable-vessel vasculitis. The large vessels are the aorta and its main branches, the medium vessels are the main visceral arteries and initial branches, and the small vessels are the intraparenchymal vessels and analog veins. There is an overlap between these vasculitis types; for example, LVV predominantly involves large vessels; however, it can also affect medium and small vessels. In variable-vessel vasculitis, there is no predominance of vessel size involvement. Tissue biopsy of the large or medium vessels is often not feasible; therefore, imaging plays a crucial role in diagnosing idiopathic vasculitides. Considering the limitations of spatial resolution across all available modalities for small-vessel vasculitis, this manuscript focused on vasculitis mainly involving the large and medium vessels.


Noncerebral Vasculitis

Noncerebral Vasculitis. LVV includes 2 subtypes: giant-cell arteritis (GCA) and Takayasu arteritis (TAK), of which GCA is more common. GCA is an idiopathic, inflammatory, granulomatous vasculitis involving predominantly the large arteries in older patients (>50 years of age). GCA affects the supra-aortic vessels, especially the extracranial branches of the carotid artery, such as the superficial temporal artery (referred to as cranial-GCA [c-GCA]). Classically, a diagnosis of GCA requires temporal artery ultrasound (US) or temporal artery biopsy. However, a growing body of literature has demonstrated the involvement of the extracranial large arteries, particularly the aorta and its main branches, which is known as large-vessel GCA (LV-GCA). The American College of Rheumatology classification criteria underperforms in classifying patients with LV-GCA. A retrospective study by Muratore et al [1] demonstrated that American College of Rheumatology criteria are inadequate to classify patients with LV-GCA. Therefore, patients with suspected GCA require supplemental imaging studies in addition to temporal artery US or biopsy [2]. In this regard, the trial of tocilizumab for GCA, which is a large randomized controlled trial in GCA, included patients with imaging-confirmed LV-GCA who did not meet the American College of Rheumatology criteria [3]. Interestingly, patients with LV-GCA compared to other patients with GCA, present less frequently with jaw claudication or ischemic symptoms and have a higher incidence of relapse, have greater cumulative glucocorticoid exposure, and are more frequently treated with steroid-sparing agents, such as the interleukin-6-receptor blocker tocilizumab [1]. Polymyalgia rheumatica (PMR) is a disorder in the same disease spectrum as GCA and can be found in association with GCA or as an isolated phenomenon [4].


Noncerebral Vasculitis

Noncerebral Vasculitis. Reprint requests to: publications@acr.org


Noncerebral Vasculitis

Noncerebral Vasculitis

Noncerebral Vasculitis. Noncerebral Vasculitis


Noncerebral Vasculitis

Noncerebral Vasculitis. from asymptomatic presentations to nonspecific constitutional symptoms and major ischemic events. Although the histopathology of TAK shares similarities with that of GCA, biopsy material from the large arteries is rarely obtained in TAK. The diagnosis of TAK typically requires a combination of physical examination, laboratory findings, and imaging findings.


Noncerebral Vasculitis

Noncerebral Vasculitis. Variable-vessel vasculitis subtypes such as Cogan or Behcet disease can involve the large vessels, particularly the aorta. Although the literature is limited on imaging features of Cogan or Behcet vasculitis, case reports and series have demonstrated similarities with LVV. Because of the limitation of the peer-reviewed literature, the focus of this manuscript will be on LVV.


Noncerebral Vasculitis

Noncerebral Vasculitis. MVV predominantly involves medium-sized arteries, although arteries of any size can be involved. Polyarteritis nodosa (PAN) and Kawasaki disease are the 2 types of MVV [6]. PAN affects medium and small visceral vessels (particularly renal arteries), and there is an association with hepatitis B virus. Kawasaki disease is a self-limiting acute necrotizing vasculitis that affects medium and small vessels and is most prevalent in Asian populations. Kawasaki disease commonly affects the coronary arteries in 15% to 20% of patients [7].


Noncerebral Vasculitis

Noncerebral Vasculitis. Special Imaging Considerations CT and CTA CT or CT angiography (CTA) are cross-sectional imaging modalities with an excellent spatial resolution and faster scan time. Although assessment of the vessel wall is possible with contrast-enhanced CT, the proper modality is CTA. CT without intravenous (IV) contrast material is limited for vascular assessment. However, CTA can be acquired as a biphasic study, including noncontrast and arterial phase, or as a triphasic study with the addition of a delayed or venous phase for proper vessel lumen and wall assessment. In addition, electrocardiogram (ECG)-gated CTA exhibits motionless aortic root and ascending aorta [8]. In most cases, CTA of the chest, abdomen, and pelvis ensures coverage of the entire vasculature in the abdomen. In cases of coronary artery involvement, dedicated coronary CTA displays potential vessel involvement.


Noncerebral Vasculitis

Noncerebral Vasculitis. FDG-PET/CT Whole Body Inflammatory cells in the inflamed vessel wall can accumulate fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG); thus, FDG-PET/CT can be used in the diagnosis of vasculitis [9]. Similar to other indications, patient preparation includes 6 hours of fasting before administering the FDG tracer injection and limiting strenuous exercise before the study. Although FDG-PET/CT can be acquired as a standard 60- to 90-minute delay after the injection for vasculitis, a few studies have suggested that a 120- to 180-minute delay could lead to higher diagnostic accuracy [10,11]. In 1 study, the preferred scan time for optimal vessel wall inflammation was 2.5 hours with a target glucose level of <7.0 mmol/L (<126 mg/dL) [12]. In patients with coronary artery involvement/suspected coronary artery vasculitis, myocardial suppression should be achieved via diet, and ECG-gated images should be obtained [13]. Recently, there has been emerging literature describing FDG uptake in the head and neck arteries, particularly in the temporal and maxillary arteries, which could aid the simultaneous diagnosis of c-GCA and LV-GCA [14,15].