Hydronephrosis on Prior Imaging Unknown Cause. CTU Without and With IV Contrast Although there is relatively limited evidence to support the use of CTU without and with IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause, CTU is useful for investigating the etiology of hydronephrosis. CTU provides a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. In a prospective study evaluating 70 patients with renal colic or hematuria, CTU was performed after hydronephrosis was confirmed with US and was able to detect 100% of renal calculi but was less sensitive in detection of other causes of obstruction [28].


Hydronephrosis on Prior Imaging Unknown Cause. DTPA Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. However, tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored for imaging only studies [11,12]. DRG with DTPA is useful for estimating single-kidney GFR, although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13].


Hydronephrosis on Prior Imaging Unknown Cause. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. MAG3 Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11]. Further, DRG with urethral catheter has been suggested for patients with bilateral hydronephrosis or hydroureteronephrosis with postvoid residual <150 mL to help differentiate potential etiologies [2]. Tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Tubular tracers such as MAG3 are favored over the use of DTPA for imaging only studies, because DTPA DRG may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function [11,12].


Hydronephrosis on Prior Imaging Unknown Cause. Hydronephrosis on Prior Imaging-Unknown Cause MRI Abdomen and Pelvis Without and With IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy.


Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. More comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy.


Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. MRU Without and With IV Contrast There is some evidence for use of MRU without and with IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without and with IV contrast is useful for investigating the etiology of hydronephrosis and in combination with anatomical imaging can provide a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information.


Hydronephrosis on Prior Imaging Unknown Cause. Multiple studies report similar findings between MRU and DRG for diagnostic evaluation of hydronephrosis. In a prospective study, Claudon et al [14] compared MRU without and with IV contrast with MAG3 or DTPA DRG in 295 adult and pediatric patients with hydronephrosis and clinical suspicion for chronic or intermittent obstruction, including both symptomatic and asymptomatic patients and excluding those with acute urinary obstruction or solitary or transplant kidney. They reported equivalence of MRU with renal scintigraphy for diagnostic evaluation of split renal function in moderately dilated kidneys, with a standard deviation of approximately 12% between the two; for severely dilated kidneys, they note a mean underestimation by MRU of split renal function by 4%. They conclude that substitution of DRG by MRU is acceptable for moderately dilated kidneys but remains questionable for severely dilated kidneys. Notably, most of the included patients were children <2 years of age, and the MRU technique used included a diuretic component.


Hydronephrosis on Prior Imaging Unknown Cause. In a prospective study of 13 people without and 15 people with hydronephrosis, Wang et al [13] reported significant correlation between MRU and DRG estimations of single-kidney GFR and that MRU is comparable to DRG for estimation of GFR in the setting of hydronephrosis. They note that both MRU and DRG may somewhat overestimate global GFR in the setting of obstructive hydronephrosis.


Hydronephrosis on Prior Imaging Unknown Cause. MRU Without IV Contrast There is some evidence for use of MRU without IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without IV contrast is useful for investigating the etiology of hydronephrosis and can be combined with anatomical imaging to provide more information than anatomical imaging alone but does not provide the level of functional imaging attainable with MRU without and with IV contrast.


Hydronephrosis on Prior Imaging Unknown Cause. Hydronephrosis on Prior Imaging-Unknown Cause In a prospective study of 55 patients with hydronephrosis detected on US for urologic symptoms, excluding patients with abnormal renal function given contraindication for IVU, Muthusami et al [30] compared static heavily T2- weighted MRU to reference IVU and determined that MRU had high sensitivity and specificity for detecting (95% and 100%, respectively) and grading (Spearman correlation coefficient 0.92) hydronephrosis, as well as identifying the location of obstruction (90% and 99%, respectively) if present. The authors conclude that static MRU can replace IVU when the latter is contraindicated or technically difficult. The authors note that MRU sensitivity for hydronephrosis grading increased with grade of obstruction.


Hydronephrosis on Prior Imaging Unknown Cause. MRU can be useful in patients with renal colic and concern for obstruction. Semins et al [31], in a prospective study of 22 patients with renal colic, concluded that noncontrast half-Fourier acquisition single-shot turbo spin-echo MRU can reliably detect presence of upper tract obstruction using visualization of a stone and secondary signs of obstruction; using CT as the reference standard, the combination of stone or perinephric fluid and ureteral dilation gave MRU a sensitivity of 84 %, specificity of 100 %, and accuracy of 86 % (95 % CI 0.72-1.0).


Hydronephrosis on Prior Imaging Unknown Cause. Radiography Abdomen and Pelvis There is relatively limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT is more sensitive for obstructive urolithiasis.


Hydronephrosis on Prior Imaging Unknown Cause. Innes et al [32] performed a retrospective multicenter observational cohort study of 1,026 patients with renal colic, finding that adding radiography to screening for hydronephrosis (in this study, by CT) increased sensitivity in all stone categories, specifically from 39% to 68% for large stones and from 60% to 82% for interventional stones. They conclude that this level of sensitivity may be sufficient to reassure physicians about a renal colic diagnosis in the setting of known hydronephrosis without CT imaging for many patients.


Hydronephrosis on Prior Imaging Unknown Cause. In a retrospective study of 939 patients with renal colic, Abdel-Gawad et al [33] reported that KUB had limited sensitivity of 53% to 62% and specificity of 67% to 69% for the detection of ureteral calculi. Notably, 90% of stones are radio-opaque, consisting of calcium oxalate, calcium phosphate, and struvite. Although KUB may be comparatively insensitive for stones <4 mm and those in the mid and distal ureters, its use may improve stone detection rates at the margins where obstruction is not readily demonstrated with US [34].


Hydronephrosis on Prior Imaging Unknown Cause. Some studies of patients with renal colic have investigated the combination of radiography and US. Some of these have shown that combining US findings with complementary KUB improved the sensitivity for urolithiasis and had acceptable specificity when compared with either modality alone [34]. In a prospective study of 206 patients with renal colic and suspected urolithiasis, Faget et al [35] found that the combination of radiograph of the abdomen and pelvis and US enabled identification of 50% of the stones that had been identified via CT, and 68% of the stones treated by urological procedures.


Hydronephrosis on Prior Imaging Unknown Cause. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. Historically, IVP was used to evaluate hydronephrosis, but this study is considered obsolete in many settings [6].


Hydronephrosis on Prior Imaging Unknown Cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Although US allows evaluation for increased renal echogenicity, which is nonspecific but can be helpful in assessing for chronic kidney disease, US Abdomen is a less comprehensive examination of the genitourinary system than CT, MRU, renal scintigraphy, or US Color Doppler Kidneys and Bladder Retroperitoneal.


Hydronephrosis on Prior Imaging Unknown Cause. US Color Doppler Kidneys and Bladder Retroperitoneal There is substantial literature on the use of US of the kidneys in the setting of renal colic, including for initial imaging of patients with symptomatic hydronephrosis with unknown cause, and it may be useful in this setting in some clinical situations. Although renal US can identify and grade hydronephrosis, it is less useful for identification of etiology. US does allow evaluation for increased renal echogenicity, which, although nonspecific, can be helpful in assessing for chronic kidney disease. Additionally, US color Doppler kidneys and bladder retroperitoneal allows evaluation of ureteral jets, bladder distension, and postvoid residual bladder volume and can allow measurement of the prostate to evaluate for prostatomegaly. Unilateral elevation of resistive indices is nonspecific but can be seen in the setting of obstruction. However, more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy.


Hydronephrosis on Prior Imaging Unknown Cause. Hydronephrosis on Prior Imaging-Unknown Cause If the degree of hydronephrosis is unknown in a patient with hydronephrosis and renal colic, US may be useful to determine degree of hydronephrosis and therefore the likelihood of symptomatic renal stone [36]. Multiple reports indicate the diagnosis of obstructing stone can be made without further imaging after identification of hydronephrosis [37] or urolithiasis [33] in patients with renal colic. A meta-analysis by Wong et al [36] found that in patients with renal colic, moderate or greater hydronephrosis on POCUS was highly specific (94.4%) for presence of symptomatic renal stone, although they noted that severe hydronephrosis is rare and should prompt consideration of alternate causes. Similarly, Taylor et al [38] found in a study of 483 patients that US finding of either at least stones or moderate to severe hydronephrosis was 97% sensitive and 28.1% specific in predicting need for urologic intervention, noting that all 3 cases with severe hydronephrosis underwent intervention. An additional study evaluating 384 patients with unilateral flank pain found that the degree of hydronephrosis was strongly correlated with the number of calculi but weakly correlated with the size of the calculus [39].


Hydronephrosis on Prior Imaging Unknown Cause. Innes et al [16] report that patients with renal colic and with absent to mild hydronephrosis were deemed less likely to have stone passage failure and therefore do not need further imaging, although they note that CT can be useful in the setting of renal colic with moderate to severe hydronephrosis by US because these patients can be at higher risk of stone passage failure. CT is also better able to identify nonurolithiasis findings requiring additional management than US [25].


Hydronephrosis on Prior Imaging Unknown Cause. Pathan et al [22] reviewed 651 patients with POCUS and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi, provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management.


Hydronephrosis on Prior Imaging Unknown Cause. One prospective study of 46 patients with renal colic, documented ureteral stones, and identifiable ureterovesical jet investigated differences in color Doppler US after oral hydration between these presumed obstructed ureters and their nonobstructed contralateral counterparts, finding significant differences of jet frequency, duration, and peak velocity [41].


Hydronephrosis on Prior Imaging Unknown Cause. Renal and ureteral US with color Doppler can identify calculi as well as hydronephrosis in patients with renal colic, although patients who undergo US for initial evaluation are at increased likelihood of undergoing additional imaging [17]. In a prospective study of 206 patients with renal colic and suspected urolithiasis, Faget et al [35] found that the combination of radiography of the abdomen and pelvis and US enabled identification of 50% of the stones that had been identified via CT and 68% of the stones treated by urological procedures.


Hydronephrosis on Prior Imaging Unknown Cause. Variant 4: Adult. Asymptomatic hydronephrosis in a pregnant patient with unknown cause. Initial imaging. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of asymptomatic hydronephrosis in a pregnant patient with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US).


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen and Pelvis With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. Hydronephrosis on Prior Imaging-Unknown Cause CT Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. CTU Without and With IV Contrast There is limited evidence to support the use of CTU without and with IV contrast for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. DTPA Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients.


Hydronephrosis on Prior Imaging Unknown Cause. Note that use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored [11,12]. DRG with DTPA can also be used to estimate single-kidney GFR but may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13].


Hydronephrosis on Prior Imaging Unknown Cause. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. MAG3 Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients.


Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging.


Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. MRU without IV contrast may provide additional information in this setting.


Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging.


Hydronephrosis on Prior Imaging Unknown Cause. Hydronephrosis on Prior Imaging-Unknown Cause MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. MRU Without and With IV Contrast There is limited evidence to support the use of MRU without and with IV contrast for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging.


Hydronephrosis on Prior Imaging Unknown Cause. MRU Without IV Contrast Although there is limited evidence to support the use of MRU without IV contrast for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause, MRU without IV contrast is preferred over CTU in pregnant patients [15]. MRU without IV contrast may be useful in this setting in some clinical situations and can be combined with anatomical imaging to provide more information than anatomical imaging alone.


Hydronephrosis on Prior Imaging Unknown Cause. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. Historically, IVP was used to evaluate hydronephrosis, but this study is considered obsolete in many settings [6].


Hydronephrosis on Prior Imaging Unknown Cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. It may be useful if there is clinical concern for specific causes identifiable by transabdominal US, although the gravid uterus may limit sonographic evaluation of abdominopelvic structures. US abdomen is a less comprehensive examination of the genitourinary system than MRU without IV contrast or US color Doppler kidneys and bladder retroperitoneal.


Hydronephrosis on Prior Imaging Unknown Cause. Variant 5: Adult. Symptomatic hydronephrosis in a pregnant patient with unknown cause. Initial imaging. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of symptomatic hydronephrosis in a pregnant patient with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US).


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen and Pelvis With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low- dose CT protocol should be used [6].


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low-dose CT protocol should be used [6].


Hydronephrosis on Prior Imaging Unknown Cause. Hydronephrosis on Prior Imaging-Unknown Cause CT Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low-dose CT protocol should be used [6].


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. CTU Without and With IV Contrast There is limited evidence to support the use of CTU without and with IV contrast for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low-dose CT protocol should be used [6].


Hydronephrosis on Prior Imaging Unknown Cause. DTPA Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients.


Hydronephrosis on Prior Imaging Unknown Cause. Note that use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored [11,12]. DRG with DTPA can also be used to estimate single-kidney GFR but may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13].


Hydronephrosis on Prior Imaging Unknown Cause. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. MAG3 Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients.


Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging.


Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause, although MRI can play a useful adjunct role in pregnant patients with renal colic and equivocal or nondiagnostic initial US findings [17].


Hydronephrosis on Prior Imaging Unknown Cause. Hydronephrosis on Prior Imaging-Unknown Cause MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging.


Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause, although MRI can play a useful adjunct role in pregnant patients with renal colic and equivocal or nondiagnostic initial US findings [17].


Hydronephrosis on Prior Imaging Unknown Cause. MRU Without and With IV Contrast There is limited evidence to support the use of MRU without and with IV contrast for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging.


Hydronephrosis on Prior Imaging Unknown Cause. MRU Without IV Contrast There is some evidence for use of MRU without IV contrast for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI.


Hydronephrosis on Prior Imaging Unknown Cause. In a study of 24 pregnant patients with symptomatic hydronephrosis, MRU was noted to show different appearances in physiologic hydronephrosis and pathologic obstruction [44]. Multiple authors suggest that noncontrast MRU should be considered after an equivocal or nondiagnostic US in symptomatic pregnant patients with suspected urolithiasis [6,17].


Hydronephrosis on Prior Imaging Unknown Cause. In a prospective study of 55 nonpregnant patients with hydronephrosis detected on US for urologic symptoms, excluding patients with abnormal renal function given contraindication for IVU, Muthusami et al [30] compared static heavily T2-weighted MRU to reference IVU and determined that MRU had high sensitivity and specificity for detecting (95% and 100%, respectively) and grading (Spearman correlation coefficient 0.92) hydronephrosis, as well as identifying the location of obstruction (90% and 99%, respectively) if present. The authors conclude that static MRU can replace IVU when the latter is contraindicated or technically difficult. The authors note that MRU sensitivity for hydronephrosis grading increased with grade of obstruction.


Hydronephrosis on Prior Imaging Unknown Cause. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging Unknown Cause. Historically, IVP was used to evaluate symptomatic pregnant patients suspected to have renal obstruction; however, due to radiation exposure, IV contrast administration and increased usage of cross-sectional imaging, this study is considered obsolete in many settings [6].


Hydronephrosis on Prior Imaging Unknown Cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. It may be useful if there is clinical concern for specific causes identifiable by transabdominal US, although the gravid uterus may limit sonographic evaluation of abdominopelvic structures. US abdomen is a less comprehensive examination of the genitourinary system than MRU without IV contrast or US color Doppler kidneys and bladder retroperitoneal.


Hydronephrosis on Prior Imaging Unknown Cause. US Color Doppler Kidneys and Bladder Retroperitoneal US is the first-line study for diagnosis of maternal hydronephrosis or renal anatomic abnormalities [5,17,43]. In the pregnant patient with known, symptomatic hydronephrosis, specific findings on US including anteroposterior


Hydronephrosis on Prior Imaging Unknown Cause. 21 Hydronephrosis on Prior Imaging-Unknown Cause


Hydronephrosis on Prior Imaging Unknown Cause. diameter of the renal pelvis and renal RI can help differentiate benign pregnancy-related hydronephrosis and pathologic obstruction and can help predict the need for intervention.


Hydronephrosis on Prior Imaging Unknown Cause. In a prospective single-center study of 1,026 pregnant patients including 295 with hydronephrosis, Bayraktar et al [5] reported a correlation between anteroposterior diameter of the renal pelvis on US and requirement for intervention for symptomatic patients. Ercil et al [9] report the same finding in a retrospective single-center series of 246 pregnant patients with symptomatic hydronephrosis, noting that a diameter above 21 mm on the right had a sensitivity of 91% and a specificity of 84% for predicting intervention, and a diameter above 25 mm on the left had a sensitivity and specificity of 100%. Demir et al [45] reported in a study of 227 pregnant women with symptomatic hydronephrosis that intervention was found to be necessary with renal pelvis anteroposterior diameter >16.5 mm in the first two trimesters and >27.5 mm in the third trimester.


Hydronephrosis on Prior Imaging Unknown Cause. Hydronephrosis on Prior Imaging-Unknown Cause 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.


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


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Introduction/Background Lung cancer is the leading cause of cancer-related deaths in both men and women. While the incidence of the disease for men in the United States has been steadily decreasing since the 1970s, the incidence for women in the United States increased after 1975 before leveling in the 2000s [1]. The major risk factor for lung cancer is personal tobacco smoking, particularly for small-cell lung cancer (SCLC) and squamous-cell lung cancers, but other significant risk factors include exposure to second-hand smoke, environmental radon, occupational exposures, and air pollution. Education and socioeconomic status affect both incidence and outcomes, with a disproportionate amount of the disease burden seen in the poor and poorly educated. The economic cost of caring for lung cancer patients in the United States is over $12 billion per year. Mortality cost from lost productivity also numbers in the billions of dollars [2].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. aThe University of Texas MD Anderson Cancer Center, Houston, Texas. bPanel Chair, University of Chicago, Chicago, Illinois. cMassachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. dStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. eThe University of Texas MD Anderson Cancer Center, Houston, Texas. fUniversity of Southern California, Los Angeles, California. gUniversity of Kentucky, Lexington, Kentucky. hMayo Clinic, Jacksonville, Florida. iHenry Ford Cancer Institute, Detroit, Michigan. jDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. kUniversity of Kansas Medical Center, Kansas City, Kansas. lUniversity of California San Francisco, San Francisco, California. mSpecialty Chair, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. 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.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Reprint requests to: publications@acr.org


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. N Descriptor The eighth edition makes no changes from the previous edition with regard to metastatic nodal disease. The N stage is based on location of metastatic nodes. Increasing number of involved nodal stations negatively affects prognosis [5]. A lymph node size threshold of >10 mm in axial short axis diameter is considered abnormal. The prevalence of metastatic lung cancer in thoracic lymph nodes is 30% for nodes that are 10 to 15 mm in short axis diameter and 67% for nodes >15 mm [7]. Axillary lymph node metastasis occurs in 0.75% of lung cancers [8]. It is not included in the N descriptor but is considered metastatic M1 disease. Nx indicates that lymph nodes cannot be assessed [5]. N0 is consistent with lack of regional node involvement [5]. N1 includes ipsilateral peribronchial, hilar or intrapulmonary lymph node(s) [5]. N2 describes ipsilateral mediastinal or subcarinal lymph node(s) [5]. N3 includes contralateral mediastinal or hilar lymph node(s) and any supraclavicular or scalene node on either side [5].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. M Descriptor The presence of metastatic lung cancer lesions constitutes stage IV disease. Many patients with NSCLC present with metastatic disease [9], and the treatment of stage IV cancers depends on the location and number of lesions. M0 disease is consistent with no distant metastases [5]. The M1 classification is subdivided into three categories: M1a includes satellite nodule(s) in the contralateral lung and cytology proven malignant pleural or pericardial effusion [5]. M1b indicates a single extrathoracic metastasis. This category also includes metastasis in a single nonregional lymph node, considered nodes not in the N descriptor, such as enlarged axillary, internal mammary, and/or abdominal lymph node [5,6]. M1c indicates multiple extrathoracic metastases in one or more organs [5].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Stage Groups for NSCLC Stage groupings have been revised according to statistically significant differences in survival among tumors in the database. The eighth edition includes new differentiation among stage IA tumors based on size of the tumor and a new stage IIIC category for T3 and T4 tumors with N3M0 disease [6].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Classification of mucinous adenocarcinomas is also addressed. The T descriptor is based on size if confined to a single lobe. The tumor is designated as T3 if size cannot be determined but remains in a single lobe. Involvement of multiple ipsilateral lobes is T4 disease. Bilateral lesions are considered M1a [5,10].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. CT Chest For patients with known or suspected NSCLC, a chest CT with intravenous (IV) contrast is recommended. A chest CT without IV contrast may also be obtained.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Noninvasive Clinical Staging of Primary Lung Cancer Chest CT is the modality of choice for initial evaluation of the T descriptor, specifically the size and location of the primary tumor. Diagnosis of chest wall or mediastinal invasion on CT can be equivocal in cases of minimal invasion. Radiologic imaging cannot consistently detect visceral pleural invasion.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Chest CT with IV contrast can aid in the identification of mediastinal or chest wall invasion by tumor, evaluation of hilar lymph nodes, distinction of central obstructing tumor from surrounding atelectasis, and assessment for liver metastases [11,12]. Chest CT without IV contrast is often better able to characterize adrenal nodules than chest CT with contrast, but the benefit of a noncontrast chest CT for this purpose may be obviated by performance of PET or PET/CT.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Accurate N staging of the mediastinum is important in distinguishing resectable from unresectable disease. CT staging of nodal disease in the mediastinum is inadequate because of its low sensitivity and specificity of anatomic size criteria [11]. A meta-analysis of over 7,000 patients found that the prevalence of mediastinal lymph node metastasis was 30%. However, the median sensitivity of contrast-enhanced CT was 55%, and median specificity was 81% for mediastinal nodal disease using the >10-mm short axis diameter criteria [11]. Findings on chest CT of enlarged mediastinal nodes aids in guiding biopsy, as invasive staging of the mediastinum is recommended over imaging alone [11].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. The distribution of mediastinal lymph node metastases is influenced by the location of the primary tumor. Right upper lobe tumors drain to the right paratracheal nodes (2R and 4R), while right middle and lower lobe tumors most frequently drain to the lower right paratracheal and subcarinal nodes (4R and 7R). Nodal metastases for the left upper lobe are most often seen in the aorticopulmonary window and prevascular nodes (5L and 6L). Left lower lobe tumors drain to the prevascular and subcarinal nodes (6L and 7L) [13]. Tumors in the lower lobe superior segments frequently have upper mediastinal lymph node involvement (64%) compared with basal segment tumors [14].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Chest CT is adequate for the identification of contralateral lung nodules constituting M1a disease. It also identifies pleural or pericardial effusions that may need cytological confirmation if pleural or pericardial nodules are not visible. Extrathoracic M1b metastases of the adrenal glands and bone structures may be seen on a chest CT. However, adrenal nodules may not be definitively characterized by CT if IV contrast is used or if intracytoplasmic lipid content is low, which occurs in approximately one-third of adrenal adenomas. Techniques for further evaluation include PET using the tracer fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) with CT, CT adrenal washout protocol, and MR chemical shift of in- and out-of-phase imaging [15]. Liver metastases may be seen if they occur within the included segments on chest CT and are better identified on contrast-enhanced studies, particularly if lesions are small.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is recommended to evaluate for extrathoracic metastases in patients with NSCLC. It is not required for patients with stage 0 adenocarcinoma in situ with an otherwise normal chest CT examination.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. FDG-PET is reported to change management in 14% to 26% of NSCLC patients [16-18]. FDG-PET imaging is superior to CT in detection of nodal and distant metastases [19]. FDG-PET may upstage NSCLC by identifying metastases that were occult on CT imaging or downstage the malignancy by demonstrating lack of glucose metabolism in a suspected lesion [20]. Integrated FDG-PET/CT is more accurate for staging of the N and M descriptors than independent FDG-PET or diagnostic CT [21]. FDG-PET or PET/CT is reported to reduce futile thoracotomies by 20% and 17%, respectively [19,22].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. FDG-PET has sensitivity of 94% and specificity of 82% for characterization of adrenal nodules and is superior to CT alone. Lack of FDG uptake in an adrenal nodule is considered conclusive for benign adrenal adenoma and


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. obviates further workup [31]. Patients with an FDG-avid adrenal nodule as the only site of potential metastatic disease require biopsy confirmation [11].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. The sensitivity, specificity, accuracy, and negative predictive value of FDG-PET for bone metastases are >90%, which is superior to bone scintigraphy [32-35].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Liver metastases may be present in up to 3% to 4% of asymptomatic NSCLC patients at the time of presentation [36]. Although there is heterogeneous physiologic FDG activity in the liver, the accuracy of FDG-PET and PET/CT for liver metastases is reported to be 92% to 100% [37]. When findings are discordant or indeterminate, MRI and/or biopsy are appropriate strategies to evaluate liver lesions.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. FDG-PET cannot be used for tumor measurement purposes, but integrated PET/CT allows anatomic measurement on the CT portion of the examination for the T descriptor.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. CT Abdomen and Pelvis CT abdomen and pelvis with oral and IV contrast may be used as an alternate imaging modality to evaluate for extrathoracic metastasis in lung cancer patients being considered for curative therapy if FDG-PET or PET/CT is not performed [11]. Acquisitions of arterial and portal venous phase sequences are advised.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. CT abdomen and pelvis with oral and IV contrast is recommended in NSCLC patients with abnormal clinical evaluation, including signs or symptoms referable to the abdomen and pelvis and no suspicious extrathoracic findings on chest CT [11].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. All NSCLC with locally advanced stage III or stage IV disease should undergo extrathoracic imaging with either CT abdomen and pelvis or FDG-PET or PET/CT because of the likelihood of occult extrathoracic metastatic disease in up to 37% of cases [11].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Bone Scan Whole Body Technetium-99m (Tc-99m) bone scintigraphy may be used as an alternate imaging modality to evaluate for bone metastasis in NSCLC patients if FDG-PET or PET/CT is not performed or is equivocal for osseous findings.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Bone scintigraphy was historically used to detect osseous metastatic disease in lung cancer patients. A recent meta-analysis found it has a pooled sensitivity of 91.8%; however, the pooled specificity for bone metastases from lung cancer on bone scintigraphy was 68.8%, which is primarily due to confounders such as degenerative disease, inflammation, and prior trauma [38]. FDG-PET and PET/CT have significantly higher sensitivity, specificity, accuracy, and negative predictive value than bone scan [34,35].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. MRI Brain MRI brain without and with IV contrast is recommended in any patient with clinical stage II, III, or IV NSCLC, even in the absence of neurologic symptoms [39]. MRI brain without and with IV contrast is optional in patients with clinical stage IB NSCLC without neurologic symptoms [39]. MRI brain without and with IV contrast is recommended in all NSCLC patients with neurologic symptoms, regardless of stage.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. MRI brain is the preferred imaging modality for evaluation of intracranial metastases, as it is more sensitive for small brain lesions than CT [11,40]. In a meta-analysis of NSCLC patients without neurologic symptoms, the median prevalence of brain lesions was 3% [11]. However, a small study found that 22% of asymptomatic patients with tumor size >3 cm had brain metastases [41]. Any NSCLC patient with neurologic symptoms should be screened for intracranial metastasis [11]. Brain metastases have been associated with adenocarcinoma NSCLC and N2 disease [11,42].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. CT Head CT head with IV contrast can be used as an alternate imaging modality in stage III or IV NSCLC patients and NSCLC patients with neurologic symptoms if MRI head is not obtained. Dual-phase imaging may be useful in this clinical setting.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. CT scanning of the brain is an appropriate method of evaluating for brain metastases in patients with NSCLC [11]. Although MRI has greater sensitivity than CT, the identification of more and smaller brain lesions on MRI compared with CT has not been associated with better survival or the identification of more patients with brain lesions [43,44].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Noninvasive Clinical Staging of Primary Lung Cancer MRI Chest MRI chest without and with IV contrast may be indicated in specific clinical circumstances in NSCLC patients with equivocal findings on CT chest. Focused MRI of the chest may be useful in assessment of chest wall or spinal invasion and tumor involvement of mediastinal structures, including the heart, great vessels, and pericardium. MRI assessment of superior sulcus tumors for brachial plexus involvement is standard of care [45]. MRI is superior to CT for detecting involvement of the neural foramina and spinal canal. Dynamic cine MRI with free breathing can determine lack of invasion if there is respiration-coordinated sliding between the tumor and mediastinum or chest wall, and it can also evaluate for phrenic nerve involvement by lymphadenopathy or the primary tumor.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Conversely, restriction of tumor motion is not conclusive since inflammation or adhesion may also affect mobility [46,47]. MRI is also capable of distinguishing an obstructing tumor from postobstructive atelectasis. Diffusion- weighted imaging (DWI) has been shown to be equal to PET/CT in differentiation of tumor and atelectasis. In the same study, T2-weighted imaging was accurate in 76% of cases [48].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. MRI Abdomen MRI abdomen with chemical shift sequencing may be used to characterize adrenal nodules when findings on CT chest or CT abdomen are equivocal and FDG-PET or PET/CT is not performed. Indeterminate adrenal nodules may be characterized by chemical shift of in- and out-of-phase MRI to assess for the presence of small intracytoplasmic lipid volume in lipid-poor adenomas. Use of MRI for this purpose is declining because of the high sensitivity and accuracy of PET/CT in identifying adrenal metastases from lung cancer [31].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. MRI abdomen with IV contrast may be used to identify small metastatic lesions in the liver when findings are equivocal on CT chest, CT abdomen, FDG-PET, or PET/CT. MRI abdomen with IV contrast has a higher sensitivity than CT, FDG-PET, or PET/CT for detection and characterization of small liver lesions and may be used for more definitive characterization [49].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Radiography Chest Chest radiography is not sufficient for staging of NSCLC.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Variant 2: Noninvasive initial clinical staging of small-cell lung carcinoma. SCLC is an aggressive form of primary pulmonary neuroendocrine tumor with short doubling time and tendency toward early metastasis [50]. The eighth edition of the TNM staging criteria of the American Joint Committee on Cancer applies to patients with SCLC. The TNM staging criteria is recommended to be used in conjunction with the modified Veterans Administration Lung Study Group (VALSG) classification system distinguishing limited stage (LS) from extensive stage (ES) SCLC because of the ongoing use of the VALSG 2-stage classification system in general clinical practice and clinical trials [51-53]. The 5-year overall survival for LS-SCLC is 20% to 25%, while 5-year survival for ES-SCLC approaches zero [51].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. The eighth edition of the TNM criteria of the American Joint Committee on Cancer was developed under the auspices of the International Association for the Study of Lung Cancer and informed by database analysis of nearly 95,000 patients primarily from Europe and Asia [4]. Clinical noninvasive staging by radiologic imaging is the first step in determining the appropriate management for patients with SCLC.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Noninvasive Clinical Staging of Primary Lung Cancer N Descriptor In the eighth edition, the N stage is based on location of metastatic nodes. Increasing number of involved nodal stations negatively affects prognosis [5]. A lymph node size threshold of >10 mm in axial short axis diameter is considered abnormal. The prevalence of metastatic lung cancer in thoracic lymph nodes is 30% for nodes that are 10 to 15 mm in short axis diameter and 67% for nodes >15 mm [7]. Nx indicates that lymph nodes cannot be assessed [5]. N0 is consistent with lack of regional node involvement [5]. N1 includes ipsilateral peribronchial, hilar, or intrapulmonary lymph node(s) [5]. N2 describes ipsilateral mediastinal or subcarinal lymph node(s) [5]. N3 includes contralateral mediastinal or hilar lymph node(s) and any supraclavicular or scalene node on either side [5].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. M Descriptor The presence of metastatic lung cancer lesions constitutes stage IV disease. Many patients with SCLC present with metastatic disease [9], and the treatment of stage IV cancers depends on the location and number of lesions. M0 disease is consistent with no distant metastases [5]. The M1 classification is subdivided into three categories: M1a includes satellite nodule(s) in the contralateral lung and cytology proven malignant pleural or pericardial effusion [5]. M1b indicates a single extrathoracic metastasis. This category also includes metastasis in a single nonregional lymph node, considered nodes not in the N descriptor, such as axillary, internal mammary, or abdominal lymph node(s) [5,6]. M1c indicates multiple extrathoracic metastases in one or more organs [5].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Modified VALSG Staging Under the modified VALSG staging classification, SCLC is considered LS disease when it is confined to a single hemithorax (although local extension may be present); the primary tumor and regional nodes can be addressed by a single radiation port; and ipsilateral supraclavicular nodes can be included in the same radiation field as the primary tumor. Contralateral mediastinal lymph nodes and ipsilateral pleural effusion are also considered LS- SCLC [51,52].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. ES-SCLC includes disease that is not confined to a single radiation port, malignant pericardial effusion, contralateral pleural effusion, and distant hematogenous metastases [51,52].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. The classification of contralateral supraclavicular or hilar lymph nodes is controversial. These nodes should be assessed on a case-by-case basis as to whether they may be feasibly included within a single radiation port [51,52].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. In the combined TNM/VALSG approach for staging of SCLC, T1and T2 lesions and M1a ipsilateral pleural disease correspond with LS-SCLC. T3 and T4 lesions are conditional and may be LS or ES depending on the feasibility of inclusion within a single radiation port. Other M descriptors, including M1a contralateral pleural effusion, M1a pericardial effusion, M1b, and M1c comprise ES-SCLC [54].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. CT Chest For patients with known or suspected SCLC, chest CT with IV contrast is recommended. If concurrent CT abdomen is not obtained, the adrenal glands should be covered. Chest CT without IV contrast may also be used.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Chest CT is the modality of choice for initial evaluation of the SCLC. A large percentage of SCLCs arise from the central lobar or main bronchi. Consequently, the most common appearance of SCLC on imaging studies is a centrally located lung mass or mediastinal mass with hilar involvement [50]. In two-thirds of patients, tumor


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Noninvasive Clinical Staging of Primary Lung Cancer


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. tissue encases mediastinal structures, including vessels, airways, and the esophagus [50]. Diagnosis of chest wall invasion on CT can be equivocal in cases of minimal invasion. Radiologic imaging cannot dependably detect visceral pleural invasion.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Chest CT with IV contrast can aid in the identification of chest wall invasion by tumor, assessment of extent of mediastinal invasion, evaluation of additional mediastinal and hilar lymph nodes, distinction of central obstructing tumor from surrounding atelectasis, and assessment for liver metastases [50,51]. Unenhanced CT may be better able to characterize adrenal nodules.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. CT Abdomen and Pelvis CT abdomen and pelvis with oral and IV contrast is recommended in conjunction with CT chest to evaluate for extrathoracic metastasis in SCLC patients. Acquisition of arterial and portal venous phase sequences is advised. CT abdomen without IV contrast may also be obtained. Dual-phase imaging may be useful in this clinical setting.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Up to 60% of SCLC patients have metastases to the abdominal organs at presentation. The liver and adrenal gland are the most frequent site of hematogenous metastasis [55]. Traditionally, CT abdomen with IV contrast has been used to evaluate for extrathoracic metastases and distinguish between LS-SCLC and ES-SCLC. FDG-PET or PET/CT is increasingly used for this purpose and usually obviates the need for a separate CT abdomen and pelvis examination.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET or PET/CT is recommended in patients with clinical stage I or II LS-SCLC being considered for treatment with curative intent. FDG-PET or PET/CT for further staging is optional if ES-SCLC is established.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. FDG-PET has been shown on average to upstage the disease in up to 18% of patients with clinical LS-SCLC by conventional imaging. A meta-analysis of 7 prospective and retrospective trials found changes in management based on PET findings in 24% to 47% of SCLC patients [52,56,57]. A FDG-PET scan has superior sensitivity and specificity compared with CT in identification of metastatic disease other than brain metastases in SCLC patients [58-60].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Up to 60% of SCLC patients have metastases to the abdominal organs. The liver and adrenal gland are the most frequent site of hematogenous metastasis [55]. Although there is heterogeneous physiologic FDG activity in the liver, the accuracy of FDG-PET and PET/CT for liver metastases is reported at 92% to 100% [37]. When findings are discordant or indeterminate, MRI or biopsy are appropriate strategies to evaluate liver lesions. FDG-PET has sensitivity of 94% and specificity of 82% for characterization of adrenal nodules and is superior to CT alone. Lack of FDG uptake in an adrenal nodule is considered conclusive for benign adrenal adenoma and obviates further workup [31]. Patients with an FDG-avid adrenal nodule as the only site of potential metastatic disease require biopsy confirmation [51].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. The sensitivity, specificity, accuracy, and negative predictive value of FDG-PET for bone metastases is greater than 90% and is superior to bone scintigraphy [33,34].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. MRI Brain MRI brain with IV contrast is recommended in all SCLC patients. MRI brain identifies metastatic lesions in 10% to 15% of newly diagnosed SCLC patients without neurologic symptoms. Up to 12% of patients with otherwise LS-SCLC have intracranial metastases on MRI [61]. MRI is more sensitive than CT for detection of intracranial metastases. MRI brain without IV contrast may be performed.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. CT Head CT head with IV contrast can be used as an alternate imaging modality in SCLC patients if brain MRI is not performed. Although MRI has greater sensitivity for small brain metastases, CT scanning of the brain is an appropriate method of evaluating for brain metastases in patients with SCLC [51].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Bone Scan Whole Body Tc-99m bone scintigraphy may be used as an alternate imaging modality to evaluate for extrathoracic bone metastasis in SCLC patients if FDG-PET or PET/CT is not performed. Bone metastases are present at the time of diagnosis in up to 37% of SCLCs and are a poor prognostic factor [62,63]. Historically, bone scintigraphy was indicated for the workup of all SCLC patients, but FDG-PET and PET/CT have largely replaced it [51].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Noninvasive Clinical Staging of Primary Lung Cancer MRI Chest MRI chest without and with IV contrast may be indicated in specific clinical circumstances in SCLC patients with equivocal findings on CT chest. Focused MRI of the chest may be useful in assessment of chest wall or spinal invasion and tumor involvement of mediastinal structures including the heart, great vessels, or pericardium. SCLC of the superior sulcus is less common than NSCLC [64] but requires MRI evaluation for locoregional disease affecting the brachial plexus [45]. MRI is superior to CT for detecting involvement of the neural foramina and spinal canal. Dynamic cine MRI with free breathing can determine lack of invasion if there is respiration- coordinated sliding between the tumor and mediastinum or chest wall. Conversely, restriction of tumor motion is not conclusive since inflammation or adhesion may also affect mobility [46,47]. MRI is also capable of distinguishing an obstructing tumor from postobstructive atelectasis. DWI has been shown to be equal to PET/CT in differentiation of tumor and atelectasis. In the same study, T2-weighted imaging was accurate in 76% of cases [48].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. MRI Abdomen MRI abdomen with chemical shift sequencing may be used to characterize adrenal nodules when findings are equivocal on CT chest or CT abdomen and FDG-PET or PET/CT is not performed. MRI abdomen with IV contrast may be used to identify small metastatic lesions in the liver when findings are equivocal on CT chest or CT abdomen or FDG-PET or PET/CT.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Indeterminate adrenal nodules may be characterized by chemical shift of in- and out-of-phase MRI to assess for the presence of small intracytoplasmic lipid volume in lipid-poor adenomas. Use of MRI for this purpose is declining because of the high sensitivity and accuracy of PET/CT in identifying adrenal metastases from lung cancer [31].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. MRI abdomen with IV contrast has a higher sensitivity than CT, FDG-PET, or PET/CT for detection and characterization of small liver lesions and may be used for more definitive characterization [49].


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. 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.


Noninvasive Clinical Staging of Primary Lung Cancer PCAs. For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


Hematuria

Hematuria. Causes of hematuria can arise from anywhere along the urinary tract and are generally divided into nephrogenic and urogenic causes. Renal parenchymal disease is the most common benign nephrogenic cause of hematuria [1]. Common benign urogenic causes of hematuria include urolithiasis, infection, and benign prostatic hypertrophy [1]. Malignant causes can occur anywhere in the urinary tract and are the main entity that must be excluded during the imaging evaluation of hematuria.


Hematuria

Hematuria. The most common factors associated with development of a urinary malignancy include gross hematuria, male gender, age >35 years, smoking, occupational exposure to chemicals, analgesic abuse, history of urologic disease, irritative voiding symptoms, history of pelvic irradiation, chronic urinary tract infection, exposure to known carcinogenic agents or chemotherapy, and chronic indwelling foreign body [1,2].


Hematuria

Hematuria. Gross hematuria has a high association with malignancy of up to 30% to 40%, and therefore all patients with gross hematuria should have a full urologic workup [1]. Conversely, patients with microhematuria have a low risk of malignancy ranging from 2.6% to 4%, and, in most patients with asymptomatic microhematuria, a cause is never found [1,2].


Hematuria

Hematuria. Patients without risk factors and with an identified benign cause of microhematuria including vigorous exercise, infection, trauma, menstruation, or recent urologic procedure are unlikely to gain any benefit from a complete imaging workup of microhematuria [1,2,5,6]. Patients with suspected urinary tract infection as a cause of microhematuria should have urine cultures performed, preferably before antibiotic therapy, to confirm an infection [1,2]. Patients with a suspected cause of microhematuria, including interstitial cystitis or benign prostatic hyperplasia, should have the appropriate clinical workup before undertaking imaging, including a pelvic examination in women, a rectal examination in men, and cystoscopy [1,2,6]. Interstitial cystitis, in particular, should


Hematuria

Hematuria. aJohns Hopkins University School of Medicine, Washington, District of Columbia. bNational Institutes of Health Clinical Center, Bethesda, Maryland. cPanel Chair, Northwestern University, Chicago, Illinois. dPanel Vice-Chair, UT Southwestern Medical Center, Dallas, Texas. eUniversity of Rochester Medical Center, Rochester, New York. fThe University of Texas MD Anderson Cancer Center, Houston, Texas. gUniversity of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, American Society of Nephrology. hUniversity of Washington, Seattle, Washington, American Urological Association. iDuke University Medical Center, Durham, North Carolina. jEmory University School of Medicine, Atlanta, Georgia. kThomas Jefferson University Hospital, Philadelphia, Pennsylvania. lCleveland Clinic, Cleveland, Ohio. mMedical University of South Carolina, Charleston, South Carolina, American Urological Association. nUniversity of Alabama at Birmingham Medical Center, Birmingham, Alabama. oUniversity of California San Francisco School of Medicine, San Francisco, California. pUniversity of Maryland School of Medicine, Baltimore, Maryland. qRhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, Rhode Island. rSpecialty Chair, University of Alabama at Birmingham, Birmingham, Alabama.


Hematuria

Hematuria. 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.


Hematuria

Hematuria. Reprint requests to: publications@acr.org


Hematuria

Hematuria. Hematuria be considered in women with chronic pelvic pain along with microhematuria, because this diagnosis is prevalent but often difficult (glomerulonephritis, glomerulonephropathy, acute tubular necrosis, and acute kidney injury) should undergo a concurrent nephrology evaluation, but this should not preclude further evaluation of microhematuria [1,2]. Use of anticoagulant therapy does not alter the urologic evaluation of microhematuria [1,2].


Hematuria

Hematuria. Special Imaging Considerations CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases, acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases.


Hematuria

Hematuria. MR urography (MRU) is also tailored to improve imaging of the urinary system. Unenhanced MRU relies upon heavily T2-weighted imaging of the intrinsic high signal intensity from urine for evaluation of the urinary tract. IV contrast is administered to provide additional information regarding obstruction, urothelial thickening, focal lesions, and stones. A contrast-enhanced T1-weighted series should include corticomedullary, nephrographic, and excretory phase. Thin-slice acquisition and multiplanar imaging should be obtained. For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract.


Hematuria

Hematuria. Discussion of Procedures by Variant Variant 1: Microhematuria. No risk factors, or history of recent vigorous exercise, or presence of infection, or viral illness, or present or recent menstruation. Initial imaging. Patients without risk factors and with a known benign cause of microhematuria are unlikely to gain any benefit from a complete imaging workup of microscopic hematuria. Multiple studies have shown that patients in this category do not derive any benefit from imaging [1,2,6,7].


Hematuria

Hematuria. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of microhematuria. There is no relevant literature regarding the use of arteriography for the initial evaluation of microhematuria.


Hematuria

Hematuria. CT Abdomen and Pelvis For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases.


Hematuria

Hematuria. CT without IV contrast may be a reasonable option in the setting of microhematuria in patients <50 years of age [8]. There is no relevant literature regarding the use of CT with IV contrast for the initial evaluation of microhematuria.


Hematuria

Hematuria. CTU CTU CTU is not useful as a first-line imaging modality for the evaluation of microhematuria in patients with no known risk factors and with an identified benign cause of microhematuria. Lisanti et al [7] found that in 442 patients <40 years of age and without risk factors, no patient had a malignancy-related hematuria finding at CTU.


Hematuria

Hematuria. MRU MRU is not useful as a first-line imaging modality for the evaluation of microhematuria in patients with no known risk factors and with an identified benign cause of microhematuria. There is no relevant literature regarding the use of MRU for the initial evaluation of microhematuria.


Hematuria

Hematuria. Hematuria MRI Abdomen and Pelvis For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. There is no relevant literature regarding the use of MRI for the initial evaluation of microhematuria.


Hematuria

Hematuria. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of hematuria. There is no relevant literature regarding the use of radiography for the initial evaluation of microhematuria.


Hematuria

Hematuria. Radiography Intravenous Urography IV urography (IVU) is no longer used as a first-line imaging modality for the evaluation of hematuria. There is no relevant literature regarding the use of IVU for the initial evaluation of microhematuria.


Hematuria

Hematuria. US Kidneys and Bladder Retroperitoneal Ultrasound (US) is not useful as a first-line imaging modality for the evaluation of microhematuria with no known risk factors and with an identified benign cause of microhematuria.


Hematuria

Hematuria. Variant 2: Microhematuria. Patients with risk factors, without any of the following: history of recent vigorous exercise, or presence of infection or viral illness, or present or recent menstruation, or renal parenchymal disease. Initial imaging. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of microhematuria. There is no relevant literature regarding the use of arteriography for the initial evaluation of microhematuria.


Hematuria


Hematuria

Hematuria. There is no relevant literature regarding the use of CT with IV contrast or CT without IV contrast in this patient population with microhematuria. Initial studies compared CTU with other modalities but without direct comparison to conventional contrast-enhanced CT. However, in current practice, CTU has replaced conventional CT in this situation because of improved detection of urothelial lesions on CTU.


Hematuria

Hematuria. CTU CTU CTU has been shown to be the imaging study of choice for the evaluation of microhematuria because it can evaluate both nephrogenic and urogenic causes of hematuria [1,2,9-12].


Hematuria

Hematuria. In a meta-analysis, CTU proved to be a very sensitive and specific method for the detection of urothelial malignancy with pooled sensitivity of 96% and pooled specificity of 99% and was superior in direct comparison to IVU in terms of sensitivity and specificity [10].


Hematuria

Hematuria. For the detection of upper tract lesions (kidneys and ureters), CTU has been shown to be superior to IVU with an accuracy of 99.6% compared with 84.9% for IVU [12].


Hematuria

Hematuria. CTU has also been shown to be useful for the detection of lower tract lesions (bladder) [11,13]. In one study of 242 patients with microhematuria, the specificity and accuracy of CTU for the detection of lower tract lesions was 98.8% and 97.2%, respectively [11].


Hematuria

Hematuria. In comparison with MRU, one study showed that CTU provided better visibility of the urothelial structures and improved diagnostic confidence [14].


Hematuria

Hematuria. MRU MRU has decreased spatial resolution compared with CTU. Also, small nonobstructive renal calculi and other calcifications as well as small urothelial lesions may be difficult to detect at MRU [15]. However, MRI has shown comparable accuracy to CT in the detection and characterization of renal masses [16].


Hematuria

Hematuria. Hematuria MRI Abdomen and Pelvis For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. There is no relevant literature regarding the use of routine MRI with IV contrast in this patient population with microhematuria.


Hematuria

Hematuria. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of hematuria. There is no relevant literature regarding the use of radiographs for the initial evaluation of microhematuria.


Hematuria

Hematuria. Radiography Intravenous Urography IVU is no longer used as a first-line imaging modality for the evaluation of hematuria. Multiple studies have shown that IVU has a low sensitivity for the detection of renal masses and urinary tract abnormalities in general compared with CT [9,10].


Hematuria

Hematuria. US Kidneys and Bladder Retroperitoneal US is not used as a first-line imaging modality for the evaluation of microhematuria. One study of 141 patients showed US had a lower sensitivity for the detection of urinary tract abnormalities compared with both CTU and MRU [17]. However, a recent large prospective study suggests that kidney and bladder US may be adequate for initial evaluation of microhematuria [18]. In this study, urinary cancer was diagnosed in 0.4% of patients who presented with microscopic hematuria, and all the patients had a renal carcinoma [18].


Hematuria

Hematuria. Variant 3: Microhematuria. Pregnant patient. Initial imaging. Pregnant patients present with microhematuria at a rate similar to nonpregnant patients, and the rate of malignancy in this group is low [2,19].


Hematuria

Hematuria. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of microhematuria in pregnancy. There is no relevant literature regarding the use of arteriography for the initial evaluation of microhematuria.


Hematuria

Hematuria. CT Abdomen and Pelvis CT is not used as a first-line imaging modality for the evaluation of microhematuria in pregnant patients secondary to the risks of radiation exposure to the fetus. The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2].


Hematuria

Hematuria. CTU CTU is not used as a first-line imaging modality for the evaluation of microhematuria in pregnant patients secondary to the risks of radiation exposure to the fetus. The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2].


Hematuria

Hematuria. MRU MRU MRU without and with IV contrast is not used as a first-line imaging modality for the evaluation of microhematuria in pregnant patients. The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. MRU without IV contrast during pregnancy is a reasonable choice with a full workup after delivery once gynecologic bleeding and other benign causes (such as infection) have been excluded [2].


Hematuria

Hematuria. MRI with IV contrast should be avoided in pregnant patients because of uncertainty of effects of gadolinium contrast on the fetus. See the Safety Considerations in Pregnant Patients section below.


Hematuria

Hematuria. MRI Abdomen and Pelvis The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. MRI abdomen and pelvis with and without IV contrast is not used as a first- line imaging modality for the evaluation of microhematuria in pregnant patients. MRI abdomen and pelvis without IV contrast is not used as a first-line imaging modality because of the absence of heavily T2-weighted images of the urinary tract.


Hematuria

Hematuria. Hematuria MRI with IV contrast should be avoided in pregnant patients because of the uncertainty of effects of gadolinium contrast on the fetus. See the Safety Considerations in Pregnant Patients section below.


Hematuria

Hematuria. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of hematuria in pregnancy. There is no relevant literature regarding the use of radiographs for the initial evaluation of microhematuria.


Hematuria

Hematuria. Radiography Intravenous Urography IVU is not used as a first-line imaging modality for the evaluation of microhematuria in pregnancy. There is no relevant literature regarding the use of IVU for the initial evaluation of microhematuria.


Hematuria

Hematuria. US Kidneys and Bladder Retroperitoneal The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. US during pregnancy is a reasonable choice with a full workup after delivery once gynecologic bleeding and other benign causes (such as infection) have been excluded [2,19].


Hematuria

Hematuria. Variant 4: Gross hematuria. Initial imaging. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of gross hematuria. There is no relevant literature regarding the use of arteriography for the initial evaluation of gross hematuria.


Hematuria

Hematuria. CT Abdomen and Pelvis For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases.


Hematuria

Hematuria. There is no relevant literature regarding the use of CT with IV contrast or CT without IV contrast in the evaluation of gross hematuria.


Hematuria

Hematuria. CTU CTU The usefulness of CTU in the evaluation of gross hematuria has been mixed [11,13,20-23]. In one study of 150 patients, the sensitivity and specificity of CTU for the detection of bladder malignancy was 61.5% and 94.9% using cystoscopy as the reference standard [21]. However, in another study of 435 patients, CTU performed comparably to cystoscopy for the detection of bladder malignancy with sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 87%, 99%, 91%, and 98%, compared with 87%, 100%, 98%, and 98%, respectively, for cystoscopy [22]. The recent DETECT (Detecting Bladder Cancer Using the UroMark Test) 1 study recommends CTU for gross hematuria because of an upper tract tumor rate of 0.8% [18].


Hematuria

Hematuria. MRU There is no relevant literature regarding the use of MRU in patients with gross hematuria. Direct comparison of MRI and CTU sensitivity for evaluation of urothelial lesions in gross hematuria is not available in the literature.


Hematuria

Hematuria. MRI Abdomen and Pelvis For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract.


Hematuria

Hematuria. MRI without contrast may be helpful for the evaluation of gross hematuria. In one study of 130 patients, MRI had a sensitivity of 98.5% and PPV of 100% for determining the cause of gross hematuria, using cystoscopy and histopathology as the reference standards [24]. There is no relevant literature regarding the use of MRI with IV contrast in patients with gross hematuria.


Hematuria

Hematuria. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of gross hematuria. There is no relevant literature regarding the use of radiography for the evaluation of gross hematuria.


Hematuria

Hematuria

Hematuria. Hematuria


Hematuria

Hematuria. Radiography Intravenous Urography IVU is not used as a first-line imaging modality for the evaluation of gross hematuria. There is no relevant literature regarding the use of IVU for the evaluation of gross hematuria.


Hematuria

Hematuria. US Kidneys and Bladder Retroperitoneal US, including contrast-enhanced US (CEUS), is not used as first-line imaging modality for the evaluation of gross hematuria. In a study of 95 patients, US had a sensitivity, specificity, PPV, and NPV of 35.3%, 89.9%, 46.2%, and 84.9%, respectively, when using cystoscopy as the reference standard [25]. In a multicenter trial for the diagnosis of bladder cancer, US had a sensitivity, specificity, PPV, and NPV of 50.7%, 99.3%, 84.3%, and 96.5%, respectively, using cystoscopy as the reference standard and, compared with CT, had a sensitivity, specificity, PPV, and NPV of 80.5%, 97.0%, 79.3%, and 97.2%, respectively [18]. Diagnostic accuracy of US in bladder tumor detection could be significantly improved by CEUS, which allows the detection of enhancing tumors, as opposed to nonenhancing hematomas [26]. In 35 patients with cystoscopy and biopsy as the reference standard, CEUS correctly assessed tumor presence or absence in 88% of cases [27].


Hematuria

Hematuria. 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.


Hematuria

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


Chronic Dyspnea Noncardiovascular Origin. Introduction/Background Dyspnea is the subjective experience of breathing discomfort [1], often described as a feeling of breathlessness, or shortness of breath. The perception of dyspnea derives from the interactions of physiological, psychological, environmental, and social factors that may provoke various physiologic and behavioral responses. Clinical history and physical examination may provide insight into the cause or causes of dyspnea; however, laboratory and ancillary tests are also often necessary.


Chronic Dyspnea Noncardiovascular Origin. Overview of Imaging Modalities Radiography Chest The workup of chronic dyspnea is influenced by its severity, the rate of worsening, and the presence or absence of risk factors and other symptoms. The initial evaluation is aimed at determining whether the cause is related to cardiovascular disease, pulmonary disease, a combination of both, or neither. A chest radiograph will typically be performed in the initial workup. The results of the chest radiograph can help guide, and sometimes eliminate the need for, further investigation. Using an algorithmic approach, the combination of chest radiograph and laboratory evaluation may result in a specific diagnosis in one-third of cases [7].


Chronic Dyspnea Noncardiovascular Origin. CT Chest CT has an important role in the imaging evaluation of chronic dyspnea. It is useful when a radiographic abnormality requires further characterization or clinical findings necessitate additional imaging despite a normal radiograph [8,9]. For most routine applications, intravenous (IV) contrast is not needed, although it may be added when vascular abnormalities are in the differential diagnosis. CT protocols should be tailored to meet individual needs and may be determined based on radiographs and clinical features. For dyspnea, thin collimation of the lung parenchyma is essential. Most modern scanners allow this without additional data to be acquired. Adjuncts, such as expiratory images, prone images, and dynamic imaging of the airways, may be applied in certain clinical situations; therefore, knowledge of the suspected diagnosis is essential for planning the CT scan.


Chronic Dyspnea Noncardiovascular Origin. MRI Chest MRI does not currently have a significant role in the evaluation of chronic dyspnea that is not of cardiovascular origin. However, MRI may play a role in the workup of congenital anomalies and diseases of the


Chronic Dyspnea Noncardiovascular Origin. Reprint requests to: publications@acr.org


Chronic Dyspnea Noncardiovascular Origin. Chronic Dyspnea-Noncardiovascular Origin cardiopulmonary axis where both pulmonary imaging and cardiac imaging are desired in a single examination, and in the tissue characterization and assessment of extent of thoracic lesions.


Chronic Dyspnea Noncardiovascular Origin. FDG-PET/CT Skull Base to Mid-Thigh Functional information from PET using the tracer fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)/CT can complement morphologic information derived from chest radiographs and CT. Attempts have been made to determine the efficacy of FDG-PET/CT in the behavior of inflammatory cells, extent of active lung disease, and response to therapy [10]. To date, evidence is limited to small series and has not been subjected to use in pharmacologic trials.


Chronic Dyspnea Noncardiovascular Origin. US Chest Transthoracic ultrasound (US) imaging can be used for assessment of the lung periphery and pleura. Major advantages include portability, ease of use, and real-time imaging capability. US can target abnormalities and complement other imaging studies. It is particularly suited to bedside evaluation. Examples of uses in chronic dyspnea include the assessment of pleural and chest wall pathology, peripheral lung abnormalities, evaluation of diaphragmatic function, and guidance of interventional procedures.


Chronic Dyspnea Noncardiovascular Origin. Discussion of Procedures by Variant Variant 1: Chronic dyspnea. Unclear etiology. Initial imaging. Radiography Chest The chest radiograph should generally be the initial imaging study in chronic dyspnea. Pratter et al [11] reported that it added sufficient information to justify its routine use. In conjunction with cardiomyopathy, two-thirds of cases of chronic dyspnea in a pulmonary clinic were caused by asthma, COPD, and ILD. Pratter et al [7] later employed a prospective algorithmic approach to chronic dyspnea that used the chest radiograph as part of a Tier I evaluation. Karnani et al [2] advocated an algorithm that used the history and physical examination to guide appropriate testing, with the chest radiograph a component of a Level 1 diagnostic workup. Wahls [3] addressed the importance of the chest radiograph in the initial workup of chronic dyspnea in patients both with and without other physical examination findings.


Chronic Dyspnea Noncardiovascular Origin. A chest radiograph might reveal a wide variety of abnormalities in chronic dyspnea that may guide further imaging choices as outlined in subsequent variants. Examples include COPD, ILD, central airways disease, and pleural, chest wall, and diaphragmatic pathology.


Chronic Dyspnea Noncardiovascular Origin. CT Chest In cases where the chest radiograph is normal or does not provide a direct answer, CT can be beneficial for documenting abnormalities not identified on a chest radiograph and guiding further workup [8,12]. In the Multi- Ethnic Study of Atherosclerosis lung study, CT imaging for parenchymal disease was considered to be the most informative imaging test [13].


Chronic Dyspnea Noncardiovascular Origin. MRI Chest MRI has not been evaluated in a systematic manner for the assessment of patients with nonspecific chronic dyspnea, although it may have a role in specific clinical situations.


Chronic Dyspnea Noncardiovascular Origin. US Chest Transthoracic US has good test characteristics for peripheral thoracic abnormalities, although it does not provide the comprehensive evaluation that CT does in the setting of an unspecified cause.


Chronic Dyspnea Noncardiovascular Origin. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT has not been evaluated in a systematic manner for the assessment of patients with nonspecific chronic dyspnea, although it may have a role in specific clinical situations.


Chronic Dyspnea Noncardiovascular Origin. Variant 2: Chronic dyspnea. Suspected chronic obstructive pulmonary disease (COPD). Initial imaging. Radiography Chest In COPD, a radiograph can help exclude alternative diagnoses and evaluate for comorbidities and complications [14]. Wallace et al [15] reported that 14% of chest radiographs ordered during COPD evaluation detected potentially treatable causes of dyspnea other than COPD and lung cancer and that 84% of radiographs assisted management.


Chronic Dyspnea Noncardiovascular Origin. Chronic Dyspnea-Noncardiovascular Origin CT Chest CT has greater sensitivity and specificity than a chest radiograph in determining the type, extent, and distribution of emphysema and bronchial wall abnormalities [16]. CT is able to identify early changes of COPD in asymptomatic and spirometrically normal smokers [17]. It has shown that visual assessments of emphysema and airway disease are accurate and reproducible [18]. In addition, quantitative CT-derived parameters correlate with pulmonary function tests and can be used as imaging biomarkers to follow disease progression [19-23]. Findings have been shown to correlate with patient-reported measures [24-26] and to predict health status in COPD [27]. CT-based phenotypes have prognostic value in predicting future hospitalization, symptomatic decline, and mortality [28,29]. Expiratory CT has been reported to reflect airflow limitation and correlates well with levels of dyspnea [30].


Chronic Dyspnea Noncardiovascular Origin. MRI Chest Numerous MRI techniques are available to evaluate COPD, including hyperpolarized helium, T1 oxygen- enhanced mapping, and equilibrium signal mapping [31-33]. While predominately the subject of research, small studies have shown good correlation with CT-derived measures and provide a rationale for the use of MRI when quantitative imaging measures are needed.


Chronic Dyspnea Noncardiovascular Origin. US Chest US may have a role in defining pleural or diaphragmatic complications related to COPD, but there is no supporting evidence for its use as a diagnostic technique for this condition.


Chronic Dyspnea Noncardiovascular Origin. FDG-PET/CT Skull Base to Mid-Thigh There are no primary data to support the use of FDG-PET/CT to diagnose or manage COPD.


Chronic Dyspnea Noncardiovascular Origin. Variant 3: Chronic dyspnea. Suspected central airways disease. Initial imaging. Radiography Chest Chest radiographs have the potential to identify conditions of the trachea, with accuracy dependent on the condition to be identified. Compared to CT, radiographs have an accuracy of 89% [34]. It should be noted that radiographic findings may be normal or nonspecific. In a single-institution retrospective study of tracheal neoplasms, <50% were directly detectable by a chest radiograph [35].


Chronic Dyspnea Noncardiovascular Origin. CT Chest Examples of airway conditions that may result in chronic dyspnea and can be accurately diagnosed by CT include stenoses, tumors, and end-expiratory airway collapse/tracheobronchomalacia, with strong correlations when compared with bronchoscopy [36,37]. For the last condition, expiratory images are required for diagnosis. Both dynamic airway imaging and static forced expiratory imaging are able to accurately characterize airway collapse when compared with bronchoscopy [38,39]. It has been shown that the degree of expiratory collapse is greater on dynamic studies compared to static forced expiratory images, although the clinical importance of this observation remains unclear [39,40]. Forced expiratory measurements show good reproducibility in healthy volunteers [41]. Volume acquisition of the airways allows for the production of 2-D and 3-D reformations that can better delineate the extent of abnormalities, while perspective volume rendering (virtual bronchoscopy) may be helpful in preprocedural planning.