Compared with noncontrast CT, DT has demonstrated similar intrarenal stone detection rates with respect to stone counts and stone area [9]. In another study, for intrarenal stones, radiography covering the kidneys, ureters, and bladder (KUB) with DT was significantly more accurate than KUB alone (81% versus 48%), with no difference seen between KUB with DT and CT (81% versus 81%). However, in an ex vivo study, accuracy for ureteral stones was lower, with an identification rate of only 24% with KUB and DT, although it was significantly higher than that with KUB alone (13%) [10]. It should be noted that at the time of writing, DT is not available/widely used at many institutions. Lastly, for the purposes of this document, ultrasound (US) examinations for urolithiasis are assumed to include both grayscale and targeted use of color Doppler images for nonvascular assessment, the latter allowing for the assessment of twinkling artifact, appearing as an intense multicolored signal deep to a stone [11]. CT Abdomen and Pelvis Without and With IV Contrast In the genitourinary system, CT abdomen and pelvis without and with IV contrast is commonly performed to evaluate for the presence of enhancement within a renal lesion such as a cyst or mass. There is no relevant literature documenting the additional benefit of nonexcretory phase postcontrast CT in addition to noncontrast CT in the evaluation of urolithiasis. Stone location and size can be accurately depicted at noncontrast CT and have also been associated with spontaneous stone passage rates, with more proximal as well as larger stones having a higher need for intervention [3]. Furthermore, larger stone size and higher density measured at CT have also been shown to be predictors of the need for invasive management [20]. CT allows for accurate assessment of stone size, which is important in planning urologic management.
Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . Compared with noncontrast CT, DT has demonstrated similar intrarenal stone detection rates with respect to stone counts and stone area [9]. In another study, for intrarenal stones, radiography covering the kidneys, ureters, and bladder (KUB) with DT was significantly more accurate than KUB alone (81% versus 48%), with no difference seen between KUB with DT and CT (81% versus 81%). However, in an ex vivo study, accuracy for ureteral stones was lower, with an identification rate of only 24% with KUB and DT, although it was significantly higher than that with KUB alone (13%) [10]. It should be noted that at the time of writing, DT is not available/widely used at many institutions. Lastly, for the purposes of this document, ultrasound (US) examinations for urolithiasis are assumed to include both grayscale and targeted use of color Doppler images for nonvascular assessment, the latter allowing for the assessment of twinkling artifact, appearing as an intense multicolored signal deep to a stone [11]. CT Abdomen and Pelvis Without and With IV Contrast In the genitourinary system, CT abdomen and pelvis without and with IV contrast is commonly performed to evaluate for the presence of enhancement within a renal lesion such as a cyst or mass. There is no relevant literature documenting the additional benefit of nonexcretory phase postcontrast CT in addition to noncontrast CT in the evaluation of urolithiasis. Stone location and size can be accurately depicted at noncontrast CT and have also been associated with spontaneous stone passage rates, with more proximal as well as larger stones having a higher need for intervention [3]. Furthermore, larger stone size and higher density measured at CT have also been shown to be predictors of the need for invasive management [20]. CT allows for accurate assessment of stone size, which is important in planning urologic management.