CT techniques shown to improve accuracy of stone measurements include use of coronal reformations, viewing on bone window, and use of magnified views [21-23]. Lastly, noncontrast CT has also shown utility in aiding in diagnosis of flank pain other than urolithiasis [24]. CTU Without and With IV Contrast CTU involves the addition of a delayed, excretory phase images that opacifies the upper and lower urinary tracts and allows for more complete evaluation of these structures relative to nonurogram CT techniques. With urinary tract opacification, CTU confirms the ureteral location of a calculus, distinguishing from stone mimics such as an adjacent phlebolith. CTU can better confirm the degree of obstruction caused by a ureteral stone and potentially also aid in diagnosing a radiolucent stone, albeit a rare entity. However, there is no relevant literature documenting a difference in accuracy of additional excretory phase postcontrast imaging relative to noncontrast CT alone in the evaluation of urolithiasis. MRI Abdomen and Pelvis Without and With IV Contrast MRI abdomen and pelvis without and with IV contrast is defined as any MRI 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 limited literature on the use of MRI abdomen and pelvis without and with IV contrast in the evaluation of the patient with suspected urolithiasis; however, in one study, T2- weighted imaging has been shown to improve sensitivity of detection of perirenal fluid in the setting of acute calculus ureteric obstruction compared with fat stranding on unenhanced CT (77% versus 45%, respectively) [25]. In another study, also in the setting of acute ureteric obstruction, both excretory urography and T2-weighted MRI showed obstruction in a high percentage of cases [26].
Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . CT techniques shown to improve accuracy of stone measurements include use of coronal reformations, viewing on bone window, and use of magnified views [21-23]. Lastly, noncontrast CT has also shown utility in aiding in diagnosis of flank pain other than urolithiasis [24]. CTU Without and With IV Contrast CTU involves the addition of a delayed, excretory phase images that opacifies the upper and lower urinary tracts and allows for more complete evaluation of these structures relative to nonurogram CT techniques. With urinary tract opacification, CTU confirms the ureteral location of a calculus, distinguishing from stone mimics such as an adjacent phlebolith. CTU can better confirm the degree of obstruction caused by a ureteral stone and potentially also aid in diagnosing a radiolucent stone, albeit a rare entity. However, there is no relevant literature documenting a difference in accuracy of additional excretory phase postcontrast imaging relative to noncontrast CT alone in the evaluation of urolithiasis. MRI Abdomen and Pelvis Without and With IV Contrast MRI abdomen and pelvis without and with IV contrast is defined as any MRI 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 limited literature on the use of MRI abdomen and pelvis without and with IV contrast in the evaluation of the patient with suspected urolithiasis; however, in one study, T2- weighted imaging has been shown to improve sensitivity of detection of perirenal fluid in the setting of acute calculus ureteric obstruction compared with fat stranding on unenhanced CT (77% versus 45%, respectively) [25]. In another study, also in the setting of acute ureteric obstruction, both excretory urography and T2-weighted MRI showed obstruction in a high percentage of cases [26].