IVU, US, and upper gastrointestinal or small-bowel follow-through have very low yields for fistula [46,47]. MRU MRU is useful to evaluate suspected urinary tract obstruction, hematuria, and congenital anomalies, as well as postoperative anatomy. The most common MRU techniques for displaying the urinary tract can be divided into two categories: static-fluid MRU and excretory MRU. Static-fluid MRU makes use of heavily T2-weighted sequences to image the urinary tract as a static collection of fluid, can be repeated sequentially (cine MRU) to better demonstrate the ureters in their entirety and to confirm the presence of fixed stenoses, and is most successful in patients with dilated or obstructed collecting systems. Excretory MRU is performed during the excretory phase of enhancement after the IV administration of gadolinium-based contrast material. Diuretic administration is integral to excretory MRU to better demonstrate nondilated systems. Static-fluid and excretory MRU can be combined with conventional MRI for comprehensive evaluation of the urinary tract [48]. MRU can be used to evaluate the urinary tract and provides more functional information than CT provides. However, MRU is less established and less reliable and thus results in lesser diagnostic image quality relative to CTU [23]. In comparison to CTU, it necessitates a longer examination time and is less sensitive than CT for detecting urinary tract calculi. In a study of 149 patients, MRU demonstrated 69% sensitivity for detecting calculi versus 100% for CT [49]. However, MRU has shown increased sensitivity for perirenal fluid and ureteric dilatation in comparison with CT in the setting of acute obstruction [50]. Multiplanar reconstruction images in the coronal and sagittal planes are commonly included in MRU images to improve visualization of urinary tract abnormalities [27,48].
Recurrent Lower Urinary Tract Infections in Females. IVU, US, and upper gastrointestinal or small-bowel follow-through have very low yields for fistula [46,47]. MRU MRU is useful to evaluate suspected urinary tract obstruction, hematuria, and congenital anomalies, as well as postoperative anatomy. The most common MRU techniques for displaying the urinary tract can be divided into two categories: static-fluid MRU and excretory MRU. Static-fluid MRU makes use of heavily T2-weighted sequences to image the urinary tract as a static collection of fluid, can be repeated sequentially (cine MRU) to better demonstrate the ureters in their entirety and to confirm the presence of fixed stenoses, and is most successful in patients with dilated or obstructed collecting systems. Excretory MRU is performed during the excretory phase of enhancement after the IV administration of gadolinium-based contrast material. Diuretic administration is integral to excretory MRU to better demonstrate nondilated systems. Static-fluid and excretory MRU can be combined with conventional MRI for comprehensive evaluation of the urinary tract [48]. MRU can be used to evaluate the urinary tract and provides more functional information than CT provides. However, MRU is less established and less reliable and thus results in lesser diagnostic image quality relative to CTU [23]. In comparison to CTU, it necessitates a longer examination time and is less sensitive than CT for detecting urinary tract calculi. In a study of 149 patients, MRU demonstrated 69% sensitivity for detecting calculi versus 100% for CT [49]. However, MRU has shown increased sensitivity for perirenal fluid and ureteric dilatation in comparison with CT in the setting of acute obstruction [50]. Multiplanar reconstruction images in the coronal and sagittal planes are commonly included in MRU images to improve visualization of urinary tract abnormalities [27,48].