The Radiology of Upper Tract Collecting System Neoplasms

While excretory pyelography, ultrasound, PET-CT, and MRI all have roles in the assessment of upper tract neoplasms, the workhouse is the CT. Ultrasound allows for dynamic assessment of masses and PET-CT allows for assessment of metabolic activity which allows for neoplasms to be detected in what would be otherwise normal appearing lymph nodes. MRI urography can be useful but is limited by expense, length of exam, and interpretative expertise. In CT, both pre- and post-contrast imaging is needed. Split bolus techniques have allowed for the reduction of radiation. The examination can be tailored to optimally opacify the collecting system to allow for detection of filling defects. It also permits for accurate assessment of extrarenal extension of disease. Appearance of the neoplasm can be varied that include mural and polypoid and often have an irregular surface. Not only can the masses be seen but also the effect on surrounding structures causing obstructions. A wide range of non-neoplastic conditions can have a similar appearance but will present with a different clinical picture. Close collaboration between the radiologist and urologist is therefore required.