PET/CT > Normal Activity > Abdomen and Pelvis > Urinary Tracts

Urinary Tracts

Normal kidneys


FDG is primarily excreted via the genitourinary system. Unlike glucose at normal blood levels, FDG is poorly reabsorbed by the kidneys allowing filtered, highly concentrated FDG to be excreted in the urine. This results in very intense tracer activity in the renal collecting systems, ureters, and urinary bladder. Therefore, detecting pathology within or adjacent to the kidneys, ureters, and bladder can be difficult.

Normal bladder


Normally the kidneys, ureters, and bladder can be correctly identified by their anatomic locations and high level of excreted activity. Variants such as absence of a kidney, ectopic kidney, and horseshoe kidney are sometimes detected on PET imaging. Patients are asked to void immediately prior to scanning to facilitate drainage of tracer-laden urine out of the collecting systems and into the bladder so that the kidneys and the tissues adjacent to the kidneys and ureters can be better evaluated.

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