99m Tc EC Renal Scintigraphy in a Rare Case of Retrovesical Kidney: Insights Into Protocol Considerations and Diagnosis.

A 28-year-old man presenting with swollen feet underwent a 99m Technetium Ethylene-Dicysteine (EC) renal diuretic scintigraphy to evaluate the renal function, which demonstrated a zone of increased tracer uptake in the retrovesical space, indicative of an ectopic kidney with tracer accumulation in the dilated pyelocalyceal system and good excretion following Lasix administration. SPECT/CT imaging further confirmed the presence of the ectopic kidney, which was positioned horizontally just posterior to the bladder, exhibiting normal cortical thickness with a dilated pyelocalyceal system in its upper portion. This case highlights the consideration of ectopic kidney in the retrovesical masses and emphasizes the critical role of urinary catheterization and performing SPECT/CT imaging for accurately evaluating kidney function in such cases.