What type of study uses dye to visualize the kidney pelvis?

The correct answer is retrograde pyelogram, which is a specialized imaging procedure that uses a dye (contrast material) to visualize the structures of the kidney, specifically the renal pelvis and ureters. During this procedure, a catheter is inserted through the urethra, bladder, and into the ureters up to the renal pelvis, where the contrast dye is injected. This allows for detailed imaging via X-ray, showcasing any obstructions, tumors, or anatomical anomalies in the urinary tract.

In contrast, while MRI and CT scans can provide detailed images of the kidneys and surrounding structures, they do not specifically use a dye in the same manner as a retrograde pyelogram for the purpose of directly visualizing the kidney pelvis through catheterization. Although CT scans often use contrast material, the method of visualization and purpose differs from the retrograde pyelogram. Ultrasound, on the other hand, uses sound waves rather than dye to visualize structures and would not be suitable for specifically highlighting the renal pelvis in the same way a retrograde pyelogram does.