In CT urography, what phases are acquired and what information does each provide?

In CT urography, what phases are acquired and what information does each provide?

• A. Non-contrast phase for calculus; nephrographic phase for parenchymal enhancement; excretory phase for urothelium and collecting system opacification.
• B. Arterial phase for vessel mapping; portal phase for liver; delayed for function.
• C. Non-contrast for soft tissues; arterial for arteries; excretory for mucosal details.
• D. Bone phase; lipiodol phase.

Answer: (A)

The question tests how CT urography uses a sequence of phases to visualize different parts of the urinary tract. The non-contrast phase is acquired first so calcifications are visible without any interference from contrast; this makes it ideal for detecting stones. The nephrographic phase comes a short time after contrast injection to show how the renal parenchyma enhances, helping assess the shape, structure, and any focal lesions within the kidney. Finally, the excretory phase is delayed long enough for the contrast to be filtered into and outline the urothelium and collecting system, allowing clear visualization of the calyces, renal pelvis, ureters, and any filling defects or urothelial abnormalities. This combination—non-contrast for calculus, nephrographic for parenchymal enhancement, and excretory for urothelium and collecting system opacification—is precisely what the correct answer describes. Other options misstate which phases are used or what organs they reveal (for example, arterial or portal phases relate to vascular or hepatic imaging, not standard CT urography).

The question tests how CT urography uses a sequence of phases to visualize different parts of the urinary tract. The non-contrast phase is acquired first so calcifications are visible without any interference from contrast; this makes it ideal for detecting stones. The nephrographic phase comes a short time after contrast injection to show how the renal parenchyma enhances, helping assess the shape, structure, and any focal lesions within the kidney. Finally, the excretory phase is delayed long enough for the contrast to be filtered into and outline the urothelium and collecting system, allowing clear visualization of the calyces, renal pelvis, ureters, and any filling defects or urothelial abnormalities. This combination—non-contrast for calculus, nephrographic for parenchymal enhancement, and excretory for urothelium and collecting system opacification—is precisely what the correct answer describes. Other options misstate which phases are used or what organs they reveal (for example, arterial or portal phases relate to vascular or hepatic imaging, not standard CT urography).