Computed tomography

Computed tomography (CT) is the major imaging modality for renal cell carcinoma (RCC) which is the most common kidney cancer in adults and urothelial carcinoma of the bladder. CT is the essential modality for the diagnosis, treatment planning, staging, and observation of RCC. CT can be performed in various stage before and after injection of an intravenous (IV) contrast agent. Nephrographic stag is the most reliable stage for the detection of RCC. An important and one of a kind finding in RCC is tumor extension and thrombosis to inferior vena cava (IVC) and renal vein. This has been reported in 4% to 10% of all renal neoplasms, having therapeutic and prognostic importance. This invasion can only be limited to the vessel wall. CT is very useful for venous extension of RCC, best seen in the corticomedullary stage of contrast enhancement. Enhancement of the thrombus helps to differentiate tumor thrombus from bland thrombus. Although CT can be as sensitive as MRI in assessment of tumor thrombus, in some cases it may fail because of extrinsic pressure over the vein or inadequate filling of IVC.
According to Int J Urol computed tomography urography presently has a higher diagnostic accuracy for upper tract urothelial carcinoma (94.2-99.6%) than intravenous urography (80.8-84.9%), and has replaced intravenous urography as the first-line imaging test for investigating patients with a high risk of upper tract urothelial carcinoma 2. On CT images, UTUC is characterized by small filling defects, wall thickening, a mass lesion, or, in rare cases, a renal parenchyma?infiltrating lesion.
However, CT angiography, a less invasive alternative to conventional angiography, is useful for evaluating many urinary tract conditions. A radiopaque contrast agent is sometimes injected by vein (intravenously). Images are taken immediately when the contrast agent is injected, to provide more detail about the kidneys and sometimes 10 minutes later to provide more detail about the muscular tubes that carry urine from the kidneys to the bladder (ureters). Disadvantages of include when a radiopaque contrast agent is given, risk of kidney damage and allergic-type reactions CT and, exposure to significant amounts of ionizing radiation 3.