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Abstract:
Computed tomography (CT) is currently the standard modality for staging of urologic cancer in most institutions. It is used for demonstrating nodal involvement, and for demonstrating invasion of the primary lesion into surrounding fat, muscle, or other tissues or organs. It is also useful for demonstrating hepatic metastases in renal and vesical carcinomas. The problem with computed tomography, however, is that it can only show whether the nodes are large or not; neither can it show the nodal architecture, nor can it detect metastases in normal-sized nodes. Intravesical sonography has been helpful for staging papillary bladder cancer. Transrectal sonography has been somewhat helpful for demonstrating seminal vesicle invasion in patients with prostatic carcinoma. Inferior vena cavography and renal venography can be helpful for demonstrating whether a renal, renal pelvic, or adrenal carcinoma has extended into either vein. Lymphography can show nodal architecture and metastases in normal-sized nodes, and can make possible needle biopsy of abnormal-appearing nodes even if they are normal sized. The examination cannot show very small or microscopic nodal metastases, and it can miss abnormal nodes totally if they have been completely replaced by metastases. It yields false positives when fatty or fibrous infiltration of the nodes has occurred. It is used primarily for staging patients with testis or prostatic carcinoma. Bone scans are essential for staging prostatic carcinoma. Magnetic resonance imaging (MRI) is helpful in some cases of renal cell carcinoma. Multiplanar imaging prevents overstaging. It is also accurate for showing whether the renal vein or inferior vena cava are involved. Enlarged lymph nodes are easily distinguished from vessels. For staging bladder carcinoma involving the fundus or base of the bladder, MRI is better than CT. Microscopic nodal metastases, such as are common in carcinoma of the prostate, currently are not detected by any imaging modality.