IMAGING

Prospective comparison of computerized tomography and excretory urography in the initial evaluation of asymptomatic microhematuria
Gray Sears CL, Ward JF, Sears ST, Puckett MF, Kane CJ, Amling CL
Naval Medical Center San Diego, San Diego, California, USA, and Naval Hospital Okinawa, Okinawa, Japan
J Urol. 2002; 168:2457-60

• Purpose: The ideal imaging study for evaluation of the upper urinary tract in patients with macrohematuria has been debated. We retrospectively compared the diagnostic yield of computerized tomography (CT) to excretory urography (IVP) in the initial evaluation of asymptomatic microhematuria.
• Material and Methods: Between December 1998 and June 2001, 115 patients presenting with asymptomatic microhematuria underwent CT and IVP before cystoscopy. Helical CT images with 5 mm. adrenal and kidneys slices with and without contrast material were followed by delayed 5 mm. ureteral contrast images through the bladder base. Each CT and IVP was examined by a radiologist who was blinded to the result of the other imaging study. Diagnostic yields of the imaging techniques were compared using the test of 2 proportions and chi-square analysis.
• Results: Radiographic abnormalities were noted on CT or IVP in 38 patients. Sensitivity was 100% for CT and 60.5 for IVP, and specificity 97.4% for CT and 90.9% for IVP. CT accuracy was 98.3% compared to IVP accuracy which was 80.9% (p<0.001). A total of 40 nonurological diagnoses were made by CT, including 3 abdominal aortic aneurysms and 1 iliac artery aneurysm. No additional diagnoses were made by IVP. Fewer additional radiographic studies were recommended after CT than after IVP.
• Conclusions: The use of CT in the initial evaluation of asymptomatic microhematuria results in better diagnostic yield. In addition, more nonurological diagnoses can be made and less additional radiography is needed to confirm a diagnosis.
  
  
• Editorial Comment
  Radiological imaging plays an important role in the initial evaluation of patients with painless micro- or macrohematuria. Helical CT is the method of choice for evaluation of the kidneys and urinary collecting system, including renal masses, infection, trauma, and urinary calculi. This method, however, has limitations for demonstrating the urothelium, and thus IVP still remains the initial imaging procedure for evaluating hematuria in many centers. Recently, a new technique called CT-urography has been developed, and successfully used for evaluating the urothelium. CT-urography can be performed with a single detector CT, or preferably with a multi-detector row CT (multi-slice CT). With multi-slice CT, multiple channels of data are acquired simultaneously, allowing thinly collimated images to be obtained through the entire urinary tract in a single breath hold. For better demonstration of the entire ureters, usually a supplemental infusion of normal saline can be used in order to obtain maximum distension, and consequently optimal visualization of the normal anatomy of the renal pelviocalyceal system, ureters, and entire bladder .This technique also provides high resolution multiplanar and 3D image reconstructions, which are similar to the conventional IVP films. This article is significant because it shows that an excellent degree of accuracy (98.3%) compared to IVP (80.9%), can be obtained with single slice helical CT. Obviously the single detector CT-urography must be used under strict diagnostic criteria. Obviously multi-detector row CT offers better image resolution than single slice helical CT. In our opinion , there is no doubt that in the near future CT-urography will completely replace the IVP for the evaluation of patient with hematuria. Besides urological abnormalities, CT-urography can detect several causes of non-urological diseases causing hematuria. IVP is an insufficient imaging method for a complete evaluation of a patient with hematuria, and isolated — or even associated —complementary radiographic studies are usually recommended.

Reference
1. McTavish JD, Jinzaki M, Zou KH, Nawfel RD, Silverman SG: Multi–detector row CT urography: comparison of strategies for depicting the normal urinary collecting system. Radiology 2002; 225:783-90.

Dr. Adilson Prando
Department of Radiology
Vera Cruz Hospital
Campinas, São Paulo, Brazil