CURRENT PRACTICE ISSUES S35 CT Urography 1 ONLINE-ONLY CME See www.rsna .org/education /rg_cme.html. LEARNING OBJECTIVES After reading this article and taking the test, the reader will be able to:  Discuss the current role of urologic imag- ing in evaluation of patients with hema- turia.  Describe the two main techniques of CT urography and the strengths and weaknesses of each technique.  Identify the key imaging features of urothelial disease at CT urography. Akira Kawashima, MD, PhD ● Terri J. Vrtiska, MD ● Andrew J. LeRoy, MD ● Robert P. Hartman, MD ● Cynthia H. McCollough, PhD Bernard F. King, Jr, MD With the recent introduction of multi– detector row helical computed tomography (CT), the radiologic evaluation of patients with urologic disease has changed rapidly. Two major approaches to CT urography have been developed. The first approach combines axial CT with timed excretory urography (EU) performed by using conventional ra- diography, digital radiography, or CT scanned projection radiography (SPR). This approach produces traditional projection urograms, and the timed imaging technique is familiar to radiologists and clinicians. Additional excretory phase CT can be performed when the EU find- ings are positive or indeterminate. Improved CT SPR processing tech- nology produces radiographlike images, thus eliminating patient trans- portation between the CT and urography suites or the necessity for a CT suite with a ceiling-mounted x-ray tube and a modified CT table- top for performance of EU. The second approach to CT urography combines axial CT with thin-section excretory phase CT. The near- isotropic volume data set enables creation of high-resolution two- and three-dimensional reformatted images. However, the increased amount of radiation and the time required for data manipulation are concerns. Further studies evaluating large numbers of patients with various urothelial abnormalities will be necessary to determine the op- timal CT urography technique for clinical practice. © RSNA, 2004 Abbreviations: EU = excretory urography, MIP = maximum intensity projection, SPR = scanned projection radiography, 3D = three-dimensional, 2D = two-dimensional Index terms: Genitourinary system, CT, 80.12113 ● Genitourinary system, neoplasms, 80.32 ● Hematuria, 80.899 ● Urography, 80.1221 RadioGraphics 2004; 24:S35–S58 ● Published online 10.1148/rg.24si045513 ● Content Codes: 1 From the Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905. Presented as an education exhibit at the 2003 RSNA sci- entific assembly. Received March 1, 2004; revision requested March 26; final revision received June 4; accepted June 7. All authors have no financial relationships to disclose. Address correspondence to A.K. (e-mail: kawashima.akira@mayo.edu). See the commentary by Caoili and Cohan following this article. © RSNA, 2004 RadioGraphics