Mucosal detail at CT virtual reality: Surface versus volume rendering

PURPOSE: To evaluate computed tomographic virtual reality with volumetric v ersus surface rendering. MATERIALS AND METHODS: Virtual reality images were reconstructed for 27 nor mal or pathologic colonic, gastric, or bronchial structures in four ways: t he transition zone (a) reconstructed separately from the wall by using volu me rendering; (b) with attenuation equal to air; (c) with attenuation equal to wall (soft tissue); (d) with attenuation halfway between air and wall. The four reconstructed images were randomized. Four experienced imagers bli nded to the reconstruction graded them from best to worst with predetermine d criteria. RESULTS: All readers rated images with the transition zone as a separate st ructure as overwhelmingly superior (P < .001): Nineteen cases had complete concurrence among all readers. The best of the surface-rendering reconstruc tions had the transition zone attenuation equal to the wall attenuation (P < .001). The third best reconstruction had the transition zone attenuation equal to the air attenuation, and the worst had the transition zone attenua tion halfway between the air and wall attenuation. CONCLUSION: Virtual reality is best with volume rendering, with the transit ion zone (mucosa) between the wall and air reconstructed as a separate stru cture.