Virtual pyeloscopy using volumetric depth peeling

The aim of the study is to test a new volume-rendering method, volumetric depth peeling (VDP), for use in virtual pyeloscopy.

VDP was applied to axial contrast-enhanced source computed tomographic (CT) images and coronal reformatted maximum intensity projections of three contrast-filled gloves containing objects of varying density. Similar renderings were performed on CT urograms performed to evaluate hematuria (n = 20). Renderings were assessed for anatomic appearance of ureters and specific calyces in comparison with source images.

Objects of soft-tissue and calcific density ranging in size from 4 to 20 mm were identified by using VDP within the glove phantoms. Normal and deformed renal calyces were well visualized by using VDP; however, two stones were not identified. The minimal ureteral width that could be visualized was 3 mm.

VDP may be a useful technique for virtual pyeloscopy providing that a robust and user-friendly computer interface can be developed.