Virtual endoscopy of the urinary tract from T2-weighted and gadolinium-enhanced T1-weighted MR urographic images.

Purpose: To determine the diagnostic performance of T-2-weighted (T2w) and gadolinium-enhanced T-1-weighted (T1w-Gd-enhanced) MR urographic images for virtual endoscopy of the urinary tract. Materials and Methods: 36 patients underwent MR urography at 1.5 T. In each patient a T2w (3D-TSE, respiration-triggered) and a T1w-Gd-enhanced sequence (T1-FFE, breathhold) were acquired. Data reconstruction was performed as maximum intensity projection (MIP) and virtual endoscopy (VE). Results: Combined analysis of MIP and VE delineated 32 of 36 pathologies; 86% (19/22) of intraluminal pathologies could be depicted by VE and 15% (3/22) by MIP (p less than or equal to0.01). For the assessment of the renal pelvis, MIP was superior to VE in 55% (39/71). Concerning the ureter, MIP was equal in 52% (37/71) and superior to VE in 45% (32/71). For virtual ureterorenoscopy both data sets were comparable in their diagnostic performance. T2w data sets were superior for virtual cystoscopy because no contrast medium is required in cases of renal failure and sedimentation artifacts can be avoided. Conclusion: For the depiction of the upper urinary tract, MIP is in most cases equally good or superior to VE. However, virtual endoscopy of the urinary tract, especially virtual cystoscopy, is a useful tool for the depiction of intraluminal pathology.