Fig 1.
Flow chart of study patients, indications for imaging and results as determined by clinical evaluation, the results of imaging studies and the final histopathological diagnosis. (UC = Urothelial carcinoma; RCC = Renal Cell Carcinoma).
Table 1.
Magnetic Resonance (MR) and Computed Tomography (CT) Urography Imaging protocols.
Fig 2.
MR urography achieves comparable performance compared to CT urography.
Three-dimensional Volume Rendering reconstruction of the urinary tract against a faded background from the images obtained with CT urography (A) and MR urography (B) excretory phases.MR urography achieved a comparable diagnostic performance.
Fig 3.
Visualisation of tumors at CT and MR urography.
A 78 year old female patient presented with macroscopic hematuria. Axial contrast enhanced MRI (A) and CT (B) images at the level of the right renal pelvis showed an enhancing intraluminal mass (arrows) with no tumor extension outside the renal pelvis wall. A tumorous filling defect was also well visualized in the excretory phase MRU (C) and CTU (D) images and the presence of a small synchronous tumor on the opposite wall (arrowheads) was better recognized in the excretory phase images. The tumor filled the renal pelvic cavity (E, Arrow) resulting in subtotal occlusion with associated intrarenal-cavity dilatation as visualized on a postero-anterior three-dimensional volume rendering MRU. The tumor area showed restricted diffusion as estimated via the diffusion weighted imaging (F; b = 800; Arrow) with ADC values of 0.78 × 10−3 mm2/s (not shown). Final histopathology revealed a grade 2 pT1 urothelial carcinoma.
Table 2.
Visualization scores.
Table 3.
Percentage visualization of the upper urinary tract.
Fig 4.
Artefacts encountered during imaging.
The hydration protocol incorporated into the computed tomography resulted in better dilatation of the renal cavities as seen in image A (axial CT) compared to magnetic resonance excretory urography (MRU, image B), but occasionally at the expense of a contrast layering effect (Area between arrows). A susceptibility artefact due to the presence of a metallic sterilization clip in the MRU (image C, arrow) results in a void signal area. The clip produced no artefacts at CT (image D, thick arrow) and thin arrows show the position of distal ureters. The artefact at MRU impaired the visibility of a short ureteral segment as seen in the volume reconstruction MRU image E (arrow).
Table 4.
Diameter measurement of the renal pelvis and ureter.
Fig 5.
The value of MR imaging at different time intervals.
MR urography maximum intensity projections at 5 min (A), 10 min (B) and 15 min intervals after the administration of contrast show no difference in visualization of the upper urinary tract (UUT) at MR-combined different time intervals. Different segments can be better visualized at different time intervals therefore improving the overall UUT visibility and provided comparable performance with CT urography (D, volume rendering reconstruction).