Comparison of computed tomographic urography, magnetic resonance urography and the combination of diffusion weighted imaging in diagnosis of upper urinary tract cancer

Purpose: To evaluate the performance of computed tomographic urography (CTU), static-fluid magnetic resonance urography (static-fluid MRU) and combinations of CTU, static-fluid MRU and diffusion weighted imaging (DWI) in the diagnosis of upper urinary tract cancer.

Material and methods: Between January 2010 and June 2011, patients with suspected UUT cancer underwent CTU, static-fluid MRU and DWI (b=1000s/mm(2)) within a 1-week period. The diagnostic performances of CTU, static-fluid MRU and combinations of CTU, static-fluid MRU and DWI for upper urinary tract cancer were prospectively evaluated. The ureteroscopic and histopathologic findings were compared with the imaging findings.

Results: Compared to static-fluid MRU alone (sensitivity: 76/75%, reader 1/reader 2), combining DWI with MRI can increase the sensitivity (sensitivity: 84/84%, p=0.031/p=0.016) of upper urinary tract cancer diagnosis. CTU had greater sensitivity (95/94%) and accuracy (92/91%) than both static-fluid MRU (sensitivity: p<0.001/p<0.001 and accuracy: 83/81%, p=0.001/p<0.001) and static-fluid MRU with DWI (sensitivity: p=0.023/p=0.039 and accuracy: 87/85%, p=0.042/p=0.049) for the diagnosis of upper urinary tract cancers. Compared with CTU alone, CTU with DWI did not significantly increase sensitivity, specificity or accuracy. However, the diagnostic confidence was improved when the combined technique was used (p=0.031/p=0.024). Moreover, there was no significant change in sensitivity, specificity, accuracy or diagnostic confidence when static-fluid MRU was used in combination with CTU and DWI.

Conclusion: Although there is a potential role for static-fluid MRU and static-fluid MRU with DWI in urinary tract imaging, CTU is still the better choice for the diagnosis of upper urinary tract cancer. Combining DWI with CTU can help improve confidence in upper urinary tract cancer diagnoses.