MR pyelography and conventional MR imaging in urinary tract obstruction

Purpose: To evaluate the possible role of MR imaging in the assessment of p atients with urinary tract obstruction by combining conventional MR imaging and MR pyelography (MRP). Material and Methods. Forty-three patients with dilated upper urinary tract were studied with a high gradient strength 0.5 T magnet. Respiratory compe nsated T1-weighted, SE and T2-weighted TSE sequences were acquired in all p atients. MRP images were obtained by using a respiratory compensated 3D T2- weighted TSE sequence. MRP images were reconstructed with a MIP algorithm. In all cases, urography and/or ascending pyelography were also performed. I mages were independently evaluated by two radiologists. Results. The dilated tract ureter and the level of the obstruction could be correctly demonstrated in all cases. The cause of the obstruction was corr ectly demonstrated by examiner 1 in 90% and by examiner 2 in 88%. The inter observer agreement was high with a kappa-value of 0.96. Conclusion. In cases of obstructive hydroureteronephrosis MR imaging, combi ning MRP and conventional sequences, can be proposed as an accurate techniq ue in the assessment of level and cause of obstruction.