Lithiasic obstructive uropathy - Hydronephrosis characterization by magnetic resonance pyelography

Objectives: The purpose of this study was to evaluate the role of magnetic resonance (MR) pyelography in patients affected by hydronephrosis due to ureteric stones, in order to identify a pyonephrotic condition. Materials and Methods: In the last 3 years, 315 patients, who had originally been investigated by ultrasonography, were evaluated with MR pyelography in order to define the etiology of obstruction. In 67 patients hydronephrosis was referred as caused by lithiasis. Results: MR pyelography not only confirmed urinary tract dilatation in all patients, but also identified grade and site of obstruction, both in acute dilatation ( 25 patients) and in chronic obstructions ( 42 patients). In 7 patients, MR pyelography documented pyonephrosis that was obviously confirmed by nephrostomic drainage. Conclusion: MR pyelography, made with ultrafast breath-hold sequences, has a great value in identifying hydronephrosis in patients with ureteric stones. Furthermore, it provides the chance to identify pyonephrosis requiring an immediate drainage of the kidney before major complications develop.