[Evaluation of clinical usefulness of MR urography]

MR urography (MRU) is an image diagnostic method which provides us with the image of urinary retention under non-invasive procedures. This time, MRU was conducted in the patients who were suspected to have urinary passage disorder, and its clinical usefulness was compared with that of drip infusion pyelography (DIP) or retrograde pyelography (RP).

The study was conducted in 65 patients who were suspected to have obstructive uropathy based on the ultrasonographic findings. MRU was conducted by means of fast SE method to obtain heavy T2-weighted image. The urogram was reconstructed by means of MIP (maximum intensity projection) method. As imaging examinations, MRU, DIP and RP were conducted respectively in 65, 47 and 27 patients. Evaluation of clinical usefulness of MRU and its indications were conducted with respect to (1) the degree of urinary retention which is identifiable by MRU by (2) comparing performance of MRU and that of other image diagnostic methods based on the scores given to MRU and other methods according to the following scale: Urinary tract is not identifiable 0 point Urinary tract is slightly identifiable 1 point The obstructive region is almost clearly identifiable 2 points The lesion causative for obstruction is identifiable 3 points.

1) Mild urinary retention for which overall image of urinary tract was barely identifiable by DIP was identifiable by MRU. 2) In the comparison between DIP and MRU, 24 patients whose urinary tracts were totally unidentifiable by DIP was given was 2.4 points in the average for the identifiability of urinary retention by MRU. Conversely, only poor images were attainable by MRU in the patients whose urinary flow was clearly seen in DIP. The patients whose urinary flow was clearly seen in RP was give 1.9 points in the average for the identifiability of urinary retention by MRU, indicating that relatively poor images were attainable by MRU in those patients.

Mild urinary retention for which overall image of urinary tract was barely identifiable by DIP was identifiable by MRU. Therefore, it is suggested that MRU is more useful in the case that only poor images were attainable by DIP. MRU is not the one which can replace RP including urinary cytodiagnosis but is useful to identify the location of the urinary tract tumor which is unidentifiable by RP or to monitor the progress of the urinary obstruction caused by benign diseases.