MR urography may be the future of urologic imaging

MR urography offers a series of advantages that combine to make this an intriguing development in renal imaging. There is no radiation involved. The anatomic data provided are striking, covering such diverse aspects of important anatomy as locations of ectopic ureters and identification of crossing vessels at the ureteropelvic junction.

The technique also provides functional data concerning the kidney that may be equal to or better than conventional renal scans. Although not yet completely proved in my mind, its ability to better define the antenatally detected hydronephrosis patient who has a true obstructive uropathy warranting surgery is promising.

Also in development, the ability to characterize medical renal disease may prove to be a boon to pediatric nephrologists and potentially could reduce the need for kidney biopsies. Another advantage of MRU is its ability to identify embryologically abnormal kidneys. We have increasingly come to recognize how commonly this occurs with vesicoureteral reflux. The Emory group's use of the word "dysgenesis" to imply abnormal embryologic kidneys is a good term.

Unfortunately, MR urography still has some disadvantages that must be faced. The study requires sedation, which is much riskier in pediatrics than in adults, usually requiring the presence of an anesthesiologist. The cost of the procedure is still exorbitantly high, reflecting early development and the amount of equipment and manpower that goes into this study. Of course, since this is a new technology, the understanding of how to carry out these studies and how to derive the information that the Emory group has provided us does not exist in many centers.

All of these disadvantages are likely to be substantially reduced with time and development of this imaging technology. The analogy perhaps is to that of early CT scanning when it was felt that one CT scanner in a major city would be all that would be needed. I predict that we will find that MR urography will rapidly develop and eventually come to be the imaging technique of choice in adult and pediatric urology.

Dr. Snyder, a member of the Urology Times Editorial Council, is professor of surgery in the department of urology at the University of Pennsylvania School of Medicine, Philadelphia.

Howard Snyder, III, MD