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Pyelosinus backflow of urine usually occurs through infractions of the calyceal fornices from obstruction or retrograde study. The primary cause appears to be a rapid rise in intrapelvic pressure with the backflow representing a physiologic release mechanism which returns the intrapelvic pressure to normal. Pyelosinus backflow is a benign process. However, complications can occur. In some persons whose urine transport cannot accommodate periodic increased urine flow or pressure, repeated pyelosinus backflow may lead to pseudocyst (urinomas) or retroperitoneal fibrosis. Several mechanisms produce these complications in children and adults. The authors present cases of urinomas related to upper tract obstruction from posterior urethral valves as well as ureteral obstruction by tumor, post-treatment scarring, retroperitoneal fibrosis, or calculus. Intrarenal urinomas are illustrated presumably in kidneys with firm capsular attachments to the renal pelvis which do not allow retroperitoneal extravasation.

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On the basis of the principles of the time-of-flight method and the 3-D angiogram obtained by the 2-D planar image scanning technique using 90 degrees RF pulses with short repetition time, we have obtained a coronary angiogram around the heart including the coronary arteries and veins. The cine NMR imaging technique is also incorporated in synchronizing ECG R waves to reduce the motion artifact and at the same time to induce the saturation effect on the static samples. Images of the large bulk blood flow corresponding to the heart chamber and descending aorta are further removed by postprocessing. The final 3-D angiogram is then formed by stacking the 2-D images and contrast is further enhanced by the maximum ray tracing algorithm.

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