Static-fluid MRU is independent of the renal excretory function and therefore can be used to patients with nonexcreting kidneys. The T2 sequences used in this investigation (thick slab T2 sequences) differentiated between obstructed and nonobstructed ureters. The main advantage of thick slab images was the accurate delineation of nondilated ureters .
| Figure 5: (a) Coronal T2 thick-slab MRU, MRCP ASSET sequence, in a 9-year-old girl with VUR III on the right. The ureters are not displayed properly. (b) Coronal T2 thick-slab MRU from the same series of the MRCP ASSET sequence. Both ureters are depicted accurately |
Static MRU depends mostly on the existence of urine in the collecting system. Therefore, it is mostly helpful for demonstrating dilated, obstructed, pelvocalyceal systems. In such cases the thick-slab T2 sequences reveal not only the dilatation but also the point of obstruction .
| Figure 6: (a) Coronal T2 thick-slab MRU of a 7-year-old girl. The dilatation on the right is visible as well as the point of obstruction (arrow). (b) Coronal MRU with LAVA sequence, after the administration of contrast agent, revealing the dilatation but not the point of obstruction |
Normal and abnormal structures filled with fluid restrain MRU, since T2 techniques are not specific for urine but for water. In became apparent that intravenous hydration is better compared to oral hydration, before static-fluid MRU, in patients with nondistended ureters because the contrast between the bowel and fluid-filled structures is enhanced.
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