Provocative imaging. Diuretic renography.

Diuretic renography remains the noninvasive functional study of choice in patients with hydronephrosis resulting from apparent UPJ obstruction. Meticulous attention to proper patient preparation, radiopharmaceutical selection, furosemide dosage and administration, and image interpretation and an awareness of potential pitfalls are essential for accurate diagnosis. For most patients, the F + 20 protocol is sufficient, however; the F-15 protocol allows clarification in cases of equivocal baseline F + 20 studies. Invasive antegrade techniques such as the Whitaker pressure/perfusion test are best reserved for patients in whom the diagnosis remains equivocal after diuretic renography, or in patients with massive hydronephrosis or renal insufficiency. New standardized protocol guidelines should help to ensure studies that are reproducible in different nuclear medicine laboratories.