Initial Results of the Effects of Diuresis on Gadolinium Enhancement in MR Imaging of the Abdomen

The authors performed this study to assess the effects of furosemide-induced diuresis on paramagnetic contrast material enhancement at magnetic resonance (MR) imaging of the kidney, liver, spleen, and psoas muscle. Twenty-five patients (average age, 44.9 years; age range, 23–74 years; 13 men, 12 women) who were suspected of having unilateral renal hydronephrosis received 0.1 mmol/kg contrast material with a standardized injection and imaging protocol to assess organ signal intensity at 0–5 minutes after injection. All patients had a normal serum creatinine level. Imaging was performed with a 1.5-T magnet by using a fat-suppressed fast spoiled gradient-echo pulse sequence and a 70° flip angle. Eight patients received 40 mg of furosemide 10 minutes before contrast material injection. The areas of the renal cortical and medullary signal intensity curves minus baseline in the unilateral normal kidneys were significantly greater in the group who received furosemide ( P = .026 and P = .037, respectively). The areas of the renal cortical and medullary signal intensity minus baseline in the unilateral hydronephrotic kidneys were also significantly greater in the group that received furosemide ( P = .036 and P = .026, respectively). There was a statistically significant increase in splenic enhancement ( P = .02) and a tendency for increased liver ( P = .09) and psoas muscle ( P = .08) enhancement. Furosemide-induced diuresis appears to potentiate the cortical and medullary MR renogram, as well as the MR splenogram. A rapid shift in water compartmentalization from the intracellular to the extracellular space and increased renal water content with diuresis are possible explanations.