POSTERIOR LOBE OF THE PITUITARY IN DIABETES-INSIPIDUS - DYNAMIC MR IMAGING

Magnetic resonance (MR) imaging was performed in 10 subjects: four with central idiopathic diabetes insipidus (DI), two with nephrogenic DI, and four with normal pituitary glands. Characteristic high intensity of the posterior pituitary lobe was seen in all four control subjects and one case of nephrogenic DI. However, it was undetectable in all four cases of central idiopathic DI and one case of nephrogenic DI. Peak contrast enhancement of the posterior lobe occurred within 30 seconds after injection of gadopentetate dimeglumine in control subjects and in both cases of nephrogenic DI and at 30-60 seconds in one case of mild partial idiopathic DI. In contrast, no or faint early enhancement of the posterior pituitary lobe was observed in two cases of complete and one case of partial central DI. In patients with central DI, MR imaging reveals delayed enhancement of the posterior pituitary lobe compared with the early enhancement seen in subjects without central DI.