Dynamic MR imaging of neurohypophyseal germ cell tumors for differential diagnosis of infundibular diseases

Purpose: To investigate the MR dynamic patterns of neurohypophyseal germ cell tumors (GCTs) for differential diagnosis of infundibular diseases affecting young people. Material and Methods: Eleven patients with neurohypophyseal GCTs underwent dynamic MR studies with T1-weighted spin-echo (SE) or turbo SE techniques. Other infundibular lesions, including adenohypophysitis (n=3), Langerhans' cell histiocytosis (LCH, n=2), and 1 hemangioblastoma from von Hippel-Lindau disease, were also evaluated. Serial images were obtained every 15 s (turbo SE) or 30 s (SE technique) for 240 s after rapid injection of contrast medium. The dynamic patterns were analyzed quantitatively with the contrast medium enhancement ratio. Results: On dynamic MR images, GCTs typically showed a gradual enhancement increase with a peak between 105 s and 180 s, while two showed a relatively rapid increase. LCH and hemangioblastoma showed a dynamic pattern similar to GCTs, while adenohypophysitis demonstrated a sharp rise and a steeper wash-out with an obvious peak before 90 s. Conclusion: Typical dynamic pattern of GCTs was the gradual enhancement increase without wash-out. Dynamic MR imaging can distinguish GCTs from adenohypophysitis, but is not useful for differentiation from LCH.