NIMG-75THE ADVANTAGE OF ADVANCED MR IMAGING TECHNIQUES FOR THE DIAGNOSIS OF GERMINOMA

Abstract

Intracranial germinomas are rare and account for only 1.9% of primary intracranial tumors in Japan. The diagnosis of germinoma by conventional MR imaging is sometimes difficult. It has not been well documented about the advanced imaging of germinoma. The purpose of our study was to determine if advanced MR imagings could give additional information for differential diagnosis of germinoma. We retrospectively reviewed the imaging of 23 patients with primary central nervous system germinoma who were treated in our institution between Oct 2004 and November 2014. 22 patients were diagnoses by histological specimen and one case was diagnosed by imaging and increase of serum and cerebrospinal fluid hCG-β. Patients underwent conventional MR imaging and advanced MR imaging including diffusion-weighted imaging and single voxel proton MR spectroscopy. Patients age was ranging from 9 to 37-years-old (average 16.1, median 14). 21 were male, and 3 were female patients. Serum hCG-β was elevated at 20 of 23 patients. Cerebrospinal fluid hCG-β was elevated in 15 of 16 examined patients. 13 patients had single lesion, while 10 had multiple lesions, and 3 had disseminated disease. 5 of 23 tumors showed spontaneous regression after biopsy. Bithalamic extension was observed in 10 of 14 patients with pineal germinoma, but only 3 of 10 patients showed edema at thalamus. The cyst formation was observed at 11 of 23 patients. 18 of 21 examined tumors showed high intensity on diffusion-weighted imaging. High lipids peak at single voxel proton MR spectroscopy was observed in 13 of 13 examined tumors. However, other patients could not perform MR spectroscopy because of small tumor size. In conclusions, high intense on diffusion-weighted imaging and high lipids peak at single voxel proton MR spectroscopy might be the characteristics of germinoma.