Temporal lobe necrosis following radiation therapy for nasopharyngeal carcinoma: H-1 MR spectroscopic findings

Purpose: To observe the patterns of radiation-induced temporal lobe necrosi s (TLN) following radiation therapy for nasopharyngeal carcinoma (NPC), Methods and Materials: Twenty-five proton magnetic resonance spectroscopic (H-1 MRS) examinations were acquired from-13 healthy adult volunteers for c omparison with data from the patient population. There were 18 patients (28 spectral with radiologic evidence of TLN and all patients were confirmed c ases of NPC treated with radiation therapy. Six patients (33%) had a single treatment while 12 (67%) patients had two treatments. All H-1 MRS examinat ions were performed on a 2-T whole body system (Bruker) using the point-res olved spectroscopy (PRESS) method with TE = 135 ms, TR = 3000 ms, and data processed automatically using the LCModel software package for metabolite q uantification. Results: The N-acetyl-aspartate (NAA) levels were reduced in all except one spectrum (96%), Choline (Cho) was increased in 3 (11%), normal in 4 (14%), and reduced in 21 (75%) spectra, The creatine (Cr) level was normal in 8 ( 29%) spectra and reduced in 20 (71%) spectra, In four patients with normal imaging findings H-1 MRS was abnormal. Conclusion:H-1 MRS can characterize radiation-induced TLN. Spectra with inc reased Cho can be mistaken for neoplasm, Spectroscopy can also identify met abolic derangement before imaging, (C) 1999 Elsevier Science Inc.