title: 1H-MR spectroscopy and diffusion tensor imaging of normal-appearing temporal white matter in patients with nasopharyngeal carcinoma after irradiation: initial experience.
abstract: OBJECTIVE
  To detect radiation-induced changes of temporal lobe normal-appearing white mater (NAWM) following radiation therapy (RT) for nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  Seventy-five H(1)-MR spectroscopy and diffusion-tensor imaging (DTI) examinations were performed in 55 patients before and after receiving fractionated radiation therapy (total dose; 66-75GY). We divided the dataset into six groups, a pre-RT control group and five other groups based on time after completion of RT. N-acetylaspartic acid (NAA)/choline (Cho), NAA/creatine (Cr), Cho/Cr, mean diffusibility (MD), functional anisotropy (FA), radial diffusibility (λ(⊥)), and axial diffusibility (λ(||)) were calculated.
  
  
  RESULTS
  NAA/Cho and NAA/Cr decreased and λ(⊥) increased significantly within 1 year after RT compared with pre-RT. After 1 year, NAA/Cho, NAA/Cr, and λ(⊥) were not significantly different from pre-RT. In all post-RT groups, FA decreased significantly. λ(||) decreased within 9 months after RT compared with pre-RT, but was not significantly different from pre-RT more than 9 months after RT.
  
  
  CONCLUSIONS
  DTI and H(1)-MR spectroscopy can be used to detect early radiation-induced changes of temporal lobe NAWM following radiation therapy for NPC. Metabolic alterations and water diffusion characteristics of temporal lobe NAWM in patients with NPC after RT were dynamic and transient.
authors.affiliation: Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: Wei Feng
authors.initials: WF
authors.lastname: Xiong
authors.forename: Shi Jun
authors.initials: SJ
authors.lastname: Qiu
authors.forename: Hong Zhuo
authors.initials: HZ
authors.lastname: Wang
authors.forename: Xiao Fei
authors.initials: XF
authors.lastname: Lv
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000473:pathology* / Q000528:radiation effects; D001932:Brain Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D002277:Carcinoma; D003657:Decision Making; D004058:Diffusion; D056324:Diffusion Tensor Imaging / Q000379:methods*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D009413:Nerve Fibers, Myelinated / Q000473:pathology / Q000528:radiation effects; D011832:Radiation Injuries / Q000175:diagnosis* / Q000473:pathology; D011878:Radiotherapy / Q000009:adverse effects; D013702:Temporal Lobe / Q000473:pathology* / Q000528:radiation effects
chemical_list: D015415:Biomarkers