title: Diffusion tensor imaging and 1H-MRS study on radiation-induced brain injury after nasopharyngeal carcinoma radiotherapy.
abstract: OBJECTIVE
  To investigate the metabolic characteristics of the temporal lobes following radiation therapy for nasopharyngeal carcinoma using diffusion tensor imaging (DTI) and proton magnetic resonance spectroscopy ((1)H-MRS).
  
  
  METHODS
  DTI and (1)H-MRS were performed in 48 patients after radiotherapy for nasopharyngeal carcinoma and in 24 healthy, age-matched controls. All patients and controls had normal findings on conventional MRI. Apparent diffusion coefficient (ADC), fractional anisotropy (FA), three eigenvalues λ1, λ2, λ3, N-acetylaspartic acid (NAA)/choline (Cho), NAA/creatinine (Cr), and Cho/Cr were measured in both temporal lobes. Patients were divided into three groups according to time after completion of radiotherapy: group 1, less than 6 months; group 2, 6-12 months; group 3, more than 12 months. Mean values for each parameter were compared using one-way analysis of variance (ANOVA).
  
  
  RESULTS
  Mean FA in group 1 was significantly lower compared to group 3 and the control group (p < 0.05). Group-wise comparisons of apparent diffusion coefficient (ADC) values among all the groups were not significantly different. Eigenvalue λ1 was significantly lower in groups 1 and 3 compared to the control group (p < 0.05). NAA/Cho and NAA/Cr were significantly lower in each group compared to the control group (p < 0.01 for both). The decrease in NAA/Cho was greatest in group 1. There were no significant between-group differences regarding Cho/Cr.
  
  
  CONCLUSIONS
  A combination of DTI and (1)H-MRS can be used to detect radiation-induced brain injury, in patients treated for nasopharyngeal carcinoma.
authors: Department of Medical Imaging Center, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.
authors: H-Z
authors: HZ
authors: Wang
authors: S-J
authors: SJ
authors: Qiu
authors: X-F
authors: XF
authors: Lv
authors: Y-Y
authors: YY
authors: Wang
authors: Y
authors: Y
authors: Liang
authors: W-F
authors: WF
authors: Xiong
authors: Z-B
authors: ZB
authors: Ouyang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000032:analysis; D001921:Brain / Q000528:radiation effects*; D002794:Choline / Q000032:analysis; D003404:Creatinine / Q000032:analysis; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000175:diagnosis*; D011878:Radiotherapy / Q000009:adverse effects; D013702:Temporal Lobe / Q000737:chemistry; D013997:Time Factors
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003404:Creatinine; D002794:Choline