title: Distinction between recurrent glioma and radiation injury using magnetic resonance spectroscopy in combination with diffusion-weighted imaging.
abstract: OBJECTIVE
  The aim of this study was to explore the diagnostic effectiveness of magnetic resonance (MR) spectroscopy with diffusion-weighted imaging on the evaluation of the recurrent contrast-enhancing areas at the site of treated gliomas.
  
  
  METHODS
  In 55 patients who had new contrast-enhancing lesions in the vicinity of the previously resected and irradiated high-grade gliomas, two-dimensional MR spectroscopy and diffusion-weighted imaging were performed. Spectral data for N-acetylaspartate (NAA), choline (Cho), creatine (Cr), lipid (Lip), and lactate (Lac) were analyzed in conjunction with the apparent diffusion coefficient (ADC) in all patients. Diagnosis of these lesions was assigned by means of follow-up or histopathology.
  
  
  RESULTS
  The Cho/NAA and Cho/Cr ratios were significantly higher in recurrent tumor than in regions of radiation injury (p < 0.01). The ADC value and ADC ratios (ADC of contrast-enhancing lesion to matching structure in the contralateral hemisphere) were significantly higher in radiation injury regions than in recurrent tumor (p < 0.01). With MR spectroscopic data, two variables (Cho/NAA and Cho/Cr ratios) were shown to differentiate recurrent glioma from radiation injury, and 85.5% of total subjects were correctly classified into groups. However, with discriminant analysis of MR spectroscopy imaging plus diffusion-weighted imaging, three variables (Cho/NAA, Cho/Cr, and ADC ratio) were identified and 96.4% of total subjects were correctly classified. There was a significant difference between the diagnostic accuracy of the two discriminant analyses (Chi-square = 3.96, p = 0.046).
  
  
  CONCLUSIONS
  Using discriminant analysis, this study found that MR spectroscopy in combination with ADC ratio, rather than ADC value, can improve the ability to differentiate recurrent glioma and radiation injury.
authors.affiliation: Department of Radiology, Qilu Hospital of Shandong University, Jinan, China. nanwushan@yahoo.com
authors.forename: Qing-Shi
authors.initials: QS
authors.lastname: Zeng
authors.forename: Chuan-Fu
authors.initials: CF
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Jun-Hui
authors.initials: JH
authors.lastname: Zhen
authors.forename: De-Chao
authors.initials: DC
authors.lastname: Feng
mesh_terms: D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000528:radiation effects*; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000532:radiotherapy; D002794:Choline / Q000378:metabolism; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D016002:Discriminant Analysis; D005260:Female; D005910:Glioma; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D050356:Lipid Metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D011832:Radiation Injuries / Q000175:diagnosis* / Q000378:metabolism
chemical_list: D010725:Phosphocreatine; D001224:Aspartic Acid; D019344:Lactic Acid; C000179:N-acetylaspartate; D002794:Choline