Temporal lobe changes following radiation therapy: imaging and proton MR spectroscopic findings

Eur Radiol. 2001;11(2):317-24. doi: 10.1007/s003300000548.


Radiation therapy for nasopharyngeal carcinoma affects the temporal lobes. This paper characterizes proton MR spectroscopic findings of the temporal lobes and correlates them with imaging changes. Single-voxel proton MR spectroscopic examinations were acquired from 13 healthy adult volunteers (25 spectra) and 18 patients (28 spectra). All patients had biopsy-confirmed nasopharyngeal carcinoma and were previously treated with radiation therapy. Six patients (33%) had a single treatment and 12 (67%) patients had two treatments. Point resolved spectroscopy (PRESS) method was used (TR = 3,000 ms, TE = 135 ms) and data processed automatically using the LCModel software package for metabolite quantification. Voxel size and geometry were adapted to the lesion to reduce skull-base lipid contamination. The metabolites were quantitated relative to water signal. For each location, an additional non-water-suppressed reference scan in fully relaxed conditions was performed. The imaging findings were divided into four categories: I, normal; II, edema only; III, contrast-enhancing lesions; and IV, cystic encephalomalacia. The N-acetyl-aspartate levels were reduced in 27 (96%) spectra. Choline was increased in 3 (11%), normal in 4 (14%), and reduced in 21 (75%) spectra. The creatine level was normal in 8 (29%) spectra and reduced in 20 (71%) spectra. Imaging showed 4 (14%) spectra with category-I imaging findings; 5 (18%) spectra with category-II findings; 15 (54%) spectra with category-III findings; and 4 (14%) spectra with category-IV findings. Magnetic resonance spectroscopy showed reduced N-acetyl-aspartate in radiation-induced temporal lobe changes. Creatine levels were relatively more stable. Choline levels may be increased, normal, or reduced. Imaging findings ranged from normal to contrast-enhancing lesions and cystic encephalomalacia.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aspartic Acid / analogs & derivatives*
  • Aspartic Acid / analysis
  • Carcinoma / radiotherapy*
  • Chlorine / analysis
  • Creatinine / analysis
  • Diagnosis, Differential
  • Female
  • Humans
  • Magnetic Resonance Imaging*
  • Magnetic Resonance Spectroscopy*
  • Male
  • Middle Aged
  • Nasopharyngeal Neoplasms / radiotherapy*
  • Necrosis
  • Radiation Injuries / diagnosis
  • Radiation Injuries / etiology
  • Radiation Injuries / metabolism*
  • Temporal Lobe / chemistry*
  • Temporal Lobe / pathology


  • Aspartic Acid
  • Chlorine
  • N-acetylaspartate
  • Creatinine