title: Distinction between postoperative recurrent glioma and delayed radiation injury using MR perfusion weighted imaging.
abstract: BACKGROUND
  Distinction between postoperative recurrent glioma and radiation injury remains a tough diagnostic problem for routine imaging methods. The purpose of this study is to evaluate the differentiated effectiveness of perfusion weighted imaging (PWI) for the two entities.
  
  
  METHODS
  PWI was performed using Siemens 3.0-T MR system for 35 patients with new contrast-enhancing lesions at the site of treated glioma. Regions of interest (ROIs) were manually drawn at the contrast-enhancing lesion and peri-lesion edema areas. For calculation of standardised relative cerebral blood volume (rCBV) ratios, the same size ROIs were drawn at the area of contralateral hemisphere normal white matter on rCBV maps. At least five ROIs were selected at each lesion. The rCBV values were measured and the rCBV ratios were calculated. The maximum rCBV (rCBV(max)) ratio at each region was chosen for analysis. The patients were divided into two groups: tumour recurrence and radiation injury. The mean rCBV(max) ratios were compared between the two groups.
  
  
  RESULTS
  The mean rCBV(max) ratio in the contrast-enhancing lesion was significantly higher in the tumour recurrence (4.36 ± 1.98) compared with that (1.28 ± 0.64) in the radiation injury (P < 0.01). The mean rCBV(max) ratio in the peri-lesion edema was also significantly higher in the tumour recurrence (1.79 ± 0.51) compared with that (0.85 ± 0.28) in the radiation injury (P < 0.05). A recurrent tumour was suggested when the rCBV(max) ratio >2.15 based on the receiver operating characteristic curve. Four patients with recurrent tumour and three with radiation injury were misclassified.
  
  
  CONCLUSIONS
  PWI is a useful method to distinguish tumour recurrence and radiation injury.
authors.affiliation: Department of Radiology, Henan Provincial People's Hospital, Zhengzhou, China.
authors.forename: Jun-Ling
authors.initials: JL
authors.lastname: Xu
authors.forename: Da-Peng
authors.initials: DP
authors.lastname: Shi
authors.forename: She-wei
authors.initials: SW
authors.lastname: Dou
authors.forename: Yong-Li
authors.initials: YL
authors.lastname: Li
authors.forename: Feng-shan
authors.initials: FS
authors.lastname: Yan
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000209:etiology* / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D005910:Glioma / Q000473:pathology* / Q000628:therapy*; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology* / Q000601:surgery; D011182:Postoperative Care; D011832:Radiation Injuries / Q000209:etiology / Q000473:pathology*; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D055815:Young Adult