[Differentiation between glioma recurrence and radiation-induced brain injuries using perfusion-weighted magnetic resonance imaging].

OBJECTIVE

To evaluate the role of perfusion weighted imaging (PWI) in the differentiation between recurrent glioma and radiation-induced brain injuries.

METHODS

Twenty-three patients with previously resected and irradiated glioma, presenting newly developed abnormal enhancement, were included in the study. The final diagnosis was determined either histologically or clinicoradiologically. PWI was obtained with a gradient echo echo-planar-imaging (GRE-EPI)technique. The normalized relative cerebral blood volume (rCBV) ratio [rCBV (abnormal enhancement)/rCBV (contralateral tissue)], relative cerebral blood flow (rCBF) ratio [rCBF (abnormal enhancement)/rCBF(contralateral tissue)], mean transit time(MTT) ratio [MTT (abnormal enhancement)/MTT(contralateral tissue)],time to peak(TTP)ratio[TTP(abnormal enhancement)/TTP(contralateral tissue)],and bolus arrive time(BAT)ratio[BAT(abnormal enhancement)/BAT(contralateral tissue)] were calculated. The regions of interest (ROIs) consisting of 20-40mm(2) were placed in the abnormal enhanced areas on postcontrast T1-weighted images.Ten ROIs measurements were performed in each lesion.T test was used to determine whether there was a difference in the rCBV/rCBF/rMTT/rTTP/rBAT ratios between recurrent glioma and irradiated injuries.Significance was set to a P value <0.05.

RESULTS

Thirteen of the 23 patients were proved recurrent glioma and 10 were proved radiation-induced brain injuries. The rCBV ratio (3.60±3.86 vs. 0.82 ± 0.74, P = 0.000)and rCBF ratio (2.88 ± 2.27 vs. 0.84 ± 0.80, P = 0.000) in glioma recurrence were markedly higher than those in radiation injuries. The areas under rCBV and rCBF ROC curve were both 0.8763. rMTT (P=0.204), rTTP (P=0.260), and rBAT (P=0.071) ratios showed no statistical difference between the two groups.

CONCLUSION

PWI is an effective technique in distinguishing glioma recurrence from radiation injuries,and the ratios of rCBV and rCBF ratio differential diagnosis of critical value to 1.3088 and 1.1235, respectively, can be used as a reliable clinical indicator.