MR灌注成像在鉴别胶质瘤复发与放射性脑损伤中的价值

目的 分析MR灌注成像在鉴别胶质瘤复发与放射性脑损伤中的作用.方法 选取15例脑胶质瘤术后、放疗后并出现新强化灶的患者.所有患者均经二次手术病理或随访(随访时间＞6个月)证实为胶质瘤复发或放射性脑损伤.15例患者均行常规MR平扫、增强扫描和MR脑灌注成像.灌注成像采用梯度回波-回波平面成像(GRE-EPI)序列,ROI放置在横断面T1WI异常强化区域和对侧相对正常的脑白质内,大小为20～40 mm2,每个病灶测量10～15次,取平均值,计算异常强化区与对侧正常区的参数比值,包括相对脑血容量(rCBV)、相对脑血流量(rCBF)及相对平均通过时间(rMTT),采用秩和检验比较胶质瘤复发和放射性脑损伤各灌注参数.并采用ROC曲线评价rCBV、rCBF及MTT鉴别诊断两者的灵敏度及特异度.结果 15例患者最终经手术和随访证实有9例胶质瘤复发,6例放射性脑损伤.胶质瘤复发rCBV、rCBF比值的M分别为2.87(范围0.70～4.91)、1.89(范围0.64～3.96),明显高于放射性脑损伤比值[rCBV 0.70(范围0.12～1.62)、rCBF 0.56(范围0.12～2.08)],差异有统计学意义(Z值分别为-2.55、-2.08,P值均＜0.05).rCBV和rCBF比值鉴别诊断为胶质瘤复发或放射性脑损伤的ROC曲线下面积为0.893和0.821.rCBV比值≤0.77时诊断放射性脑损伤灵敏度为100.0%,rCBV比值≥2.44时诊断胶质瘤复发特异度为100.0%.结论 MR灌注成像是鉴别胶质瘤复发和放射性脑损伤的有效方法,rCBV比值和rCBF比值在鉴别诊断中具有重要价值.

Abstract：

Objective To evaluate the feasibility of perfusion weighted imaging (PWI) in the differentiation of recurrent glioma and radiation-induced brain injuries. Methods Fifteen 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) sequence. The normalized rCBV ratio[CBV(abnormal enhancement)/CBV(contralateral tissue)], rCBF ratio[CBF(abnormal enhancement)/CBF(contralateral tissue)]and rMTT ratio[(MTT abnormal enhancement)/MTT(contralateral tissue)]were calculated, respectively. The regions of interest (ROIs) consisting of 20-40 mm2 were placed in the abnormal enhanced areas on postcontrast T1-weighted images. Ten to fifteen ROIs measurements were performed in each lesion and the mean value was obtained. Mann-Whitney test was used to determine whether there was a difference in the rCBV/rCBF/MTT ratios between glioma recurrence and radiated injuries. Results Nine of the 15 patients were proved recurrent glioma,6 were proved radiation-induced brain injuries. The mean rCBV ratio[2.87(0.70-4.91)]in glioma recurrence was markedly higher than that[0.70(0.12-1.62)]in radiation injuries (Z=-2.55,P＜0.05). The mean rCBF ratio[1.89(0.64-3.96)]in glioma recurrence was markedly higher than that[0.56(0.12-2.08)]in radiation injuries (Z=-2.08,P＜0.05). The areas under rCBV and rCBF ROC curve were 0.893 and 0.821. If the rCBV ratio ≤0.77, the diagnosis sensitivity of radiation-induced brain injuries was 100.0%;If ≥2.44, the diagnosis specificity of recurrent glioma was 100.0%. Conclusion PWI was an effective technique in distinguishing glioma recurrence from radiation injuries and rCBV and rCBF ratios were of great value in the differentiation.

Differentiation between glioma recurrence and radiation-induced brain injuries using perfusion-weighted MR imaging

Objective To evaluate the feasibility of perfusion weighted imaging (PWI) in the differentiation of recurrent glioma and radiation-induced brain injuries. Methods Fifteen 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) sequence. The normalized rCBV ratio[CBV(abnormal enhancement)/CBV(contralateral tissue)], rCBF ratio[CBF(abnormal enhancement)/CBF(contralateral tissue)]and rMTT ratio[(MTT abnormal enhancement)/MTT(contralateral tissue)]were calculated, respectively. The regions of interest (ROIs) consisting of 20-40 mm2 were placed in the abnormal enhanced areas on postcontrast T1-weighted images. Ten to fifteen ROIs measurements were performed in each lesion and the mean value was obtained. Mann-Whitney test was used to determine whether there was a difference in the rCBV/rCBF/MTT ratios between glioma recurrence and radiated injuries. Results Nine of the 15 patients were proved recurrent glioma,6 were proved radiation-induced brain injuries. The mean rCBV ratio[2.87(0.70-4.91)]in glioma recurrence was markedly higher than that[0.70(0.12-1.62)]in radiation injuries (Z=-2.55,P＜0.05). The mean rCBF ratio[1.89(0.64-3.96)]in glioma recurrence was markedly higher than that[0.56(0.12-2.08)]in radiation injuries (Z=-2.08,P＜0.05). The areas under rCBV and rCBF ROC curve were 0.893 and 0.821. If the rCBV ratio ≤0.77, the diagnosis sensitivity of radiation-induced brain injuries was 100.0%;If ≥2.44, the diagnosis specificity of recurrent glioma was 100.0%. Conclusion PWI was an effective technique in distinguishing glioma recurrence from radiation injuries and rCBV and rCBF ratios were of great value in the differentiation.