儿童脑干胶质瘤磁共振酰胺质子转移加权成像的研究

Application of amide proton transfer-weighted MRI for grading of brainstem glioma in children

目的:探讨磁共振酰胺质子转移加权成像(APTw)对儿童脑干胶质瘤(BSG)病理分级的诊断及APTw信号强度与BSG增殖指数(Ki-67)的关系。方法:回顾分析2019年12月至2022年3月经手术或活检确诊的25例BSG患儿资料。其中男性16例、女性9例,年龄0.7~12.4(5.6±3.3)岁;低级别BSG患儿13例,高级别BSG患儿12例。在3.0 T磁共振成像(MRI)扫描仪上进行APTw成像和常规MR序列扫描。比较高、低级别BSG患儿的性别分布、年龄、常规MRI表现、APTw信号强度及表观扩散系数(ADC)值的差异;应用受试者工作特征(ROC)曲线评估APTw信号强度鉴别高、低级别BSG的诊断效能,计算约登指数得出最佳诊断阈值;分析APTw信号强度和Ki-67表达的相关性。结果:高、低级别BSG患儿年龄[(6.1±3.4)与(5.0±3.3)岁,t=-0.80,P=0.434]及性别分布(男/女分别为8/4、8/5,χ^(2)=0.07,P=0.790)差异均无统计学意义;高级别BSG肿瘤最大径线[(4.7±0.9)cm]明显大于低级别BSG[(3.1±1.7)cm],差异有统计学意义(t=-2.94,P=0.007)。高级别BSG的APTw信号强度最大值[APTw_(max),(4.9±0.6)%]、平均值[APTw_(mean),(3.6±0.4)%]明显高于低级别BSG[(3.0±1.2)%与(2.7±1.1)%],差异均有统计学意义(t=-5.14,P<0.001;t=-2.66,P=0.014)。APTw_(max)值区分高、低级别BSG的ROC曲线下面积(AUC)为0.897,以4.07%为APTw_(max)值的最佳诊断阈值,鉴别诊断高、低级别BSG的灵敏度为0.917,特异度为0.846。APTw_(mean)值区分高、低级别BSG的AUC为0.769,以2.85%为APTw_(mean)值的最佳诊断阈值,鉴别诊断高、低级别BSG的灵敏度为0.917,特异度为0.692。APTw_(max)值与Ki-67表达水平呈正相关(r=0.453,P=0.023)。结论:APTw成像有助于区分儿童高级别和低级别BSG,APTw_(max)值可有效评估儿童BSG的增殖活性。

Objective To evaluate the application of amide proton transfer weighted(APTw)magnetic resonance imaging(MRI)for grading of brainstem glioma(BSG)in children.Methods Twenty-five children(16 males and 9 females)aged 0.7-12.4(5.6±3.3)years were diagnosed as BSG by surgery or biopsy in Beijing Children′s Hospital from December 2019 to March 2022,including 13 cases of low-grade BSG and 12 cases of high-grade BSG.APTw imaging and conventional MRI were performed on a 3.0 T MRI scanner.The differences in gender distribution,age,conventional MRI appearance,APTw signal intensity and apparent diffusion coefficient(ADC)between children with high and low grade BSG were analyzed.Receiver operating characteristic(ROC)curve was used to analyze the efficacy of APTw signal intensity in the differential diagnosis of high and low grade BSG,and Youden index was calculated to obtain the optimal diagnostic threshold.Pearson′s correlation coefficient analysis was used to evaluate the correlation between APTw signal intensity and Ki-67 expression.Results There was no significant difference in age and gender distribution between high-grade and low-grade BSG patients.The maximum diameter of high-grade BSG was significantly larger than that of low-grade BSG[(4.7±0.9)vs.(3.1±1.7)cm;t=-2.94,P=0.007];the maximum signal intensity of APTw(APTw_(max))in high-grade BSG was significantly higher than that in low-grade BSG[(4.9±0.6)%vs.(3.0±1.2)%;t=-5.14,P<0.001];the average signal intensity of APTw(APTw_(mean))in high-grade BSG was significantly higher than that in low-grade BSG[(3.6±0.4%)vs.(2.7±1.1)%;t=-2.66,P=0.014].The area under the curve(AUC)of APTw_(max) in distinguishing high-and low-grade BSG was 0.897;with 4.07%as the optimal diagnostic threshold of APTw_(max),the sensitivity for the diagnosis of high-grade BSG was 0.917 and specificity was 0.846.The AUC of APTw_(mean) in distinguishing high-and low-grade BSG was 0.769;with 2.85%as the optimal diagnostic threshold of APTw_(mean),the sensitivity for the diagnosis of high-grade BSG was 0.917 and specificity was 0.692.There was a positive correlation between the value of APTw_(max) and Ki-67 expression(r=0.453,P=0.023).Conclusion APTw imaging is helpful to distinguish high-grade and low-grade BSG in children.APTw_(max) value can be used to effectively evaluate the proliferative activity of BSG in children.