磁共振扫描用于评价HIFU治疗乳腺癌的效果

Magnetic resonance imaging for evaluation of therapeutic effects of high intensity focused ultrasound for breast cancer

目的:探讨动态增强MRI(Dynamic contrast-enhanced MRI,DCE-MRI)对高强度聚焦超声(High intensity focused ultrasound,HIFU)治疗乳腺癌的疗效评价。方法:对8个乳腺癌病灶在HIFU治疗前及治疗后2周(其中2个在治疗后6个月及12个月)分别行MRI平扫及DCE-MRI检查,观察其在治疗前后信号改变、时间-信号强度曲线(Time-Signal Intensity Curve)、早期强化率及病灶与邻近血管关系的改变。结果:MRI平扫5个病灶中心由HIFU治疗前的等/长T_2WI信号转变为等/稍短T_2WI信号,3个病灶中心仍残留部分长T_2WI信号;DCE-MRI 5个病灶中心早期强化率由HIFU术前的60%～80%降低为<60%,3个病灶稍有降低;8个病灶时间-信号强度曲线(HIFU术前5个呈A型、3个呈B型)均无明显峰值出现;3D-MIP重建后8个病灶所在区域由HIFU术前混杂高信号及周围明显絮网状小血管影及增粗迂曲血管影转变为无强化及周围无明显絮网状血管影显示。结论:DCE-MRI可作为评价HIFU治疗乳腺癌疗效首选的无创性影像学检查方法。

Objective：To verify the applicability of Dynamic Contrast Enbanced Magnetic Resonance Imaging （DCE-MRI） to evaluate the breast cancer therapy using the high intensity focused ultrasound（HIFU）. Methods： Both DCE-MRI and conventional T1W/T2W images were acquired for the total 8 subjects. Two consecutive scans were performed for every patient（before operation and 2 weeks after operation） while four were performed for only 2 patients（additional for 6 months and 12 months after operation）. The breast cancer therapy by HIFU was assessed by comparing the changes of signal,the dynamic patterns of time-signal intensity curve,the early-phase contrast enhancement ratios and vessel anatomies around cancer focuses. Results： The shortened T2 signals were observed in cancer focuses of 5 subjects while 3 still showed longer T2 values which were differentiated by the high intensity in T2W images. The early-phase contrast enhancement ratios of those 5 subjects decreased from 60%-80% to 〈60% after the HIFU therapy,but this was less proved for the other 3. No clear signal peaks were observed in the dynamic enhancement time-signal intensity curve for all subjects,while before the surgery 5 curves are in Type A and others in Type B. After the therapy,no enhanced complex vaseulatures were discernible around cancer focuses for all subjects, compared to the clear visibility of complicated high intensity vaseulatures with main vessels enlarged and curved in the pre-surgery scans. Conclusions：As a novel noninvasive imaging technique,the DCE-MRI can be used to effectively evaluate the HIFU therapy for breast cancer.