MR扩散加权成像在骨肉瘤新辅助化疗疗效评估中的价值

Assessment of the responses to neoadjuvant chemotherapy of osteosarcoma by diffusion-weighted MR image： initial results

目的探讨MRDWI对骨肉瘤新辅助化疗效果评估的价值。方法36例原发性骨肉瘤患者新辅助化疗（顺铂＋甲氨喋呤＋表阿霉素＋异环磷酰胺）前、后进行常规MRI、DWI。检查采用1．5T超导型MR仪，测定化疗前、后肿瘤内活性肿瘤组织、坏死区及肿瘤平均ADC值变化。术后病理肿瘤坏死率评估按Huvos标准分级。用两独立样本t检验法检验化疗反应不同2组病例的各项指标。结果36例化疗后肿瘤内活性肿瘤组织和坏死区的ADC值分别为（1．06±0．30）×10^-3mm^2／s和（2．39±0．44）×10^-3mm^2／s，坏死区ADC值明显高于活性肿瘤组织，两者间差异有统计学意义（t=3．515，P〈0．05）。25例化疗反应良好组肿瘤平均ADC值由化疗前的（1．18±0．19）×10^-3mm^2／s增加至化疗后（2．27±0．20）×10^-3mm^2／s，11例化疗反应不佳组的平均ADC值从化疗前（1．45±0．11）×10^-3mm^2／s增加至化疗后（1．83±0．16）×10^-3mm^2／s，两组间化疗前后ADC值变化差异有统计学意义（t=4．981，P〈0．01）。结论DWI能够区分新辅助化疗后骨肉瘤内活性肿瘤组织与坏死组织，进而对骨肉瘤化疗效果的评估有一定价值，结合常规MR检查，对手术计划的制定、术后化疗方案的选择及判断患者预后有重要帮助。

Objective To determine the utility of diffusion-weighted magnetic resonance imaging （ MR DWI ） in detecting tumor necrosis with histological correlation after neoadjuvant chemotherapy. Methods Conventional MR/ and DWI were obtained from 36 patients with histological proven osteosareoma. Magnetic resonance examinations were performed in all patients before and after 4 cycles of preoperative neoadjuvant chemotherapy. Apparent diffusion coefficients （ADC） were calculated. The degree of tumor necrosis was assessed using the histological Havos classification after chemotherapy. t-test was performed for testing changes in ADC value between the 2 groups. P value less than 0. 05 were considered as a statistically significant difference. Results The differences in ADC between viable [ （1.06 ±0. 30） × 10^-3mm^2/s] and necrotic [ （2. 39 ±0. 44） × 10^-3mm^2/s] tumor were significant （t = 3. 515 ,P 〈0. 05）. Changes in ADC value was greater in good responses to neoadjuvant chemotherapy than in poor responses, the ADC value in good responses was increased from （1.18 ±0. 19） × 10^-3 mm^2/s to （2. 27±0. 20） × 10^-3 mm^2/s, the corresponding value in poor responses was increased from （1.45 ± 0. 11 ） × 10^-3 mm^2/s to （1.83 ±0. 16） × 10^-3 mm^2/s. There was significant difference in changes of ADC values between good responses and poor responses （ t = 4. 981, P 〈 0. 01 ）. Conclusion Diffusion-weighted MRI permits recognition of tumor necrosis induced by chemotherapy in osteosarcoma. DWI is correlated directly with tumor necrosis. They have potential utility in evaluating the preoperative chemotherapy response in patients with primary osteosarcoma.