Seierstad Therese, Folkvord Sigurd, Røe Kathrine, Flatmark Kjersti, Skretting Arne, Olsen Dag Rune
Department of Medical Physics, Rikshospitalet-Radiumhospitalet Medical Center, Oslo, Norway.
Neoplasia. 2007 May;9(5):392-400. doi: 10.1593/neo.07154.
The purpose of this study was to evaluate the possible use of changes in apparent diffusion coefficient (ADC) measured by magnetic resonance imaging for pretreatment prediction and early detection of tumor response in a mouse model during fractionated chemoradiotherapy.
Athymic mice with bilateral HT29 xenografts on rear flanks were allocated into three groups: control, capecitabine, and capecitabine and oxaliplatin. The left flanks of the mice received daily irradiation. T2 and diffusion images were acquired before therapy and weekly for the following 9 weeks. Pretreatment and changes in ADC were calculated and compared with tumor doubling growth delay.
No correlations between pretreatment ADC and changes in tumor volumes after therapy were seen. All treated tumors, except those receiving capecitabine (P = .06), showed increased mean tumor ADC values 11 days after initialization of therapy (P < .05) before returning to pretreatment values within 5 days posttherapy (day 18 after onset of therapy). This increase in mean tumor ADC showed a strong positive correlation (r = 0.92, P < .01) with mean tumor doubling growth delay.
Pretreatment ADC values did not predict the effectiveness of therapy, whereas early changes in mean ADC quantitatively correlated with treatment outcome.
本研究旨在评估磁共振成像测量的表观扩散系数（ADC）变化在小鼠模型中用于分次放化疗期间肿瘤反应的预处理预测和早期检测的可能性。
将双侧后腹侧植入HT29异种移植瘤的无胸腺小鼠分为三组：对照组、卡培他滨组以及卡培他滨与奥沙利铂联合组。小鼠的左侧腹侧每天接受照射。在治疗前及随后9周每周采集T2和扩散图像。计算预处理时及ADC的变化，并与肿瘤倍增生长延迟进行比较。
未观察到预处理时的ADC与治疗后肿瘤体积变化之间存在相关性。除接受卡培他滨治疗的肿瘤外（P = 0.06），所有接受治疗的肿瘤在治疗开始11天后平均肿瘤ADC值均升高（P < 0.05），然后在治疗后5天内（治疗开始后第18天）恢复到预处理值。平均肿瘤ADC的这种升高与平均肿瘤倍增生长延迟呈强正相关（r = 0.92，P < 0.01）。
预处理时的ADC值不能预测治疗效果，而平均ADC的早期变化与治疗结果存在定量相关性。
