Department of Radiation Oncology, UZ Gasthuisberg, Leuven, Belgium.
Int J Radiat Oncol Biol Phys. 2012 Feb 1;82(2):863-70. doi: 10.1016/j.ijrobp.2010.12.063. Epub 2011 Mar 11.
To evaluate diffusion-weighted magnetic resonance imaging (DWI) for response prediction before and response assessment during and early after preoperative radiochemotherapy (RCT) for locally advanced rectal cancer (LARC).
Twenty patients receiving RCT for LARC underwent MRI including DWI before RCT, after 10-15 fractions and 1 to 2 weeks before surgery. Tumor volume and apparent diffusion coefficient (ADC; b-values: 0-1000 s/mm(2)) were determined at all time points. Pretreatment tumor ADC and volume, tumor ADC change (∆ADC), and volume change (∆V) between pretreatment and follow-up examinations were compared with histopathologic findings after total mesorectal excision (pathologic complete response [pCR] vs. no pCR, ypT0-2 vs. ypT3-4, T-downstaging or not). The discriminatory capability of pretreatment tumor ADC and volume, ∆ADC, and ∆V for the detection of pCR was compared with receiver operating characteristics analysis.
Pretreatment ADC was significantly lower in patients with pCR compared with patients without (in mm(2)/s: 0.94 ± 0.12 × 10(-3) vs. 1.19 ± 0.22 × 10(-3), p = 0.003), yielding a sensitivity of 100% and specificity of 86% for detection of pCR. The volume reduction during and after RCT was significantly higher in patients with pCR compared with patients without (in %: ΔV(during): -62 ± 16 vs. -33 ± 16, respectively, p = 0.015; and ΔV(post): -86 ± 12 vs. -60 ± 21, p = 0.012), yielding a sensitivity of 83% and specificity of 71% for the ΔV(during) and, respectively, 83% and 86% for the ΔV(post). The ∆ADC during (ΔADC(during)) and after RCT (ΔADC(post)) showed a significantly higher value in patients with pCR compared with patients without (in %: ΔADC(during): 72 ± 14 vs. 16 ± 12, p = 0.0006; and ΔADC(post): 88 ± 35 vs. 26 ± 19, p = 0.0011), yielding a sensitivity and specificity of 100% for the ΔADC(during) and, respectively, 100% and 93% for the ΔADC(post).
These initial findings indicate that DWI, using pretreatment ADC, ΔADC(during), and ΔADC(post) may be useful for prediction and early assessment of pathologic response to preoperative RCT of LARC, with higher accuracy than volumetric measurements.
评估扩散加权磁共振成像（DWI）在局部晚期直肠癌（LARC）术前放化疗（RCT）前后的预测反应和早期评估的应用。
20 名接受 LARC RCT 的患者在 RCT 前、第 10-15 次放疗后以及手术前 1-2 周进行 MRI 检查，包括 DWI。在所有时间点均测定肿瘤体积和表观扩散系数（ADC；b 值：0-1000 s/mm²）。比较治疗前肿瘤 ADC 和体积、治疗前后 ADC 变化（∆ADC）和体积变化（∆V）与全直肠系膜切除术后的组织病理学结果（完全病理缓解 [pCR]与无 pCR、ypT0-2 与 ypT3-4、降期或无降期）。通过接收者操作特性分析比较治疗前肿瘤 ADC 和体积、∆ADC 和 ∆V 对 pCR 检测的鉴别能力。
pCR 患者的治疗前 ADC 明显低于无 pCR 患者（以 mm²/s 表示：0.94 ± 0.12×10⁻³ 与 1.19 ± 0.22×10⁻³，p=0.003），检测 pCR 的敏感性为 100%，特异性为 86%。pCR 患者的治疗期间和治疗后肿瘤体积减少明显高于无 pCR 患者（以%表示：ΔV（治疗期间）：-62 ± 16 与 -33 ± 16，p=0.015；和 ΔV（治疗后）：-86 ± 12 与 -60 ± 21，p=0.012），治疗期间和治疗后体积减少的敏感性分别为 83%和特异性为 71%，而敏感性和特异性分别为 83%和 86%。pCR 患者的治疗期间（ΔADC（治疗期间））和治疗后（ΔADC（治疗后））ADC 变化值明显高于无 pCR 患者（以%表示：ΔADC（治疗期间）：72 ± 14 与 16 ± 12，p=0.0006；和 ΔADC（治疗后）：88 ± 35 与 26 ± 19，p=0.0011），治疗期间和治疗后 ADC 变化的敏感性和特异性分别为 100%和 93%。
这些初步发现表明，DWI 利用治疗前 ADC、ΔADC（治疗期间）和 ΔADC（治疗后），可能有助于预测和早期评估 LARC 术前 RCT 的病理反应，其准确性高于体积测量。
