Department of Radiology, Samsung Medicine Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Br J Radiol. 2012 May;85(1013):577-86. doi: 10.1259/bjr/68424021. Epub 2011 Feb 22.
To evaluate the added value of diffusion-weighted imaging (DWI) in combination with T(2) weighted imaging (T2WI) compared with T2WI alone or positron emission tomography (PET)/CT for detecting viable tumour after neoadjuvant chemoradiation therapy (CRT) in patients with locally advanced rectal cancer.
50 consecutive patients with locally advanced rectal cancer (≥T3 or lymph node positive) who underwent neoadjuvant CRT and subsequent surgery were enrolled in this retrospective study. All patients underwent 3.0 T rectal MRI and PET/CT after completing CRT. For qualitative analysis, two radiologists independently reviewed T2WI alone and DWI with T2WI over a 1-month interval. One nuclear medicine physician reviewed PET/CT images using a five-point scale. Diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting viable tumour were assessed. For quantitative analysis, the apparent diffusion coefficients (ADCs) of the lesions were measured and compared between the viable tumour group and non-viable tumour groups.
For detecting viable tumours, DWI with T2WI improved diagnostic accuracies (Reviewer 1 detected 90%; Reviewer 2, 86%) over T2WI alone (Reviewer 1 detected 76%, p=0.5; Reviewer 2, 64%, p=0.013) or PET/CT (48%, p<0.001). The sensitivity of DWI with T2WI (Reviewer 1 detected 98%; Reviewer 2, 91%) was significantly higher than those of T2WI alone (Reviewer 1 detected 77%; Reviewer 2, 64%) or PET-CT (43%, p<0.05). Only for Reviewer 2 was the NPV of DWI with T2WI (43%) significantly different from that of PET/CT (17%, p<0.05). The specificities and PPVs of DWI with T2WI were not improved over those of T2WI alone or of PET/CT (both p>0.05). The mean ADC of the viable tumour group (0.93 × 10(-3) mm(2) sc(-1)) was significantly lower than that of the non-viable tumour group (1.55 × 10(-3) mm(2) sc(-1), p<0.0001).
Adding DWI to T2WI is helpful for detecting viable tumours after neoadjuvant CRT compared with T2WI alone or PET/CT in patients with locally advanced rectal cancer.
评估弥散加权成像（DWI）联合 T2 加权成像（T2WI）与 T2WI 或正电子发射断层扫描（PET）/CT 相比，在检测局部进展期直肠癌新辅助放化疗后存活肿瘤方面的附加价值。
本回顾性研究纳入了 50 例局部进展期直肠癌（≥T3 或淋巴结阳性）患者，所有患者均接受新辅助放化疗和随后的手术治疗。所有患者均在完成放化疗后接受 3.0 T 直肠 MRI 和 PET/CT。定性分析中，两名放射科医生在 1 个月的间隔内分别对 T2WI 与 DWI 联合 T2WI 进行独立评估。一名核医学医师使用五分制对 PET/CT 图像进行评估。评估检测存活肿瘤的诊断准确性、敏感性、特异性、阳性预测值（PPV）和阴性预测值（NPV）。定量分析中，测量并比较了存活肿瘤组与非存活肿瘤组的病变表观扩散系数（ADC）。
与 T2WI 相比，DWI 联合 T2WI 可提高诊断准确性（医生 1 检测出 90%；医生 2 检测出 86%）（医生 1 检测出 76%，p=0.5；医生 2 检测出 64%，p=0.013）或 PET/CT（48%，p<0.001）。DWI 联合 T2WI 的敏感性（医生 1 检测出 98%；医生 2 检测出 91%）明显高于 T2WI 单独（医生 1 检测出 77%；医生 2 检测出 64%）或 PET-CT（43%，p<0.05）。只有医生 2 的 DWI 联合 T2WI 的阴性预测值（43%）与 PET/CT（17%）有显著差异（p<0.05）。DWI 联合 T2WI 的特异性和 PPV 与 T2WI 单独或 PET/CT 相比没有提高（均 p>0.05）。存活肿瘤组的平均 ADC 值（0.93×10(-3)mm(2)sc(-1))明显低于非存活肿瘤组（1.55×10(-3)mm(2)sc(-1)，p<0.0001）。
与 T2WI 或 PET/CT 相比，DWI 联合 T2WI 有助于检测局部进展期直肠癌新辅助放化疗后存活肿瘤。
