Hosonuma Tomonori, Tozaki Mitsuhiro, Ichiba Noriatsu, Sakuma Tohru, Hayashi Daichi, Yanaga Katsuhiko, Fukuda Kunihiko
Department of Surgery, Jikei University School of Medicine, Tokyo, Japan.
Magn Reson Med Sci. 2006 Dec;5(4):173-7. doi: 10.2463/mrms.5.173.
The purpose of this study was to assess the potential role of diffusion-weighted imaging (DWI) using low and high b-values to detect rectal cancer.
The subjects were 15 patients diagnosed endoscopically with rectal cancer (m in 1 patient, sm in 0, mp in 3, ss in 7, se in 1, a in 3) and 20 patients diagnosed endoscopically with colon cancer and no other lesions (control group). Magnetic resonance imaging was performed using a 1.5T system. DWI was performed in the axial plane using echo planar imaging sequence (repetition time/echo time 1200/66, field of view 306x350 mm, reconstruction matrix 156x256, pixel size 2.0x1.4x8.0 mm) and acquired with 2 b-values (50 and 800 s/mm2). Low and high b-value DW images were analyzed visually. A lesion was positive by detection of a focal area of high signal in the rectum in high b-value images. The apparent diffusion coefficient (ADC) values of areas of high signal in high b-value images were calculated from the low and high b-value images.
High b-value images enabled visualization of all 15 rectal cancers. In the control group, 13 cases were classified as negative and 7 cases as positive for rectal cancer. Sensitivity for detection of rectal cancer was 100% (15/15), and specificity was 65% (13/20). The mean ADC values in 7 patients with false-positive lesions and in 15 patients with rectal cancer were 1.374x10(-3) mm2/s (standard deviation [SD]: 0.157) and 1.194x10(-3) mm2/s (SD: 0.152), respectively (P=0.026).
DWI with low and high b-values may be used to screen for rectal cancer.
本研究旨在评估使用低b值和高b值的扩散加权成像（DWI）检测直肠癌的潜在作用。
研究对象为15例经内镜诊断为直肠癌的患者（1例为m期，0例为sm期，3例为mp期，7例为ss期，1例为se期，3例为a期）以及20例经内镜诊断为结肠癌且无其他病变的患者（对照组）。使用1.5T系统进行磁共振成像。在轴位平面采用回波平面成像序列进行DWI（重复时间/回波时间1200/66，视野306×350mm，重建矩阵156×256，像素大小2.0×1.4×8.0mm），并采用2个b值（50和800s/mm²）进行采集。对低b值和高b值的DWI图像进行视觉分析。在高b值图像中，通过检测直肠内的高信号灶来判定病变为阳性。根据低b值和高b值图像计算高b值图像中高信号区域的表观扩散系数（ADC）值。
高b值图像能够显示所有15例直肠癌。在对照组中，13例被分类为直肠癌阴性，7例为阳性。检测直肠癌的敏感性为100%（15/15），特异性为65%（13/20）。7例假阳性病变患者和15例直肠癌患者的平均ADC值分别为1.374×10⁻³mm²/s（标准差[SD]：0.157）和1.194×10⁻³mm²/s（SD：0.152）（P = 0.026）。
使用低b值和高b值的DWI可用于直肠癌筛查。
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