Takeuchi Mitsuru, Sasaki Shigeru, Ito Masato, Okada Shinsuke, Takahashi Satoru, Kawai Tatsuya, Suzuki Kaori, Oshima Hidekazu, Hara Masaki, Shibamoto Yuta
Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
Radiology. 2009 Apr;251(1):112-21. doi: 10.1148/radiol.2511080873.
To prospectively evaluate the ability of diffusion-weighted (DW) magnetic resonance (MR) imaging to be used to determine the T stage of bladder cancer and to measure the correlation between the apparent diffusion coefficient (ADC) and histologic grade.
This study was approved by the local institutional review board. All patients gave written informed consent. Forty patients with a total of 52 bladder tumors underwent MR imaging that included DW imaging. Histologic grade was determined for all tumors. Two radiologists interpreted four image sets (ie, T2-weighted images alone, T2-weighted plus DW images, T2-weighted plus dynamic contrast agent-enhanced images, all three image types together). Conventional criteria were used for interpreting T2-weighted and contrast-enhanced images. For DW images, new staging criterion developed on the basis of the hypothesis that tumors, submucosal tissue, and muscles show high, low, and intermediate signal intensity, respectively, was used. The McNemar test was used to examine differences in accuracy, sensitivity, and specificity. Differences in the performance were analyzed by comparing the areas under the receiver operating characteristic curves (A(z) values). To compare ADCs between three histologic grades, analysis of variance was used.
The overall accuracy of T stage diagnosis was 67% for T2-weighted images alone, 88% for T2-weighted plus DW images, 79% for T2-weighted plus contrast-enhanced images, and 92% for all three image types together. The overall accuracy, specificity, and A(z) for diagnosing T2 or higher stages were significantly improved by adding DW images (P < .01). The mean ADC of G3 tumors was significantly lower than that of G1 and G2 tumors (P < .01).
DW images provided useful information for evaluating the T stage of bladder cancer, particularly in differentiating T1 or lower tumors from T2 or higher tumors. The ADC may in part predict the histologic grade of bladder cancer.
前瞻性评估扩散加权磁共振成像用于确定膀胱癌T分期以及测量表观扩散系数（ADC）与组织学分级之间相关性的能力。
本研究经当地机构审查委员会批准。所有患者均签署了书面知情同意书。40例共有52个膀胱肿瘤的患者接受了包括扩散加权成像的磁共振成像检查。对所有肿瘤确定组织学分级。两名放射科医生解读四组图像（即仅T2加权图像、T2加权加扩散加权图像、T2加权加动态对比剂增强图像、所有三种图像类型）。采用传统标准解读T2加权图像和对比增强图像。对于扩散加权图像，使用基于肿瘤、黏膜下组织和肌肉分别显示高、低和中等信号强度这一假设制定的新分期标准。采用McNemar检验来检查准确性、敏感性和特异性的差异。通过比较受试者操作特征曲线下面积（A(z)值）分析性能差异。为比较三种组织学分级之间的ADC，采用方差分析。
仅T2加权图像的T分期诊断总体准确率为67%，T2加权加扩散加权图像为88%，T2加权加对比增强图像为79%，所有三种图像类型一起为92%。通过添加扩散加权图像，诊断T2期或更高分期的总体准确率、特异性和A(z)值均显著提高（P < 0.01）。G3肿瘤的平均ADC显著低于G1和G2肿瘤（P < 0.01）。
扩散加权图像为评估膀胱癌的T分期提供了有用信息，特别是在区分T1期或更低期肿瘤与T2期或更高期肿瘤方面。ADC可能部分预测膀胱癌的组织学分级。
