Department of Radiology, GATA Haydarpasa Teaching Hospital, Istanbul, Turkey.
Clin Imaging. 2012 Jan-Feb;36(1):1-7. doi: 10.1016/j.clinimag.2011.04.001.
The purpose of the study was to differentiate between benign and malignant thyroid nodules using nodule-spinal cord signal intensity and nodule apparent diffusion coefficient (ADC) ratios on diffusion-weighted magnetic resonance imaging (DW-MRI).
Forty-four patients (27 females, 17 males; mean age, 49 years) with nodules who underwent DW-MRI were included in this study. The images were acquired with 0, 50, 400 and 1000 s/mm(2)b values. ADC maps were calculated afterwards. Fine needle aspiration biopsies (FNAB) were performed at the same day with DW-MRI acquisition. The diagnosis in patients where malignity was detected after FNAB was confirmed by histopathologic analysis of the operation material. The signal intensities of the spinal cord and the nodule were measured additionally, over b-1000 diffusion-weighted images. Nodule/cord signal intensity (SI) ratios were obtained and the digital values were calculated by dividing to ADC values estimated for each nodule. Statistical analysis was performed.
The (nodule SI-cord SI)/nodule ADC ratio is calculated in the DW images, and a statistically significant relationship was found between this ratio and the histopathology of the nodules (P<.001). The ratio was determined as 0.27 in benign and 0.86 in malignant lesions. The result of receiver operating characteristic (ROC) analysis was statistically significant, and the area under curve (100%) was considerably high. The threshold value was calculated as 0.56 according to the ROC analysis. According to this threshold value, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy rates for (nodule SI/cord SI)/ADC ratios in differentiating benign from malignant thyroid nodules are calculated as 100%, 97%, 83%, 100%, and 98%, respectively.
We have found that (nodule/cord SI)/nodule ADC ratio has the highest values for sensitivity and specificity among the tests defined for characterization of nodules.
本研究旨在通过磁共振弥散加权成像（DW-MRI）测量结节-脊髓信号强度比和结节表观弥散系数（ADC）比，鉴别甲状腺良恶性结节。
本研究共纳入 44 例（27 名女性，17 名男性；平均年龄 49 岁）行 DW-MRI 检查的患者。采集 0、50、400 和 1000 s/mm2b 值图像，计算 ADC 图。同日在 DW-MRI 采集时行细针穿刺活检（FNAB）。对 FNAB 发现恶性的患者，根据手术标本的组织病理学分析进行诊断。在 DW 图像上测量脊髓和结节的信号强度，并在 b-1000 弥散加权图像上计算数字值，计算结节/脊髓信号强度（SI）比值，并将其除以每个结节的 ADC 值。进行统计学分析。
DW 图像上计算（结节 SI-脊髓 SI）/结节 ADC 比值，该比值与结节的组织病理学存在显著相关性（P<.001）。良性结节比值为 0.27，恶性结节比值为 0.86。ROC 分析结果具有统计学意义，曲线下面积（100%）较高。根据 ROC 分析，阈值为 0.56。根据该阈值，（结节 SI/脊髓 SI）/ADC 比值鉴别甲状腺良恶性结节的灵敏度、特异度、阳性预测值、阴性预测值和准确率分别为 100%、97%、83%、100%和 98%。
我们发现，（结节/脊髓 SI）/结节 ADC 比值在结节性质评估的各项检测中具有最高的灵敏度和特异度。
