Bulakbasi Nail, Guvenc Inanc, Onguru Onder, Erdogan Ersin, Tayfun Cem, Ucoz Taner
Department of Radiology, Gulhane Military Medical Academy, Etlik, 06018 Ankara, Turkey.
J Comput Assist Tomogr. 2004 Nov-Dec;28(6):735-46. doi: 10.1097/00004728-200411000-00003.
ADC calculation can improve the diagnostic efficacy of MR imaging in brain tumor grading and differentiation.
Apparent diffusion coefficient (ADC) values and ratios of 33 low-grade (23 astrocytomas, 10 oligodendrogliomas) and 40 high-grade (25 metastases and 15 high-grade astrocytomas) malignant tumors were prospectively evaluated.
Tumoral ADC values (r=-0.738, P <0.000) and ratios (r=-0.746, P < 0.000) were well correlated with higher degree of malignancy and quite effective in grading of malignant brain tumors (P < 0.000). By using cutoff values of 0.99 for tumoral ADC value and 1.22 for normalized ADC ratio, the sensitivity of MR imaging could be increased from 72.22% to 93.75% and 90.63%, the specificity from 81.08% to 92.68% and 90.24%, PPV from 78.79% to 90.91% and 87.88%, and NPV from 75.00% to 95.00% and 92.50%, respectively.
ADC calculation was quite effective in grading of malignant brain tumors but not in differentiation of them and added more information to conventional contrast-enhanced MR imaging.
表观扩散系数（ADC）计算可提高磁共振成像（MR成像）在脑肿瘤分级和鉴别诊断中的效能。
前瞻性评估了33例低级别（23例星形细胞瘤、10例少突胶质细胞瘤）和40例高级别（25例转移瘤和15例高级别星形细胞瘤）恶性肿瘤的表观扩散系数（ADC）值及比值。
肿瘤ADC值（r = -0.738，P <0.000）和比值（r = -0.746，P <0.000）与更高的恶性程度密切相关，在恶性脑肿瘤分级中相当有效（P <0.000）。采用肿瘤ADC值的截断值0.99和标准化ADC比值的截断值1.22，MR成像的敏感性可分别从72.22%提高到93.75%和90.63%，特异性从81.08%提高到92.68%和90.24%，阳性预测值从78.79%提高到90.91%和87.88%，阴性预测值从75.00%提高到95.00%和92.50%。
ADC计算在恶性脑肿瘤分级中相当有效，但在鉴别诊断中无效，且为传统的对比增强MR成像增加了更多信息。
