Department of Radiodiagnosis, All India Institute of Medical Sciences (A.I.I.M.S.), Ansari Nagar, New Delhi, 110029, India.
Eur Radiol. 2013 Jan;23(1):272-9. doi: 10.1007/s00330-012-2577-0. Epub 2012 Jul 15.
To evaluate the diffusion characteristics of inflammatory renal lesions and assess whether apparent diffusion coefficient (ADC) values can distinguish them from renal-cell carcinomas (RCCs).
Eighty-eight patients underwent multidetector computed tomography (MDCT), magnetic resonance imaging (MRI) and diffusion-weighted (DW) MRI (at b values of 0 and 500 s/mm(2)) for characterisation of focal renal lesions. On retrospective evaluation, 15 patients had 20 inflammatory lesions and 33 patients had 36 RCCs. DW images were compared and receiver operating characteristic (ROC) curves were drawn to establish cut-off ADC values.
All inflammatory lesions and 91.7% of RCCs showed restricted diffusion. DW images showed markedly restricted diffusion in fluid intensity areas of abscesses, whereas RCCs showed free diffusion in their cystic portions. Quantitatively, both abscesses and RCCs showed ADC values significantly lower than normal renal parenchyma [1.12 and 1.56 respectively vs 2.34 (× 10(-3) mm(2)/s) for normal kidney] (P < 0.0001 for both) and significantly different from each other (P < 0.0001). ROC analysis in differentiating inflammatory lesions and RCC revealed high sensitivity (100%) and specificity (78.1%) for cut-off ADC value of 1.41 (× 10(-3) mm(2)/s).
Both abscess and RCC showed restricted diffusion, the former did so to a greater extent, distinctly in fluid components. Thus, ADC values provide an additional paradigm for characterisation of indeterminate renal lesions.
评估炎症性肾病变的弥散特征，评估表观弥散系数（ADC）值是否可鉴别此类病变与肾细胞癌（RCC）。
88 例患者行多排 CT（MDCT）、磁共振成像（MRI）及弥散加权（DW）MRI（b 值分别为 0 和 500 s/mm²）检查以明确局灶性肾病变的性质。回顾性评估中，15 例患者有 20 个炎症性病变，33 例患者有 36 个 RCC。对比 DW 图像并绘制受试者工作特征（ROC）曲线以确定 ADC 值的截断值。
所有炎症性病变及 91.7%的 RCC 表现为弥散受限。脓肿的液体信号区 DW 图像呈明显弥散受限，而 RCC 的囊性部分表现为自由弥散。定量分析示，脓肿及 RCC 的 ADC 值均显著低于正常肾实质[分别为 1.12 和 1.56（×10⁻³mm²/s）比正常肾脏的 2.34（×10⁻³mm²/s）]（P<0.0001），且彼此之间差异有统计学意义（P<0.0001）。鉴别炎症性病变与 RCC 的 ROC 分析显示，ADC 值截断值为 1.41（×10⁻³mm²/s）时，诊断敏感度为 100%，特异度为 78.1%。
脓肿和 RCC 均表现为弥散受限，前者程度更重，尤其在液体成分中。因此，ADC 值为不典型肾病变的定性提供了另一种方法。
