From The Johns Hopkins University School of Medicine, Baltimore, MD.
Neurology. 2019 Sep 10;93(11):e1076-e1084. doi: 10.1212/WNL.0000000000008092. Epub 2019 Aug 8.
To determine the utility of quantitative metrics obtained from fMRI using diffusion-weighted imaging (DWI)/apparent diffusion coefficient (ADC) mapping compared with metabolic (F-fluorodeoxyglucose [FDG]-PET/CT) imaging in patients with neurofibromatosis type 1 (NF1) for the characterization of peripheral nerve sheath tumors (PNSTs) as benign or malignant.
This Institutional Review Board-approved, Health Insurance Portability and Accountability Act-compliant study retrospectively reviewed imaging of 55 PNSTs in 21 patients with NF1. Imaging included anatomic (unenhanced T1, fluid-sensitive, contrast-enhanced T1-weighted), functional DWI (b = 50, 400, 800 s/mm) and ADC mapping, magnetic resonance sequences, and FDG-PET/CT imaging. Anatomic (size), functional (minimum ADC values), and metabolic (maximum standardized uptake values [SUVmax]) imaging characteristics were recorded. ADC values were correlated with SUVmax. With histologic correlation for all malignant PNSTs (MPNSTs) or clinical or imaging stability (>12 months) for benign lesions used as reference standards, diagnostic accuracy was calculated.
Of 55 PNSTs, there were 19 (35%) malignant and 36 (65%) benign PNSTs. Benign PNSTs were overall smaller than MPNSTs (largest diameter 4.3 ± 1.3 vs 8.2 ± 3.3 cm, respectively, = 0.014). Benign PNSTs had higher ADCmin (×10 mm/s) than MPNSTs (1.6 ± 0.4 vs 0.6 ± 0.2, respectively, < 0.0001) and lower SUVmax than MPNSTs (3.2 ± 1.8 vs 8 ± 3.9, < 0.0001, respectively). ADCmin correlated inversely with SUVmax (correlation coefficient = -0.0.58, < 0.0001). Maintaining a sensitivity of 100% with threshold values of ADCmin ≤1 or SUVmax >3.2, DWI yielded a specificity of 94% while FDG-PET/CT offered a specificity of 83%.
Both quantitative metabolic imaging and functional imaging offer high sensitivity for the characterization of PNSTs in NF1; however, DWI/ADC mapping offers increased specificity and may be a more useful modality.
This study provides Class II evidence that for patients with NF1, MRI using DWI/ADC mapping accurately distinguishes malignant and benign PNSTs.
确定使用磁共振弥散加权成像（DWI）/表观弥散系数（ADC）映射获得的功能磁共振成像（fMRI）定量指标在神经纤维瘤病 1 型（NF1）患者外周神经鞘肿瘤（PNST）特征中的效用，以区分良性或恶性肿瘤。
本研究经机构审查委员会批准，符合《健康保险流通与责任法案》的规定，回顾性分析了 21 例 NF1 患者 55 个 PNST 的影像学资料。影像学包括解剖学（未增强 T1、液体敏感、对比增强 T1 加权）、功能 DWI（b 值为 50、400、800 s/mm）和 ADC 图、磁共振序列和 F-氟脱氧葡萄糖（FDG）-正电子发射断层扫描/计算机断层扫描（PET/CT）成像。记录解剖学（大小）、功能（最小 ADC 值）和代谢（最大标准化摄取值 [SUVmax]）影像学特征。分析 ADC 值与 SUVmax 的相关性。以所有恶性外周神经鞘瘤（MPNST）的组织学相关性或良性病变的临床或影像学稳定性（>12 个月）作为参考标准，计算诊断准确性。
在 55 个 PNST 中，有 19 个（35%）为恶性，36 个（65%）为良性。良性 PNST 总体上比 MPNST 小（最大直径分别为 4.3±1.3cm 和 8.2±3.3cm， = 0.014）。良性 PNST 的 ADCmin（×10mm/s）高于 MPNST（分别为 1.6±0.4 和 0.6±0.2， < 0.0001），SUVmax 低于 MPNST（分别为 3.2±1.8 和 8±3.9， < 0.0001）。ADCmin 与 SUVmax 呈负相关（相关系数 = -0.058， < 0.0001）。以 ADCmin≤1 或 SUVmax＞3.2 为阈值，DWI 具有 100%的敏感性，特异性为 94%，而 FDG-PET/CT 的特异性为 83%。
定量代谢成像和功能成像均能高度敏感地对 NF1 患者的 PNST 进行特征描述；然而，DWI/ADC 图提供了更高的特异性，可能是一种更有用的方式。
本研究提供了 II 级证据，表明对于 NF1 患者，DWI/ADC 磁共振成像能准确区分恶性和良性 PNST。
