From the Departments of Radiology.
Clin Nucl Med. 2021 Apr 1;46(4):289-296. doi: 10.1097/RLU.0000000000003485.
The aim of this study was to examine the MRI and FDG PET/CT imaging features of pathologically proven schwannomas.
This institutional review board-approved retrospective study examined biopsy-proven schwannomas that underwent FDG PET/CT and/or MRI at our institution between January 1, 2002, and April 1, 2018. PET/CT features analyzed included SUVmax, metabolic ratios, volumetric metabolic measures, presence of calcification, and pattern of FDG activity. MRI features included T1/T2 signal, enhancement pattern, margins, perilesional edema, presence of muscular denervation, and size.
Ninety-five biopsy-proven schwannomas were identified (40 with both PET and MRI, 35 with PET only, and 20 with MRI only), 46 females and 49 males, average age of 57.7 ± 15.3 years. The average largest dimension was 4.6 ± 2.7 cm, the average SUVmax was 5.4 ± 2.7, and lesion SUVmax/liver SUVmean was 2.2 ± 1.2. Eleven (15%) of 75 lesions had SUVmax greater than 8.1, 26/75 (35%) had SUVmax greater than 6.1, and 14/75 (19%) had lesion SUVmax/liver SUVmean greater than 3.0. On MRI, 29/53 (55%) demonstrated internal nonenhancing areas. Twenty-eight (70%) of 40 lesions with both MRI and PET demonstrated at least 1 imaging feature concerning for malignant peripheral nerve sheath tumor (irregular margins, internal nonenhancement, perilesional edema, heterogeneous FDG uptake, or SUVmax >8.1). Lesions with heterogeneous FDG activity had higher SUVmax (6.5 ± 0.5 vs 4.7 ± 0.4, P = 0.0031) and more frequent internal nonenhancement on MRI (P = 0.0218).
Schwannomas may be large, be intensely FDG avid, and demonstrate significant heterogeneity, features typically associated with malignant peripheral nerve sheath tumors. A significant proportion exhibit FDG activity above cutoff levels previously thought useful in differentiating malignant from benign peripheral nerve sheath tumors.
本研究旨在探讨经病理证实的神经鞘瘤的 MRI 和 FDG PET/CT 影像学特征。
本回顾性研究经机构审查委员会批准，纳入 2002 年 1 月 1 日至 2018 年 4 月 1 日期间在我院行 FDG PET/CT 和/或 MRI 检查且经活检证实为神经鞘瘤的患者。分析 PET/CT 特征包括 SUVmax、代谢比值、容积代谢指标、钙化情况和 FDG 活性模式。MRI 特征包括 T1/T2 信号、增强模式、边界、瘤周水肿、肌肉失神经支配情况和大小。
共确定 95 例经活检证实的神经鞘瘤（40 例同时行 PET 和 MRI 检查，35 例仅行 PET 检查，20 例仅行 MRI 检查），其中女性 46 例，男性 49 例，平均年龄 57.7±15.3 岁。平均最大直径为 4.6±2.7cm，平均 SUVmax 为 5.4±2.7，病灶 SUVmax/肝脏 SUVmean 为 2.2±1.2。75 个病灶中有 11 个（15%）SUVmax 大于 8.1，26/75（35%）SUVmax 大于 6.1，14/75（19%）病灶 SUVmax/肝脏 SUVmean 大于 3.0。在 MRI 上，29/53（55%）显示内部无增强区。40 例同时行 MRI 和 PET 检查的病灶中，28 例（70%）至少有 1 种影像学特征提示恶性外周神经鞘瘤（不规则边界、内部无增强、瘤周水肿、FDG 摄取不均匀或 SUVmax＞8.1）。FDG 摄取不均匀的病灶 SUVmax 更高（6.5±0.5 比 4.7±0.4，P=0.0031），MRI 上更常显示内部无增强（P=0.0218）。
神经鞘瘤可能较大，FDG 摄取强烈，表现出明显的异质性，这些特征通常与恶性外周神经鞘瘤有关。相当一部分病灶的 FDG 活性高于先前认为有助于区分恶性和良性外周神经鞘瘤的临界值。
