Division of Neurosurgery, Toronto Western Hospital, University of Toronto, Toronto, Canada.
Neurosurgery. 2009 Oct;65(4 Suppl):A160-70. doi: 10.1227/01.NEU.0000337597.18599.D3.
Benign plexiform neurofibromas (PNfib), especially those occurring in patients with neurofibromatosis type 1, are at a significant risk of progressing to a malignant peripheral nerve sheath tumor (MPNST). Early diagnosis, followed by radical surgery and adjuvant radiation to maintain local tumor control, is of critical importance to prevent metastasis and subsequent mortality from MPNSTs. However, early diagnosis is hampered by the sensitivity of current imaging modalities such as computed tomography (CT) or magnetic resonance imaging to reliably detect this malignant transformation, which can occur heterogeneously in a PNfib to a MPNST. 18Fluorodeoxyglucose (18FDG)-positron emission tomography (PET) is linked to metabolism and proliferation of tissues and has been widely used in oncology including PNSTs. 18FDG-PET/CT has the added advantage of fusing metabolic and anatomic imaging data sets.
In this prospective study, 9 neurofibromatosis type 1-associated PNfibs suspected to have undergone transformation to an MPNST were preoperatively evaluated by 18FDG-PET/CT and magnetic resonance imaging. A detailed histological evaluation correlated the average and regional standard uptake value (SUV) from the 18FDG-PET/CT to grade of malignancy of the suspected MPNST.
Imaging from 18FDG-PET/CT and associated SUV of the suspected MPNSTs demonstrated either a homogeneous or a heterogeneous pattern. Stratification of the maximal SUV to low (<4.0), intermediate (4.0-7.0), or high (>7.0) correlated to the proliferative index (Ki-67) and grade of MPNST. A maximal SUV of more than 7.0 was closely correlated to a focus of malignant transformation.
This study, on a limited number of cases, demonstrates the potential use of 18FDG-PET/CT to augment management of PNfibs, especially in the context of neurofibromatosis type 1, which is characterized by multiple tumors. The addition of CT anatomic imaging to 18FGD-PET can facilitate targeting biopsies to metabolic hot spots, to further augment diagnostic sensitivity. Much larger numbers of MPNSTs, which can only be accrued in a collaborative manner among institutions, are required to further assess the specificity and sensitivity of 18FDG-PET/CT in the diagnosis of MPNSTs.
良性丛状神经纤维瘤（PNfib），特别是发生于神经纤维瘤病 1 型患者的丛状神经纤维瘤，存在显著进展为恶性外周神经鞘瘤（MPNST）的风险。早期诊断，随后进行根治性手术和辅助放疗以维持局部肿瘤控制，对于预防 MPNST 的转移和随后的死亡率至关重要。然而，目前的成像方式如计算机断层扫描（CT）或磁共振成像（MRI）的敏感性有限，难以可靠地检测到这种恶性转化，PNfib 向 MPNST 的恶性转化可以是异质性的。18 氟脱氧葡萄糖（18FDG）-正电子发射断层扫描（PET）与组织的代谢和增殖有关，已广泛应用于包括 PNST 在内的肿瘤学中。18FDG-PET/CT 具有融合代谢和解剖成像数据集的额外优势。
在这项前瞻性研究中，对 9 例疑有恶性转化为 MPNST 的神经纤维瘤病 1 型相关 PNfib 进行了术前 18FDG-PET/CT 和磁共振成像检查。详细的组织学评估将 18FDG-PET/CT 的平均和区域标准摄取值（SUV）与可疑 MPNST 的恶性程度相关联。
18FDG-PET/CT 的影像学表现和相关 SUV 显示疑似 MPNST 呈均匀或不均匀模式。将最大 SUV 分层为低（<4.0）、中（4.0-7.0）或高（>7.0）与增殖指数（Ki-67）和 MPNST 分级相关。最大 SUV 大于 7.0 与恶性转化的焦点密切相关。
这项基于有限数量病例的研究表明，18FDG-PET/CT 具有辅助管理 PNfib 的潜力，特别是在神经纤维瘤病 1 型的背景下，该疾病以多发性肿瘤为特征。将 CT 解剖成像添加到 18FGD-PET 中可以促进对代谢热点的靶向活检，从而进一步提高诊断敏感性。需要更多的 MPNST 病例（只能通过机构间的合作来获得），以进一步评估 18FDG-PET/CT 在诊断 MPNST 中的特异性和敏感性。
