Utility of 18F-FDG PET with a Semi-Quantitative Index in the Detection of Sarcomatous Transformation in Patients with Neurofibromatosis Type 1

Abstract BACKGROUND Plexiform neurofibromas (PN) are a hallmark feature of Neurofibromatosis type 1 (NF1). 10% of PN undergo malignant transformation. As malignant peripheral nerve sheath tumors are a leading cause of death in NF1-patients, early detection of malignancy is essential. 2-deoxy-2-[ 18F]fluoro-D-glucose [18F]FDG PET/CT imaging is used in patients with NF1 to judge malignant transformation. AIMS: The present study evaluated [18F]FDG PET/MRI in pediatric NF1 patients at high risk for MPNST and its utility as a possible screening tool for malignant transformation of yet asymptomatic lesions. METHODS Patients aged 0-25 with symptomatic and asymptomatic neurofibromas who underwent PET/MRI from 2014 to 2021 were included. Chart review of imaging data, clinical and histological findings was performed retrospectively. RESULTS 41 patients (18 female) with a median age at first PET/MRI of 16.87 years (6.21-24.41) were included. 40 lesions were operated as indicated by clinical (e.g. pain, rapid growth) or imaging findings. Based on histopathological analysis 7 lesions in 4 patients were categorized as malignant, 3 as atypical neurofibromatous neoplasms of uncertain biologic potential (ANNUBP). 4/7 malignant and 2/3 ANNUBP lesions were asymptomatic (i.e. without rapid growth, pain, neurologic dysfunction). 5/7 symptomatic tumors were without significant FDG-PET and proven benign by histology. 18 lesions (2 symptomatic) in 9 patients that showed an increased uptake suspect of malignant transformation were histologically classified as benign. None of the patients died during follow-up, 1 symptomatic MPNST patient received postsurgical radio- and chemotherapy. CONCLUSION Our data indicate that malignant transformation of PN also occurs in asymptomatic patients. [18F]FDG PET/MRI is feasible in pediatric and adolescent patients with the tumor predisposition syndrome NF1 and is an alternative to PET/CT when assessing for malignancy thereby drastically reducing radiation exposure. Early detection through screening of high-risk NF1 patients with [18F]FDG PET/MRI could potentially increase overall survival by facilitating early curative resection.

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Metabolic Tumour Burden Measured by 18F-FDG PET/CT Predicts Malignant Transformation in Patients with Neurofibromatosis Type-1

PLoS ONE ◽

10.1371/journal.pone.0151809 ◽

2016 ◽

Vol 11 (3) ◽

pp. e0151809 ◽

Cited By ~ 16

Author(s):

Axel Van Der Gucht ◽

Ouidad Zehou ◽

Soraya Djelbani-Ahmed ◽

Laurence Valeyrie-Allanore ◽

Nicolas Ortonne ◽

...

Keyword(s):

Malignant Transformation ◽

Neurofibromatosis Type 1 ◽

Fdg Pet ◽

Neurofibromatosis Type ◽

Tumour Burden ◽

Pet Ct ◽

18F Fdg ◽

Fdg Pet Ct

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Safe marginal resection of atypical neurofibromas in neurofibromatosis type 1

Journal of Neurosurgery ◽

10.3171/2019.7.jns191353 ◽

2020 ◽

Vol 133 (5) ◽

pp. 1516-1526 ◽

Cited By ~ 4

Author(s):

Charlie N. Nelson ◽

Eva Dombi ◽

Jared S. Rosenblum ◽

Markku M. Miettinen ◽

Tanya J. Lehky ◽

...

Keyword(s):

Neurofibromatosis Type 1 ◽

Fdg Pet ◽

Standardized Uptake Value ◽

Neurofibromatosis Type ◽

Subtotal Resection ◽

Histopathological Analysis ◽

Low Grade ◽

Surgical Morbidity ◽

Peripheral Nerve Sheath Tumors

OBJECTIVEPatients with neurofibromatosis type 1 (NF1) are predisposed to visceral neurofibromas, some of which can progress to premalignant atypical neurofibromas (ANFs) and malignant peripheral nerve sheath tumors (MPNSTs). Though subtotal resection of ANF may prevent malignant transformation and thus deaths with no neural complications, local recurrences require reoperation. The aim of this study was to assess the surgical morbidity associated with marginal resection of targeted ANF nodules identified via preoperative serial volumetric MRI and 18F-FDG-PET imaging.METHODSThe authors analyzed clinical outcomes of 16 NF resections of 21 tumors in 11 NF1 patients treated at the NIH Clinical Center between 2008 and 2018. Preoperative volumetric growth rates and 18F-FDG-PET SUVMax (maximum standardized uptake value within the tumor) of the target lesions and any electromyographic or nerve conduction velocity abnormalities of the parent nerves were measured and assessed in tandem with postoperative complications, histopathological classification of the resected tumors, and surgical margins through Dunnett’s multiple comparisons test and t-test. The surgical approach for safe marginal resection of ANF was also described.RESULTSEleven consecutive NF1 patients (4 male, 7 female; median age 18.5 years) underwent 16 surgical procedures for marginal resections of 21 tumors. Preoperatively, 13 of the 14 (93%) sets of serial MRI studies and 10 of the 11 (91%) 18F-FDG-PET scans showed rapid growth (≥ 20% increase in volume per year) and avidity (SUVMax ≥ 3.5) of the identified tumor, respectively (median tumor size 48.7 cm3; median growth rate 92% per year; median SUVMax 6.45). Most surgeries (n = 14, 88%) resulted in no persistent postoperative parent nerve–related complications, and to date, none of the resected tumors have recurred. The median length of postoperative follow-up has been 2.45 years (range 0.00–10.39 years). Histopathological analysis confirmed significantly greater SUVMax among the ANFs (6.51 ± 0.83, p = 0.0042) and low-grade MPNSTs (13.8, p = 0.0001) than in benign neurofibromas (1.9).CONCLUSIONSThis report evaluates the utility of serial imaging (MRI and 18F-FDG-PET SUVMax) to successfully detect ANF and demonstrates that safe, fascicle-sparing gross-total, extracapsular resection of ANF is possible with the use of intraoperative nerve stimulation and microdissection of nerve fascicles.

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