Evaluation of the most commonly used (semi-)quantitative parameters of 18F-FDG PET/CT to detect malignant transformation of neurofibromas in 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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Evaluation of intratumoural heterogeneity on 18F-FDG PET/CT for characterization of peripheral nerve sheath tumours in neurofibromatosis type 1

European Journal of Nuclear Medicine and Molecular Imaging ◽

10.1007/s00259-012-2314-6 ◽

2012 ◽

Vol 40 (5) ◽

pp. 685-692 ◽

Cited By ~ 39

Author(s):

Johannes Salamon ◽

Thorsten Derlin ◽

Peter Bannas ◽

Jasmin D. Busch ◽

Jochen Herrmann ◽

...

Keyword(s):

Peripheral Nerve ◽

Neurofibromatosis Type 1 ◽

Neurofibromatosis Type ◽

Nerve Sheath ◽

Pet Ct ◽

Intratumoural Heterogeneity ◽

18F Fdg ◽

Fdg Pet Ct

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[18F]FDG PET/CT quantitative parameters for the prediction of histological response to induction chemotherapy and clinical outcome in patients with localised bone and soft-tissue Ewing sarcoma

European Radiology ◽

10.1007/s00330-021-07841-w ◽

2021 ◽

Author(s):

Alessio Annovazzi ◽

Virginia Ferraresi ◽

Vincenzo Anelli ◽

Renato Covello ◽

Sabrina Vari ◽

...

Keyword(s):

Soft Tissue ◽

Clinical Outcome ◽

Induction Chemotherapy ◽

Ewing Sarcoma ◽

Fdg Pet ◽

Histological Response ◽

Quantitative Parameters ◽

Pet Ct ◽

18F Fdg ◽

Fdg Pet Ct

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Imaging biomarkers for malignant peripheral nerve sheath tumors in neurofibromatosis type 1

Neurology ◽

10.1212/wnl.0000000000008092 ◽

2019 ◽

Vol 93 (11) ◽

pp. e1076-e1084 ◽

Cited By ~ 7

Author(s):

Shivani Ahlawat ◽

Jaishri O. Blakeley ◽

Fausto J. Rodriguez ◽

Laura M. Fayad

Keyword(s):

Fdg Pet ◽

Neurofibromatosis Type ◽

Nerve Sheath Tumors ◽

Peripheral Nerve Sheath Tumors ◽

Pet Ct ◽

Adc Values ◽

Adc Mapping ◽

Fdg Pet Ct

ObjectiveTo determine the utility of quantitative metrics obtained from fMRI using diffusion-weighted imaging (DWI)/apparent diffusion coefficient (ADC) mapping compared with metabolic (18F-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.MethodsThis 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/mm2) 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.ResultsOf 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, p = 0.014). Benign PNSTs had higher ADCmin (×10−3 mm2/s) than MPNSTs (1.6 ± 0.4 vs 0.6 ± 0.2, respectively, p < 0.0001) and lower SUVmax than MPNSTs (3.2 ± 1.8 vs 8 ± 3.9, p < 0.0001, respectively). ADCmin correlated inversely with SUVmax (correlation coefficient r = −0.0.58, p < 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%.ConclusionsBoth 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.Classification of evidenceThis study provides Class II evidence that for patients with NF1, MRI using DWI/ADC mapping accurately distinguishes malignant and benign PNSTs.

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