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

In patients with neurofibromatosis type 1, transformation of neurofibromas into a malignant peripheral nerve sheath tumor (MPNST) is a severe complication of the disease. Fluorine-18-fluorodeoxyglucose PET/computed tomography (PET/CT) is a viable option for detecting malignant tumors in neurofibromatosis type 1 patients. The aim of this review was to assess the diagnostic performance of the most frequently used parameters of PET/CT in detecting MPNST. An extensive computer search was performed using the Cochrane Library, Pubmed, and Medline/Embase databases. Two reviewers independently extracted data of relevant studies and assessed the methodological quality (QUADAS-2). The diagnostic performance of PET/CT parameters in individual studies was determined by calculating a diagnostic odds ratio (DOR) using the absolute numbers of true-positive, true-negative, false-positive, and false-negative test results. A total of eight studies were included, of which three evaluated the standardized uptake value as a diagnostic parameter, two assessed the tumor-to-liver (T/L) ratio, and three articles described both parameters. The cut-off values for maximum standardized uptake value (SUVmax) ranged from 3.2 to 4.5; for the T/L ratio, the cut-off values were between 1.0 and 4.3. The sensitivity and specificity ranged from 90 to 100% and from 80 to 100%, respectively (SUVmax). T/L ratios were associated with 92-100% sensitivity and 72-94% specificity. The corresponding DORs ranged from 57 to 145 (SUVmax) and 35 to 655 (T/L ratio). Both the SUV and the T/L ratio are associated with high sensitivity combined with acceptable specificity in detecting MPNST. There is a tendency toward higher DORs using the T/L ratio, but the number of studies is limited.

Malignant Peripheral Nerve Sheath Tumor in a Patient with Neurofibromatosis and Primary Hyperparathyroidism

“…Plexiform variants of MPNSTs carry the highest risk. 3 Hyperparathyroidism in association with NF1 is also a rare occurrence that has been previously described in the literature. Here, we present the case of a patient with neurofibromatosis, primary hyperparathyroidism, and suprarenal MPNST.…”

Role of [18F]FDG PET/CT in the differential diagnosis of a supraclavicular lump: neurofibromatosis disease

“…Neurofibromas are the most prevalent benign peripheral nerve sheath tumor classically associated with neurofibromatosis (NF) but also can appear as solitary lesions [1,2]. Those related to NF carry an increased risk of malignant transformation (2-13%), consequently, some cut-off values of SUVmax have been proposed based on a SUVmax greater than 3.2 [3] and lesion-to-liver (T/L) values over 1.5 [4,5,6] but the role of [ 18 F]FDG PET/CT remains still under discussion at this point [7,8]. Complete surgical excision is the treatment of choice in most patients, retaining systemic treatments such as recently FDA-approved selumetinib (tyrosine kinase inhibitor) for diffuse NF cases [9].…”

Oncological Treatment Considerations Differ across Surgical Subspecialties Treating Malignant Peripheral Nerve Sheath Tumors: An International Survey

“…However, preoperative identification of malignancy in NF1 patients is particularly difficult, as atypical and plexiform neurofibromas can present similarly to MPNSTs. Recent research has shown that FDG-PET scans can be helpful in distinguishing malignant from benign lesions, differentiating MPNSTs from neurofibromas with an 80% specificity and almost 100% sensitivity [25,26], which is why an NF1 consensus does recommend performing it [22]. Others have shown that diffusion-weighted imaging sequences in MRI can differentiate malignancy with 100% specificity; however these techniques are not standard of care in many centers [24].…”