title: Potential role of 18fluorodeoxyglucose-positron emission tomography/computed tomography in differentiating benign neurofibroma from malignant peripheral nerve sheath tumor associated with neurofibromatosis 1.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital, University of Toronto, Toronto, Canada.
authors.forename: Konstantina
authors.initials: K
authors.lastname: Karabatsou
authors.forename: Tim-Rasmus
authors.initials: TR
authors.lastname: Kiehl
authors.forename: David M
authors.initials: DM
authors.lastname: Wilson
authors.forename: Aaron
authors.initials: A
authors.lastname: Hendler
authors.forename: Abhijit
authors.initials: A
authors.lastname: Guha
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D018317:Nerve Sheath Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D009455:Neurofibroma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D009456:Neurofibromatosis 1 / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D010525:Peripheral Nerves / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D010524:Peripheral Nervous System Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D049268:Positron-Emission Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18