title: Utility of 18F-FDG-PET/CT in patients suspected of paraneoplastic neurological syndrome: importance of risk classification.
abstract: OBJECTIVE
  To assess the diagnostic impact of 18F-FDG-PET/CT in patients suspected of paraneoplastic neurological syndrome (PNS) based on our own pre-test risk classification (PRC).
  
  
  METHODS
  A multicenter retrospective longitudinal study was conducted from 2006 to 2014. We designed a seven-point scoring system using the clinical syndrome characteristics [classical (CS) and non-classical syndromes (NCS)] and its location (central, peripheral, in the neuromuscular junction or combined), onconeural antibodies and tumor markers. Patients were classified as low (score 0-2), intermediate (3-4) and high (5-7) pre-test risk of PNS. FDG-PET/CT was classified as negative or positive. Final diagnosis according Graus' criteria (definite, possible or no PNS) was established. Relations between clinical and metabolic variables with the final diagnosis were studied.
  
  
  RESULTS
  73 patients were included, with a follow-up time of 33 months. Eleven (15 %) patients were finally diagnosed with neoplasm (8 invasive cancers). Ultimately, 13 (18 %) and 24 (33 %) subjects were diagnosed as definite or possible PNS. All the patients with final diagnosis of neoplasm had a CS (p = 0.005). PET/CT was helpful to diagnose 6/8 (75 %) invasive cancers. PET/CT findings were associated with the final diagnosis of neoplasm (p = 0.003) and the diagnosis of PNS attending to Graus' criteria (p = 0.019). PRC showed significant association with the final diagnosis of neoplasm and PET/CT results. A majority of patients (10/11) diagnosed of neoplasm had intermediate/high-risk.
  
  
  CONCLUSIONS
  Our PRC seems to be a valid tool to select candidates for PET/CT imaging in this setting. PET/CT detected malignancy in a significant proportion of patients with invasive cancer.
authors.affiliation: Nuclear Medicine Department, University General Hospital, C/Obispo Rafael Torija s/n, 13005, Ciudad Real, Spain. fjpena@msn.com.
authors.forename: F J
authors.identifier: http://orcid.org/0000-0003-1993-6813
authors.initials: FJ
authors.lastname: Pena Pardo
authors.affiliation: Nuclear Medicine Department, University General Hospital, C/Obispo Rafael Torija s/n, 13005, Ciudad Real, Spain.
authors.forename: A M
authors.initials: AM
authors.lastname: García Vicente
authors.affiliation: Mathematics Department, Castilla La Mancha University, Ciudad Real, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Amo-Salas
authors.affiliation: Mathematics Department, Castilla La Mancha University, Ciudad Real, Spain.
authors.forename: J F
authors.initials: JF
authors.lastname: López-Fidalgo
authors.affiliation: Neurology Department, Virgen de la Salud Hospital, Toledo, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Garrido Robles
authors.affiliation: Internal Medicine Department, University Hospital, Albacete, Spain.
authors.forename: J Á
authors.initials: JÁ
authors.lastname: de Ayala Fernández
authors.affiliation: Neurology Department, Mancha Centro Hospital, Alcázar de San Juan, Ciudad Real, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Del Saz Saucedo
authors.affiliation: Neurology Department, Puertollano Hospital, Ciudad Real, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Muñoz Pasadas
authors.affiliation: Nuclear Medicine Department, University General Hospital, C/Obispo Rafael Torija s/n, 13005, Ciudad Real, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Soriano Castrejón
mesh_terms: D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009367:Neoplasm Staging; D009422:Nervous System Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D010257:Paraneoplastic Syndromes / Q000000981:diagnostic imaging* / Q000473:pathology; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011379:Prognosis; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG; PET/CT; Paraneoplastic neurological syndrome; Risk classification