title: Potential for differentiation of glioma recurrence from radionecrosis using integrated18F-fluoroethyl-L-tyrosine (FET) positron emission tomography/magnetic resonance imaging: A prospective evaluation.
abstract: OBJECTIVE
  To assess the utility of 18F-fluoroethyl-L-tyrosine (FET) positron emission tomography/magnetic resonance imaging (PET/MRI) in distinguishing recurrence from radionecrosis.
  
  
  METHODS
  Thirty-two patients (25 males, 7 females) of glioma who had already undergone surgery/chemoradiotherapy and had enhancing brain lesions suspicious of recurrence were evaluated using integrated 18F-FET PET/MRI, and followed up with histopathology or clinical follow-up and/or MRI/PET/MRI imaging. Manually drawn regions of interest over areas of maximal enhancement or FET uptake were used to calculate tumor to background ratios [TBRmax, TBRmean], choline: creatine ratio [Cho: Cr ratio], normalized relative cerebral blood volume [N rCBVmean] and apparent diffusion coefficient [ADCmean]. Correlations were evaluated using Pearson's coefficient. Accuracy of each parameter was calculated using independent t-test and receiver operator curve (ROC) analysis while utility of all four parameters together using multivariate analysis of variance (MANOVA) for differentiating recurrence vs. radionecrosis was evaluated. Positive histopathology and imaging/clinical follow up served as the gold standard.
  
  
  RESULTS
  Twenty-four of the 32 patients were diagnosed with recurrent disease and 8 with radiation necrosis. Significant correlations were observed between TBRmaxand N rCBVmean (ρ =0.503; P = 0.003), TBRmean, and N rCBVmean (ρ =0.414; P = 0.018), TBRmaxand ADCmean (ρ = -0.52; P = 0.002), and TBRmeanand ADCmean(ρ = -0.518; P = 0.002). TBRmax, TBRmean, ADCmean, Cho: Cr ratios, and N rCBVmeanwere significant in differentiating recurrence from radiation necrosis with an accuracy of 94.1%, 88.2%, 80.4%, 96.4%, and 89.9%, respectively. MANOVA indicated that combination of all parameters demonstrated better evaluation of recurrence vs. necrosis than any single parameter. The diagnostic accuracy, sensitivity, and specificity using all MRI parameters were 93.75%, 96%, and 85.7%, and using all FET PET/MRI parameters was 96.87%, 100%, and 85.7%, respectively.
  
  
  CONCLUSIONS
  Synergetic effect of multiple MR parameters evaluated together in addition to FET PET uptake highlights the fact that integrated 18F-FET PET/MRI might have the potential to impact management of patients with glioma by timely and conclusive recognition of true recurrence from radiation necrosis.
authors.affiliation: Department of Neurosurgery, Institute of Neuro Sciences, Indraprastha Apollo Hospitals, Sarita Vihar, New Delhi, India.
authors.forename: Shanti K
authors.initials: SK
authors.lastname: Sogani
authors.affiliation: Department of Molecular Imaging and Nuclear Medicine, Indraprastha Apollo Hospitals, Sarita Vihar, New Delhi, India.
authors.forename: Amarnath
authors.initials: A
authors.lastname: Jena
authors.affiliation: Department of Molecular Imaging and Nuclear Medicine, Indraprastha Apollo Hospitals, Sarita Vihar, New Delhi, India.
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Taneja
authors.affiliation: Department of Molecular Imaging and Nuclear Medicine, Indraprastha Apollo Hospitals, Sarita Vihar, New Delhi, India.
authors.forename: Aashish
authors.initials: A
authors.lastname: Gambhir
authors.affiliation: Molecular Imaging and Research Centre, Institute of Nuclear Medicine and Allied Sciences, Brig. SK Mazumdar Road, Timarpur, Delhi, India.
authors.forename: Anil K
authors.initials: AK
authors.lastname: Mishra
authors.affiliation: Molecular Imaging and Research Centre, Institute of Nuclear Medicine and Allied Sciences, Brig. SK Mazumdar Road, Timarpur, Delhi, India.
authors.forename: Maria M
authors.initials: MM
authors.lastname: D'Souza
authors.affiliation: Institute of Radiation Oncology, Indraprastha Apollo Hospitals, Sarita Vihar, New Delhi, India.
authors.forename: Sapna M
authors.initials: SM
authors.lastname: Verma
authors.affiliation: Molecular Imaging and Research Centre, Institute of Nuclear Medicine and Allied Sciences, Brig. SK Mazumdar Road, Timarpur, Delhi, India.
authors.forename: Puja P
authors.initials: PP
authors.lastname: Hazari
authors.affiliation: Department of Molecular Imaging and Nuclear Medicine, Indraprastha Apollo Hospitals, Sarita Vihar, New Delhi, India.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Negi
authors.affiliation: Institute of Radiation Oncology, Indraprastha Apollo Hospitals, Sarita Vihar, New Delhi, India.
authors.forename: Ganesh K R
authors.initials: GK
authors.lastname: Jadhav
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009336:Necrosis / Q000000981:diagnostic imaging / Q000473:pathology; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D011832:Radiation Injuries / Q000000981:diagnostic imaging* / Q000473:pathology; D014443:Tyrosine / Q000031:analogs & derivatives*; D055815:Young Adult
chemical_list: C545932:(18F)fluoroethyltyrosine; D014443:Tyrosine