title: Relationship between PET-FDG and MRI apparent diffusion coefficients in brain tumors.
abstract: OBJECTIVE
  The aim of this study was to investigate the relationship between 2-deoxy-2[(18)F]fluoro-D-glucose ([(18)F]FDG) positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging (DWI) with apparent diffusion coefficients (ADC) in brain tumors.
  
  
  METHODS
  Fifteen patients with 18 metastatic brain lesions underwent gadolinium-enhanced fast spoiled gradient echo (Gd-FSPGR), DWI with ADC maps, and [(18)F]FDG PET. Spherical three-dimensional tumor and contralateral control regions of interest (ROIs) were drawn on Gd-FSPGR, ADC and PET images, Gd-FSPGR being the target for statistical parametric mapping with realigned ADC and PET to calculate ROI ratios; linear regression analysis was performed.
  
  
  RESULTS
  An inverse correlation (r(2)=0.2746, P=0.0256) was found between PET and ADC ratios; plotting ratios: when PET ratios were high, ADC ratios were low, while, when ADC ratios were high, PET ratios were low.
  
  
  CONCLUSIONS
  Our preliminary data suggest an inverse relationship between PET and ADC indices. Hypercellular areas could increase impedance to water diffusion, resulting in low ADC values and high [(18)F]FDG uptake, while lower cellularity areas show increased ADC with decreased [(18)F]FDG uptake.
authors.affiliation: Nuclear Medicine Section, Department of Surgical, Radiological and Odontostomatological Sciences, University of Perugia, Perugia, Italy. mednuc@unipg.it
authors.forename: B
authors.initials: B
authors.lastname: Palumbo
authors.forename: F
authors.initials: F
authors.lastname: Angotti
authors.forename: G D
authors.initials: GD
authors.lastname: Marano
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D004058:Diffusion; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography
chemical_list: D019788:Fluorodeoxyglucose F18