title: Correlation of 6-18F-fluoro-L-dopa PET uptake with proliferation and tumor grade in newly diagnosed and recurrent gliomas.
abstract: 6-(18)F-fluoro-l-dopa ((18)F-FDOPA) measured with PET as a biomarker of amino acid uptake has been investigated in brain tumor imaging. The aims of the current study were to determine whether the degree of (18)F-FDOPA uptake in brain tumors predicted tumor grade and was associated with tumor proliferative activity in newly diagnosed and recurrent gliomas.
  
  
  METHODS
  Fifty-nine patients (40 men, 19 women; mean age ± SD, 44.4 ± 12.3 y) with newly diagnosed (n = 22) or recurrent (n = 37) gliomas underwent (18)F-FDOPA PET perioperatively. Tumor tissue was obtained by resection or biopsy in all patients. The tumor grade and Ki-67 proliferation index were obtained by standard pathology assays. Tumor (18)F-FDOPA uptake was quantified by determining various standardized uptake value (SUV) parameters (mean SUV, maximum SUV [SUVmax], mean values of voxels with top 20% SUVs, and tumor-to-normal-brain tissue ratios) that were then correlated with histopathologic grade and Ki-67 proliferation index.
  
  
  RESULTS
  Fifty-nine lesions in 59 patients were analyzed. (18)F-FDOPA uptake was significantly higher in high-grade than in low-grade tumors for newly diagnosed tumors (SUVmax, 4.22 ± 1.30 vs. 2.34 ± 1.35, P = 0.005) but not for recurrent tumors that had gone through treatment previously (SUVmax, 3.36 ± 1.26 vs. 2.67 ± 1.18, P = 0.22). An SUVmax threshold of 2.72 differentiated low-grade from high-grade tumors, with a sensitivity and specificity of 85% and 89%, respectively, using receiver-operating-characteristic curve analysis (area under the curve, 0.86). (18)F-FDOPA PET uptake correlated significantly with Ki-67 tumor proliferation index in newly diagnosed tumors (r = 0.66, P = 0.001) but not in recurrent tumors (r = 0.14, P = 0.41).
  
  
  CONCLUSIONS
  (18)F-FDOPA uptake is significantly higher in high-grade than in low-grade tumors in newly diagnosed but not recurrent tumors that had been treated previously. A significant correlation between (18)F-FDOPA uptake and tumor proliferation in newly diagnosed tumors was observed, whereas this correlation was not identified for recurrent tumors. Thus, (18)F-FDOPA PET might serve as a noninvasive marker of tumor grading and might provide a useful surrogate of tumor proliferative activity in newly diagnosed gliomas.
authors.affiliation: Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Fueger
authors.forename: Johannes
authors.initials: J
authors.lastname: Czernin
authors.forename: Timothy
authors.initials: T
authors.lastname: Cloughesy
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Silverman
authors.forename: Cheri L
authors.initials: CL
authors.lastname: Geist
authors.forename: Martin A
authors.initials: MA
authors.lastname: Walter
authors.forename: Christiaan
authors.initials: C
authors.lastname: Schiepers
authors.forename: Phioanh
authors.initials: P
authors.lastname: Nghiemphu
authors.forename: Albert
authors.initials: A
authors.lastname: Lai
authors.forename: Michael E
authors.initials: ME
authors.lastname: Phelps
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005910:Glioma / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; C103149:2,6-difluoro-3,4-dihydroxyphenylalanine; D004295:Dihydroxyphenylalanine