title: 13N-ammonia combined with 18F-FDG could discriminate between necrotic high-grade gliomas and brain abscess.
abstract: OBJECTIVE
  Accurate prediction of brain abscess is beneficial for timely management. In this study, we investigated the utility of 13N-ammonia and its combination with 18F-FDG in differentiating brain abscess from necrotic high-grade gliomas.
  
  
  METHODS
  Thirteen patients with ring-like enhancement high-grade gliomas and 11 patients with brain abscess were recruited in our study. All of them underwent both 18F-FDG and 13N-ammonia PET imaging. Lesion uptake was evaluated by lesion to normal gray matter ratio (L/N). Histopathology diagnosis was obtained for all the patients after PET imaging.
  
  
  RESULTS
  The L/N values of 18F-FDG were not significantly different between brain abscess and necrotic high-grade gliomas (P = 0.35). The uptake of 13N-ammonia in gliomas was higher than that in abscess lesions (L/N: 1.38 ± 0.31 vs 0.84 ± 0.18, P < 0.001). The receiver operating characteristic curve analysis determined the optimal L/N cutoff value (13N-ammonia) of 1.0 with the area under the curve of 0.94 and the overall accuracy of 87.5%. Discriminant analysis demonstrated that the combination of 18F-FDG and 13N-ammonia could distinguish the 2 clinical entities with higher accuracy of 95%, and only 1 necrotic glioma lesion was misclassified into the abscess group.
  
  
  CONCLUSIONS
  13N-ammonia is effective in distinguishing brain abscess from necrotic high-grade gliomas, and its combination with 18F-FDG could further elevate the diagnostic accuracy.
authors.affiliation: From the Department of Nuclear Medicine, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
authors.forename: Xinchong
authors.initials: X
authors.lastname: Shi
authors.forename: Chang
authors.initials: C
authors.lastname: Yi
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Chen
authors.forename: Ganghua
authors.initials: G
authors.lastname: Tang
authors.forename: Xiangsong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D000641:Ammonia / Q000008:administration & dosage; D001922:Brain Abscess / Q000000981:diagnostic imaging* / Q000473:pathology; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage; D005910:Glioma / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009336:Necrosis / Q000000981:diagnostic imaging; D009590:Nitrogen Radioisotopes / Q000008:administration & dosage; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D014057:Tomography, X-Ray Computed
chemical_list: D009590:Nitrogen Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D000641:Ammonia