title: In vivo single-voxel proton MR spectroscopy in brain lesions with ring-like enhancement.
abstract: It is often difficult to make a correct diagnosis of ring-like enhanced lesions on Gd-enhanced MR brain images. To differentiate these lesions using proton MR spectroscopy (1H-MRS), we retrospectively evaluated the correlation between the 1H-MR spectra and histopathological findings. We evaluated proton MR spectra obtained from the lesions in 45 patients, including metastasis (n = 19), glioblastoma (n = 10), radiation necrosis (n = 7), brain abscess (n = 5), and cerebral infarction (n = 4). The rate of misdiagnosis was found to be lowest at the threshold level of 2.48 for the (choline containing compounds)/(creatine and phosphocreatine) ratio (Cho/Cr) obtained from the whole lesions, which include the enhanced rim and the non-enhanced inner region. That is, the positively predictive values of a Cho/Cr greater than 2.48 for diagnosing metastasis or glioblastoma was 88.9 and 60.0%, respectively, and the positively predictive value of a Cho/Cr less than 2.48 for diagnosing radiation necrosis or cerebral infarction was 71.4 and 100%, respectively. For further differentiating between metastasis and glioblastoma, information about the presence and absence of an N-acetyl-aspartate (NAA) peak and lipid- or lactate-dominant peak was found to be useful. In 73.7% of metastasis cases a lipid-dominant peak was observed in the whole lesion without an NAA peak in the inner region, whereas the same pattern was observed in only 10% of the glioblastoma cases. Correlation with the histopathological findings showed that a high Cho signal is suggestive of neoplasm. Lipid signal in the non-enhanced central region was correlated to necrosis. Lactate signals were often observed in glioblastoma, abscess and sometimes metastasis, presumably reflecting the anaerobic glycolysis by the living cells in the ring-like enhanced rim. Single-voxel proton MR spectroscopy may serve as a potential tool to provide useful information of differentiation of ring-like enhanced lesions that cannot be diagnosed correctly using enhanced MR images alone.
authors.affiliation: Department of Neurosurgery, Asahikawa Medical College, Asahikawa, Hokkaido 078-8510, Japan. tekimura-nsu@umin.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Kimura
authors.forename: K
authors.initials: K
authors.lastname: Sako
authors.forename: T
authors.initials: T
authors.lastname: Gotoh
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology; D001922:Brain Abscess / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D001927:Brain Diseases / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D001932:Brain Neoplasms / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology; D002544:Cerebral Infarction / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D002794:Choline / Q000032:analysis; D003401:Creatine / Q000032:analysis; D003937:Diagnosis, Differential; D005260:Female; D005909:Glioblastoma / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D010725:Phosphocreatine / Q000032:analysis; D011832:Radiation Injuries / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D012189:Retrospective Studies
chemical_list: D010725:Phosphocreatine; D003401:Creatine; D002794:Choline