title: Decreased cerebral glucose metabolism in patients with brain tumors: an effect of corticosteroids.
abstract: The authors measured cerebral glucose metabolism (CMRglu) using [18F]fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) in patients with brain tumors to evaluate the effect of exogenous corticosteroids (in this instance, dexamethasone) on glucose metabolism. Fifty-six FDG-PET studies obtained in 45 patients with unilateral supratentorial brain tumors were analyzed. Patients with brain tumors were divided into three groups: 1) patients with cushingoid symptoms, who had been treated with combinations of radiotherapy and chemotherapy taking oral dexamethasone; 2) patients not taking dexamethasone but treated with radiotherapy; and 3) patients not taking dexamethasone who had not been treated with radiotherapy. Serial FDG-PET scans were obtained in eight of the cushingoid patients. Glucose metabolism was measured in the contralateral cerebral and ipsilateral cerebellar hemispheres in patients and compared to measurements taken from 19 normal volunteers. The authors found that in the cushingoid brain tumor patients there was a marked reduction in CMRglu compared to normal volunteers and other brain tumor patients (Kruskal-Wallis test; p 0.001). In the majority of patients who had serial FDG-PET scans, there was a decline in glucose metabolism over time and in one patient, in whom dexamethasone was reduced in dosage, there was a subsequent increase in CMRglu. The authors conclude that there is a generalized reduction in CMRglu in brain tumor patients taking dexamethasone compared to other brain tumor patients and normal volunteers, and that this effect is independent of radiotherapy, concurrent anticonvulsant medication, and transhemispheric functional disconnection (transhemispheric diaschisis).
authors.affiliation: Neuroimaging Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Fulham
authors.forename: A
authors.initials: A
authors.lastname: Brunetti
authors.forename: L
authors.initials: L
authors.lastname: Aloj
authors.forename: R
authors.initials: R
authors.lastname: Raman
authors.forename: A J
authors.initials: AJ
authors.lastname: Dwyer
authors.forename: G
authors.initials: G
authors.lastname: Di Chiro
mesh_terms: D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000627:therapeutic use; D001921:Brain / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism*; D016022:Case-Control Studies; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism; D003131:Combined Modality Therapy; D003480:Cushing Syndrome / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D003847:Deoxyglucose / Q000031:analogs & derivatives; D003907:Dexamethasone / Q000008:administration & dosage / Q000627:therapeutic use*; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015173:Supratentorial Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology / Q000532:radiotherapy; D014055:Tomography, Emission-Computed
chemical_list: D000927:Anticonvulsants; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D003907:Dexamethasone; D003847:Deoxyglucose; D005947:Glucose