title: Quantitative imaging of spontaneous neuromagnetic activity for assessing cerebral ischemia using sLORETA-qm.
abstract: To image cerebral neural activity in ischemic areas, we proposed a novel technique to analyze spontaneous neuromagnetic fields based on standardized low-resolution brain electromagnetic tomography modified for a quantifiable method (sLORETA-qm). Using a 160-channel whole-head-type magnetoencephalographic system, cerebral magnetic fields were obtained pre- and postoperatively from 5 patients with unilateral internal carotid artery occlusive disease and 16 age-matched healthy volunteers. For quantitative imaging, voxel-based time-averaged intensities of slow waves in 4 frequency bands (0.3-2 Hz, 2-4 Hz, 4-6 Hz and 6-8 Hz) were obtained by the proposed technique based on sLORETA-qm. Positron emission tomography with (15)O gas inhalation ((15)O-PET) was also performed in these patients to evaluate cerebral blood flow and metabolism. In all 5 patients, slow waves in every frequency band were distributed in the area of cerebrovascular insufficiency, as confirmed by (15)O-PET preoperatively. In 4 patients, slow-wave intensities in theta bands (4-6 Hz, 6-8 Hz) decreased postoperatively along with improvements in cerebral blood flow and metabolism, whereas delta bands (0.3-2 Hz, 2-4 Hz) showed no significant differences between pre- and postoperatively. One patient with deterioration of cerebral infarction after surgery showed marked increases in slow-wave intensities in delta bands (0.3-2 Hz, 2-4 Hz) postoperatively, with distribution close to the infarct region. The proposed quantitative imaging of spontaneous neuromagnetic fields enabled clear visualization and alternations of cerebral neural conditions in the ischemic area. This technique may offer a novel, non-invasive method for identifying cerebral ischemia, although further studies in a larger number of patients are warranted.
authors.affiliation: Department of Neurosurgery, Hokuto Hospital, Obihiro, Japan. s-sakamoto@med.osaka-cu.ac.jp
authors.forename: Shinichi
authors.initials: S
authors.lastname: Sakamoto
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Naohiro
authors.initials: N
authors.lastname: Tsuyuguchi
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Terakawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Ohata
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inoue
authors.forename: Yukio
authors.initials: Y
authors.lastname: Miki
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Hara
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Kazumi
authors.initials: K
authors.lastname: Nitta
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sawa
authors.forename: Akira
authors.initials: A
authors.lastname: Satone
authors.forename: Wataru
authors.initials: W
authors.lastname: Ide
authors.forename: Ikuo
authors.initials: I
authors.lastname: Hashimoto
authors.forename: Hajime
authors.initials: H
authors.lastname: Kamada
mesh_terms: D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology; D002544:Cerebral Infarction / Q000000981:diagnostic imaging / Q000473:pathology; D004401:Dysarthria / Q000473:pathology; D004569:Electroencephalography; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D010291:Paresis / Q000473:pathology; D049268:Positron-Emission Tomography