title: Effects of cerebral ischemia on evoked cerebral blood oxygenation responses and BOLD contrast functional MRI in stroke patients.
abstract: OBJECTIVE
  To evaluate the mechanisms of failure of blood oxygenation level-dependent (BOLD) imaging in stroke, we compared the evoked cerebral blood oxygenation (CBO) responses and activation volumes (AVs) of BOLD functional MRI (fMRI) in chronic stroke patients with moderate and severe cerebral ischemia.
  
  
  METHODS
  We measured the evoked CBO responses in the primary sensorimotor cortex (PSMC) by means of near-infrared spectroscopy during contralateral motor tasks. We compared the AV of BOLD-functional MRI in the PSMC on the nonlesion and lesion sides. Single-photon emission computed tomography was used to classify ischemic status as moderate (slight reduction of regional cerebral blood flow and cerebrovascular reserve capacity [CVRC]) or severe (marked reduction of regional cerebral blood flow and CVRC; ie, misery perfusion).
  
  
  RESULTS
  In age-matched controls, deoxyhemoglobin concentration decreased with concomitant increases in oxyhemoglobin and total hemoglobin concentrations during activation. The PSMC on the nonlesion side exhibited a normal CBO response pattern. On the lesion side, moderate cerebral ischemia did not affect the CBO response pattern, but severe cerebral ischemia caused an increase of deoxyhemoglobin during the task, associated with increases of oxyhemoglobin and total hemoglobin. Moderate cerebral ischemia induced only a slight reduction of the AV on the lesion side; however, severe cerebral ischemia markedly reduced the AV on the lesion side. The BOLD signal did not change in some areas of the PSMC on the lesion side in severe cerebral ischemia, whereas it tended to decrease in other areas during the tasks.
  
  
  CONCLUSIONS
  Misery perfusion caused a marked reduction of the AV on BOLD imaging, associated with an increase of deoxyhemoglobin concentration during activation. BOLD-fMRI investigations of stroke patients should be performed while giving consideration to baseline circulatory status. Functional near-infrared spectroscopy could be an alternative means to assess the CVRC.
authors.affiliation: Department of Neurosurgery, Nihon University School of Medicine, 30-1, Oyaguchi-Kamimachi, Itabashi-ku, Tokyo 173-8610, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Murata
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sakatani
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hoshino
authors.forename: Norio
authors.initials: N
authors.lastname: Fujiwara
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Kano
authors.forename: Shin
authors.initials: S
authors.lastname: Nakamura
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Katayama
mesh_terms: D000328:Adult; D000368:Aged; D002545:Brain Ischemia / Q000097:blood / Q000000981:diagnostic imaging / Q000473:pathology*; D002560:Cerebrovascular Circulation; D002908:Chronic Disease; D005260:Female; D018737:Hand Strength; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D002546:Ischemic Attack, Transient / Q000097:blood / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000098:blood supply / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D010100:Oxygen / Q000097:blood*; D010108:Oxyhemoglobins / Q000032:analysis; D011597:Psychomotor Performance; D013003:Somatosensory Cortex / Q000098:blood supply / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D019265:Spectroscopy, Near-Infrared; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin; D010100:Oxygen