Article

BOLD functional MRI may overlook activation areas in the damaged brain.

Department of Neurosurgery, Nihon University School of Medicine, Tokyo, Japan.
Acta neurochirurgica. Supplement 02/2003; 87:59-62. pp.59-62
Source: PubMed

ABSTRACT Clinical applications of blood-oxygenation-level-dependent contrast functional MRI (BOLD-fMRI) have been rapidly moving toward routine non-invasive cortical mapping in the patients with brain disorders. However, it is not yet clear whether the damaged brain shows same cerebral blood oxygenation (CBO) changes during neuronal activation as those in the normal adult. We compared the activation mapping obtained by BOLD-fMRI and the evoked-CBO changes measured by near infrared spectroscopy (NIRS) in normal adults (6 cases) and patients with damaged brain (6 cases of cerebral ischemia and 10 cases of brain tumors in or adjacent to the motor cortex). BOLD-fMRI demonstrated robust activation areas in the primary sensorimotor cortex (PSMC) during contralateral hand grasping tasks in all of the normal adults; however, in the cerebral ischemia (6 cases) and the brain tumors (2 cases), BOLD-fMRI demonstrated only limited activation areas in the PSMC on the lesion side during the task. NIRS demonstrated an increase of focal concentration of oxyhemoglobin and total hemoglobin at the PSMC during the task in all of the normal adults and the patients, indicating the presence of rCBF increase in response to neuronal activation. A focal concentration of deoxyhemoglobin decreased during the task in the normal adults, however, in the patients that showed limited activation areas by BOLD-fMRI, deoxyhemoglobin concentrations increased during the entire course of the task. In summary, the evoked-CBO changes occurring in the damaged brain differed from those in the normal brain. This indicates that BOLD-fMRI may overlook activation areas in the damaged brain.

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    Article: Reliability of near-infrared spectroscopy measures of cerebral oxygenation and blood volume during handgrip exercise in nondisabled and traumatic brain-injured subjects.
    Yagesh Bhambhani, Ram Maikala, Mamdouh Farag, Gary Rowland
    [show abstract] [hide abstract]
    ABSTRACT: We compared the test-retest reliability of near-infrared spectroscopy (NIRS) measures of cerebral oxygenation and blood volume during a rhythmic handgrip exercise in 13 nondisabled subjects and 25 subjects with moderate to severe traumatic brain injury (TBI). Subjects with TBI (average Glasgow Coma Scale score = 4.2, average time since injury = 21 mo) had completed an acute brain injury rehabilitation program. After 2 min of rest, each subject performed 60 s of maximal rhythmic handgrip contractions with the right hand in two trials 24 to 48 h apart. We used NIRS to measure cerebral oxygenation and blood volume responses from the left prefrontal lobe. Both groups' cerebral oxygenation and blood volume increased during handgrip contractions. The change in cerebral oxygenation was significantly lower in subjects with TBI compared with nondisabled subjects. Intraclass correlations between the two trials for cerebral oxygenation and blood volume were 0.83 and 0.80, respectively, in nondisabled subjects and 0.70 and 0.64, respectively, in subjects with TBI. The findings indicate that NIRS is a reliable noninvasive technique for evaluating cerebral oxygenation and blood volume changes during motor function. NIRS can be useful in monitoring recovery of cerebral oxygenation during rehabilitation of patients with TBI.
    The Journal of Rehabilitation Research and Development 43(7):845-56. · 1.78 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

2 cases
 
6 cases
 
blood-oxygenation-level-dependent contrast functional MRI
 
brain disorders
 
cerebral blood oxygenation
 
cerebral ischemia
 
contralateral hand grasping tasks
 
damaged brain
 
deoxyhemoglobin concentrations
 
focal concentration
 
lesion side
 
limited activation areas
 
neuronal activation
 
normal adult
 
normal brain
 
primary sensorimotor cortex
 
rCBF increase
 
robust activation areas
 
routine non-invasive cortical
 
showed limited activation areas
 

K Sakatani