The Stability of the Blood Oxygenation Level-Dependent Functional MRI Response to Motor Tasks Is Altered in Patients With Chronic Ischemic Stroke

Abstract

Background and Purpose-Functional MRI is a powerful tool to investigate recovery of brain function in patients withstroke. An inherent assumption in functional MRI data analysis is that the blood oxygenation level-dependent (BOLD) signal is stable over the course of the examination. In this study, we evaluated the validity of such assumption in patients with chronic stroke. Methods-Fifteen patients performed a simple motor task with repeated epochs using the paretic and the unaffected hand in separate runs. The corresponding BOLD signal time courses were extracted from the primary and supplementary motor areas of both hemispheres. Statistical maps were obtained by the conventional General Linear Model and by a parametric General Linear Model. Results-Stable BOLD amplitude was observed when the task was executed with the unaffected hand. Conversely, the BOLD signal amplitude in both primary and supplementary motor areas was progressively attenuated in every patient when the task was executed with the paretic hand. The conventional General Linear Model analysis failed to detect brain activation during movement of the paretic hand. However, the proposed parametric General Linear Model corrected the misdetection problem and showed robust activation in both primary and supplementary motor areas. Conclusions-The

Activation of Brain Sensorimotor Network by Somatosensory Input in Patients with Hemiparetic Stroke: A Functional MRI Study

“…This reduction may reflect the sensorimotor network damage caused by stroke, although the fMRI BOLD response could be reduced in the cerebral hemisphere of the lesion side (Murata et al, 2006;Mazzetto-Betti et al, 2010). Nevertheless, the result confirms the possibility of inducing sensorimotor transformations even in severely impaired stroke patients.…”

Arterial Spin Labeling and Blood Oxygen Level-Dependent MRI Cerebrovascular Reactivity in Cerebrovascular Disease: A Systematic Review and Meta-Analysis

“…Apart from this wide variability, one can also notice that there is a considerable overlap between the different groups presented in the different papers. For example, the patients in the study of Goode et al [27] have BOLD values in a similar range in their ipsilateral hemisphere as the CVR values found in the contralateral hemispheres of the study of Mazzetto-Betti et al [33] or Mandell et al [32] . Despite this overlap, there seems to be a trend toward higher CVR values from the ipsilateral to the contralateral hemisphere and to the control hemispheres.…”

“…Thirteen studies found a lower CVR in the ipsilateral compared to the contralateral hemisphere [5, 25, 26, 28, 29, 31, 33, 35, 38-40, 43, 46] . Three of these 13 295 studies found significant differences [5,28,33] . Two studies showed similar results in the ipsilateral and contralateral hemispheres [27,42] .…”

“…Nevertheless, we did decide to include these studies as they are commonly used due to their ease of implementation as compared to other vasodilatory stimuli. However, we do want to point out that out of the 7 studies with significant differences in BOLD CVR between the ipsilateral and contralateral hemisphere, 3 studies applied a functional task [22,33,34] . In addition to these studies not necessarily reflecting 'pure' CVR, their study results could also have been affected by poor task performance of the subjects.…”

The Value of Resting-State Functional Magnetic Resonance Imaging in Stroke

“…Alterations in the BOLD signal (eg, decreased amplitude) that result from mere vascular changes have been shown in patients with cerebrovascular disease. [46][47][48] Thus far, all studies examining the effect of changes in neurovascular coupling have used task-based fMRI. It is yet to be determined how such changes affect functional connectivity based on rs-fMRI.…”