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

Autor(es)

Mazzetto-Betti, Kelley C. ^[1] ; Leoni, Renata F. ^{[2, 3]} ; Pontes-Neto, Octavio M. ^[1] ; Santos, Antonio C. ^{[2, 1]} ; Leite, Joao P. ^[1] ; Silva, Afonso C. ; de Araujo, Draulio B. ^{[4, 1, 3, 5]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, FMRP, Dept Neurosci & Behav Sci, BR-14049 Ribeirao Preto - Brazil

^[2] Natl Inst Neurol Disorders & Stroke, Cerebral Microcirculat Unit, Lab Funct & Mol Imaging, NIH, Bethesda, MD - USA

^[3] Univ Sao Paulo, Dept Math & Phys, FFCLRP, BR-14049 Ribeirao Preto - Brazil

^[4] Univ Fed Rio Grande do Norte, Coordenacao CDI, HUOL, BR-59012300 Natal, RN - Brazil

^[5] Edmond & Lily Safra Int Inst Neurosci Natal, Natal, RN - Brazil

• Tipo de documento: Artigo Científico
• Fonte: STROKE; v. 41, n. 9, p. 1921-1926, SEP 2010.
• Citações Web of Science: 16

Resumo

Background and Purpose-Functional MRI is a powerful tool to investigate recovery of brain function in patients with stroke. 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 use of data analysis tools that are built on the premise of a stable BOLD signal may lead to misdetection of functional regions and underestimation of brain activity in patients with stroke. The present data urge the use of caution when relying on the BOLD response as a marker of brain reorganization in patients with stroke. (Stroke. 2010; 41:1921-1926.) (AU)

• Processo FAPESP: 05/03225-7 - Caracterização das respostas hemodinâmicas de imagens funcionais por ressonância magnética e suas aplicações a pacientes com Estenose carotidea e Epilepsia
• Beneficiário: Draulio Barros de Araujo
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores