RESUMO
OBJECTIVES: Atherosclerotic stenosis of the middle cerebral artery (MCA) is one of the causes of ischemic stroke, but aside from investigations using magnetic resonance angiography (MRA), studies evaluating stenosis are rare. The purpose of this study was to assess dynamic changes of MCA cross section between the systolic and diastolic phases in patients with cerebral infarction using 3·0-Tesla magnetic resonance imaging (3T MRI). METHODS: We assessed 12 stroke patients with M1 stenosis in the MCA and 12 healthy volunteers. We measured MCA cross sections (proximal/distal to stenosis and on the stenosis) in the systolic and diastolic phases by synchronizing imaging with heartbeats, as well as the maximum flow velocity by using cine-phase contrast (PC) MRI. Each patient also underwent conventional MRA. RESULTS: Differences in cross sections between systolic and diastolic phases were significantly smaller in the stenosed artery compared to the distal (P < 0·05) and proximal areas (P < 0·01) in stroke patients. The difference in maximal blood velocity between systolic and diastolic phases at the M1 stenosis was significantly larger than that in the area proximal to the stenosis (P < 0·05). DISCUSSION: We clearly demonstrated dynamic cross-sectional changes in the stenotic areas by 3T MRI, suggesting hemodynamic shear stress, which may further enhance MCA atherosclerosis.
Assuntos
Arteriosclerose Intracraniana/patologia , Imageamento por Ressonância Magnética/métodos , Artéria Cerebral Média/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Isquemia Encefálica/patologia , Isquemia Encefálica/fisiopatologia , Constrição Patológica , Feminino , Humanos , Arteriosclerose Intracraniana/fisiopatologia , Angiografia por Ressonância Magnética , Imageamento por Ressonância Magnética/instrumentação , Masculino , Pessoa de Meia-Idade , Artéria Cerebral Média/fisiopatologia , Acidente Vascular Cerebral/patologia , Acidente Vascular Cerebral/fisiopatologiaRESUMO
The purpose of this study was to improve the visualization of long-axis black-blood imaging of the carotid arteries. We experimented on phantom and in-vivo study of 3 dimension (3D) inversion recovery T(1) turbo field echo combined with phase sensitive inversion recovery (PSIR-3D IR-T(1)TFE) at 3.0 Tesla. As a result, the contrast has been improved by calculated images of PSIR-3D IR-T(1)TFE set to inversion time (TI) 350 ms that is shorter than null point of blood. This displays that the contrast between blood and tissues can be improved when the longitudinal magnetization of blood is a negative. Therefore, the visualization of long-axis black-blood imaging of the carotid arteries has been improved by the calculated images of PSIR-3D IR-T(1)TFE set to TI that is shorter than null point of blood.