In vivo displacement encoding using stimulated echo magnetic resonance imaging (DENSE-MRI) has been optimized and shown to be technically feasible in the carotid arteries of healthy volunteers at 1.5T and 3.0T. Strain measurements calculated from DENSE displacement values have also been validated at both field strengths supporting the use of DENSE-MRI as a means to map the pulsatile strain in the carotid artery wall. Atherosclerotic lesions have been shown to localize to regions of excessive stretching of the arterial wall and since these atherosclerotic plaques are the source of emboli and/or thrombi that cause stroke, DENSE-MRI strain measurements may provide early diagnosis for stroke. The goals of this competitive renewal are two fold: First, DENSE strain patterns in atherosclerotic plaques will be determined using an in vitro model of the carotid arteries. The model will be created using polyvinyl alcohol cryogel that has been shown to mimic the material properties of human arteries. Using a variable blood pump and molds that range in thickness and stenosis, different physiological conditions can be created. These conditions will then be imaged with DENSE MRI to determine their effects on the strain maps. The in vitro results will enable the interpretation of in vivo results. The second goal will be to expand the study to determine strain patterns in patients with known atherosclerosis and compare these results with age-matched, healthy subjects. Multi-sequence MRI will also be acquired providing structural imaging of plaque such as IMT thickness, plaque load, and degree of stenosis. Patient histories will provide risk factors for stroke (such as age, sex, BMI, BP, HDL count, and clinical history). These measures will providing a grading of severity with which strain can be compared. The hypothesis is that strain maps will be significantly different in patients with plaques and that these strain measurements will significantly correlate with morphological and clinical measures of atherosclerosis. The results of the study will define the strain pattern for atherosclerotic plaques in the carotid arteries and provide correlates to risk factors for stroke. These results can be used for patient monitoring to determine therapeutic efficacy and may provide the basis for future studies to establish DENSE-MRI as a diagnostic tool for early diagnosis and answer the critical clinical question of plaque vulnerability.
|Program type||Predoctoral Fellowship|
|Effective start/end date||07/01/2008 → 06/30/2009|