Magnetic resonance imaging studies of right ventricular regional mechanical function
Cardiac disease is a major health problem. However, conventional methods for studying cardiac function have many limitations, particularly for the right ventricle. This dissertation describes the implementation and evaluation of a noninvasive method for studying normal regional right ventricular (RV) function and for investigating the influence of chronic pulmonary hypertension (PH) on regional RV function. This method employs a fast breath-hold segmented k-space magnetic resonance imaging (MRI) sequence with magnetic "myocardial tagging". A tailored receive-only cardiac coil was designed to enhance the MR image quality. The coil consists of two overlapping coil elements. This coil can be used either as a quadrature surface coil or as a phased-array coil. Through phantom experiments and images of the heart it was shown that the cardiac coil improved image quality in the heart. Using the MR tagging breath-hold sequence, the specially designed cardiac coil, and advanced computer analysis tools, the RV regional mechanical function was quantified. The 1D strain, 2D deformation (strains) and motion, and 3D midwall surface deformation and motion of the right ventricular free wall (RVFW) and septal (SEPT) wall were measured and quantified in normal (NL) subjects, in patients with mild to moderate PH, and in patients with severe PH. Differences in patterns of contraction were detected between NL subjects and PH patients in the RVFW and SEPT wall. First, it was discovered that the normal RVFW regional function was not uniform. Second, the RVFW and septal contraction was found to be globally reduced in PH patients as compared to NL subjects, with greatest decreases in the RV outflow tract and in the basal SEPT wall region. Finally in severe PH, deformation was demonstrated to be more reduced than in mild to moderate PH. The development of improved means to evaluate cardiac function should lead to both a better understanding of the mechanisms of normal and abnormal function and a useful clinical tool for diagnosis and management of cardiac disease. The long term aim of this work is to provide a novel and clinically valuable method to follow PH patients noninvasively with prognostically important parameters.
Fayad, Zahi Adel, "Magnetic resonance imaging studies of right ventricular regional mechanical function" (1996). Dissertations available from ProQuest. AAI9627917.