| Description |
This dissertation comprises two separate studies: 1) efficacy of an anabolic steroid, oxandrolone, on the energy utilization of the heart of a lamb born with single ventricle (SV) physiology using 31P MR spectroscopy (MRS) and 2) signal behavior of ultra-high-b radial diffusion weighted imaging (UHb-rDWI) in healthy and multiple sclerosis (MS) subjects. SV infants have the highest mortality of all infants that have congenital heart defects. Their inability to gain weight appropriately may be due to high cardiac energy requirements from their shunt dependent physiology. We hypothesize that oxandrolone, which is already known to markedly improve the nutritional state of burn patients, will improve the energy utilization in the heart. We tested our hypothesis on SV modelled lambs using 31P MRS, home built 1H/31P double tuned radio frequency (RF) coil, and 1H and 31P T/R switches. We monitored cardiac energy in the lamb by quantitatively evaluating the first-order forward reaction rate (kf) of the creatine-kinase (CK) reaction in the heart. Spinal cord injury due to pathologies, such as MS, may include demyelination and/or axonal damage and lead to varying degrees of neurologic deficit. Noninvasive imaging biomarkers for earlier disease detection and monitoring in the follow-up and treatment stages would be a significant advancement in patient care. Moreover, imaging of the cervical spinal cord (CSC) is technically challenging because of the low signal to noise ratio from the small cross section of the cord, susceptibility artifact due to tissue-bone interface, and motion induced artifact from breathing and swallowing. To resolve these challenges, we used the UHb-rDWI technique and a CSC dedicated phased array RF coil. We studied the behavior of UHb-rDWI signal over the range of b-values from 0 sec/mm2 to 7348 sec/mm2 in the CSC of healthy and MS subjects over multiple time points. In the normal CSC, the signal decays fast at low b and slowly at UHb (b>4000 sec/mm2). In MS patients, the region affected by active lesions revealed a marked decrease in signal intensities in UHb region. UHb-rDWI could, therefore, be used for establishing an imaging biomarker to distinguish inflammation, demyelination, and axonal loss in the CSC. |
