Date of Award
2007
Degree Type
Thesis
Degree Name
Master of Science
Program
Medical Biophysics
Supervisor
Terry Thompson, PhD
Second Advisor
Gerald Moran, PhD
Abstract
It is not always practical or ethical to use humans for optimization and testing of MR pulse sequences especially when dealing with neonates and children where the MR relaxation parameters (T1 and T2) are substantially different from adults because of the changes in water content during development. Thus5 a tissue mimicking MR phantom would be useful. Polyvinyl Alcohol Cryogel (PVA-C) is a non-toxic material that has been shown to have MR relaxation characteristics similar to aorta5 muscle and fat. To date, no work has been done on the characterization of the electrical properties of PVA-C which could benefit several areas such as matching MR coil loading at high field, and developing a tissue phantom for electrical impedance tomography (EIT). Our objective is to validate PVA-C as a viable phantom material for various human tissues (matching both the MRI and electrical properties). For normal tissue the Ti and T2 values can range from 450ms to 2900ms (for 1.5 T — 3 T) and 40ms to 280ms, respectively. Again for normal tissues, the conductivity ranges from 0.0295 S/m to 0.744 S/m and permittivity ranges from 40 — 400*106. The first experiment involved measuring the relaxation times of PVA-C (made with water) as the %PVA was varied from 3-30% by weight. These samples all underwent 1 ffeeze/thaw cycle (FTC) and the ffeeze/thaw rate (FTR) was kept constant at O.l°C∕minute. The Ti and T2 relaxation times were found to increase with increasing %PVA. At 1.89T the ranges were 0.68 + 0.04 s
Recommended Citation
Wilson, Kyle, "CHARACTERIZATION OF MAGNETIC RESONANCE AND ELECTRICAL PROPERTIES OF POLYVINYL ALCOHOL CRYOGEL" (2007). Digitized Theses. 4915.
https://ir.lib.uwo.ca/digitizedtheses/4915