Gadolinium-based contrast agents (GBCAs) have been used in hospitals worldwide for the past three decades to increase contrast for magnetic resonance imaging (MRI), thus allowing for more accurate diagnoses. When first developed, GBCA complexes were thought to be completely stable, and excreted from the body within hours. However, GBCAs have since been shown to deposit in organs such as bone, suggesting complex dissociation. GBCA safety has now become one of the biggest concerns in the field of radiology, with the clinical implications of retained Gd remaining unknown. A non-invasive technique to measure retained Gd in the body would allow for investigation of the potential negative health effects of GBCAs.
In this thesis, the technique of x-ray fluorescence (XRF) to detect retained gadolinium (Gd) in bone following the administration of GBCAs is investigated. The research employs a series of bone phantom measurements to determine the feasibility of using an XRF-based detection system to perform non-invasive in vivo measurements of Gd in human tibia bones. Minimum detection limits (MDLs) of the XRF detection system are calculated to assess the feasibility of performing a human measurement in a realistic time. Through these experiments, the XRF detection system developed in this thesis work is deemed feasible for human measurements of Gd in bone.
The second half of this thesis work involves performing the first non-invasive measurements of Gd in bone in a small population: 11 exposed individuals who had previously received GBCA, and 11 controls. The result of this work is promising, as the XRF system is successful in measuring Gd in bone in vivo. Additionally, the Gd bone concentration of the exposed group is significantly higher than the control group. Following this small pilot study, additional measurements are conducted on individuals self-reporting symptoms of Gd toxicity. Gd concentrations in bone and urine are compared for three groups: symptomatic exposed, non symptomatic exposed, and control. The concentration of Gd in bone and urine for the symptomatic exposed group is significantly higher. However, there is no correlation between the amount of Gd in bone and urine, suggesting a secondary storage site for Gd in the body, other than bone. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/24801 |
| Date | January 2019 |
| Creators | Lord, Michelle |
| Contributors | McNeill, Fiona, Chettle, David, Medical Physics |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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