UCSF

Computed tomography (CT) is a one of the essential imaging modalities widely used in clinical diagnosis. To further increase the diagnostic value of CT, contrast agents, based on iodine or barium, are routinely administered to patients for enhancement blood vessels and organ parenchyma for various clinical indications. Over the course of the last four decades, there have been dramatic improvements in CT technology, including the more recent introduction of dual-energy CT (DECT) technology that enables the simultaneous image acquisition at two different x-ray tube potentials (ie. 80 kVp and 140 kVp), such that materials can be differentiated based on characteristic x-ray attenuation properties. However, a major limitation with the currently available contrast agents is that the elements iodine and barium cannot be readily distinguished due to their near-identical 80:140 kVp CT number ratios.

The objective of my thesis work is to explore viable formulations of a novel CT contrast material, based on silica microparticles. Four common excipients were tested to formulate a suspension of silica microparticles such that the solution is 1) stable, 2) homogenous, and 3) sufficiently nonviscous for translation towards potential clinical applications as an oral enteric contrast agent. Formulations were evaluated for stability at 30°C and 4°C over a period of 10 days; homogeneity was assessed by CT scanning and analysis of attenuation; viscosity measurements were obtained via a falling-ball viscometer method. One of the four excipients achieved all three criteria as stated above, and allows for further in-depth development towards pre-clinical testing and future clinical use.