Graduation Year


Document Type




Degree Granting Department

Biomedical Engineering

Major Professor

Yvonne Moussy, Ph.D.


Autoradiography, Dexamethasone, Diffusion, Subcutaneous tissue, Tritium


The MicroImager is a fast, high resolution, real time, digital autoradiographic imaging tool with broad applications. This study utilizes the MicroImager to evaluate radiolabeled drug behavior in subcutaneous tissue. Experiments were conducted in conjunction with mathematical models to determine the diffusion coefficient (D) and elimination constant (k) for radiolabeled dexamethasone. Osmotic pumps containing [3H]dexamethasone were implanted into rat subcutaneous tissue over 6h, 24 h, and 60 h. Local tissue was explanted and slides were prepared for imaging. The MicroImager was then used to quantify the local concentration of 3H-dexamethasone in the tissue surrounding the tip of the osmotic pump. Betavision+ software was used to obtain local concentration profiles. These were then compared to a mathematical model to determine the diffusion coefficient and elimination constant for the radiolabeled drug. The diffusion coefficient for dexamethasone in rat subcutaneous tissue is 4.11 ± 1.77 x 10-10 m2/s. The elimination constant is 3.65 ± 2.24 x 10-5 s-1.A similar experiment was conducted to determine the diffusion coefficient through different means. [3H]dexamethasone was injected into the rat subcutaneous tissue for a 2.5 min and a 20 min period. A different mathematical model was applied and the diffusion coefficient was found to be 4.01 ± 2.01 x 10-10 m2/s.