Collaborating with Dr. Ravindra Pandey (Cell Stress Biology), our lab has been developing and characterizing novel, multi-functional imaging agents for use in both imaging and photodynamic therapy (PDT). Combining imaging capabilities with a tumor-specific therapeutic has multiple advantages, including improved tumor boundary delineation and non-invasive tracking of tumor uptake and pharmacokinetics. These capabilities may lead to improved prognostic indicators on the efficacy of PDT treatment based upon imaging biomarkers.
Dynamic-contrast enhanced MR imaging is being utilized to probe changes in vascular function as a result of chemotherapy (e.g. doxorubicin) or biophysical therapies such as PDT or whole body hyperthermia. The microvasculature architecture within tumors differs from normal vasculature in a number of ways. Tumor vasculature is chaotic and hyper-permeable, often exhibiting reduced blood flow, which in turn can reduce the efficacy of anti-cancer treatments. Using MRI, changes in tumor blood flow and vascular function can be studied in situ, leading to greater understanding of the vascular effects of such treatments and potentially to better outcomes.
Critical to this work is the ability to perform rapid measurement of tissue relaxation rates in vivo with a high degree of accuracy and sensitivity. Balanced, steady-state free precession (bSSFP) imaging is being explored in a preclinical environment as a means of rapid relaxometry, as it offers many advantages over alternative methods, namely a) high signal to noise ratios, b) improved spatial homogeneity over a large volume, c) short acquisition times, and d) simultaneous extraction of both T1 and T2 relaxation rates within a single MRI dataset. This methodology is currently being applied for use in novel contrast agent development, microvascular assessment, and high-resolution in vivo microscopy.