Nikki Okwelogu, MD RESIDENT UCSF Profile Publications Evaluation of a Novel Tantalum Oxide-Based Contrast Agent for Liver Imaging and Tumor Detection in Dual-Energy CT: A Preclinical Proof-of-Concept Study. Performance of an Intravascular Tantalum Oxide-Based Nanoparticle Computed Tomography Contrast Agent in Preclinical Hepatic Tumor Detection. Novel intravascular tantalum oxide-based contrast agent achieves improved vascular contrast enhancement and conspicuity compared to Iopamidol in an animal multiphase CT protocol. Ultrasound-guided bursal injections. See All Publications