Case Report: Preliminary evaluation of time-resolved imaging of contrast kinetics magnetic resonance imaging for assessing temporal enhancement patterns in small animal head and neck tumors

Abstract

Time-resolved magnetic resonance angiography provides dynamic information on contrast passage reflecting tumor vascularity and enhancement kinetics. Time-Resolved Imaging of Contrast KineticS (TRICKS) is established in veterinary medicine for vascular mapping; however, its specific utility for evaluating intratumoral enhancement heterogeneity and treatment response has not been described. This case series aimed to evaluate the feasibility of TRICKS for assessing temporal enhancement patterns and semi-quantitative temporal indices in small animal head and neck tumors undergoing radiation therapy. Three client-owned animals (two dogs with intracranial meningiomas and one cat with ceruminous gland adenocarcinoma) underwent MRI including TRICKS, as well as triple-phase computed tomography, for diagnostic evaluation, radiation therapy planning, or post-treatment follow-up. Across all cases, TRICKS provided temporally resolved enhancement information that was not appreciable on conventional contrast-enhanced T1-weighted MRI or triple-phase CT. TRICKS delineated delayed peripheral filling, inward-progressive enhancement, and intratumoral temporal heterogeneity, enabling clearer differentiation of rapidly enhancing regions from delayed or suspected non-enhancing components. Semi-quantitative parameters (enhancement integral, mean time to enhance, maximum slope of increase, and mean slope of decrease) demonstrated regional differences consistent with these enhancement patterns. In two cases, TRICKS identified post-radiation changes and delineated non-enhancing parenchymal defects chronologically prior to their clear appearance on other modalities. These exploratory findings suggests TRICKS can provide time-resolved enhancement surrogates in veterinary patient tumors, contributing to improved characterization of tumor compartmentalization and post-treatment evaluation. However, this serves as a preliminary technical feasibility report, and further studies with larger cohorts and histopathological validation are warranted to validate these observations.