Purpose: To determine the feasibility of using a quantitative digital subtractionangiography (qDSA) technique for characterizing changes in hepatic arterial blood velocity during transarterial embolization (TAE).
Material and Methods: Six ~50 kg domestic swine underwent incremental (embolicparticles delivered in 0.5-3mL aliquots) and non-incremental bland transarterial embolization of second-order hepatic artery branches to partial and sub-stasis angiographic endpoints. Digital subtraction angiography (DSA) sequences were acquired before, during, and after embolization. Following embolization, embolized lobes were assessed on histopathology for changes including signs of acute ischemic damage and tissue embolic particle density. A post-hoc analysis of all DSA acquisitions used a shifted-least squares approach for calculating blood velocities relative to baseline in target vessels. A linear regression analysis was used to analyze embolization degree and embolic particle density with respect to relative reductions in blood velocity.
Results: Embolizations performed to greater degrees of stasis had a statistically significant greater reduction in mean blood velocity relative to baseline as calculated by the qDSA method (57.0%±2.4% for partial stasis, 76.3%±11.3% for sub-stasis, p = 0.05). In incremental embolizations, all embolized arteries exhibited moderate-tostrong (R2, 0.6-0.92) linear decreases in qDSA calculated blood velocity (7.9%±2.0% reduction per mL of embolic particles). On pathologic analysis, the degree of embolization as calculated by qDSA had a moderate-to-strong linear correlation (R2=0.73) with the embolic particle density of ischemic regions within the embolized lobe.
Conclusions: The qDSA method was able to quantify linear velocity reductions during a liver embolization procedure. The calculated velocity reductions correlated with angiographic endpoints and tissue-level changes.