Feasibility of contrast-enhanced ultrasound for evaluating radiation-associated hepatic perfusion changes in Beagle dogs: an exploratory study

Radiation-induced liver disease (RILD) can result from radiation therapy (RT) for hepatic tumors, but early detection remains challenging. This study evaluated contrast-enhanced ultrasound (CEUS) for assessing early radiation-associated hepatic perfusion alterations in dogs. Four healthy Beagle dogs underwent stereotactic body radiation therapy (SBRT). A total of 30 Gy was administered to one hepatic region, while 15 Gy was delivered to another. Blood tests, B-mode ultrasound, and CEUS were performed pre-radiation, one day after irradiation, and weekly for eight weeks. CEUS parameters, including peak intensity (PI), time to peak (TTP), Up-slope, and hepatic artery to vein transit time (HA-HVTT), were analyzed. Serum hepatobiliary enzyme activities increased post-radiation, peaking at week 6, although these temporal trends were not statistically significant. B-mode ultrasound showed no echogenicity changes, but CEUS revealed temporal alterations in PI, TTP, and Up-slope within the irradiated regions. Although the small sample size and strict multiplicity adjustments limited formal statistical significance, the 30 Gy region exhibited consistent trends of PI and Up-slope decrease, alongside a TTP increase. The 15 Gy region demonstrated a statistically significant PI reduction at specific time points, with less apparent changes in TTP or Up-slope. HA-HVTT remained unchanged. CEUS detected early radiation-associated hepatic perfusion alterations undetectable by B-mode ultrasound. PI, TTP, and Up-slope may serve as non-invasive parameters for monitoring early hepatic perfusion alterations.