Bilateral Subcutaneous Rat Tumor Model Perfused by the Iliolumbar Artery: A Simplified and Versatile Platform for Transarterial Therapy Studies

<b>Purpose:</b> To evaluate the feasibility of a bilateral flank subcutaneous rat tumor model perfused by the iliolumbar artery, as a reproducible platform for preclinical transarterial therapy research. <b>Material and Methods:</b> Eighteen male Lewis rats (median body weight: 295 g; interquartile range: 289-301 g) received bilateral flank implantation of tumor fragments from a pancreatic ductal adenocarcinoma (DSL-6A/C1) that had developed subcutaneously in a donor rat. Upon reaching ≥8 mm in diameter, rats underwent angiography via tail artery access. A microcatheter was advanced into the iliolumbar artery through the aorta, and digital subtraction angiography was used to assess tumor staining. In two animals, either isosulfan blue or fluorescent-labeled nanoparticles were selectively injected via the iliolumbar artery to corroborate radiographic assessment of tumor perfusion. The animal that received fluorescent-labeled nanoparticles was euthanized 24 hours after injection for near-infrared imaging. The remaining rats underwent embolization and were monitored for 72 hours to assess safety. <b>Results:</b> The tumor engraftment rate was 97.2% (35/36). Selective iliolumbar artery catheterization was successful in all rats (100%), with a median procedure time of 20 minutes (interquartile range: 15-25). Digital subtraction angiography confirmed tumor staining in all of the evaluable tumors. Isosulfan blue injection via the iliolumbar artery resulted in whole-tumor staining. Fluorescence imaging revealed higher fluorescent signal intensity in the treated tumor compared with the contralateral side. No major complications, including skin ischemia, claudication, or paralysis were observed. <b>Conclusions:</b> This minimally-invasive model allows for highly reproducible subcutaneous tumor engraftment and reliable selective iliolumbar artery catheterization, providing a straightforward, technically feasible, and practical platform for transarterial therapy studies in rats.