A new single-center retrospective study published in the European Journal of Nuclear Medicine and Molecular Imaging aims to change that. Researchers at Beijing Tsinghua Changgung Hospital analyzed 290 consecutive patients with unresectable hepatocellular carcinoma who underwent yttrium-90 selective internal radiation therapy between October 2022 and December 2025. Among them, 91 were flagged on pre-treatment imaging as potentially receiving tumor blood flow from the inferior phrenic artery, and 78 ultimately had angiographically confirmed supply from that vessel. The team then compared the two main ways interventional radiologists handle the artery: threading microspheres directly through it into the tumor, or deliberately plugging it with coils so that tumor blood flow is redirected back into the liver’s own arterial network.

The technical foundation of the study lies in meticulous pre-procedural mapping. Every patient underwent hepatic digital subtraction angiography combined with cone-beam computed tomography, a pairing that allows physicians to see not just the two-dimensional course of the vessels but the full three-dimensional territory each artery perfuses. A technetium-99m macroaggregated albumin injection followed by SPECT/CT simulation calculated the lung shunt fraction, ensuring that too many microspheres would not escape to the lungs, and post-treatment PET/CT verified where the radioactive spheres actually landed. Using a 2.1 French goose-neck microcatheter, the team achieved superselective catheterization of the inferior phrenic artery in 88.6 percent of attempted cases, demonstrating that even this small, tortuous vessel can be reliably accessed when combined angiographic and tomographic guidance is used.

The decision-making algorithm the researchers propose hinges on two variables: the volume of tumor fed by the inferior phrenic artery and the anatomy of any non-target branches that could carry microspheres into dangerous territory. When the artery perfused at least 20 milliliters of tumor and risky branches could be managed, the team favored direct infusion of yttrium-90 microspheres through the vessel, reserving prophylactic coil embolization for high-risk offshoots such as suprarenal, esophageal, pericardial, or pulmonary shunt branches. When the perfused tumor volume fell below 20 milliliters or non-target vessels could not be safely catheterized, the team simply embolized the artery trunk with coils, wagering that intrahepatic arteries would compensate. Forty-five patients landed in the infusion group and 33 in the embolization group, with the infusion cohort predictably carrying heavier tumor burdens and more advanced disease.

The anatomical findings reinforce how distinctive the inferior phrenic artery can be. The right inferior phrenic artery dominated as the parasitic feeding vessel in 89.8 percent of cases, with the left artery accounting for only 7.7 percent and dual supply appearing in 2.5 percent. Most of these arteries originated from the celiac trunk or directly from the abdominal aorta, though a striking 21.8 percent arose from the renal artery. The median radioactivity delivered through the inferior phrenic artery was a modest 0.3 gigabecquerels, yet the dosimetric payoff was substantial: the median tumor-absorbed dose in the infusion group reached 92 Gy, with three-quarters of those patients receiving at least 61 Gy, approaching the 100 to 250 Gy window widely recommended for hepatocellular carcinoma.

Perhaps the most eye-catching result concerns the embolization strategy, which has always rested on an assumption that had never been carefully quantified. If you plug the parasitic artery, does tumor blood flow really reroute to intrahepatic vessels in time to matter? By comparing intra-procedural cone-beam CT with post-treatment PET/CT, the researchers found that approximately 88 percent of the territory originally supplied by the inferior phrenic artery received yttrium-90 microspheres through compensatory intrahepatic pathways, with more than half of lesions achieving complete hemodynamic compensation. Critically, the compensatory rate held steady regardless of tumor size, suggesting that flow redistribution after coil embolization is a robust phenomenon rather than a fortunate accident, and providing quantitative reassurance comparable to the 83.8 percent redistribution rate previously reported with glue embolization.

On efficacy, direct infusion through the inferior phrenic artery consistently outperformed embolization. Using the modified Response Evaluation Criteria in Solid Tumors, the objective response rate in the infusion group climbed from 60.0 percent at one month to 82.3 percent at three months, whereas the embolization group moved from 48.5 percent to 69.7 percent over the same intervals. The gap between the groups widened to 12.6 percentage points by three months, and the complete response rate in the infusion group surged from 17.8 percent to 46.7 percent, an absolute gain of 28.9 percentage points that far outpaced the 21.2 percent rise seen in the embolization cohort. Disease control rates exceeded 93 percent at one month in both groups, underscoring that neither strategy leaves patients behind.

Safety is where lingering fears about extrahepatic radiation have historically been most vocal, and the study directly confronts them. Mean whole-lung absorbed dose was 9.53 Gy, comfortably below the 20 Gy clinical threshold, with no significant differences between groups in lung volume, lung shunt fraction, or lung dose. The overall adverse event rate was 17.8 percent in the infusion group and 9.1 percent in the embolization group, a difference that was not statistically significant, and every reported event was a mild to moderate, reversible thoracic complaint. No severe treatment-related complications occurred in either arm, an outcome the authors attribute to the discipline of combined DSA-CBCT anatomical evaluation paired with prophylactic embolization of non-target branches whenever they were visualized.

The study’s authors are candid about its limits. As a single-center retrospective analysis, it carries inherent selection bias, and the infusion group’s higher tumor burden and greater proportion of Barcelona Clinic Liver Cancer stage C patients may confound the efficacy comparison. Only three-month tumor response was assessed, leaving progression-free survival and overall survival unmeasured, and the team calls for long-term follow-up and multicenter prospective validation before the algorithm becomes standard practice. Even so, the work represents the largest head-to-head comparison of inferior phrenic artery strategies in yttrium-90 radioembolization to date, and it delivers something the field has lacked: a concrete, volume-based decision rule. Direct infusion when the artery feeds at least 20 milliliters of tumor and the plumbing cooperates; embolization when it does not. For the roughly one in three hepatocellular carcinoma patients whose tumors recruit this diaphragmatic artery, that clarity could mean the difference between an incomplete treatment and a truly definitive one.

Subject of Research: Inferior phrenic artery management strategies during yttrium-90 selective internal radiation therapy for hepatocellular carcinoma.

Article Title: Interventional strategies for inferior phrenic artery management in yttrium‑90 selective internal radiation therapy for hepatocellular carcinoma: A single‑center retrospective study

Article References: Liao, Y., Huang, X., Liang, Z., Ma, J., Feng, X., Fu, W., Liang, B., Yang, S., Li, G., Bao, L., Zhang, T., Zheng, L., Liu, C., Tang, M., Zhang, L., & Dong, J. (2026). Interventional strategies for inferior phrenic artery management in yttrium‑90 selective internal radiation therapy for hepatocellular carcinoma: A single‑center retrospective study. European Journal of Nuclear Medicine and Molecular Imaging. https://doi.org/10.1007/s00259-026-08170-0

Image Credits: AI Generated

DOI: 10.1007/s00259-026-08170-0

Keywords: yttrium-90, selective internal radiation therapy, hepatocellular carcinoma, inferior phrenic artery, radioembolization, interventional radiology, cone-beam computed tomography, lung shunt fraction, mRECIST, extrahepatic collateral supply, tumor response, coil embolization