Radioembolization, also known as selective internal radiation therapy, involves threading tiny radioactive microspheres through the arteries that feed liver tumors, delivering high doses of radiation directly to cancerous tissue while sparing healthy liver. The field has steadily moved toward increasingly selective strategies, with radiation segmentectomy now often favored over whole-liver or lobar approaches because it can treat early hepatocellular carcinoma in an ablative manner. But greater selectivity comes at a price: when a patient has multiple tumors in different liver segments, physicians frequently need to access several separate injection positions within the arterial network, and each repositioning step creates a practical dilemma that has long frustrated operators.

The problem is fundamentally one of contamination. Conventional microcatheters have a single lumen that serves both as the guidewire track and the injection channel. Once radioactive microspheres have passed through that channel, any subsequent manipulation of a guidewire through the same space risks smearing radioactive material onto the wire and, by extension, the sterile field. Current clinical practice therefore mandates discarding the microcatheter after each injection position and inserting a fresh one for the next target vessel. That approach generates additional radioactive waste, extends procedure time, and adds cost, particularly in complex cases where selective catheterization is technically demanding.

The Utrecht team hypothesized that a catheter with two physically separate lumens could eliminate this risk entirely. They employed a 3.2-Fr dual-lumen microcatheter, the Sasuke device from Asahi Intecc in Japan, which was originally designed for cardiac interventions. The device features a rapid-exchange lumen extending from the catheter tip to an exit port located 20 centimeters proximally, which accommodates a 0.016-inch guidewire, and an over-the-wire lumen that runs from the proximal catheter end to an exit port just 6.5 millimeters from the tip, which serves as the microsphere injection pathway. Because the guidewire and the microspheres travel through entirely separate channels, they never come into contact, theoretically eliminating guidewire contamination regardless of how many times the catheter is repositioned.

The technique itself unfolds in a deliberate sequence. After standard femoral arterial access with a 6-Fr sheath, a 6-Fr guiding catheter was advanced into the celiac trunk, since the 3.2-Fr microcatheter is too large to pass through standard 4 to 5 Fr diagnostic catheters. The dual-lumen microcatheter was then navigated to the first target vessel over the guidewire. Once the position was confirmed, the guidewire was retracted so that its tip resided safely within the rapid-exchange lumen, well away from any microspheres. Two microsphere administration systems were connected to the injection lumen through a three-way stopcock, the first dose was delivered, and the lumen was thoroughly flushed with saline. To move to the second site, the guidewire was simply advanced again through its dedicated lumen to steer the catheter to the next target, retracted once more, and the second dose was injected through the same channel.

The first patient was an 80-year-old man with two hepatocellular carcinoma lesions, one in liver segment 4 and one in segment 8, undergoing radioembolization work-up. The dual-lumen microcatheter successfully delivered scout doses of holmium-166 microspheres to both positions, first through the left hepatic artery and then, after repositioning, through the segment 8 artery. Cone-beam computed tomography from both positions demonstrated the expected vascular territories, and subsequent single-photon emission computed tomography confirmed adequate microsphere distribution to both tumors. The total procedure, from vascular access to closure, took 95 minutes, with cumulative fluoroscopy time of 18 minutes and 50 seconds and a total dose-area product of 330 Gy·cm².

The second case put the technique to a therapeutic test. A 79-year-old patient with neuroendocrine tumor liver metastases required treatment doses at two positions, the right hepatic artery and the segment 4 artery. Using a single dual-lumen microcatheter, the team delivered a first therapeutic dose of 4100 MBq of holmium-166 microspheres into the right hepatic artery and then repositioned to deliver a second dose of 3000 MBq into the segment 4 artery. One technical wrinkle emerged: at both injections, pressure inside the administration system rose rapidly to its maximum, indicated by the fluid level in the V-vial climbing to the rubber septum, so the team injected at a substantially reduced rate with roughly 20 seconds of additional time between flushing and microsphere administration to allow pressure normalization. A calibrated dose calibrator confirmed no significant residual activity afterward, and post-procedural imaging verified adequate microsphere distribution. This procedure took just 65 minutes, with 14 minutes and 29 seconds of fluoroscopy and a dose-area product of 86.3 Gy·cm².

Critically, radiation safety monitoring validated the central premise of the approach. As part of standard institutional protocol, all disposable materials, including the guidewire, were surveyed with a contamination monitor after each procedure. In both cases, count rates fell below the institutional threshold of 200 counts per second, the level below which materials can be discarded as regular non-radioactive waste. Catheter repositioning in both procedures was accomplished smoothly without technical difficulties, suggesting that maintaining the guidewire within its own lumen throughout the procedure neither impedes navigation nor compromises delivery precision.

The researchers are candid about the technique’s limitations. The 3.2-Fr outer diameter exceeds the typical 2.7-Fr profile of standard microcatheters, requiring guiding catheters rather than conventional diagnostic ones, a setup change that some centers may need to make. The injection port sits 6.5 millimeters proximal to the catheter tip, meaning the tip must be advanced slightly beyond the intended injection point, which could prove difficult in small vessels, and the protruding tip could theoretically pick up surface contamination. More significantly, the narrow 0.016-inch inner diameter of each lumen generates higher injection pressures than standard microcatheters, and not all microsphere delivery systems tolerate this. The instructions for use of widely used yttrium-90 glass and resin microsphere systems recommend minimum inner diameters of 0.020 and 0.021 inches respectively, making pressure compatibility an important barrier to broader adoption.

Two complementary developments could ease that constraint. Pressure-resistant delivery systems, such as the recently introduced SIROS system for yttrium-90 resin microspheres, may better accommodate narrow-lumen catheters; in a retrospective study of 48 SIROS administrations through a microcatheter with a 0.021-inch inner diameter, mean residual activity was just 4.9 percent, and 94 percent of administrations retained less than 10 percent residual activity with a double-flush protocol. Alternatively, manufacturers could design dual-lumen catheters specifically for microsphere delivery, with a larger dedicated injection lumen and a smaller guidewire channel. The authors also note that delivering predetermined doses at multiple positions currently requires multiple administration systems connected via stopcocks, and point to dose-titration systems such as the Eye90 microsphere platform as potential solutions. Guidewireless steerable microcatheters offer another route around contamination, having achieved guidewire-free catheterization in 93 percent of applications in a 50-patient multicenter trial, but they carry elevated risks of vessel injury and catheter kinking, particularly in tortuous or very wide vessels. The dual-lumen approach retains guidewire support throughout, trading a slightly larger catheter profile for potentially safer navigation.

For now, the findings rest on just two cases performed by a single experienced operator at one institution, without a control group for comparison, so the authors caution that the results do not yet support routine clinical use. Still, the proof of principle is compelling: a single catheter served two injection positions in each patient, no guidewire contamination was detected, and the technique could plausibly cut radioactive waste and procedure time in multi-position treatments. The team, whose work is supported by the European Union-funded IMAGIO consortium under the Innovative Health Initiative, calls for larger studies evaluating the technique with different microspheres and delivery systems, assessing its applicability to more complex multi-position procedures, and directly comparing repositioning time, total procedure duration, and residual activity against conventional single-lumen catheter exchange. If those studies bear out the promise, a device borrowed from the cardiology catheterization lab may become a quiet workhorse of precision liver cancer therapy.

Subject of Research: Dual-lumen microcatheter technique for multi-position radioembolization of liver tumors

Article Title: Dual-lumen microcatheter facilitating multiple injection positions in radioembolization: proof of principle

Article References: Smits, M. L. J., Wijnen, N., Lam, M. G. E. H., de Bruijne, J., & Vonken, E.-J. P. A. (2026). Dual-lumen microcatheter facilitating multiple injection positions in radioembolization: proof of principle. CVIR Oncology, 2(1), Article 28. https://doi.org/10.1007/s44343-026-00055-1

Image Credits: AI Generated

DOI: 10.1007/s44343-026-00055-1

Keywords: dual-lumen microcatheter, radioembolization, guidewire contamination, holmium-166 microspheres, radiation segmentectomy, liver tumors, interventional radiology, hepatocellular carcinoma, microsphere delivery, catheter repositioning, Dual-lumen, microcatheter