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Theranostics. 2019 Jan 25;9(3):868-883. doi: 10.7150/thno.29381. eCollection 2019.

Radioembolization of Hepatocellular Carcinoma with Built-In Dosimetry: First in vivo Results with Uniformly-Sized, Biodegradable Microspheres Labeled with 188Re.

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Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC Canada.
Department of Radiology, University of British Columbia, Vancouver, BC Canada.
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC Canada.
The Vancouver Prostate Cancer Centre and Department of Urologic Sciences, University of British Columbia, Vancouver, BC Canada.
Department of Interventional Radiology, Vancouver General Hospital, Vancouver, BC Canada.


A common form of treatment for patients with hepatocellular carcinoma (HCC) is transarterial radioembolization (TARE) with non-degradable glass or resin microspheres (MS) labeled with 90Y (90Y-MS). To further simplify the dosimetry calculations in the clinical setting, to have more control over the particle size and to change the permanent embolization to a temporary one, we developed uniformly-sized, biodegradable 188Re-labeled MS (188Re-MS) as a new and easily imageable TARE agent. Methods: MS made of poly(L-lactic acid) were produced in a flow focusing microchip. The MS were labeled with 188Re using a customized kit. An orthotopic HCC animal model was developed in male Sprague Dawley rats by injecting N1-S1 cells directly into the liver using ultrasound guidance. A suspension of 188Re-MS was administered via hepatic intra-arterial catheterization 2 weeks post-inoculation of the N1-S1 cells. The rats were imaged by SPECT 1, 24, 48, and 72 h post-radioembolization. Results: The spherical 188Re-MS had a diameter of 41.8 ± 6.0 µm (CV = 14.5%). The site and the depth of the injection of N1-S1 cells were controlled by visualization of the liver in sonograms. Single 0.5 g tumors were grown in all rats. 188Re-MS accumulated in the liver with no deposition in the lungs. 188Re decays to stable 188Os by emission of β¯ particles with similar energy to those emitted by 90Y while simultaneously emitting γ photons, which were imaged directly by single photon computed tomography (SPECT). Using Monte Carlo methods, the dose to the tumors was calculated to be 3-6 times larger than to the healthy liver tissue. Conclusions: 188Re-MS have the potential to become the next generation of β¯-emitting MS for TARE. Future work revolves around the investigation of the therapeutic potential of 188Re-MS in a large-scale, long-term preclinical study as well as the evaluation of the clinical outcomes of using 188Re-MS with different sizes, from 20 to 50 µm.


188Re; beta radiation therapy; liver cancer; microspheres; monosized; radioembolization

Conflict of interest statement

Competing Interests: The authors have declared that no competing interest exists.

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