Transarterial Radioembolization for Management of Hepatocellular Carcinoma.

Transarterial radioembolization (TARE) with Yttrium-90 (Y90) is a growing area of study due to its benefits in early-, intermediate-, and late-stage hepatocellular carcinoma. Treatment intent, including curative therapy, bridging to transplant, and downstaging disease, informs treatment approach and dosimetry goals. Radiation lobectomy (RL) and radiation segmentectomy (RS) are the 2 main forms of Y90 administration which have shown improved survival outcomes with the development of personalized dosimetry. RS aims to achieve complete pathological necrosis with dose escalation and RL aims for local disease control as well as induction of contralateral lobe hypertrophy to improve hepatic reserve. Furthermore, TARE has been validated in head-to-head comparison to other locoregional and systemic therapies. Lastly, early potential exists for combination therapy between TARE and immune checkpoint inhibitors for advanced stage disease.

Voxel-based tumor dose correlates to complete pathologic necrosis after transarterial radioembolization for hepatocellular carcinoma.

PURPOSE: The transarterial radioembolization (TARE) dose is traditionally calculated using the single-compartment Medical Internal Radiation Dose (MIRD) formula. This study utilized voxel-based dosimetry to correlate tumor dose with explant pathology in order to identify dose thresholds that predicted response. METHODS: All patients with HCC treated with TARE using yttrium-90 [90Y] glass microspheres at a single institution between January 2015 - June 2023 who underwent liver transplantation were eligible. The [90Y] distribution and dose-volume histograms were determined using Simplicity90 (Mirada Medical, Oxford UK) with a Bremsstrahlung SPECT/CT. A complete response was assigned if explant pathology showed complete necrosis and the patient had not undergone additional treatments to the same tumor after TARE. Logistic regression and receiver operator characteristic (ROC) curves were constructed to evaluate dose thresholds correlated with response. RESULTS: Forty-one patients were included. Twenty-six (63%) met criteria for complete response. Dose to 95% (D95), 70% (D70), and 50% (D50) of the tumor volume were associated with likelihood of complete response by logistic regression (all p < 0.05). For lesions with complete response versus without, the median D95 was 813 versus 232 Gy, D70 was 1052 versus 315 Gy, and D50 was 1181 versus 369 Gy (all p < 0.01). A D95 > 719 Gy had the highest accuracy at 68% (58% sensitivity, 87% specificity) for predicting complete response. Median percent of tumor volume receiving at least 100 Gy (V100), 200 Gy (V200), 300 Gy (V300), and 400 Gy (V400) also differed by pathologic response: the median V100, V200, V300, and V400 was 100% versus 99%, 100% versus 97%, 100% versus 74%, and 100% versus 43% in the complete response versus non-complete response groups, respectively (all p < 0.05). CONCLUSION: Voxel-based dosimetry was well-correlated with explant pathology. The D95 threshold had the highest accuracy, suggesting the D95 may be a relevant target for multi-compartment dosimetry.

Ultrastable PLGA-Coated 177Lu-Microspheres for Radioembolization Therapy of Hepatocellular Carcinoma.

Transarterial radioembolization (TARE) is a highly effective localized radionuclide therapy that has been successfully used to treat hepatocellular carcinoma (HCC). Extensive research has been conducted on the use of radioactive microspheres (MSs) in TARE, and the development of ideal radioactive MSs is crucial for clinical trials and patient treatment. This study presents the development of a radioactive MS for TARE of HCC. These MSs, referred to as 177Lu-MS@PLGA, consist of poly(lactic-co-glycolic acid) (PLGA) copolymer and radioactive silica MSs, labeled with 177Lu and then coated with PLGA. It has an extremely high level of radiostability. Cellular experiments have shown that it can cause DNA double-strand breaks, leading to cell death. In vivo radiostability of 177Lu-MS@PLGA is demonstrated by microSPECT/CT imaging. In addition, the antitumor study has shown that TARE of 177Lu-MS@PLGA can effectively restrain tumor growth without harmful side effects. Thus, 177Lu-MS@PLGA exhibits significant potential as a radioactive MS for the treatment of HCC.

Defining textbook outcome for selective internal radiation therapy of hepatocellular carcinoma: an international expert study.

BACKGROUND: A textbook outcome (TO) is a composite indicator covering the entire intervention process in order to reflect the "ideal" intervention and be a surrogate for patient important outcomes. Selective internal radiation therapy (SIRT) is a complex multidisciplinary and multistep intervention facing the challenge of standardization. This expert opinion-based study aimed to define a TO for SIRT of hepatocellular carcinoma. METHODS: This study involved two steps: (1) the steering committee (4 interventional radiologists) first developed an extensive list of possible relevant items reflecting an optimal SIRT intervention based on a literature review and (2) then conducted an international and multidisciplinary survey which resulted in the final TO. This survey was online, from February to July 2021, and consisted three consecutive rounds with predefined settings. Experts were identified by contacting senior authors of randomized trials, large observational studies, or studies on quality improvement in SIRT. This study was strictly academic. RESULTS: A total of 50 items were included in the first round of the survey. A total of 29/40 experts (73%) responded, including 23 interventional radiologists (79%), three nuclear medicine physicians (10%), two hepatologists, and one oncologist, from 11 countries spanning three continents. The final TO consisted 11 parameters across six domains ("pre-intervention workup," "tumor targeting and dosimetry," "intervention," "post-90Y imaging," "length of hospital stay," and "complications"). Of these, all but one were applied in the institutions of > 80% of experts. CONCLUSIONS: This multidimensional indicator is a comprehensive standardization tool, suitable for routine care, clinical round, and research.

Introduction to interventional oncology: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper.

Interventional radiology (IR) is a valuable resource when caring for pediatric solid tumor patients. As minimally invasive, image-guided procedures become more relied upon to answer challenging diagnostic questions and provide alternative therapeutic options, IR is poised to become a contributing member of the multidisciplinary oncology team. Improved imaging techniques allow for better visualization during biopsy procedures, transarterial locoregional treatments have the potential to deliver targeted cytotoxic therapy while limiting systemic side effects, and percutaneous thermal ablation can be used to treat chemo-resistant tumors of various solid organs. Additionally, interventional radiologists are able to perform routine, supportive procedures for oncology patients that include central venous access placement, lumbar punctures, and enteric feeding tube placements with high levels of technical success and excellent safety profiles.

Cancer Immunology: Impact of Radioembolization of Hepatocellular Carcinoma on Immune Response Modulation.

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer and the fourth most common cause of cancer mortality. The tumor microenvironment is increasingly recognized as having a central role in HCC carcinogenesis; factors such as tumor and immune cell interactions, cytokines, and extracellular matrix have key roles. Transarterial radioembolization (TARE) is a locoregional therapy for HCC that not only has a direct tumoricidal effect but also induces an immune response against tumor cells with subsequent immunogenic cell death. This TARE-induced tumor immunogenicity occurs through enhancement of tumor-associated antigen expression and recruitment and diversification of tumor-infiltrating lymphocytes. In addition, immunologic biomarkers, including neutrophil-to-lymphocyte ratio, lymphocyte count, and cytokine levels, may be useful for predicting outcomes after TARE. Early data are promising regarding the potential synergistic benefit of treatment algorithms that combine TARE and immunotherapies, and interest is growing in the clinical application of such combinations. The purpose of this article is to provide an overview of cancer immunology, summarize the available data on the biologic effects of TARE on local and systemic immune responses, and explore the potential role of the combination of TARE and immunotherapy for HCC.

Friend or Foe? Locoregional Therapies and Immunotherapies in the Current Hepatocellular Treatment Landscape.

Over the last several decades, a number of new treatment options for patients with hepatocellular carcinoma (HCC) have been developed. While treatment decisions for some patients remain clear cut, a large numbers of patients have multiple treatment options, and it can be hard for multidisciplinary teams to come to unanimous decisions on which treatment strategy or sequence of treatments is best. This article reviews the available data with regard to two treatment strategies, immunotherapies and locoregional therapies, with a focus on the potential of locoregional therapies to be combined with checkpoint inhibitors to improve outcomes in patients with locally advanced HCC. In this review, the available data on the immunomodulatory effects of locoregional therapies is discussed along with available clinical data on outcomes when the two strategies are combined.

Radiofrequency ablation vs radiation therapy vs transarterial chemoembolization vs yttrium 90 for local treatment of liver cancer - a systematic review and network meta-analysis of survival data.

INTRODUCTION: The comparative effectiveness of radiofrequency ablation (RFA), radiation therapy (RT), transarterial chemoembolization (TACE) and transarterial radioembolization with Yttrium-90 (Y90) relative to one another for the treatment of hepatocellular carcinoma (HCC) is unclear. The aim of this systematic review and network meta-analysis is to compare RFA to RT to TACE to Y90 in the treatment of HCC. METHODS: Pubmed, Embase and Cochrane CENTRAL were searched up until April 19, 2021. Observational analyses with propensity score matched (PSM) cohort analyses and randomized controlled trials (RCT) reporting on two or more treatments relative to one another with respect to overall survival (OS) and/or progression free survival (PFS) were included. Survival data were extracted from Kaplan-Meier survival curves, and meta-analyzed using a multivariate network meta-analysis. RESULTS: After exclusions, 24 RCTs or PSM observational studies reporting on 5549 patients were included. While 1-year OS was greater for Y90 than TACE (RR 0.85, 95% CI: 0.72-0.99), all other 1-year OS comparisons across the 4 modalities yielded similar OS, and there were no differences across any modalities in 2-year and 3-year OS. TACE had a modest PFS advantage relative to RFA (RR 0.81, 95% CI: 0.68-0.95) and RT (RR 0.65, 95% CI: 0.51-0.83) at 2 years. CONCLUSION: All modalities assessed resulted in similar OS, which explains the current heterogenous practice patterns. This conclusion may assist in decision making based on administrative and patient costs, and implementation of these modalities. Other factors such as toxicity rate specific to individual patients could not be assessed using network meta-analysis and may also play a role in selection of modality. Further studies, ideally using PSM cohort analyses or RCT study design, reporting on OS, PFS, local control, complete response and toxicity are needed prior to drawing definitive conclusions.

Role of Interventional Radiology in Pediatric Cancer Patients.

PURPOSE OF REVIEW: Pediatric interventional radiology (IR) is a growing subspecialty. Here, we review the current role of IR in children with cancer, which uses imaging such as ultrasound, fluoroscopy, and computed tomography to perform minimally invasive procedures. These include biopsy, needle localization, central venous access, thermal ablation, transarterial chemoembolization, transarterial radioembolization with yttrium-90, non-tunneled/tunneled drainage catheter placement, and lymphatic interventions. RECENT FINDINGS: Although locoregional therapies for the treatment of cancer in adults are common, they are less common in children, perhaps due to the relative rarity of cancer in children, their typically better performance status, and paucity of comorbidities. Preliminary results from small-scale studies for ablation, transarterial chemoembolization, and transarterial radioembolization with yttrium-90 used in the front-line armamentarium of curative therapy are encouraging. Pediatric IR offers an array of minimally invasive procedures intended to diagnose and treat pediatric cancer patients. However, more research is required to determine the efficacy of locoregional therapy in children and to define the clinical scenarios where benefit is likely to be optimized.

Selective internal radiation therapy for hepatocellular carcinoma: A 15-year multicenter Australian cohort study.

BACKGROUND AND AIM: The exact place for selective internal radiation therapy (SIRT) in the therapeutic algorithm for hepatocellular carcinoma (HCC) is debated. There are limited data on its indications, efficacy, and safety in Australia. METHODS: We performed a multicenter retrospective cohort study of patients undergoing SIRT for HCC in all Sydney hospitals between 2005 and 2019. The primary outcome was overall survival. Secondary outcomes were progression-free survival and adverse events. RESULTS: During the study period, 156 patients underwent SIRT across 10 institutions (mean age 67 years, 81% male). SIRT use progressively increased from 2005 (n = 2), peaking in 2017 (n = 42) before declining (2019: n = 21). Barcelona Clinic Liver Cancer stages at treatment were A (13%), B (33%), C (52%), and D (2%). Forty-four (28%) patients had tumor thrombus. After a median follow-up of 13.9 months, there were 117 deaths. Median overall survival was 15 months (95% confidence interval 11-19). Independent predictors of mortality on multivariable analysis were extent of liver involvement, Barcelona Clinic Liver Cancer stage, baseline ascites, alpha fetoprotein, and model for end-stage liver disease score. Median progression-free survival was 6.0 months (95% confidence interval 5.1-6.9 months). Following SIRT, 11% of patients were downstaged to curative therapy. SIRT-related complications occurred in 17%: radioembolization-induced liver disease (11%), pneumonitis (3%), gastrointestinal ulceration, and cholecystitis (1% each). Baseline ascites predicted for radioembolization-induced liver disease. CONCLUSION: We present the largest Australian SIRT cohort for HCC. We have identified several factors associated with a poor outcome following SIRT. Patients with early-stage disease had the best survival with some being downstaged to curative therapy.

A Prognostic Prediction Model of Transarterial Radioembolization in Hepatocellular Carcinoma: SNAP-HCC.

BACKGROUND: Prognosis prediction in patient with hepatocellular carcinoma (HCC) after transarterial radioembolization (TARE) remains difficult. The aim of this study was to develop a prognostic model to aid in the decision to use TARE. METHODS: A total of 174 patients in Korea who underwent TARE for HCC as the initial treatment were included. We developed a prediction model for overall survival (OS) based on independent risk factors for OS and validated the model by bootstrap method. RESULTS: The median maximal size of the tumors was 8.2 cm, the median number of tumors was 2, and the median albumin level was 4.0 g/dL. Portal vein tumor thrombosis was found in 46.0% (Vp1-3 [39.7%] and Vp4 [6.3%]). Four independent risk factors associated with OS (maximal tumor size, tumor number, albumin, and portal vein tumor thrombosis) were used to develop the SNAP-HCC score. Bootstrap validation of the scoring index determined that the Harrell's c-index for OS was 0.756 (95% confidence interval: 0.729-0.783). Patients grouped based on their SNAP-HCC (scores 0-5) were well discriminated, with significant differences between the groups (all P < 0.05). Patients with SNAP-HCC < 3 showed significantly longer OS than patients with SNAP-HCC ≥ 3 (P < 0.001). The respective survival probabilities at years 1 and 3 were 0.81 and 0.73 in the low-risk (SNAP-HCC < 3) and 0.32 and 0.14 in the high-risk (SNAP-HCC ≥ 3) patients. CONCLUSIONS: The SNAP-HCC scoring system predicted the outcome of HCC patients undergoing TARE as an initial treatment. This model could be helpful for initial planning the treatment of HCC patients.

[International comparison of radiological aspects of the new German S3 guideline on hepatocellular carcinoma and intrahepatic cholangiocarcinoma]. / Radiologische Aspekte der neuen deutschen S3-Leitlinie zum hepatozellulären Karzinom und biliären Karzinomen im internationalen Vergleich.

The updated German S3 guideline "Diagnostics and therapy of hepatocellular carcinoma and biliary carcinomas" covers two tumor entities. The original guideline published in 2013 focusing only on the diagnosis and therapy of hepatocellular carcinoma (HCC) has been expanded to include intrahepatic cholangiocarcinoma. These guidelines were developed within the framework of the guideline program on oncology of the Scientific Medical Society e. V. (AWMF), the German Cancer Society (DKG) and German Cancer Aid Society (DKG) under the auspices of the German Society for Digestive and Metabolic Diseases (DGVS). In addition to updated recommendations regarding histopathology, radiological diagnostics and treatments, the main innovations of the revised guidelines on HCC include a complete revision of the section on the systemic therapeutic approach in advanced stages of the disease. This article presents the significance of the current recommendations for diagnostic and interventional radiology in comparison to other national and international guidelines and should serve to improve the quality of patient care through more widespread dissemination.

Locoregional Therapies in the Treatment of 3- to 5-cm Hepatocellular Carcinoma: Critical Review of the Literature.

OBJECTIVE. Treatment options for hepatocellular carcinoma (HCC) continue to expand. However, given the complexity of the patients including factors such as codominant cirrhosis or portal hypertension and transplant status, it can be difficult to know which treatment is most advantageous. The choice of HCC treatment is perhaps most complex in the setting of HCCs that are 3-5 cm. This article reviews the evidence for locoregional therapies in treating 3- to 5-cm HCCs. CONCLUSION. Combination therapy with transarterial chemoembolization (TACE) and ablation has the most robust and highest level of evidence to support its efficacy and therefore should be considered first-line therapy for nonresectable HCCs that measure 3-5 cm. The studies support that TACE followed by ablation is superior to either TACE alone or ablation alone. Data for transarterial radioembolization (TARE) to treat HCCs in this specific size range are very limited. Additional data are needed about the comparative effectiveness of TACE-ablation combination and TARE and how the TACE-ablation combination compares with surgical resection.

Renal and Intestinal Excretion of 90Y and 166Ho After Transarterial Radioembolization of Liver Tumors.

OBJECTIVE. The aim of this study was to evaluate the amount of free radioactivity in renal and intestinal excretions during the first 48 hours after transarterial radioembolization (TARE) procedures on the liver. SUBJECTS AND METHODS. Urinary, intestinal, and biliary excretions of patients who underwent TARE with three different types of microspheres were collected during a postinterventional period of 48 hours (divided into two 24-hour intervals). Radioactivity measurements were performed. The detected amounts of activity were correlated to clinical and procedural characteristics, times of excretion, and microsphere types. RESULTS. Twenty-four patients were evaluated, 10 treated with 90Y-glass, 10 with 90Y-resin, and four with 166Ho-poly-L-lactic acid (PLLA) microspheres. Activity excretion occurred in all cases. The highest total excretion proportions of the injected activities were 0.011% for 90Y-glass, 0.119% for 90Y-resin, and 0.005% for 166Ho-PLLA microspheres. Intestinal excretion was markedly less than renal excretion (p < 0.001). Excretion after TARE with 90Y-resin was statistically significantly higher than with 90Y-glass or 166Ho-PLLA micro-spheres (p = 0.002). For each microsphere type, the excreted activity was independent of the activity of the injected microspheres. CONCLUSION. Renal and intestinal excretion of radioactivity after TARE is low but not negligible. The radiation risk for individuals interacting with patients can be minimized if contact with urine and bile is avoided, particularly during the first 24 hours after the procedure.

Transarterial radioembolization in patients with hepatocellular carcinoma of intermediate B2 substage.

PURPOSE: Patients with hepatocellular carcinoma (HCC) of intermediate stage (BCLC-B according to the Barcelona Clinic Liver Cancer classification) are a heterogeneous group with different degrees of liver function impairment and tumour burden. The recommended treatment is transarterial chemoembolization (TACE). However, patients in this group may be judged as poor candidates for TACE because the risk-benefit ratio is low. Such patients may receive transarterial radioembolization (TARE) only by entering a clinical trial. Experts have proposed that the stage could be further divided into four substages based on available evidence of treatment benefit. We report here, for the first time, the outcome in patients with BCLC-B2 substage HCC treated with TARE. METHODS: A retrospective analysis of the survival of 126 patients with BCLC-B2 substage HCC treated with TARE in three European hospitals was performed. RESULTS: Overall median survival in patients with BCLC-B2 substage was not significantly different in relation to tumour characteristics; 19.35 months (95% CI 8.27-30.42 months) in patients with a single large (>7 cm) HCC, and 18.43 months (95% CI 15.08-21.77 months) in patients with multinodular HCC (p = 0.27). However, there was a higher proportion of long-term survivors at 36 months among those with a single large tumour (29%) than among those with multiple tumours (16.8%). CONCLUSION: Given the poor efficacy of TACE in treating patients with BCLC-B2 substage HCC, TARE treatment could be a better choice, especially in those with a large tumour.

The Beauty and Bane of Pressure-Directed Embolotherapy: Hemodynamic Principles and Preliminary Clinical Evidence.

OBJECTIVE: Particulate emboli are passive agents that follow blood flow. Deployed antireflux devices obstruct blood flow. CONCLUSION: The aim of this review is to describe the complex hemodynamic alterations to blood flow caused by the deployment of antireflux devices and the resulting changes to embolic distribution. The therapeutic goal is optimization of embolization safety and efficacy.

Safety of transarterial radioembolization with Yttrium-90 glass microspheres without cystic artery occlusion.

PURPOSE: To assess radiation-induced cholecystitis in cases of cystic artery origin nearby the treatment zone for transarterial radioembolization (TARE) treatment. MATERIALS AND METHODS: Patients with primary or secondary malignant liver tumors treated with TARE, in whom cystic artery was located in the surrounding area of the treatment zone on 99m-technetium-MAA angiograms, were included in this study. Whole liver dose, tumor dose and healthy injected liver dose, lung dose and if applicable the gallbladder dose were all calculated by using the Medical Internal Radiation Dose (MIRD) formula from SPECT-CT images. Qualitative and quantitative assessment of the gallbladder was performed on SPECT-CT. The observed adverse events were classified according to the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE v5.0). RESULTS: A total of 34 TARE procedures from 29 patients (18 men and 11 women), with a mean age of 65 ± 13.3 years meeting the inclusion criteria, were involved in the current study. The mean tumor dose, healthy injected liver dose, healthy whole liver dose and gallbladder dose were 204.9 ± 66.8 Gy, 70.5 ± 15.7 Gy, 31.1 ± 12.7 Gy and 96.4 ± 53.4 Gy, respectively. The mean follow-up period was 14 ± 5.2 months. Qualitative assessment revealed gallbladder radioactivity on SPECT-CT in 11 (32.3%) patients with six mild and five moderate-severe radioactivities. There were no detected grade 2 or 3 adverse events. CONCLUSION: TARE is safely performed without cystic artery embolization when its origin is close to the treatment area.

Other non-surgical treatments for liver cancer.

Interventional radiology plays a major role in the modern management of liver cancers, in primary hepatic malignancies or metastases and in palliative or curative situations. Radiological treatments are divided in two categories based on their approach: endovascular treatment and direct transcapsular access. Endovascular treatments include mainly three applications: transarterial chemoembolization (TACE), transarterial radioembolization (TARE) and portal vein embolization (PVE). TACE and TARE share an endovascular arterial approach, consisting of a selective catheterization of the hepatic artery or its branches. Subsequently, either a chemotherapy (TACE) or radioembolic (TARE) agent is injected in the target vessel to act on the tumor. PVE raises the volume of the future liver remnant in extended hepatectomy by embolizing a portal vein territory which results in hepatic regeneration. Direct transcapsular access treatments involve mainly three techniques: radiofrequency thermal ablation (RFA), microwave thermal ablation (MWA) and percutaneous ethanol injection (PEI). RFA and MWA procedures are almost identical, their clinical applications are similar. A probe is deployed directly into the tumor to generate heat and coagulation necrosis. PEI has known implications based on the chemical toxicity of intra-tumoral injection with highly concentrated alcohol by a thin needle.

Single-Session Ablative Transarterial Radioembolization for Patients with Hepatocellular Carcinoma to Streamline Care: An Initial Experience.

PURPOSE: Transarterial radioembolization (TARE) for hepatocellular carcinoma (HCC) is performed after a mapping angiogram involving infusion of radiolabeled macroaggregated albumin to assess for non-target embolization and pulmonary shunting. The purpose of this case series was to evaluate the safety and feasibility of single-session TARE without the initial procedure. MATERIALS AND METHODS: A single-institution case series of 16 consecutive procedures on 15 patients with 18 tumors who underwent an attempted single-session TARE procedures with glass microspheres are presented. A lung shunt fraction (LSF) of 5% was assumed for planning purposes. RESULTS: Sixty-seven percent (10/15) of patients were male with a median age of 72 years. Median tumor size was 2.5 cm (IQR 2.0-3.2 cm). Sixteen of the 18 targeted tumors were untreated prior to the single-session TARE. Rate of technical success was 88% (14/16). Two patients did not ultimately receive a single-session TARE due to intraprocedural findings. The mean administered activity was 2.0 GBq, and the mean MIRD dose was 464 Gy based on pre-treatment anatomic imaging and 800 Gy based on cone-beam CT. There were no cases of radiation pneumonitis. Mean post-procedural calculated lung dose was 4.9 Gy (range 3.1-9.3) based on SPECT. CONCLUSIONS: An initial experience with single-session TARE using Y-90 glass microspheres without pre-procedural mapping angiography and lung shunt estimation demonstrates that it is a feasible and safe treatment option for select patients with small (< 5 cm) HCC. LEVEL OF EVIDENCE IV: Level 4 case series.

Use of dose-volume histograms for metabolic response prediction in hepatocellular carcinoma patients undergoing transarterial radioembolization with Y-90 resin microspheres.

INTRODUCTION: Voxel-based dosimetry offers improved outcomes in the treatment of hepatocellular carcinoma (HCC) with transarterial radioembolization (TARE) using glass microspheres. However, the adaptation of voxel-based dosimetry to resin-based microspheres has been poorly studied, and the prognostic relevance of heterogeneous dose distribution remains unclear. This study aims to explore the use of dose-volume histograms for resin microspheres and to determine thresholds for objective metabolic response in HCC patients treated with resin-based TARE. METHODS: We retrospectively reviewed HCC patients who underwent TARE with Y-90-loaded resin microspheres in our institution between January 2021 and December 2022. Voxel-based dosimetry was performed on post-treatment Y-90 PET/CT images to extract parameters including mean dose absorbed by the tumor (mTD), the percentage of the targeted tumor volume (pTV), and the minimum doses absorbed by consecutive percentages within the tumor volume (D10, D25, D50, D75, D90). Assessment of metabolic response was done according to PERCIST criteria with F-18 FDG PET/CT imaging at 8-12 weeks after the treatment. RESULTS: This study included 35 lesions targeted with 22 TARE sessions in 19 patients (15 males, 4 females, mean age 60 ± 13 years). Objective metabolic response was achieved in 43% of the lesions (n = 15). Responsive lesions had significantly higher mTD, pTV, and D25-D90 values (all p < 0.05). Optimal cut-off values for mTD, pTV, and D50 were 94.6 Gy (sensitivity 73%, specificity 70%, AUC 0.72), 94% (sensitivity 73%, specificity 55%, AUC 0.64), and 91 Gy (sensitivity 80%, specificity 80%, AUC 0.80), respectively. CONCLUSION: Parameters derived from dose-volume histograms could offer valuable insights for predicting objective metabolic response in HCC patients treated with resin-based TARE. If verified with larger prospective cohorts, these parameters could enhance the precision of dose distribution and potentially optimize treatment outcomes.