Outcomes in Patients with Macrotrabecular-Massive Subtype Hepatocellular Carcinoma Treated with Yttrium-90 Transarterial Radioembolization.

PURPOSE: To compare the outcomes of yttrium-90 transarterial radioembolization (TARE) in patients with hepatocellular carcinoma (HCC) with and without macrotrabecular-massive (MTM) subtypes. MATERIALS AND METHODS: Forty-one consecutive patients with HCC (male, 90.3%; mean age, 65.3 years [SD ± 10.7]) who underwent yttrium-90 TARE between September 2014 and January 2022 were grouped into the MTM-HCC (n = 17, 41.5%) and non-MTM-HCC (n = 24, 58.5%) groups based on their histopathological subtypes. Demographic, clinical, and radiological characteristics were compared. Survival, univariate, and multivariate analyses were performed, and prognostic factors were evaluated. RESULTS: In MTM-HCC group, the rates of moderately to poorly differentiated tumors were significantly higher (13/17 vs 8/16, P = .007), and new intrahepatic/extrahepatic metastases were detected more frequently (12/17 vs 15/24, P = .038). Median overall survival (OS) in the cohort was 29 months (range, 17.1-40.9 months), whereas patients with MTM-HCC had a significantly shorter median OS (20 vs 44 months, P = .014). In univariate analysis, MTM-HCC subtype (hazard ratio [HR], 2.690; P = .021), the presence of satellite nodules (HR, 3.810; P = .004), and macrovascular invasion (HR, 3.321; P = .012) were identified as significant prognostic factors. In multivariate analysis, MTM-HCC subtype and macrovascular invasion were determined as independent poor prognostic factors (P = .038 and P = .012, respectively). CONCLUSIONS: In patients with HCC treated with yttrium-90 TARE, both the rates of moderately to poorly differentiated histopathological classes and the development of intrahepatic or extrahepatic metastases were significantly higher in the MTM-HCC subtype. OS was worse in patients with MTM-HCC, and macrovascular invasion and MTM-HCC subtype were identified as independent poor prognostic factors.

Histopathologic Changes after Yttrium-90 Radioembolization of Colorectal Liver Metastases: A Pilot Feasibility Study.

PURPOSE: To evaluate the histopathologic changes and potential correlations of tumor absorbed dose (TAD) after yttrium-90 transarterial radioembolization (TARE) for colorectal liver metastases (CLMs). MATERIALS AND METHODS: This prospective pilot study assessed 12 patients with 13 CLMs through positron emission tomography (PET)/computed tomography (CT)-guided biopsies before, immediately after TARE (T0), and 3 weeks after TARE (T3). Subsequent sampling from the same location was enabled by fiducial placement. Biopsy samples were evaluated with hematoxylin and eosin, TUNEL, Ki67, OxPhos, caspase-3 (CC3), and pH2AX antibodies. Proliferation changes (Ki67) and double-strand DNA breaks (DSBs) were evaluated quantitatively. TAD was calculated on post-TARE PET/CT scan of the biopsy needle location at T0 and T3. RESULTS: Median TAD at 3 weeks after TARE was 162 Gy (interquartile range (IQR), 92-211 Gy). DSBs decreased significantly from T0 (median, 77%; IQR, 75%-100%) to T3 (median, 14%; IQR, 0%-54%; P = .028). A decrease in Ki67 was also documented (median, 73%; IQR, 70%-80% at T0 vs median, 41%; IQR, 0%-66% at T3; P = .046). There was a strong positive correlation between TAD and DSBs at T0 (r[9] = 0.68) and a strong negative correlation at T3 (r[10] = -0.855; P = .042 and P = .002, respectively). There was a strong negative correlation between TAD and Ki67 at both T0 (r[9] = -0.733; P = .025) and T3 (r[10] = -0.681; P = .030). Tumors that exhibited caspase-3 activation (8/13, 62%) at either T0 or T3 time point were more likely to develop progression (7/8 [88%] vs 1/5 [20%]; P = .015). CONCLUSIONS: Post-TARE biopsy can be used to assess TAD and histopathologic changes. Significant decreases in DSBs and proliferation index were noted after TARE. Post-TARE CC3 activation deserves further exploration.

Multidisciplinary Delphi Consensus on Safety of Combining Transarterial Radioembolization with Yttrium-90 Microspheres with Systemic Anticancer Agents for the Treatment of Liver Malignancy.

PURPOSE: To provide guidance, via multidisciplinary consensus statements, on the safety interactions between systemic anticancer agents (such as radiosensitizing chemotherapy, immunotherapy, targeted therapy, and peptide receptor radionuclide therapy) and transarterial radioembolization (TARE) with yttrium-90 (90Y)-labeled microspheres in the treatment of primary and metastatic liver malignancies. MATERIALS AND METHODS: A literature search identified 59 references that informed 26 statements on the safety of 90Y TARE combined with systemic therapies. Modified Delphi method was used to develop consensus on statements through online anonymous surveys of the 12 panel members representing the fields of interventional radiology, medical oncology, surgical oncology, hepatology, and pharmacy, focusing on hepatocellular carcinoma (HCC), metastatic colorectal cancer (mCRC), neuroendocrine tumors, metastatic breast cancer, and intrahepatic cholangiocarcinoma. RESULTS: High-level evidence was limited. Level 1 data in patients with mCRC suggest that some radiosensitizing chemotherapies (eg, oxaliplatin) require temporary dose reduction when used concomitantly with 90Y TARE, and some targeted therapies (eg, vascular endothelial growth factor inhibitors and antiangiogenic tyrosine kinase inhibitors) should be avoided for at least 4 weeks before 90Y TARE. In patients with HCC, the feasibility of 90Y TARE and immunotherapy has been demonstrated with Level 4 evidence. Data are more limited for other primary and secondary liver malignancies, and consensus statements were driven by expert opinion (Level 5). CONCLUSIONS: Given the absence of evidence-based guidelines on the safety of 90Y TARE in combination with systemic anticancer therapy, these consensus statements provide expert guidance on the potential risks when considering specific combinations.

Imageable Radioembolization Microspheres for Treatment of Unresectable Hepatocellular Carcinoma: Interim Results from a First-in-Human Trial.

PURPOSE: To determine 6-month interim safety, effectiveness, and multimodal imageability of imageable glass microsphere yttrium-90 (90Y) radioembolization for unresectable hepatocellular carcinoma (HCC) in a first-in-human trial. MATERIALS AND METHODS: Imageable microspheres (Eye90 Microspheres; ABK Biomedical, Halifax, Nova Scotia, Canada), a U.S. Food and Drug Administration (FDA) Breakthrough-Designated Device consisting of glass radiopaque 90Y microspheres visible on computed tomography (CT) and single photon emission CT (SPECT), were used to treat 6 subjects with unresectable HCC. Patients underwent selective (≤2 segments) treatment in a prospective open-label pilot trial. Key inclusion criteria included liver-only HCC, performance status ≤1, total lesion diameter ≤9 cm, and Child-Pugh A status. Prospective partition dosimetry was utilized. Safety (measured by Common Terminology Criteria for Adverse Events [CTCAE] v5), multimodal imageability on CT and SPECT, and 3- and 6-month imaging response by modified Response Evaluation Criteria in Solid Tumors on magnetic resonance (MR) imaging were evaluated. RESULTS: Seven tumors in 6 subjects were treated and followed to 180 days. Administration success was 100%. Microsphere distribution measured by radiopacity on CT correlated with SPECT. Ninety-day target lesion complete response (CR) was observed in 3 of 6 subjects (50%) and partial response (PR) in 2 (33.3%). At 180 days, target lesion CR was maintained in 3 subjects (50%) and PR in 1 (16.7%). Two subjects could not be reassessed, having undergone intervening chemoembolization. All subjects reported adverse events (AEs), and 5 reported AEs related to treatment. There were no treatment-related Grade ≥3 AEs. CONCLUSIONS: Radioembolization using imageable microspheres was safe and effective in 6 subjects with unresectable HCC at 6-month interim analysis. Microsphere distribution by radiopacity on CT correlated with radioactivity distribution by SPECT, providing previously unavailable CT-based tumor targeting information.

Tumor Size and Watershed Area Correlate with Incomplete Treatment and Tumor Progression after Selective Radioembolization for Hepatocellular Carcinoma.

PURPOSE: To identify factors of incomplete treatment after segmental transarterial radioembolization (TARE) for treatment-naive and solitary hepatocellular carcinoma (HCC). MATERIALS AND METHODS: A total of 75 consecutive patients (age, 68.5 years [SD ± 8.0]; 25/75 [33.3%] women) with treatment-naive, solitary HCC underwent segmental or subsegmental TARE with glass microspheres (tumor size, 3.8 cm [SD ± 2.2]; administered dose, 222.6 Gy [SD ± 123.9]) at a single institution from November 2015 to June 2022. Radiologic response and progression-free survival (PFS) were assessed as per modified Response Evaluation Criteria in Solid Tumors. RESULTS: Complete treatment was achieved in 48 of 75 (64.0%) patients (mean follow-up, 33.2 months [SD ± 27.4]). Patients with incomplete treatment (27/75, 36%) presented with larger tumor size (5.0 [SD ± 2.5] vs 3.1 [SD ± 1.6] cm; P = .0001), with more tumors located in the watershed zone (81.5% vs 41.7%; P = .001). These patients were less likely to be bridged to transplant or resection (22.2% vs 52.1%; P = .015). Watershed tumors demonstrated worse target tumor PFS (median PFS, 19 months vs not reached; P = .0104) and overall PFS (9.1 months vs not reached; P = .0077). Watershed location was associated with worse PFS among tumors >3 cm in size (8.4 months vs not reached; P = .035) but not in tumors ≤3 cm in size (52.2 months vs not reached; P = .915). CONCLUSIONS: Tumor size and watershed location were associated with incomplete treatment after segmental TARE for HCC. Watershed tumors were associated with worse PFS, particularly tumors larger than 3 cm. These tumors may require careful treatment planning and repeated treatments to ensure a durable response.

Predictive Dosimetry and Outcomes of Hepatocellular Carcinoma Treated by Yttrium-90 Resin Microsphere Radioembolization: A Retrospective Analysis Using Technetium-99m Macroaggregated Albumin SPECT/CT and Planning Software.

PURPOSE: To characterize estimated mean absorbed tumor dose (ADT), objective response (OR), and estimated target dose of hepatocellular carcinoma (HCC) after resin microsphere yttrium-90 (90Y) radioembolization using partition dosimetry. MATERIALS AND METHODS: In this retrospective, single-center study, multicompartment dosimetry of index tumors receiving 90Y radioembolization between October 2015 and June 2022 was performed using a commercial software package and pretreatment technetium-99m macroaggregated albumin single photon emission computed tomography (SPECT)/computed tomography (CT). In total, 101 patients with HCC underwent 102 treatments of 127 index tumors. Patients underwent imaging every 2-3 months after treatment to determine best response per modified Response Evaluation Criteria in Solid Tumors (mRECIST). Best response was defined as the greatest response category per mRECIST and categorized as OR or nonresponse (NR). A Cox proportional hazards model evaluated the probability of tumor OR and progression-free survival using ADT. RESULTS: The median follow-up period was 148 days (interquartile range [IQR], 92-273 days). The median ADT of OR was 141.9 Gy (IQR, 89.4-215.8 Gy) compared with the median ADT of NR treatments of 70.8 Gy (IQR, 42.0-135.3 Gy; P < .001). Only ADT was predictive of response (hazard ratio = 2.79 [95% confidence interval {CI}: 1.44-5.40]; P = .003). At 6 months, an ADT of 157 Gy predicted 90.0% (95% CI: 41.3%-98.3%) probability of OR. At 1 year, an ADT of 157 Gy predicted 91.6% (95% CI: 78.3%-100%) probability of progression-free survival. Partition modeling and delivered activity were predictive of progression (P = .021 and P = .003, respectively). CONCLUSIONS: For HCC treated with resin microspheres, tumors receiving higher ADT exhibited higher rates of OR. An ADT of 157 Gy predicted 90.0% OR at 6 months.

Modified Radiation Lobectomy Strategy of Radioembolization for Right-Sided Unresectable Primary Liver Tumors.

PURPOSE: To assess the safety and effectiveness of using modified radiation lobectomy (mRL) to treat primary hepatic tumors located in the right hepatic lobe (Segments V-VIII) and to determine future liver remnant (FLR) hypertrophy. MATERIALS AND METHODS: A retrospective review was performed at a single institution to include 19 consecutive patients (7 females, 12 males) who underwent single-session mRL for right-sided primary hepatic tumors: 15 received segmentectomy plus lobectomy (segmental dose of >190 Gy and lobar dose of >80 Gy); 4 were treated with the double-segmental approach (dominant segments of >190 Gy and nondominant segments of >80 Gy). Treated tumors included 13 hepatocellular carcinoma (HCC), 4 cholangiocarcinoma (CCA), and 2 mixed-type HCC-CCA with a median dominant tumor size of 5.3 cm (interquartile range [IQR], 3.7-7.3 cm). FLR of the left hepatic lobe was measured at baseline, T1 (4-8 weeks), T2 (2-4 months), T3 (4-6 months), and T4 (9-12 months). RESULTS: Objective tumor response and tumor control were achieved in 17 of the 19 (89.5%) and 18 of the 19 (94.7%) patients, respectively. FLR hypertrophy was observed at T1 (median, 47.8%; P = .025), T2 (median, 48.4%; P = .012), T3 (median, 50.4%; P = .015), and T4 (median, 59.1%; P < .001). Patients without cirrhosis demonstrated greater hypertrophy by 6 months (median, 55.8% vs 47.2%; P = .031). One patient developed a Grade 3 adverse event (ascites requiring paracentesis) at 1-month follow-up. Grade ≥2 serum toxicities were associated with worse baseline Child-Pugh Score, serum albumin, and total bilirubin (P < .05). Among 7 patients who underwent neoadjuvant mRL, 2 underwent resection and 1 received liver transplant. CONCLUSIONS: mRL appears safe and effective for treatment of right-sided primary hepatic tumors with the benefit of promoting FLR hypertrophy.

Multicenter evaluation of the safety and efficacy of selective internal radiation therapy with yttrium-90 resin microspheres in Taiwan: data from the RESIN registry.

BACKGROUND AND AIM: The REgistry of Selective Internal radiation therapy in AsiaNs (RESIN) was a multicenter, single-arm, prospective, observational study of 90Y resin microspheres in patients with hepatocellular carcinoma (HCC) or metastatic colorectal cancer (mCRC) from Taiwan. RESIN is the first real-life clinical study of this therapy in an Asian cohort. Study objectives were to evaluate the safety and efficacy of 90Y resin microspheres. METHODS: Adults with HCC or mCRC scheduled to receive SIRT with 90Y resin microspheres were included. Primary endpoints were best overall response rate (ORR), adverse events, and changes from baseline in liver function. Secondary efficacy endpoints included overall survival (OS). RESULTS: Of 107 enrolled patients, 83 had HCC, and 24 had mCRC. ORR was 55.41% (HCC) and 33.33% (mCRC). Of 58 HCC patients with 6-month post-SIRT data, 13.79% (n = 8) had resection, transplantation, transarterial chemoembolization, or radiofrequency ablation as the result of down-staging or down-sizing of their lesions. One hundred and ten treatment emergent adverse events (TEAEs) were reported in 51 patients, and five serious adverse events (SAEs) were reported in five patients. The most frequent TEAEs were abdominal pain, nausea and decreased appetite (HCC), and abdominal pain, decreased appetite, fatigue, and vomiting (mCRC). Two deaths due to SAEs (probably related to SIRT) were reported, both in patients with extensive HCC, active hepatitis infection, and other comorbidities. Median OS was 24.07 (HCC) and 12.66 (mCRC) months. CONCLUSIONS: Safety and efficacy outcomes with the routine use of SIRT with 90Y resin microspheres in Taiwan are consistent with published data.

Utility of Early Posttreatment PET/CT Evaluation Using FDG or 18F-FCH to Predict Response to 90Y Radioembolization in Patients With Hepatocellular Carcinoma.

BACKGROUND. Assessment of hepatocellular carcinoma (HCC) treatment response after transarterial radioembolization (TARE) is challenging, because response by conventional imaging criteria may not become apparent until 6 months after treatment. Though HCC exhibits variable avidity for FDG, some cases of HCC without avidity for FDG show avidity for 18F-fluorocholine (18F-FCH). OBJECTIVE. The purpose of this study was to evaluate the utility of early posttreatment evaluation by PET/CT using FDG or 18F-FCH to predict 6-month treatment response and survival after TARE in patients with HCC. METHODS. This retrospective study included 37 patients (mean age, 67 years; 34 men, three women) with documented HCC treated by TARE who underwent both pre-treatment FDG PET/CT and 18F-FCH PET/CT and early FDG PET/CT and/or 18F-FCH PET/CT 4-8 weeks after treatment; FDG PET/CT and 18F-FCH PET/CT examinations were performed on separate dates. Only one of 73 initially identified potentially eligible patients was excluded because of lack of HCC avidity for both FDG and 18F-FCH. Response assessment by modified RECIST (mRECIST) on multiphase CT or MRI was performed at 1 month and 6 months in 23 patients. Early responses seen on PET/CT and 1-month mRECIST response were assessed as predictors of 6-month mRECIST response. Univariable and multivariable predictors of overall survival (OS) were identified. RESULTS. On pretreatment PET/CT, 28 (76%) patients were FDG-positive (showed visual uptake on FDG PET/CT and tumor-to-normal liver ratio > 1.15), 15 (41%) were FCH-positive (showed visual uptake on 18F-FCH PET/CT), and six (16%) were both FDG-positive and FCH-positive. Twelve of 28 FDG-positive HCCs exhibited early response by FDG PET/CT; seven of 15 FCH-positive HCCs exhibited early response by 18F-FCH PET/CT. Twelve (52%) patients exhibited 6-month mRECIST response. Response seen on early posttreatment PET/CT exhibited 100% (12/12) sensitivity and 100% (11/11) specificity for 6-month mRECIST response, whereas 1-month mRECIST response exhibited 67% (8/12) sensitivity and 100% (11/11) specificity for 6-month mRECIST response. Response seen on early posttreatment PET/CT was a significant independent predictor of OS on univariable (hazard ratio [HR], 0.4; 95% CI, 0.2-0.9; p = .03) and multivariable (HR, 0.2; 95% CI, 0.1-0.8; p = .01) analyses. CONCLUSION. Early evaluation after TARE by PET/CT using FDG or 18F-FCH may pre dict 6-month response and OS in patients with HCC. CLINICAL IMPACT. Early posttreatment evaluation with PET/CT could help more reliably identify true nonresponders after TARE, which in turn could prompt early response-adapted therapeutic management.

Locoregional Liver-Directed Therapies to Treat Unresectable Colorectal Liver Metastases: A Review

An estimated 70% of patients with colorectal cancer will develop liver metastases during the course of their disease. While the first-line treatment for hepatic metastases is resection, most patients with colorectal liver-only or liver-dominant metastases (CRLM) present with unresectable disease and are not surgical candidates. In the past decade, locoregional liver-directed therapies have demonstrated safety and efficacy in the treatment of patients with unresectable CRLM and chemotherapy-refractory disease. These treatments can be used to attempt conversion to surgical resectability, can control local disease progression, and have the potential to prolong survival. However, they have not yet become the standard of care in many practices. Each treatment has unique risks, and the clinical data are heterogeneous and thus difficult to interpret. In this article, we will review the most recent, high-impact literature on 3 common locoregional therapies used in the treatment of patients with unresectable CRLM: hepatic artery infusion pump chemotherapy, stereotactic body radiation therapy, and selective internal radiation therapy with yttrium-90 embolization. Ultimately, for this patient population, clinical decision-making requires a multidisciplinary discussion which should take into account individual patient characteristics and clinical expertise available at the treatment facility.

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.

Efficacy and safety of peptide receptor radionuclide therapy in advanced radioiodine-refractory differentiated thyroid cancer and metastatic medullary thyroid cancer: a systematic review.

BACKGROUND: It has been shown that a subgroup of patients with differentiated thyroid cancer (DTC) and medullary thyroid carcinoma (MTC) would progress to advanced stages of thyroid cancer. Therefore, the present study was done to systematically review available evidence in order to investigate efficacy and safety of peptide receptor radionuclide therapy (PRRT) in the patients with advanced radioiodine refractory differentiated thyroid cancer (RR-DTC) and metastatic MTC. METHODS: For this purpose, relevant studies investigated safety and efficacy of PRRT in the patients with advanced RR-DTC and metastatic MTC were identified by searching Medline (Pubmed, Ovid, and Ebsco), Scopus, Embase, Web of Science, and Cochrane Library databases (from database inception to March 24, 2021). The review was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. Searching was done independently by two investigators. Two researchers independently extracted the data and any disagreement was adjudicated by consensus. Quality of the studies was assessed using the tool of case reports/series in systematic reviews. RESULTS: Among 2284 related papers, 41 papers met the inclusion criteria. A total of 157 patients with RR-DTC were treated with PPRT. Biochemical and objective responses (partial and complete) were observed in 25.3 and 10.5% of patients, respectively. Among 220 patients with metastatic MTC, biochemical and objective responses were observed in 37.2 and 10.6% of the patients, respectively. Forty-six deaths were reported in 95 patients with advanced RR-DTC. In addition, 63 deaths were observed in 144 patients with metastatic MTC. Major side effects were reported in 124 patients treated with 90Y -based agent. In the patients treated with 177Lu-DOTA-TATE and 111In-Octreotide, mild and transient hematologic or renal complications were reported. CONCLUSION: Findings of the study revealed that in the absence of the established treatment for the patients with RR-DTC and metastatic MTC, PRRT could be effective with few adverse events. TRIAL REGISTRATION: PROSPERO registration number: CRD42019125245 .

Correlation and Agreement of Yttrium-90 Positron Emission Tomography/Computed Tomography with Ex Vivo Radioembolization Microsphere Deposition in the Rabbit VX2 Liver Tumor Model.

PURPOSE: To demonstrate a stronger correlation and agreement of yttrium-90 (90Y) positron emission tomography (PET)/computed tomography (CT) measurements with explant liver tumor dosing compared with the standard model (SM) for radioembolization. MATERIALS AND METHODS: Hepatic VX2 tumors were implanted into New Zealand white rabbits, with growth confirmed by 7 T magnetic resonance imaging. Seventeen VX2 rabbits provided 33 analyzed tumors. Treatment volumes were calculated from manually drawn volumes of interest (VOI) with three-dimensional surface renderings. Radioembolization was performed with glass 90Y microspheres. PET/CT imaging was completed with scatter and attenuation correction. Three-dimensional ellipsoid VOI were drawn to encompass tumors on fused images. Tumors and livers were then explanted for inductively coupled plasma (ICP)-optical emission spectroscopy (OES) analysis of microsphere content. 90Y PET/CT and SM measurements were compared with reference standard ICP-OES measurements of tumor dosing with Pearson correlation and Bland-Altman analyses for agreement testing with and without adjustment for tumor necrosis. RESULTS: The median infused activity was 33.3 MBq (range, 5.9-152.9). Tumor dose was significantly correlated with 90Y PET/CT measurements (r = 0.903, P < .001) and SM estimates (r = 0.607, P < .001). Bland-Altman analyses showed that the SM tended to underestimate the tumor dosing by a mean of -8.5 Gy (CI, -26.3-9.3), and the degree of underestimation increased to a mean of -18.3 Gy (CI, -38.5-1.9) after the adjustment for tumor necrosis. CONCLUSIONS: 90Y PET/CT estimates were strongly correlated and had better agreement with reference measurements of tumor dosing than SM estimates.

Pathologic Response of Hepatocellular Carcinoma Treated with Yttrium-90 Glass Microsphere Radiation Segmentectomy Prior to Liver Transplantation: A Validation Study.

PURPOSE: To evaluate the pathologic outcomes of hepatocellular carcinoma (HCC) treated with Yttrium-90 radiation segmentectomy using glass microspheres prior to liver transplantation and explore parameters associated with pathologic necrosis. MATERIALS AND METHODS: A single-institution retrospective analysis of HCC patients who received radiation segmentectomy prior to liver transplantation from November 2016 to May 2020 was performed. Patients were included if the treatment angiosome encompassed the entire tumor and could be correlated with available gross pathology. Archived histology slides were reviewed for percentage of pathologic necrosis. Thirty-three patients with 37 tumors were evaluated. The median tumor size was 2.3 cm (range, 1-6.7 cm). RESULTS: All tumors received a single treatment. The median time from radiation segmentectomy to transplantation was 206 days (range, 58-550 days). Objective response per Modified Response Evaluation Criteria in Solid Tumors (mRECIST) was 92% (complete response, 76%; partial response, 16%). A total of 68% (n = 25) of tumors demonstrated ≥99% pathologic necrosis. Complete pathologic necrosis was present in 53% and 75% of tumors treated with >190 Gy (n = 18) and >500 Gy (n = 8) single-compartment Medical Internal Radiation Dose, respectively. Complete response per mRECIST, posttreatment angiosome T1 hypointensity, dose >190 Gy, microsphere specific activity >297 Bq, and a longer time between treatment and transplant were associated with ≥99% tumor necrosis (P < .05). No posttransplant tumor recurrences occurred within a median follow-up of 604 days (range, 138-1,223 days). CONCLUSIONS: Radiation segmentectomy can serve as an ablative modality for the treatment of HCC prior to liver transplant.

Induction of Contralateral Hepatic Hypertrophy by Unilobar Yttrium-90 Transarterial Radioembolization versus Portal Vein Embolization: An Animal Study.

PURPOSE: To compare hepatic hypertrophy in the contralateral lobe achieved by unilobar transarterial radioembolization (TARE) versus portal vein embolization (PVE) in a swine model. METHODS: After an escalation study to determine the optimum dose to achieve hypertrophy after unilobar TARE in 4 animals, 16 pigs were treated by TARE (yttrium-90 resin microspheres) or PVE (lipiodol/n-butyl cyanoacrylate). Liver volume was calculated based on CT before treatment and during 6 months of follow-up. Independent t-test (P < .05) was used to compare hypertrophy. The relationship between hypertrophy after TARE and absorbed dose was calculated using the Pearson correlation. RESULTS: At 2 and 4 weeks after treatment, a significantly higher degree of future liver remnant hypertrophy was observed in the PVE group versus the TARE group, with a median volume gain of 31% (interquartile range [IQR]: 16%-66%) for PVE versus 23% (IQR: 6%-36%) for TARE after 2 weeks and 51% (IQR: 47%-69%) for PVE versus 29% (IQR: 20%-50%) for TARE after 4 weeks. After 3 and 6 months, hypertrophy converged without a statistically significant difference, with a volume gain of 103% (IQR: 86%-119%) for PVE versus 82% (IQR: 70%-96%) for TARE after 3 months and 115% (IQR: 70%-46%) for PVE versus 86% (IQR: 58%-111%) for TARE after 6 months. A strong correlation was observed between radiation dose (median 162 Gy, IQR: 139-175) and hypertrophy. CONCLUSIONS: PVE resulted in rapid hypertrophy within 1 month of the procedure, followed by a plateau, whereas TARE resulted in comparable hypertrophy by 3-6 months. TARE-induced hypertrophy correlated with radiation absorbed dose.

Tumor-to-Normal Ratio Relationship between Planning Technetium-99 Macroaggregated Albumin and Posttherapy Yttrium-90 Bremsstrahlung SPECT/CT.

PURPOSE: To quantify the relationship of the tumor-to-normal ratio (TNR) attained from the technetium-99m macroaggregated albumin (MAA) and posttreatment yttrium-90 bremsstrahlung (Y90-Brem) single-photon emission computerized tomography (SPECT)/computer tomography (CT) studies in patients with hepatocellular carcinoma (HCC) treated with glass microspheres. MATERIALS AND METHODS: Retrospectively, a total of 190 consecutive patients with HCC who underwent 204 MAA and Y90-Brem SPECT/CT for glass microsphere Y90 radiation segmentectomy (Y90-RS) or lobar treatment (Y90-RLT) between 2013 and 2018 were included. Semi-automated regions-of-interests were drawn around the targeted tumor and nontumoral liver tissue on the SPECT/CT studies. TNR values from MAA and Y90-Brem SPECT/CT were compared using paired t-tests, Pearson correlation, and median with interquartile ranges (IQR). RESULTS: The mean TNR for MAA and Y90-Brem SPECT/CT was 2.96 ± 1.86 (median, 2.64; IQR, 2.50) and 2.29 ± 1.10 (median, 2.06; IQR, 1.05), respectively (P < .0001). The mean Y90-RLT TNR was 2.88 ± 1.67 (median, 2.59; IQR, 0.83) and 2.17 ± 0.89 (median, 1.98; IQR, 0.81) for MAA and Y90-Brem SPECT/CT, respectively (P < .0001). The mean Y90-RS TNR was 3.02 ± 2.01 (median, 2.87; IQR, 3.01) and 2.39 ± 1.25 (median, 2.11; IQR, 1.28) for MAA and Y90-Brem SPECT/CT, respectively (P = .0003). TNR attained from MAA and Y90 SPECT/CT studies showed a moderate correlation in a positive linear fashion for the overall (r = 0.54; P < .001), Y90-RLT (r = 0.66, P < .001), and Y90-RS cohorts (r = 0.48, P < .001). CONCLUSIONS: The TNR attained from Y90-Brem SPECT/CT is often underestimated, positively correlated, and less variable than that attained from MAA SPECT/CT.

Safety and Efficacy of Segmental Yttrium-90 Radioembolization for Hepatocellular Carcinoma after Transjugular Intrahepatic Portosystemic Shunt Creation.

PURPOSE: To evaluate safety and efficacy of segmental yttrium-90 (Y90) radioembolization for hepatocellular carcinoma (HCC) after transjugular intrahepatic portosystemic shunt (TIPS) placement. The hypothesis was liver sparing segmental Y90 for HCC after TIPS would provide high antitumor response with a tolerable safety profile. MATERIALS AND METHODS: This single-arm retrospective study included 39 patients (16 women, 23 men) with ages 49-81 years old who were treated with Y90. Child-Pugh A/B liver dysfunction was present in 72% (28/39) with a median Model for End-stage Liver Disease score of 18 (95% confidence interval, 16.4-19.4). Primary outcomes were clinical and biochemical toxicities and antitumor imaging response by World Health Organization (WHO) and European Association for the Study of the Liver (EASL) criteria. Secondary outcomes were orthotopic liver transplantation (OLT), time to progression (TTP), and overall survival (OS) estimates by the Kaplan-Meier method. RESULTS: The 30-day mortality was 0%. Grade 3+ clinical adverse events and grade 3+ hyperbilirubinemia occurred in 5% (2/39) and 0% (0/39), respectively. Imaging response was achieved in 58% (22/38, WHO criteria) and 74% (28/38, EASL criteria), respectively. Median TTP was 16.1 months for any cause and 27.5 months for primary index lesions. OLT was completed in 88% (21/24) of listed patients at a median time of 6.1 months (range, 0.9-11.7 months). Median OS was 31.6 months and 62.9 months censored and uncensored to OLT, respectively. CONCLUSIONS: Segmental Y90 for HCC appears safe and efficacious in patients after TIPS. Preserved transplant eligibility suggests that Y90 is a useful tool for bridging these patients to liver transplantation.

Transarterial Radioembolization with Yttrium-90 Glass Microspheres: Distribution of Residual Activity and Flow Dynamics during Administration.

PURPOSE: To evaluate the microsphere flow dynamics and residual yttrium-90 (90Y) activity during and after transarterial radioembolization with glass microspheres and to assess the distribution and predilection sites of residual activity in the administration devices. MATERIALS AND METHODS: In this laboratory investigation, after 18 consecutive clinical transarterial radioembolization and 4 ex vivo experimental procedures with 90Y glass microspheres, the distribution of residual activity in the administration devices was assessed by activimeter and positron emission tomography (PET)/CT measurements. During ex vivo procedures, microsphere outflow from the administration device was assessed by dynamic scintigraphic measurements. RESULTS: Mean residual activity was 3.4% ± 1.7 (range, 0.9%-8.8%). Calculations showed a negative correlation between relative residual activity and prescribed activity (r = -0.4258, P = .0486) and a positive correlation between absolute residual activity and prescribed activity (r = 0.5345, P = .0104). The main predilection site was the Luer-Lok microcatheter connector. Lower activities were detected in the dose vial. Flow measurements showed that more than 98% of the final injected activity was transferred to the patient with the first 20 mL of saline solution. CONCLUSIONS: Residual activity in the standard administration device for glass microsphere radioembolization is considered to be low compared with similar procedures, but is variable. The microsphere flow profile shows an initial peak, resulting in a rapid activity transfer at the beginning of the injection process. The findings may have implications for safe handling of the administration device and for dose calculation of 90Y glass microspheres.

Quality of Life after Radioembolization for Hepatocellular Carcinoma Using a Digital Patient-Reported Outcome Tool.

Health-related quality of life (HRQoL) measurements are important for patient care, and emerging bundles in value-based care are placing an increasing emphasis on tying reimbursement to patient surveys. A multicenter pilot study was carried out to assess the efficacy of an automated digital patient engagement (DPE) platform for collecting HRQoL measurements at baseline and at 2- to 4-week intervals through 90 days after transarterial radioembolization (TARE) with yttrium-90 (90Y) treatments for hepatocellular carcinoma (HCC). The results revealed a survey completion of 78.4% and demonstrated only 4 of 35 individual symptom instances across all time points of transient worsening relative to baseline. Most importantly, the DPE platform provided an effective means for deploying and collecting patient-reported outcome measures.

Prospective Study of Systemic Yttrium-90 Elution during Radioembolization of Hepatic Metastases.

PURPOSE: To evaluate total blood radioactivity (BR) after SIR-Spheres yttrium-90 (90Y) radioembolization and differences in BR based on delivery method. MATERIALS AND METHODS: Twenty participants with hepatic metastases undergoing first radioembolization were prospectively enrolled from December 2017 to June 2018. Blood samples were drawn at baseline and 0, 10, 20, 60, and 120 minutes after 90Y administration. BR was measured with a γ-counter and scaled by estimated blood volume. Percentage of instilled radioactivity in the bloodstream was calculated as area under the fitted curve, and differences between delivery methods were examined with nonparametric statistical tests. RESULTS: In 10 participants, resin microspheres were instilled with 50% Isovue 300 diluted in saline solution in the D line, and 10 others were treated with dextrose 5% in water (D5W) in the D line. Median administered activities were 944 MBq (range, 746-1,993 MBq) and 1,213 MBq (range, 519-2,066 MBq), respectively. Fraction of 90Y in blood was significantly higher with dilute contrast agent than with D5W (median, 0.5% of injected activity vs 0.2%; P = .001). Among all participants, the maximum activity delivered was 2,066 MBq, and a maximum of 1% of administered radioactivity was measured as free 90Y in blood. Assuming these highest-case values and complete decay of all free 90Y in bone, a dose to red marrow of 132.3 mGy was calculated by Organ Level INternal Dose Assessment/EXponential Modeling. CONCLUSIONS: Blood sampling after radioembolization allowed for estimation of the time-activity curve and BR. Delivery with 50% contrast agent in saline solution resulted in a significant increase in BR vs D5W, even though the total BR for both groups was nominal.