The role of biomarkers and dosimetry parameters in overall and progression free survival prediction for patients treated with personalized 90Y glass microspheres SIRT: a preliminary machine learning study.

BACKGROUND: Overall Survival (OS) and Progression-Free Survival (PFS) analyses are crucial metrics for evaluating the efficacy and impact of treatment. This study evaluated the role of clinical biomarkers and dosimetry parameters on survival outcomes of patients undergoing 90Y selective internal radiation therapy (SIRT). MATERIALS/METHODS: This preliminary and retrospective analysis included 17 patients with hepatocellular carcinoma (HCC) treated with 90Y SIRT. The patients underwent personalized treatment planning and voxel-wise dosimetry. After the procedure, the OS and PFS were evaluated. Three structures were delineated including tumoral liver (TL), normal perfused liver (NPL), and whole normal liver (WNL). 289 dose-volume constraints (DVCs) were extracted from dose-volume histograms of physical and biological effective dose (BED) maps calculated on 99mTc-MAA and 90Y SPECT/CT images. Subsequently, the DVCs and 16 clinical biomarkers were used as features for univariate and multivariate analysis. Cox proportional hazard ratio (HR) was employed for univariate analysis. HR and the concordance index (C-Index) were calculated for each feature. Using eight different strategies, a cross-combination of various models and feature selection (FS) methods was applied for multivariate analysis. The performance of each model was assessed using an averaged C-Index on a three-fold nested cross-validation framework. The Kaplan-Meier (KM) curve was employed for univariate and machine learning (ML) model performance assessment. RESULTS: The median OS was 11 months [95% CI: 8.5, 13.09], whereas the PFS was seven months [95% CI: 5.6, 10.98]. Univariate analysis demonstrated the presence of Ascites (HR: 9.2[1.8,47]) and the aim of SIRT (segmentectomy, lobectomy, palliative) (HR: 0.066 [0.0057, 0.78]), Aspartate aminotransferase (AST) level (HR:0.1 [0.012-0.86]), and MAA-Dose-V205(%)-TL (HR:8.5[1,72]) as predictors for OS. 90Y-derived parameters were associated with PFS but not with OS. MAA-Dose-V205(%)-WNL, MAA-BED-V400(%)-WNL with (HR:13 [1.5-120]) and 90Y-Dose-mean-TL, 90Y-D50-TL-Gy, 90Y-Dose-V205(%)-TL, 90Y-Dose- D50-TL-Gy, and 90Y-BED-V400(%)-TL (HR:15 [1.8-120]) were highly associated with PFS among dosimetry parameters. The highest C-index observed in multivariate analysis using ML was 0.94 ± 0.13 obtained from Variable Hunting-variable-importance (VH.VIMP) FS and Cox Proportional Hazard model predicting OS, using clinical features. However, the combination of VH. VIMP FS method with a Generalized Linear Model Network model predicting OS using Therapy strategy features outperformed the other models in terms of both C-index and stratification of KM curves (C-Index: 0.93 ± 0.14 and log-rank p-value of 0.023 for KM curve stratification). CONCLUSION: This preliminary study confirmed the role played by baseline clinical biomarkers and dosimetry parameters in predicting the treatment outcome, paving the way for the establishment of a dose-effect relationship. In addition, the feasibility of using ML along with these features was demonstrated as a helpful tool in the clinical management of patients, both prior to and following 90Y-SIRT.

Evaluation of a prototype metal artifact reduction algorithm for cone beam CT in patients undergoing radioembolization.

Metal artifacts notoriously pose significant challenge in computed tomography (CT), leading to inaccuracies in image formation and interpretation. Artifact reduction tools have been designed to improve cone beam computed tomography (CBCT) image quality by reducing artifacts caused by certain high-density materials. Metal artifact reduction (MAR) tools are specific algorithms that are applied during image reconstruction to minimize or eliminate artifacts degrading CBCT images. The purpose of the study is to evaluate the effect of a MAR algorithm on image quality in CBCT performed for evaluating patients before transarterial radioembolization (TARE). We retrospectively included 40 consecutive patients (aged 65 ± 13 years; 23 males) who underwent 45 CBCT examinations (Allura FD 20, XperCT Roll protocol, Philips Healthcare, Best, The Netherlands) in the setting of evaluation for TARE between January 2017 and December 2018. Artifacts caused by coils, catheters, and surgical clips were scored subjectively by four readers on a 5-point scale (1 = artifacts affecting diagnostic information to 5 = no artifacts) using a side-by-side display of uncorrected and MAR-corrected images. In addition, readers scored tumor visibility and vessel discrimination. MAR-corrected images were assigned higher scores, indicating better image quality. The differences between the measurements with and without MAR were most impressive for coils with a mean improvement of 1.6 points (95%CI [1.5 1.8]) on the 5-point likert scale, followed by catheters 1.4 points (95%CI [1.3 1.5]) and clips 0.7 points (95%CI [0.3 1.1]). Improvements for other artifact sources were consistent but relatively small (below 0.25 points on average). Interrater agreement was good to perfect (Kendall's W coefficient = 0.68-0.95) and was higher for MAR-corrected images, indicating that MAR improves diagnostic accuracy. A metal artifact reduction algorithm can improve diagnostic and interventional accuracy of cone beam CT in patients undergoing radioembolization by reducing artifacts caused by diagnostic catheters and coils, lowering interference of metal artifacts with adjacent major structures, and improving tumor visibility.

Transcatheter pseudo-vascular isolation for localization and concentration of a large molecule theranostic probe into a transgenic OncoPIG kidney tumor.

INTRODUCTION: Great strides have been made identifying molecular and genetic changes expressed by various tumor types. These molecular and genetic changes are used as pharmacologic targets for precision treatment using large molecule (LM) proteins with high specificity. Theranostics exploits these LM biomolecules via radiochemistry, creating sensitive diagnostic and therapeutic agents. Intravenous (i.v.) LM drugs have an extended biopharmaceutical half-life thus resulting in an insufficient therapeutic index, permitting only palliative brachytherapy due to unacceptably high rates of systemic nontarget radiation doses to normal tissue. We employ tumor arteriole embolization isolating a tumor from the systemic circulation, and local intra-arterial (i.a.) infusion to improve uptake of a LM drug within a porcine renal tumor (RT). METHODS: In an oncopig RT we assess the in vivo biodistribution of 99mTc-labeled macroaggregated albumin (MAA) a surrogate for a LM theranostics agent in the RT, kidney, liver, spleen, muscle, blood, and urine. Control animals underwent i.v. infusion and experimental group undergoing arteriography with pseudovascular isolation (PVI) followed by direct i.a. injection. RESULTS: Injected dose per gram (%ID/g) of the LM at 1 min was 86.75 ± 3.76 and remained elevated up to 120 min (89.35 ± 5.77) with i.a. PVI, this increase was statistically significant (SS) compared to i.v. (13.38 ± 1.56 and 12.02 ± 1.05; p = 0.0003 p = 0.0006 at 1 and 120 min respectively). The circulating distribution of LM in the blood was less with i.a. vs i.v. infusion (2.28 ± 0.31 vs 25.17 ± 1.84 for i.v. p = 0.033 at 1 min). Other organs displayed a trend towards less exposure to radiation for i.a. with PVI compared to i.v. which was not SS. CONCLUSION: PVI followed by i.a. infusion of a LM drug has the potential to significantly increase the first pass uptake within a tumor. This minimally invasive technique can be translated into clinical practice, potentially rendering monoclonal antibody based radioimmunotherapy a viable treatment for renal tumors.

Optimal patient selection for yttrium-90 glass plus chemotherapy in the treatment of colorectal liver metastases: additional quality of life, efficacy, and safety analyses from the EPOCH study.

BACKGROUND: Evaluating transarterial radioembolization (TARE) in patients with metastatic colorectal carcinoma of the liver who have progressed on first-line chemotherapy (EPOCH) demonstrated superior outcomes using yttrium-90 glass microspheres plus chemotherapy (TARE/Chemo) vs chemotherapy (Chemo) to treat colorectal liver metastases. Additional exploratory analyses were undertaken to assess the impact of TARE/Chemo on efficacy, safety, time to subsequent therapy, time to deterioration in quality of life (QoL), and identify criteria for improved patient selection. METHODS: Time to deterioration in QoL was analyzed for the primary study population. Subsequently, a post hoc analysis was undertaken to identify subgroups for which time to deterioration in QoL was improved with TARE/Chemo vs Chemo. Progression-free survival (PFS), hepatic (h)PFS, time to subsequent therapy, and safety outcomes were compared between treatments. RESULTS: The primary population showed no significant difference in time to deterioration in QoL between treatment arms; however, significance was seen in 2 identified subgroups, namely: Subgroup A (N = 303) which excluded patients with both Eastern Cooperative Oncology Group (ECOG) 1 and baseline CEA ≥ 35 ng/mL from both treatment arms; subgroup B (N = 168) additionally excluded patients with KRAS (Kirsten rat sarcoma) mutation. In subgroup A, TARE/Chemo patients (N = 143) demonstrated superior outcomes vs Chemo (N = 160): PFS (9.4 vs. 7.6 months, hazard ratio (HR): 0.64; 1-sided P = .0020), hPFS (10.8 vs. 7.6 months, HR: 0.53; 1-sided P < .0001), time to deterioration in QoL (5.7 vs. 3.9 months, HR: 0.65; 1-sided P = .0063), and time to subsequent therapy (21.2 vs. 10.5 months, HR: 0.52; 1-sided P < .0001). Subgroup B patients showed similar but larger significant differences between treatment arms. Median PFS, hPFS, and time to deterioration in QoL were numerically greater for TARE/Chemo in both subgroups vs the primary population, with the greatest magnitude of difference in subgroup B. Both subgroups exhibited higher percentage of CEA responders and improved ORR with TARE/Chemo vs chemo alone. Safety (reported as event rate/100 patient-years) was higher with Chemo in all populations. Additional efficacy analyses in the primary population are also reported. CONCLUSIONS: Careful patient selection, including consideration of the prognostic factors ECOG, baseline CEA, and KRAS status, sets outcome expectations in patients with colorectal liver metastases suitable for TARE/Chemo as second-line treatment (Trial Registry Number: NCT01483027).

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.

Outcomes Analysis of 90Y Radioembolization for Tumors Other Than Metastatic Colorectal Cancer from the RESiN (Radiation-Emitting SIR-spheres in Non-resectable liver tumors) Registry.

PURPOSE: To characterize the response and survival outcomes of yttrium-90 transarterial radioembolization (90Y-TARE) for unresectable, liver-dominant metastases from primary neoplasms other than colorectal carcinoma. MATERIALS AND METHODS: This study included 1474 patients enrolled in the RESiN registry who received resin 90Y-TARE as part of their oncologic management for unresectable primary or secondary liver tumors (NCT02685631). 33% (481/1474) were treated for liver metastases of non-colorectal origin (m-nonCRC), compared to 34% (497/1474) treated for colorectal liver metastases (mCRC) and 34% (496/1474) treated for hepatocellular carcinoma (HCC). Treatment response and cancer survival probabilities were computed and compared for each primary cancer type. The Kaplan-Meier method and log-rank test were used to compare survival outcomes. RESULTS: Radiological responses were observed in 12 unique cancer types, mostly heavily pre-treated malignancies refractory to multiple lines of systemic therapies. The overall use of resin 90Y-TARE in m-nonCRC resulted in better treatment outcomes in terms of duration of response, progression free survival, time to progression and overall survival (P = 0.04, P = 0.02, P = 0.01, P = 0.04). Analyses of cancer cell types revealed that metastatic neuroendocrine tumor, sarcoma, and ovarian, renal, prostate, and breast cancers were associated with superior treatment outcomes, whereas worse treatment outcomes were observed in metastatic lung, gastric, pancreatic and esophageal cancers. CONCLUSION: Real-world data demonstrate the use of resin 90Y-TARE in m-nonCRC refractory to standard chemotherapy. For some cell types, this expanded use achieved superior treatment outcomes relative to the reference standard of mCRC, suggesting the need for inquiry into broadened indications for 90Y-TARE.

Clinical Results of Holmium-166 Radioembolization with Personalized Dosimetry for the Treatment of Hepatocellular Carcinoma.

Transarterial radioembolization (TARE) with 166Ho-loaded microspheres is an established locoregional treatment for hepatocellular carcinoma (HCC), introduced in 2010. This study evaluates the clinical outcome of patients with HCC who underwent 166Ho-TARE with personalized dosimetry. Twenty-seven patients with 36 TARE procedures were analyzed. Treatment planning, execution, and evaluation was possible without complications in all cases. At the 3-month follow-up, disease control in the treated liver was achieved in 81.8% of patients (complete remission, partial remission, and stable disease in 36.4%, 31.8%, and 13.6%, respectively). The median overall survival (OS) was 17.2 months, and progression-free survival (PFS) in the treated liver was 11 months. Statistically significant positive correlations were observed between the achieved radiation dose for the tumor and both PFS (r = 0.62, p < 0.05) and OS (r = 0.48, p < 0.05), suggesting a direct dose-response relationship. The calculated achieved dose was 8.25 Gy lower than the planned dose, with relevant variance between planned and achieved doses in individual cases. These results confirm the efficacy of the 166Ho-TARE holmium platform and underscore the potential of voxel-based, personalized dosimetry to improve clinical outcomes.

Immune modulation in untreated, contralateral hepatic metastases after Y90-radioembolization of microsatellite stable (MSS) colorectal cancer.

PURPOSE: To assess immunogenic effects in unembolized contralateral tumor after single lobar Y90-radioembolization (SIRT) of colorectal liver metastases(CRLM). MATERIAL AND METHODS: The analysis comprised 10 patients with microsatellite stable (MSS) CRLM scheduled for staged treatment in the prospective BLINDED trial. Eligibility criteria included bilobar metastatic disease with >5 lesions without any treatment within 3 weeks. Baseline biopsy was followed by initial SIRT treatment of one liver lobe, followed by a second biopsy of yet untreated tumors in the other liver lobe at a median of 13 (4-49) days immediately prior to second treatment. Tumor biopsies and peripheral blood mononuclear cells (PBMC) were collected before treatments for immune cell analysis. Patients were stratified into "responders" and "non-responders" based on tumor control or progression during follow up. RESULTS: At baseline, responders (n=4) displayed lower concentrations of FoxP3+ cells and co-location of CD4+FoxP3+ cells than non-responders (both p=0.02) in tumor tissues. At second biopsy, non-responders showed a higher CD68+ macrophage density (p=0.0014) than responders. Responders displayed fewer CD4+FoxP3+ T cells than CD8+ T cells at all timepoints (p=0.02 and p=0.0428). Non-responders demonstrated a trending increase of CD68+ macrophages (p=0.062), as well as a higher CD8+PD1+/CD8+ ratio (p=0.062). PBMC of non-responders displayed lower CD8+PD1+ T cells and CD8+PD1+/CD8+ ratio at both timepoints. CONCLUSION: SIRT induces local immunogenic effects in non-exposed MCC CRLM, as well as systemic exhaustion of immune cells in non-responders. Clinical implications such as a prognostic role or synergism of SIRT and checkpoint inhibition in MSS CRLM warrant further investigation.

Thymic Carcinoma Presenting as a Mediastinal Mass Resembling a Cardiac Tumor.

Thymoma and thymic carcinomas are a few of the rarest malignancies seen in humankind. They are mostly seen in the Asian population, many of which are reported in the Southeast Asia region like Japan, China, Vietnam, etc. They usually can be a sequela of other underlying conditions such as myasthenia gravis or some unknown mutations that express later in life.   Our patient is a young 41-year-male, a healthy and active individual who presented for evaluation of acute shortness of breath, two months after recovering from SARS-CoV-19 infection. His shortness of breath progressed while on oxygen and diuretics, a Point of Care Ultrasound (POCUS) showed cardiac tamponade and moderate pleural effusion. A Computerized Tomographic (CT) scan of the chest/abdomen/pelvis showed cardiomegaly, pleural effusion, and a mass abutting the heart. A pericardiocentesis revealed malignant cells. Thymic carcinoma was confirmed with a core biopsy and the patient was initiated on treatment rapidly to help improve symptoms and contain the growing mass.  .

Implications of lung shunt fraction calculation discrepancy in Yttrium-90 radioembolization treatment from 2D planar vs 3D single photon emission CT imaging.

The safety and efficacy of Yttrium-90 (Y-90) radio-embolization therapy is partly dependent on the lung shunt fraction (LSF). There may be a notable disparity between LSF when calculated using 2D planar imaging vs 3D single photon emission CT (SPECT); this can affect the total allowable Y-90 dose delivered and therefore change the effectiveness of the procedure. The case presented demonstrates an 81% decrease in LSF when calculated by SPECT as compared to 2D planar imaging. This case highlights the importance of considering the imaging technique and the potential discrepancies that can arise between planar and SPECT imaging in LSF assessment.

Y-90 PET/MR imaging optimization with a Bayesian penalized likelihood reconstruction algorithm.

Positron Emission Tomography (PET) imaging after 90 Y liver radioembolization is used for both lesion identification and dosimetry. Bayesian penalized likelihood (BPL) reconstruction algorithms are an alternative to ordered subset expectation maximization (OSEM) with improved image quality and lesion detectability. The investigation of optimal parameters for 90 Y image reconstruction of Q.Clear, a commercial BPL algorithm developed by General Electric (GE), in PET/MR is a field of interest and the subject of this study. The NEMA phantom was filled at an 8:1 sphere-to-background ratio. Acquisitions were performed on a PET/MR scanner for clinically relevant activities between 0.7 and 3.3 MBq/ml. Reconstructions with Q.Clear were performed varying the ß penalty parameter between 20 and 6000, the acquisition time between 5 and 20 min and pixel size between 1.56 and 4.69 mm. OSEM reconstructions of 28 subsets with 2 and 4 iterations with and without Time-of-Flight (TOF) were compared to Q.Clear with ß = 4000. Recovery coefficients (RC), their coefficient of variation (COV), background variability (BV), contrast-to-noise ratio (CNR) and residual activity in the cold insert were evaluated. Increasing ß parameter lowered RC, COV and BV, while CNR was maximized at ß = 4000; further increase resulted in oversmoothing. For quantification purposes, ß = 1000-2000 could be more appropriate. Longer acquisition times resulted in larger CNR due to reduced image noise. Q.Clear reconstructions led to higher CNR than OSEM. A ß of 4000 was obtained for optimal image quality, although lower values could be considered for quantification purposes. An optimal acquisition time of 15 min was proposed considering its clinical use.

Diagnosis and management of radiation cholecystitis as a complication of Y90 radioembolization for hepatocellular carcinoma.

Radiation induced cholecystitis is a known but rare complication of Yttrium90 (Y90) radioembolization of hepatic tumors due to nontarget embolization. Many documented cases of radiation induced cholecystitis have been treated with cholecystectomy, which is significant given the typical patient population undergoing radioembolization tends to be of higher surgical risk. Here, we present a case of a 68 year old male who developed radiation induced cholecystitis status post hepatic radioembolization that resolved with conservative management alone. This case highlights that radiation induced cholecystitis may be successfully and safely treated conservatively.

Adaptive design of experiments to fit surrogate Gaussian process regression models allows fast sensitivity analysis of the input waveform for patient-specific 3D CFD models of liver radioembolization.

BACKGROUND AND OBJECTIVE: Patient-specific 3D computational fluid dynamics (CFD) models are increasingly being used to understand and predict transarterial radioembolization procedures used for hepatocellular carcinoma treatment. While sensitivity analyses of these CFD models can help to determine the most impactful input parameters, such analyses are computationally costly. Therefore, we aim to use surrogate modelling to allow relatively cheap sensitivity analysis. As an example, we compute Sobol's sensitivity indices for three input waveform shape parameters. METHODS: We extracted three characteristic shape parameters from our input mass flow rate waveform (peak systolic mass flow rate, heart rate, systolic duration) and defined our 3D input parameter space by varying these parameters within 75 %-125 % of their nominal values. To fit our surrogate model with a minimal number of costly CFD simulations, we developed an adaptive design of experiments (ADOE) algorithm. The ADOE uses 100 Latin hypercube sampled points in 3D input space to define the initial design of experiments (DOE). Subsequently, we re-sample input space with 10,000 Latin Hypercube sampled points and cheaply estimate the outputs using the surrogate model. In each of 27 equivolume bins which divide our input space, we determine the most uncertain prediction of the 10,000 points, compute the true outputs using CFD, and add these points to the DOE. For each ADOE iteration, we calculate Sobol's sensitivity indices, and we continue to add batches of 27 samples to the DOE until the Sobol indices have stabilized. RESULTS: We tested our ADOE algorithm on the Ishigami function and showed that we can reliably obtain Sobol's indices with an absolute error <0.1. Applying ADOE to our waveform sensitivity problem, we found that the first-order sensitivity indices were 0.0550, 0.0191 and 0.407 for the peak systolic mass flow rate, heart rate, and the systolic duration, respectively. CONCLUSIONS: Although the current study was an illustrative case, the ADOE allows reliable sensitivity analysis with a limited number of complex model evaluations, and performs well even when the optimal DOE size is a priori unknown. This enables us to identify the highest-impact input parameters of our model, and other novel, costly models in the future.

Percutaneous liver-directed therapies of intrahepatic cholangiocarcinoma.

Cholangiocarcinoma is a hepatobiliary malignancy which can manifest anywhere along the biliary tree. Intrahepatic cholangiocarcinoma occurs in the liver within or beyond the second order bile ducts. The prognosis for patients with intrahepatic cholangiocarcinoma is poor, even when successfully resected there is a very high rate of local recurrence. The available systemic therapies are currently limited and have high rates of toxicity. Percutaneous and transarterial liver-directed therapies can be used to treat intrahepatic cholangiocarcinoma with results comparable to current standard of care systemic therapies in some circumstances. This manuscript will review these the techniques and efficacy of percutaneous and transarterial liver-directed therapies for intrahepatic cholangiocarcinoma.

Prognostic Value of Liver Biomarkers in Hepatocellular Carcinoma Patients Undergoing Yttrium 90 Transarterial Radioembolization (TARE): A Retrospective Pilot Study.

INTRODUCTION: Hepatocellular carcinoma (HCC) is a common cause of cancer-related death worldwide. The prognosis for HCC depends on the tumor stage, and curative therapies are more accessible in the early stages. However, effective treatments are available even in advanced stages. Transarterial radioembolization (TARE) is an alternative to transarterial chemoembolization (TACE) with reduced risk and extended disease progression time. Identifying prognostic indicators and treatment response biomarkers remains crucial. The purpose of this study was to assess the association between biomarkers related to fibrosis, liver function, and immune inflammation with tumor response to yttrium 90 transarterial radiotherapy (Y90 or TARE) in patients with HCC. METHODS: This study enrolled patients who underwent Y90 radiotherapy for bridging, downstaging, or palliative treatment after discussion in a multidisciplinary tumor board. Using the modified Response Evaluation Criteria in Solid Tumors (mRECIST), tumor response was classified into two groups: "responders" (complete and partial response) and "non-responders" (stable and progressive disease). Logistic regression analysis was used to evaluate the association between predictors, biomarkers such as aspartate aminotransferase (AST)-to-platelet ratio index (APRI), fibrosis-4 (FIB-4), albumin-bilirubin (ALBI) score, model for end-stage liver disease (MELD) score, MELD sodium, and the systemic immune-inflammatory indexes, at established cut-offs and tumor response. RESULTS: Of 35 patients, 22 (63%) were Whites and non-Hispanics, 32 (91%) were diagnosed with cirrhosis, and 14 (40%) of these had a viral etiology. According to mRECIST, 18 (51%) patients were classified as "responders." In multivariable logistic regression analysis, biomarkers associated with tumor response were ALBI score ≤-2.8 (odds ratio (OR) 6.1, 95%CI 2.7-14.4) and the neutrophil-to-lymphocyte ratio (NLR) ≤ 1.92 (OR 5.1, 95%CI 0.8-11.9). Biomarkers had moderate accuracy in predicting tumor response (C-statistic 0.75). CONCLUSION: The ALBI score is a reliable predictor of treatment response following TARE. The NLR index may offer further prognostic information, and both biomarkers can be used in combination; however, further research in larger sample sets is needed.

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.

Dose-Response Relationship in Patients with Liver Metastases from Neuroendocrine Neoplasms Undergoing Radioembolization with 90Y Glass Microspheres.

The benefit of multicompartment dosimetry in the radioembolization of neuroendocrine neoplasms is not firmly established. We retrospectively assessed its potential with patient outcome. Methods: Forty-three patients were eligible. The association of mean absorbed dose (MAD) for tumors and treatment response was tested per lesion with a receiver operating characteristic curve analysis, and the association of MAD with progression-free survival (PFS) and overall survival was tested per patient using uni- and multivariate Cox regression analyses. Results: The area under the curve for treatment response based on MAD was 0.79 (cutoff, 196.6 Gy; P < 0.0001). For global PFS, grade (grade 2 vs. 1: hazard ratio [HR], 2.51; P = 0.042; grade 3 vs. 1: HR, 62.44; P < 0.001), tumor origin (HR, 6.58; P < 0.001), and MAD (HR, 0.998; P = 0.003) were significant. For overall survival, no prognostic parameters were significant. Conclusion: In line with prior publications, a MAD of more than 200 Gy seemed to favor treatment response. MAD was also associated with PFS and may be of interest for radioembolization planning for neuroendocrine neoplasm patients.

Transarterial Radioembolization (TARE) Global Practice Patterns: An International Survey by the Cardiovascular and Interventional Radiology Society of Europe (CIRSE).

PURPOSE: An international survey was conducted by the Cardiovascular Interventional Radiological Society of Europe (CIRSE) to evaluate radioembolization practice and capture opinions on real-world clinical and technical aspects of this therapy. MATERIALS AND METHODS: A survey with 32 multiple choice questions was sent as an email to CIRSE members between November and December 2022. CIRSE group member and sister societies promoted the survey to their local members. The dataset was cleaned of duplicates and entries with missing data, and the resulting anonymized dataset was analysed. Data were presented using descriptive statistics. RESULTS: The survey was completed by 133 sites, from 30 countries, spanning 6 continents. Most responses were from European centres (87/133, 65%), followed by centres from the Americas (22/133, 17%). Responding sites had been performing radioembolization for 10 years on average and had completed a total of 20,140 procedures over the last 5 years. Hepatocellular carcinoma treatments constituted 56% of this total, colorectal liver metastasis 17% and cholangiocarcinoma 14%. New sites had opened every year for the past 20 years, indicating the high demand for this therapy. Results showed a trend towards individualized treatment, with 79% of responders reporting use of personalized dosimetry for treatment planning and 97% reporting routine assessment of microsphere distribution post-treatment. Interventional radiologists played an important role in referrals, being present in the referring multi-disciplinary team in 91% of responding centres. CONCLUSION: This survey provides insight into the current state of radioembolization practice globally. The results reveal the increasing significance placed on dosimetry, evolving interventional techniques and increased technology integration.

Safety and efficacy of Holmium-166 selective internal radiotherapy of primary and secondary liver cancer confirmed by real-world data.

Purpose: Holmium-166 has emerged as a promising option for selective internal radiotherapy (SIRT) for hepatic malignancies, but data on routine clinical use are lacking. The purpose of this study was to describe the safety and effectiveness of Holmium-166 SIRT in real-world practice through retrospective analysis of a multicenter registry. Methods: Retrospective analysis was conducted on Holmium-166 SIRT procedures performed between July 15, 2019, and July 15, 2021, across seven European centers. Treatment planning, treatment realization and post-treatment follow-up were conducted according to routine local practice. Safety and effectiveness data were extracted from the patients' health records. Primary endpoint analysis was assessed for the entire study population with separate analysis for subgroups with hepatocellular carcinoma, metastatic colorectal cancer and intrahepatic cholangiocarcinoma. Results: A total of 167 SIRT procedures in 146 patients (mean age 66 ± 11 years, 68% male) were retrospectively evaluated. Most common tumor entities were hepatocellular carcinoma (n=55), metastatic colorectal cancer (n=35), intrahepatic cholangiocarcinoma (n=19) and metastatic neuroendocrine tumors (n=10). Nine adverse events grade ≥ 3 according to Common Terminology Criteria for Adverse Events were recorded, including one fatal case of radioembolization-induced liver disease. Response rates and median overall survival for the above mentioned subgroups were comparable to results from previous Holmium-166 trials as well as to results from Yttrium-90 registries. Conclusion: This study confirms that the safety and effectiveness of Holmium-166 SIRT derived from prospective trials also applies in routine clinical practice, reinforcing its potential as a viable treatment option for primary and secondary liver cancer.

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

PURPOSE: To Describe 6-Month safety, efficacy and multimodal imageability after imageable glass Yttrium-90 radioembolization for unresectable Hepatocellular Carcinoma (HCC) in a First-in Human Trial METHODS: Eye90 microspheres® (Eye90), an FDA Breakthrough Designated Device, are glass radiopaque Y-90 microspheres visible on CT and SPECT/CT. Six subjects with unresectable HCC underwent selective (≤ 2 segments) Eye90 treatment in a prospective open-label pilot trial. Key inclusion criteria included liver only HCC, ECOG ≤ 1, total lesion length ≤ 9 cm and Child-Pugh A. Prospective partition dosimetry was utilized. Safety, biochemistry, toxicity, adverse events (AE), multimodal imageability on CT and SPECT/CT and 3 and 6-month MRI local modified RECIST (mRECIST) response was evaluated. RESULTS: 6 subjects with HCC (7 lesions) were treated with Eye90 and followed to 180 days. Administration success was 100%. Eye90 CT radiopacity distribution correlated with SPECT/CT. Target lesion complete response was observed in 3 of 6 subjects (50%) and partial response in 2 (33.3%). Two subjects could not be assessed at 180 days. At 180 days, target lesion complete response was maintained in 3 subjects (50%) and partial response in 1 (16.7%). All subjects reported AEs, and 5 reported AEs related to treatment. There were no treatment related serious AEs. CONCLUSIONS: Eye90 was safe and effective in six subjects with unresectable HCC up to 6 months. Eye90 was imageable via CT and SPECT/CT with correlation between CT radiopacity and SPECT/CT radioactivity distribution. Eye90 provided previously unavailable CT based tumor targeting information.