Y90 Radioembolization Dosimetry: Concepts for the Interventional Radiologist

New frontiers in radioembolization

Radioembolization is a locoregional transarterial therapy that combines radionuclide and micron-sized beads to deliver radiation internally to the target tumors based on the arterial blood flow. While initially developed as a palliative treatment option, radioembolization is now used for curative intent treatment, neoadjuvant therapy, and method to downstage or bridge for liver transplant. Radioembolization has become increasingly utilized and is an important therapeutic option for the management of hepatocellular carcinoma and liver metastasis. This article provides an overview of the techniques, challenges, and novel developments in radioembolization, including new dosimetry techniques, radionuclides, and new target tumors.

Using Voxel-Based Dosimetry to Evaluate Sphere Concentration and Tumor Dose in Hepatocellular Carcinoma Treated with Yttrium-90 Radiation Segmentectomy with Glass Microspheres

PURPOSE

To utilize voxel-based dosimetry following radiation segmentectomy (RS) to understand microsphere distribution and validate current literature regarding radiologic and pathologic outcomes.

MATERIALS AND METHODS

A retrospective, single-center analysis of patients with solitary hepatocellular carcinoma (N = 56) treated with yttrium-90 (90Y) RS with glass microspheres (Therasphere; Boston Scientific, Marlborough, Massachusetts) from 2020 to 2022 was performed. Posttreatment voxel-based dosimetry was evaluated using Mirada DBx Build 1.2.0 Simplicit90Y software (Boston Scientific) and utilized to calculate sphere concentration to tumor as well as D70 (minimum dose to 70% total tumor volume), D90, and D99. Time to progression (TTP), treatment response, and adverse events were studied.

RESULTS

Fifty-six solitary tumors were analyzed with a median tumor diameter of 3.4 cm (range, 1.2-6.8 cm) and median tumor absorbed dose of 732 Gy (range, 252-1,776 Gy). Median sphere activity (SA) at the time of delivery was 1,446 Bq (range, 417-2,621 Bq). Median tumor sphere concentration was 12,868 spheres/mL (range, 2,655-37,183 spheres/mL). Sphere concentration into tumor and normal tissue was inversely correlated with perfused treatment volume (R2 = 0.21 and R2 = 0.39, respectively). Of the 51 tumors with posttreatment imaging, objective response was noted in 49 patients (96%) and complete response in 42 patients (82%). The median TTP was not reached with a 2-year progression rate of 11%. Fifteen patients underwent liver transplant. Median tumor necrosis was 99% (range, 80%-100%). Lower tumor volumes and higher D99 were associated with complete pathologic necrosis (P < .001 and P = .022, respectively).

CONCLUSIONS

Voxel-based dosimetry following 90Y radioembolization can be utilized to account for sphere deposition and distribution into tumor. Ablative RS with high SA yields durable radiologic and pathologic outcomes.

Contralateral Hypertrophy Post Yttrium-90 Transarterial Radioembolization in Patients With Hepatocellular Carcinoma and Portal Vein Tumor Thrombus

Objectives Contralateral hypertrophy of non-irradiated liver following Yttrium-90 (90Y) transarterial radioembolization (TARE) is increasingly recognized as an option to facilitate curative surgical resection in patients that would otherwise not be surgical candidates due to a small future liver remnant (FLR). This study aimed to investigate the correlation between patient features and liver hypertrophy and identify potential predictors for liver growth in patients with hepatocellular carcinoma (HCC) and portal vein tumor thrombus (PVTT) undergoing TARE. Methodology Twenty-three patients with HCC and PVTT were included. Contralateral liver hypertrophy was assessed at six months posttreatment based on CT or MRI imaging. Thirteen patient features were selected for statistical and prediction analysis. Univariate Spearman correlation and analysis of variance (ANOVA) tests were performed. Subsequently, four feature-selection methods based on multivariate analysis were used to improve model generalization performance. The selected features were applied to train linear regression models, with fivefold cross-validation to assess the performance of the predicted models. Results The ratio of disease-free target liver volume to spared liver volume and total liver volume showed the highest correlations with contralateral hypertrophy (P-values = 0.03 and 0.05, respectively). In three out of four feature-selection methods, the feature of disease-free target liver volume to total liver volume ratio was selected, having positive correlations with the outcome and suggesting that more hypertrophy may be expected when more volume of disease-free liver is irradiated. Conclusions Contralateral hypertrophy post-90Y TARE can be an option for facilitating surgical resection in patients with otherwise small FLR.

Cholecystitis induced by Yttrium-90 radioembolization of advanced liver tumors: prospective evaluation of a management algorithm in 197 consecutive patients

BACKGROUND

Cholecystitis is a rare but dolorous complication after Y90-radioembolization of liver malignancies.

PURPOSE

To decide the occlusion of the cystic artery (CA) to prevent cholecystitis after Y90 radioembolization using an algorithm.

MATERIAL AND METHODS

In 130 patients, the gallbladder was at risk of embolization as the right liver lobe was targeted. Precautionary measures (e.g. coil occlusion of the cystic artery) were decided by enhancement of the gallbladder in pre-treatment Tc99m-MAA SPECT/CT and performed directly before Y90 radioembolization. In non-enhancing cases, the CA was left open. The outcome was determined by clinical symptoms of acute or chronic cholecystitis as well as imaging and laboratory parameters. Findings were additionally classified according to the Tokyo Guidelines of acute cholecystitis.

RESULTS

Only 16 patients demonstrated enhancement of the gallbladder in Tc99m-MAA SPECT/CT. Including additional indications from angiographic findings, prophylactic measures were scheduled in 22 patients (standard of care). Thus, 121 patients were at risk of non-target embolization to the gallbladder during Y90 microsphere administration (investigative arm). Four cases (3.0%) of cholecystitis occurred by clinical presentation: two patients with onset of acute symptoms within 48 h after Y90 radioembolization ("embolic cholecystitis") and two patients with late onset of symptoms ("radiogenic cholecystitis"). The incidence of cholecystitis was not significantly more frequent without indication of precautionary measures (investigative cohort 2.9% vs. standard of care 4.7%; P = 0.53).

CONCLUSION

The overall incidence of cholecystitis after Y90 radioembolization is low. Determination of cystic artery intervention using Tc99m-MAA SPECT/CT successfully balances the incidence of symptomatic cholecystitis with unnecessary vessel occlusion.

Radiation Segmentectomy for the Treatment of Primary Hepatic Malignancies of the Caudate Lobe: A Case Series

PURPOSE

Tumors involving the caudate lobe present a unique therapeutic challenge due to their complex anatomy and the safety and efficacy of locoregional therapy can be variable. The purpose of this study is to analyze the outcomes of radiation segmentectomy for primary caudate lobe tumors.

MATERIALS AND METHODS

Eight patients [5 women and 3 men; median age = 69 y (range 50-79)] that underwent transarterial radioembolization (TARE) using yttrium-90 (Y90) glass microspheres for primary caudate lobe tumors (hepatocellular carcinoma = 6, intrahepatic cholangiocarcinoma = 2) from August 2017 to March 2021 were retrospectively analyzed. Descriptive statistics, treatment parameters, tumor response (using modified response evaluation criteria in solid tumors), adverse events [using common terminology criteria for adverse events (CTCAE)], and survival outcomes were evaluated.

RESULTS

Eight primary caudate lobe tumors with a median size of 2.2 cm [interquartile range (IQR), 1.7-3.3] and Child-Pugh class A liver function underwent TARE of the caudate lobe. The median radiation dose was 596 Gy (IQR 356-1585), median total activity was 0.84 GBq (IQR 0.56-1.31), median specific activity was 473 Bq/sphere (IQR 226-671), and the median number of Y90 microspheres used was 1.4 million (IQR 1.2-3.4). All complications were CTCAE grade 1, and no clinically significant hilar plate complications were observed. In targeted tumors, complete response was seen in all patients.  At a median follow-up period of 16.6 months (IQR 6.6-21.6) 75% (6/8) of patients were alive with no in-field progression.

CONCLUSION

Radiation segmentectomy of primary caudate lobe tumors appears effective and is well tolerated in this limited case series within the described treatment parameters.

LEVEL OF EVIDENCE

Level 4, Case Series.

Woodhead G, D'Souza D, Flanagan S, Golzarian J, Young S. Lung shunt fraction quantification methods in radioembolization: What you need to know

In some patients undergoing radioembolization, lung toxicity is a limiting factor when calculating their dose. At the same time, it is known that the lung shunt fraction (LSF) is overestimated by the mapping exam. Furthermore, there are multiple methods to measure LSF. Planar measurement is both the most commonly utilized and easiest to perform, however new dosimetry software provides the ability to use more advanced 3D techniques. This paper reviews the different LSF calculation methods and elucidates the available data comparing the techniques, clinical relevance, and dose calculation.

Oncopharmacology in Interventional Radiology

The broad scope of malignancies treated in interventional oncology is mirrored by the breadth of oncotherapeutics, drugs used to treat cancer. Many of these treatments are administered endovascularly, though a group of therapies can be delivered percutaneously. Perhaps the best taxonomy of oncotherapeutics is based on their biological inactivity or activity and the mechanism by which they interact with treated and targeted tissues. As the fields of interventional oncology and oncotherapeutics continue to grow and expand, this framework may provide a more organized approach in helping distinguish and select the best therapy for patients.

Selective Internal Radiation Therapy with Yttrium-90 for Intrahepatic Cholangiocarcinoma: A Systematic Review on Post-Treatment Dosimetry and Concomitant Chemotherapy

Selective internal radiation therapy (SIRT) with yttrium-90 (90Y)-loaded microspheres is increasingly used for the treatment of Intrahepatic Cholangiocarcinoma (ICC). Dosimetry verifications post-treatment are required for a valid assessment of any dose-response relationship. We performed a systematic review of the literature to determine how often clinics conducted post-treatment dosimetry verification to measure the actual radiation doses delivered to the tumor and to the normal liver in patients who underwent SIRT for ICC, and also to explore the corresponding dose-response relationship. We also investigated other factors that potentially affect treatment outcomes, including the type of microspheres used and concomitant chemotherapy. Out of the final 47 studies that entered our study, only four papers included post-treatment dosimetry studies after SIRT to quantitatively assess the radiation doses delivered. No study showed that one microsphere type provided a benefit over another, one study demonstrated better imaging-based response rates associated with the use of glass-based TheraSpheres, and two studies found similar toxicity profiles for different types of microspheres. Gemcitabine and cisplatin were the most common chemotherapeutic drugs for concomitant administration with SIRT. Future studies of SIRT for ICC should include dosimetry to optimize treatment planning and post-treatment radiation dosage measurements in order to reliably predict patient responses and liver toxicity.

Hepatocellular carcinoma radiation segmentectomy treatment intensification prior to liver transplantation increases rates of complete pathologic necrosis: an explant analysis of 75 tumors

PURPOSE

To verify the correlation between yttrium-90 glass microsphere radiation segmentectomy treatment intensification of hepatocellular carcinoma (HCC) and complete pathologic necrosis (CPN) at liver transplantation.

METHODS

A retrospective, single center, analysis of patients with HCC who received radiation segmentectomy prior to liver transplantation from 2016 to 2021 was performed. The tumor treatment intensification cohort (n = 38) was prescribed radiation segmentectomy as per response recommendations identified in a previously published baseline cohort study (n = 37). Treatment intensification and baseline cohort treatment parameters were compared for rates of CPN. Both cohorts were then combined for an overall analysis of treatment parameter correlation with CPN.

RESULTS

Sixty-three patients with a combined 75 tumors were analyzed. Specific activity, dose, and treatment activity were significantly higher in the treatment intensification cohort (all p < 0.01), while particles per cubic centimeter of treated liver were not. CPN was achieved in 76% (n = 29) of tumors in the treatment intensification cohort compared to 49% (n = 18) in the baseline cohort (p = 0.013). The combined cohort CPN rate was 63% (n = 47). ROC analysis showed that specific activity ≥ 327 Bq (AUC 0.75, p < 0.001), dose ≥ 446 Gy (AUC 0.69, p = 0.005), and treatment activity ≥ 2.55 Gbq (AUC 0.71, p = 0.002) were predictive of CPN. Multivariate logistic regression demonstrated that a specific activity ≥ 327 Bq was the sole independent predictor of CPN (p = 0.013).

CONCLUSION

Radiation segmentectomy treatment intensification for patients with HCC prior to liver transplantation increases rates of CPN. While dose strongly correlated with pathologic response, specific activity was the most significant independent radiation segmentectomy treatment parameter associated with CPN.

Unusual Radiotracer Deposition to the Forearm After Intrahepatic Injection of 99mTc-Macroaggregated Albumin Using a Transradial Approach

ABSTRACT

Arterial mapping and 99mTc-macroaggregated albumin (99mTc-MAA) hepatic perfusion imaging are routinely performed before 90Y radioembolization of hepatic tumors. These procedures serve multiple purposes, including an anatomical survey of hepatic arterial anatomy, interrogating expected microsphere distribution to avoid nontargeted embolization during therapy, and evaluating for possible hepatopulmonary shunting. We present a case where 99mTc-MAA planar images revealed unexpected soft tissue uptake within the left forearm, an unexpected complication that may result from residual 99mTc-MAA in the catheter being expelled as the catheter is removed, which is particularly important to avoid during the 90Y radioembolization procedure given the risk for associated radionecrosis.

Radiation Segmentectomy for the Treatment of Solitary Hepatocellular Carcinoma: Can Outcomes Be Compared to Surgical Resection?

PURPOSE

To investigate outcomes of radiation segmentectomy (RS) versus standard-of-care surgical resection (SR) as a quality endeavor.

MATERIALS AND METHODS

A multisite, retrospective, analysis of treatment-naïve patients who received either RS or SR was performed. Inclusion criteria were solitary HCC ≤8 cm, Eastern Cooperative Oncology Cohort performance status 0-1, and absence of macrovascular invasion or extrahepatic disease. Target tumor and overall progression, time-to-progression (TTP), and overall survival were assessed. Outcomes were censored for liver transplantation.

RESULTS

123 patients were included (RS:57, SR:66). Tumor size, Child-Pugh class, ALBI score, platelet count, and fibrosis stage were significantly different between cohorts (p≤0.01). Grade ≥3 adverse events per Clavien-Dindo classification occurred in 0 RS vs 13(20%) SR patients. Target tumor progression occurred in 3(5%) RS and 5(8%) SR patients, and overall progression in 19(33%) RS and 21(32%) SR patients. Median overall TTP was 21.9 and 29.4 months after RS and SR, respectively (95%CI:15.5-28.2 and 95%CI:18.5-40.3, p=0.03). Overall TTP subgroup analyses showed no difference between cohorts with fibrosis stage 3-4 (p=0.26) and platelets <150x10⁹/L (p=0.29). The overall progression hazard ratio for RS vs SR was not significant per multivariate cox regression analysis (1.16, 95%CI:0.51-2.63, p=0.71). Median overall survival was not reached for either cohort. Propensity scores were calculated but were too dissimilar for matching.

CONCLUSION

Radiation segmentectomy and surgical resection are performed in different patient populations, which limits comparison. Radiation segmentectomy approaches surgical resection outcomes, with a lower incidence of major adverse events, in patients who are not eligible for hepatectomy.

Radioembolization for the Treatment of Hepatocellular Carcinoma: The Road to Personalized Dosimetry and Ablative Practice

Radioembolization dosimetry for the treatment of hepatocellular carcinoma has evolved alongside our understanding of best practice for this therapy. At the core of advances in dosimetry are personalized and ablative applications of radioembolization, which have generated paradigm shifts in both safety and efficacy. This review provides a summary of fundamental radioembolization dosimetry concepts and narrates how our approach to treating patients has shifted from conventional to tailored and definitive therapy.

Safety and initial efficacy of ablative radioembolization for the treatment of unresectable intrahepatic cholangiocarcinoma

PURPOSE

To investigate safety, response, and survival after ablative glass microsphere ⁹⁰Y radioembolization for unresectable intrahepatic cholangiocarcinoma.

MATERIALS AND METHODS

A retrospective review of 37 radioembolizations in 28 patients treated with single compartment dose of ≥190 Gy encompassing >75% of the largest tumor was performed. Tumors were assessed for stage, morphology, and arterial supply. Response per Modified Response Evaluation Criteria in Solid Tumors (mRECIST), freedom from progression (FFP), progression-free survival (PFS), overall survival (OS), biochemical hepatic function, performance status, and adverse events were investigated.

RESULTS

The median highest dose per patient was 256.8 Gy (195.7-807.8). Objective response at 3 months was 94.1% (complete 44.1% and partial 50%). Median OS was not reached and the 30-month OS rate was 59%, with a median follow-up of 13.4 months (5.4-39.4). FFP in the radiated field and overall FFP at 30 months were 67% and 40%, respectively. Favorable arterial supply was associated with improved OS (p = 0.018). Unfavorable arterial supply was associated with worse OS [HR 5.7 (95% CI 1.1-28.9, p = 0.034)], and PFS [HR 5.9 (95% CI 1.9-18.4, p = 0.002)]. Patients with mass-forming tumors had a survival benefit (p = 0.002). Laboratory values and performance status did not significantly change 3 months after radioembolization. Grade 3 and 4 adverse events occurred in 2 (7.1%) patients.

CONCLUSIONS

Radioembolization of unresectable intrahepatic cholangiocarcinoma with ablative intent has a high response rate, promising survival, and is well tolerated.

Comparison of the Uptake of Hepatocellular Carcinoma on Pre-Therapeutic MDCT, CACT, and SPECT/CT, and the Correlation with Post-Therapeutic PET/CT in Patients Undergoing Selective Internal Radiation Therapy

(1) Background: To comparatively analyze the uptake of hepatocellular carcinoma (HCC) on pre-therapeutic imaging modalities, the arterial phase multi-detector computed tomography (MDCT), the parenchymal phase C-arm computed tomography (CACT), the Technetium⁹⁹m-macroaggregates of human serum albumin single-photon emission computed tomography/computed tomography (SPECT/CT), and the correlation to the post-therapeutic Yttrium⁹⁰ positron emission tomography/computed tomography (PET/CT) in patients with selective internal radiation therapy (SIRT). (2) Methods: Between September 2013 and December 2016, 104 SIRT procedures were performed at our institution in 74 patients with HCC not suitable for curative surgery or ablation. Twenty-two patients underwent an identical sequence of pre-therapeutic MDCT, CACT, SPECT/CT, and post-therapeutic PET/CT with a standardized diagnostic and therapeutic protocol. In these 22 patients, 25 SIRT procedures were evaluated. The uptake of the HCC was assessed using tumor-background ratio (TBR). Therefore, regions of interest were placed on the tumor and the adjacent liver tissue on MDCT (TBR^MDCT), CACT (TBR^CACT), SPECT/CT (TBR^SPECT/CT), and PET/CT (TBR^PET/CT). Comparisons were made with the Friedman test and the Nemenyi post-hoc test. Correlations were analyzed using Spearman’s Rho and the Benjamini–Hochberg method. The level of significance was p < 0.05. (3) Results: TBR on MDCT (1.4 ± 0.3) was significantly smaller than on CACT (1.9 ± 0.6) and both were significantly smaller compared to SPECT/CT (4.6 ± 2.0) (pFriedman-Test < 0.001; pTBR^MDCT/TBR^CACT = 0.012, pTBR^MDCT/TBR^SPECT/CT < 0.001, pTBR^CACT/TBR^SPECT/CT < 0.001). There was no significant correlation of TBR on MDCT with PET/CT (rTBR^MDCT/TBR^PET/CT = 0.116; p = 0.534). In contrast, TBR on CACT correlated to TBR on SPECT/CT (rTBR^CACT/TBR^SPECT/CT = 0.489; p = 0.004) and tended to correlate to TBR on PET/CT (rTBR^CACT/TBR^PET/CT =0.365; p = 0.043). TBR on SPECT/CT correlated to TBR on PET/CT (rTBR^SPECT/CT/TBR^PET/CT = 0.706; p < 0.001) (4) Conclusion: The uptake assessment on CACT was in agreement with SPECT/CT and might be consistent with PET/CT. In contrast, MDCT was not comparable to CACT and SPECT/CT, and had no correlation with PET/CT due to the different application techniques. This emphasizes the value of the CACT, which has the potential to improve the dosimetric assessment of the tumor and liver uptake for SIRT.

Conventional Hepatic Volumetry May Lead to Inaccurate Segmental Yttrium-90 Radiation Dosimetry

OBJECTIVE

To compare radioembolization treatment zone volumes from mapping cone beam CT (CBCT) versus planning CT/MRI and to model their impact on dosimetry.

METHODS

Y90 cases were retrospectively identified in which intra-procedural CBCT angiograms were performed. Segmental and lobar treatment zone volumes were calculated with semi-automated contouring using Couinaud venous anatomy (planning CT/MRI) or tumor angiosome enhancement (CBCT). Differences were compared with a Wilcoxon signed-rank test. Treatment zone-specific differences in segmental volumes by volumetric method were also calculated and used to model differences in delivered dose using medical internal radiation dosimetry (MIRD) at 200 and 120 Gy targets. Anatomic, pathologic, and technical factors likely affecting segmental volumes by volumetric method were evaluated.

RESULTS

Forty segmental and 48 lobar CBCT angiograms and corresponding planning CT/MRI scans were included. Median Couinaud- and CBCT-derived segmental volumes were 281 and 243 mL, respectively (p = 0.005). Differences between Couinaud and CBCT lobar volumes (right, left) were not significant (p = 0.24, p = 0.07). Couinaud overestimated segmental volumes in 28 cases by a median of 98 mL (83%) and underestimated in 12 cases by median 69 mL (20%). At a 200 Gy dose target, Couinaud estimates produced median delivered doses of 367 and 160 Gy in these 28 and 12 cases. At a 120 Gy target, Couinaud produced doses of 220 and 96 Gy. Proximal vs. distal microcatheter positioning, variant arterial anatomy, and tumor location on or near segmental watersheds were leading factors linked to volumetric differences.

CONCLUSION

Use of CBCT-based volumetry may allow more accurate, personalized dosimetry for segmental Y90 radioembolization.

Determination of tumour dose response threshold and implication on survival in patients with HCC treated with Y90 radiation segmentectomy: a simple semi-quantitative analysis

PURPOSE

To evaluate the relationship between Yttrium-90 (Y90) tumour dose and response rate in patients with hepatocellular carcinoma (HCC) who undergo Y90 radiation segmentectomy (Y90-RS) and to determine implication on overall survival (OS).

MATERIALS AND METHODS

Post Y90-RS Bremsstrahlung single-photon emission computed tomography/CT of 105 HCC patients with 110 treatments performed with glass microspheres was retrospectively analysed. The dose-volume histogram of the targeted tumour was determined with commercially available dosimetry software. Tumour response at 3 months was evaluated using modified Response Evaluation Criteria in Solid Tumours. Tumour dose thresholds associated with the objective response with 80% specificity were then used to evaluate implication on OS using Kaplan-Meier estimation and log-rank analysis.

RESULTS

Tumour dose thresholds to predict objective response with 80% specificity were the following: maximum tumour dose (748 Gy), mean tumour dose (568 Gy), minimum tumour dose of 30% tumour volume (608 Gy), minimum tumour dose of 50% tumour volume (565 Gy), minimum tumour dose of 70% tumour volume (464 Gy) and minimum tumour dose of 100% tumour volume (213 Gy). These parameters all significantly predicted tumour response with areas under the ROC curve of >0.6. Mean tumour dose of ≥250 Gy predicted median OS of 43.67 vs. 17.87 months for others (P = 0.026). Minimum dose ≥180 Gy to 100% of tumour volume predicted median OS of 44.93 vs. 35.87 months for others (P = 0.043).

CONCLUSION

In patients with HCC undergoing Y90-RS, mean tumour dose ≥250 Gy and minimum tumour dose of ≥180 Gy to 100% of tumour volume are both significantly correlated with higher objective tumour response and prolonged survival.

Biochemical Safety of Ablative Yttrium-90 Radioembolization for Hepatocellular Carcinoma as a Function of Percent Liver Treated

Purpose

Transarterial radioembolization can serve as an ablative therapy for early-stage hepatocellular carcinoma (HCC). Given the volumetric variability of liver segments, this study aimed to characterize the safety of ablative radioembolization by determining percent liver treated (%LT) thresholds associated with biochemical toxicity.

Patients and Methods

Patients with HCC receiving a single ablative radioembolization treatment using glass microspheres from 2017 through 2020 were reviewed. %LT was calculated as treatment angiosome volume divided by whole liver volume. Biochemical toxicities were defined as increases in Albumin-Bilirubin (ALBI) grade or Child-Pugh (CP) class compared to baseline and albumin or bilirubin adverse events (AEs) per the Common Terminology Criteria for Adverse Events. Receiver operating characteristic curves and multivariate logistic regression analyses were performed to assess the impact of %LT on toxicities.

Results

Of 141 patients analyzed, 53% (n=75) were ALBI 1, 45% (n=64) ALBI 2, 79% (n=111) CP-A, and 21% (n=30) CP-B. A %LT ≥14.5% was associated with grade/class increases in ALBI 2 (p≤0.01) and CP-B patients (p=0.026). In multivariate analysis, a %LT ≥14.5% was an independent predictor of increases in the ALBI 2 and CP-B groups (p<0.01). No significant %LT threshold was found for ALBI 1 and CP-A patients. No grade 3/4 albumin or bilirubin AEs were reported, while grade 2 AEs were related to an initial whole liver volume <1.3 L (p≤0.01).

Conclusion

Patients with ALBI 2 and CP-B liver function are less likely to have an increase in their respective grade/class when treating <14.5% of the liver using glass microspheres. ALBI 1 and CP-A patients showed no definitive %LT threshold for biochemical toxicity within the range of this study.

The use of neoadjuvant lobar radioembolization prior to major hepatic resection for malignancy results in a low rate of post hepatectomy liver failure

Background

Neoadjuvant yttrium-90 transarterial radioembolization (TARE) is increasingly being used as a strategy to facilitate resection of otherwise unresectable tumors due to its ability to generate both tumor response and remnant liver hypertrophy. Perioperative outcomes after the use of neoadjuvant lobar TARE remain underinvestigated.

Methods

A single center retrospective review of patients who underwent lobar TARE prior to major hepatectomy for primary or metastatic liver cancer between 2007 and 2018 was conducted. Baseline demographics, radioembolization parameters, pre- and post-radioembolization volumetrics, intra-operative surgical data, adverse events, and post-operative outcomes were analyzed.

Results

Twenty-six patients underwent major hepatectomy after neoadjuvant lobar TARE. The mean age was 58.3 years (17-88 years). 62% of patients (n=16) had primary liver malignancies while the remainder had metastatic disease. Liver resection included right hepatectomy or trisegmentectomy, left or extended left hepatectomy, and sectorectomy/segmentectomy in 77% (n=20), 8% (n=2), and 15% (n=4) of patients, respectively. The mean length of stay was 8.3 days (range, 3-33 days) and there were no grade IV morbidities or 90-day mortalities. The incidence of post hepatectomy liver failure (PHLF) was 3.8% (n=1). The median time to progression after resection was 4.5 months (range, 3.3-10 months). Twenty-three percent (n=6) of patients had no recurrence. The median survival was 28.9 months (range, 16.9-46.8 months) from major hepatectomy and 37.6 months (range, 25.2-53.1 months) from TARE.

Conclusions

Major hepatectomy after neoadjuvant lobar radioembolization is safe with a low incidence of PHLF.

The joint use of 99mTc-MAA-SPECT/CT and cone-beam CT optimizes radioembolization planning

Purpose

To determine which imaging method used during radioembolization (RE) work-up: contrast-enhanced computed tomography (CECT), ^99mTc-MAA-SPECT/CT or cone beam-CT (CBCT), more accurately predicts the final target volume (TgV) as well as the influence that each modality has in the dosimetric calculation.

Methods

TgVs from ^99mTc-MAA-SPECT/CT, CECT and CBCT were consecutively obtained in 24 patients treated with RE and compared with ⁹⁰Y PET/CT TgV. Using the TgVs estimated by each imaging modality and a fictitious activity of 1 GBq, the corresponding absorbed doses by tumor and non-tumoral parenchyma were calculated for each patient. The absorbed doses for each modality were compared with the ones obtained using ⁹⁰Y PET/CT TgV.

Results

^99mTc-MAA-SPECT/CT predicted ⁹⁰Y PET/CT TgV better than CBCT or CECT, even for selective or superselective administrations. Likewise, ^99mTc-MAA-SPECT/CT showed dosimetric values more similar to those obtained with ⁹⁰Y PET/CT. Nevertheless, CBCT provided essential information for RE planning, such as ensuring the total coverage of the tumor and, in cases with more than one feeding artery, splitting the activity according to the volume of tumor perfused by each artery.

Conclusion

The joint use of ^99mTc-MAA-SPECT/CT and CBCT optimizes dosimetric planning for RE procedures, enabling a more accurate personalized approach.

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.

Prognostic Significance of Neutrophil to Lymphocyte Ratio Dynamics in Patients with Hepatocellular Carcinoma Treated with Radioembolization Using Glass Microspheres

PURPOSE

To study the prognostic significance of neutrophil and lymphocyte dynamics in patients with hepatocellular carcinoma (HCC) treated with radioembolization.

METHODS

A retrospective, single-center review of clinical records and treatment parameters (liver volume treated, administered activity, and radiation dose) in consecutive patients who received radioembolization for HCC was performed between August 20, 2015, and May 24, 2019. Neutrophil and lymphocyte variables associated with overall survival (OS) were determined by Barcelona Clinic Liver Cancer (BCLC) stage and were correlated with radioembolization treatment parameters. Statistical methods included Wilcoxon signed-rank test, univariate, and multivariate Cox regression analysis; receiver operating characteristic analysis; and the Kaplan-Meier method.

RESULTS

One hundred sixty-three patients with a median 67.0 years of age were included for analysis. Eighty-one percent of patients received segmental radioembolization with a median treatment dose of 358 Gray (interquartile range 256-497). The post-treatment lymphocyte count decreased significantly in 94.5 % (p < 0.001) of patients but was not predictive of OS (p = 0.248). The pre-procedure neutrophil to lymphocyte ratio (NLR_pre) was not predictive of OS (p = 0.891), and the 1-month post-procedure NLR was a borderline independent predictor of OS (p = 0.05). The NLR ratio (NLRR = NLR_{post-procedure}/NLR_pre) (Hazard ratio [HR], 1.31; 95% Cl, 1.04-1.66) and change in NLR (ΔNLR= NLR_{post-procedure} - NLR_pre) (HR, 1.09; 95% CI, 1.02-1.15) were associated with worse OS in BCLC C patients. NLRR (> 3.17) and ΔNLR (> 3.74) were independent predictors when adjusted for tumor presentation, treatment parameters, and liver function. Volume of liver treated and administered activity positively correlated with NLRR and ΔNLR (p < 0.001).

CONCLUSION

A decrease in lymphocyte count is common after radioembolization, but of little clinical impact. Neither pre-treatment or post-treatment NLR was a predictor of survival in our study population. NLRR and ΔNLR were independent predictors of survival in BCLC stage C disease and had positive correlations with volume of liver tissue treated and administered activity.

Quantitative Assessment of the Hemodynamic Effects of Intra-Arterial Nitroglycerin on Hepatocellular Carcinoma using Two-Dimensional Perfusion Angiography

PURPOSE

To determine the hemodynamic effects of intra-arterial nitroglycerin on hepatocellular carcinoma (HCC) using 2-dimensional (2D) perfusion angiography.

MATERIALS AND METHODS

Two-dimensional perfusion angiograms obtained prior to radioembolization from September 2019 to February 2020 were retrospectively reviewed. The inclusion criteria were the presence of Liver Imaging Reporting and Data System-5 tumors and angiographically distinguishable tumor and background liver. The exclusion criteria were previously treated tumors and motion-degraded studies. Thirteen patients with 2D perfusion angiograms obtained before and 2 minutes ± 1 after the administration of intra-arterial nitroglycerin were analyzed. The mean patient age was 72 years ± 9 and 11 of 13 (85%) had cirrhosis. The mean maximum tumor dimension was 4.6 cm ± 2.1. Eight tumors were in the right lobe and 5 were in the left lobe. The tumor and background liver 2D perfusion data were processed and the areas under the time-density curves were calculated. The relative perfusion of HCC to background liver was compared before and after nitroglycerin administration using a 2-tailed paired t-test.

RESULTS

The mean rate of contrast administration was 1.4 mL/s ± 0.7 and the mean volume administered was 7.1 mL ± 3.3. The mean nitroglycerin dose was 281 μg ± 69. Ten of 13 patients (77%) demonstrated a relative increase in tumor perfusion. The mean HCC to background liver area under the curve ratio was 1.94 ± 0.76 before and 2.40 ± 0.89 after nitroglycerin administration (P < .05).

CONCLUSIONS

Intra-arterial nitroglycerin increases previously untreated HCC perfusion relative to background liver as measured by 2D perfusion angiography, but this effect is variable among patients and should be validated with 3-dimensional imaging techniques.

Evaluation of the Safety and Feasibility of Same-Day Holmium-166 -Radioembolization Simulation and Treatment of Hepatic Metastases

PURPOSE

To evaluate the safety and feasibility of same-day treatment, including the simulation procedure for assessment of intrahepatic and extrahepatic distribution of the microspheres, with holmium-166 (¹⁶⁶Ho)-radioembolization.

MATERIALS AND METHODS

This was a secondary analysis of patients included in the 4 prospective studies (HEPAR I, HEPAR II, HEPAR PLuS, and SIM) on ¹⁶⁶Ho-radioembolization. The technical success rate of the same-day treatment protocol, defined as the number of patients who completed the same-day treatment, was measured. Total in-room time, duration of the scout procedure, time to imaging, and duration of the treatment procedure were recorded. Reasons for discontinuation or adjustment of treatment were identified. Adverse events that occurred during the treatment day were recorded.

RESULTS

One hundred five of 120 scheduled patients completed the same-day treatment with ¹⁶⁶Ho-radioembolization (success rate, 88%). After the simulation procedure, treatment was cancelled in 15 patients because of extrahepatic deposition (n = 8), suboptimal tumor targeting (n = 1), unanticipated vascular anatomy (n = 5), and dissection (n = 1). In another 14 patients, the treatment plan was adjusted. The median total procedure time (ie, simulation, imaging, and treatment) was 6:39 hours:minutes (range, 3:58-9:17 hours:minutes). Back pain was a major same-day treatment-related complaint (n = 28).

CONCLUSION

¹⁶⁶Ho-radioembolization as a same-day treatment procedure is feasible in most selected patients, although treatment was adjusted in 12% of patients and cancelled in 12% of patients. This approach might be beneficial for a select patient population, such as patients needing a radiation segmentectomy.

Chemorefractory liver metastasis from cervical cancer successfully treated with a combination of yttrium-90 and immunotherapy

Liver metastases in cervical cancer is rare and can be difficult-to-treat. The current guidelines established by the Gynecologic Oncology Group recommend platinum-based systemic chemotherapy in combination with an anti-angiogenic agent such as bevacizumab, however, overall survival remains poor following diagnosis and options for patients who fail chemotherapy are limited. Yttrium-90 (Y90) radioembolization (RE) has shown great promise in the treatment of chemo-refractory colorectal liver metastases. We describe a 30-year-old female with a history of stage IB endocervical adenocarcinoma who later developed metastases to the liver, that were unresponsive to multiple chemotherapeutics and chemoembolization, and was successfully treated with Y90 RE with concurrent systemic Pembrolizumab. The Y90 RE treatment resulted in positive clinical and imaging responses with improvement in her quality of life, all of which continue to persist at the time of writing this manuscript about 8-months into her RE treatment.