90Y Microsphere Radioembolization Research Articles

MIRD Pamphlet No. 29: MIRDy90-A 90Y Research Microsphere Dosimetry Tool.

90Y-microsphere radioembolization has become a well-established treatment option for liver malignancies and is one of the first U.S. Food and Drug Administration-approved unsealed radionuclide brachytherapy devices to incorporate dosimetry-based treatment planning. Several different mathematical models are used to calculate the patient-specific prescribed activity of 90Y, namely, body surface area (SIR-Spheres only), MIRD single compartment, and MIRD dual compartment (partition). Under the auspices of the MIRDsoft initiative to develop community dosimetry software and tools, the body surface area, MIRD single-compartment, MIRD dual-compartment, and MIRD multicompartment models have been integrated into a MIRDy90 software worksheet. The worksheet was built in MS Excel to estimate and compare prescribed activities calculated via these respective models. The MIRDy90 software was validated against available tools for calculating 90Y prescribed activity. The results of MIRDy90 calculations were compared with those obtained from vendor and community-developed tools, and the calculations agreed well. The MIRDy90 worksheet was developed to provide a vetted tool to better evaluate patient-specific prescribed activities calculated via different models, as well as model influences with respect to varying input parameters. MIRDy90 allows users to interact and visualize the results of various parameter combinations. Variables, equations, and calculations are described in the MIRDy90 documentation and articulated in the MIRDy90 worksheet. The worksheet is distributed as a free tool to build expertise within the medical physics community and create a vetted standard for model and variable management.

Pre- and post-treatment image-based dosimetry in 90Y-microsphere radioembolization using the TOPAS Monte Carlo toolkit

Objective. To evaluate the pre-treatment and post-treatment imaging-based dosimetry of patients treated with 90Y-microspheres, including accurate estimations of dose to tumor, healthy liver and lung. To do so, the Monte Carlo (MC) TOPAS platform is in this work extended towards its utilization in radionuclide therapy. Approach. Five patients treated at the Massachusetts General Hospital were selected for this study. All patients had data for both pre-treatment SPECT-CT imaging using 99mTc-MAA as a surrogate of the 90Y-microspheres treatment and SPECT-CT imaging immediately after the 90Y activity administration. Pre- and post-treatment doses were computed with TOPAS using the SPECT images to localize the source positions and the CT images to account for tissue inhomoegeneities. We compared our results with analytical calculations following the voxel-based MIRD scheme. Main results. TOPAS results largely agreed with the MIRD-based calculations in soft tissue regions: the average difference in mean dose to the liver was 0.14 Gy GBq−1 (2.6%). However, dose distributions in the lung differed considerably: absolute differences in mean doses to the lung ranged from 1.2 to 6.3 Gy GBq−1 and relative differences from 153% to 231%. We also found large differences in the intra-hepatic dose distributions between pre- and post-treatment imaging, but only limited differences in the pulmonary dose. Significance. Doses to lung were found to be higher using TOPAS with respect to analytical calculations which may significantly underestimate dose to the lung, suggesting the use of MC methods for 90Y dosimetry. According to our results, pre-treatment imaging may still be representative of dose to lung in these treatments.

Intercomparison of Geant4 low energy electromagnetic models in 90Y dosimetry

This work shows the comparison between Geant4 low energy electromagnetic physics lists G4EmLi-vermorePhysics, G4EmPenelopePhysics, G4EmLowEPPhysics, and G4EmDNAPhysics_option2 when simulating the energy deposition of low mono-energetic electrons and β− emitted from 90Y isotope. The simulation time and influence of production cut were considered. In the sense of balance between the accuracy and computer resource, G4EmPenelopePhysics can be proposed as the best physics model for our future Treatment Planning System (TPS) for treating liver cancer using 90Y microsphere radioembolization therapy.

Abstract No. 554 Improving accuracy of predicted lung dosimetry in 90Y-microsphere radioembolization with 99mTc-MAA planar scintigraphy

Standard-of-care (SOC) 90Y-microsphere radioembolization planning estimates the predicted lung shunt fractions (LSFs) and lung doses (LDs) using 99mTc-macro-aggregated albumin (MAA) planar imaging and assumes 1 kg lung mass (LM). These SIR-Spheres and TheraSphere package insert acquisition and analysis instructions generally overestimate the actual LSF, LM, and LD. The goal of this work is to provide recommendations on improved planar LSF calculation (i.e., view and contour selection and liver shine-through correction) and lung mass (LM) estimation for more accurate planar LD prediction. We compared the accuracy of planar LSFs and assumed LMs in planar LD estimations to 99mTc-MAA SPECT/CT-based LSFs, LMs, and LDs in 52 consecutive patients with hepatocellular carcinoma who underwent treatment planning for 90Y glass microsphere radioembolization. A recommended planar LD calculation (i.e., LSF and lung mass estimations) was determined by comparing the absolute errors relative to SPECT/CT-based values and categorizing the likelihood (Negligible/Possible/Likely/Definite) the planar values would impact patient care. All planar LSF and LD calculations were significantly greater than the corresponding SPECT/CT values (p ≤ 0.01, paired t-test). In general, SOC geometric mean planar LSFs had significantly larger errors (med: 0.04, max: 0.12) and more Pos/Lik/Def adverse clinical impact cases (71%) than other planar LSF calculations. These values decreased to a median 0.02, maximum 0.07, and 22% when calculating LSF using only the view with the highest abdominal counts and applying a simple liver shine-through correction. Similarly, SOC LD calculation using a reference 1 kg LM had significantly larger errors (med. 4 Gy, max. 23 Gy) and more Pos/Lik/Def adverse clinical impact cases (30%) than LD calculated with the improved LSF and patient-specific lung mass (med. 2 Gy, max. 17 Gy, 16%). We recommend predicting LD with planar imaging using: LSF calculated from the liver-shine-through-corrected total lung counts (equal to 215% the left lung counts), liver counts in only the view with the highest abdominal frame counts, and patient-specific LM from chest CT densitovolumetry.

Early metabolic response assessment of breast cancer liver metastases: 4-week posttreatment FDG PET predicts survival after 90Y microsphere radioembolization.

To evaluate the feasibility of early metabolic response assessment with 18F-FDG PET/CT in patients with breast cancer liver metastases 4 weeks after radioembolization with Yttrium-90 labeled microspheres. 25 patients (mean age 58y, range 40-74) with advanced stage liver metastases of breast cancer were treated with 1.9 ± 0.4 GBq of 90Y-microspheres in the salvage setting and underwent 18F-FDG PET/CT at baseline and 4 weeks post-radioembolization. 14 patients (56 %) had an excessive hepatic tumor burden (> 50 % of total liver volume), 21 patients (84 %) had extrahepatic disease. Liver lesions with the highest SUVmax were selected as target lesions and a cut-off was set at 50 % reduction to separate responders from non-responders. The predictive impact of metabolic response on overall survival (OS) was investigated along with other prognostic factors. The median OS in this highly advanced metastatic cohort was 7 months (95 % CI, 5-9). All patients had a reduction in SUVmax (mean ΔSUVmax: -49 ± 26 %) at 4 weeks post-treatment. Patients with > 50 % SUVmax reduction survived longer (median OS 13 mo, 95 % CI 8-18) than the remaining patients (median OS 4 mo, 95 % CI 2-6; p = 0.001). From all investigated baseline factors including age, performance status, and presence of extra-hepatic disease, only the hepatic tumor burden had a significant impact on OS (p = 0.02). This is the first preliminary evidence in breast cancer that early post-radioembolization molecular response assessment of treated liver metastases - as early as 4 weeks posttreatment - may predict survival. If confirmed by larger series, FDG PET/CT could be considered for early response-adapted treatment modifications.

Impact of 90Y PET gradient-based tumor segmentation on voxel-level dosimetry in liver radioembolization

BackgroundThe purpose was to validate 90Y PET gradient-based tumor segmentation in phantoms and to evaluate the impact of the segmentation method on reported tumor absorbed dose (AD) and biological effective dose (BED) in 90Y microsphere radioembolization (RE) patients. A semi-automated gradient-based method was applied to phantoms and patient tumors on the 90Y PET with the initial bounding volume for gradient detection determined from a registered diagnostic CT or MR; this PET-based segmentation (PS) was compared with radiologist-defined morphologic segmentation (MS) on CT or MRI. AD and BED volume histogram metrics (D90, D70, mean) were calculated using both segmentations and concordance/correlations were investigated. Spatial concordance was assessed using Dice similarity coefficient (DSC) and mean distance to agreement (MDA). PS was repeated to assess intra-observer variability.ResultsIn phantoms, PS demonstrated high accuracy in lesion volumes (within 15%), AD metrics (within 11%), high spatial concordance relative to morphologic segmentation (DSC > 0.86 and MDA < 1.5 mm), and low intra-observer variability (DSC > 0.99, MDA < 0.2 mm, AD/BED metrics within 2%). For patients (58 lesions), spatial concordance between PS and MS was degraded compared to in-phantom (average DSC = 0.54, average MDA = 4.8 mm); the average mean tumor AD was 226 ± 153 and 197 ± 138 Gy, respectively for PS and MS. For patient AD metrics, the best Pearson correlation (r) and concordance correlation coefficient (ccc) between segmentation methods was found for mean AD (r = 0.94, ccc = 0.92), but worsened as the metric approached the minimum dose (for D90, r = 0.77, ccc = 0.69); BED metrics exhibited a similar trend. Patient PS showed low intra-observer variability (average DSC = 0.81, average MDA = 2.2 mm, average AD/BED metrics within 3.0%).Conclusions90Y PET gradient-based segmentation led to accurate/robust results in phantoms, and showed high concordance with MS for reporting mean tumor AD/BED in patients. However, tumor coverage metrics such as D90 exhibited worse concordance between segmentation methods, highlighting the need to standardize segmentation methods when reporting AD/BED metrics from post-therapy 90Y PET. Estimated differences in reported AD/BED metrics due to segmentation method will be useful for interpreting RE dosimetry results in the literature including tumor response data.

Clinical feasibility of 90Y digital PET/CT for imaging microsphere biodistribution following radioembolization

The purpose of this study was to evaluate the clinical feasibility of next generation solid-state digital photon counting PET/CT (dPET/CT) technology and imaging findings in patients following 90Y microsphere radioembolization in comparison with standard of care (SOC) bremsstrahlung SPECT/CT (bSPECT/CT). Five patients underwent SOC 90Y bremsstrahlung imaging immediately following routine radioembolization with 3.5±1.7GBq of 90Y-labeled glass microspheres. All patients also underwent dPET/CT imaging at 29±11h following radioembolization. Matched pairs comparison was used to compare image quality, image contrast and 90Y biodistribution between dPET/CT and bSPECT/CT images. Volumetric assessments of 90Y activity using different isocontour thresholds on dPET/CT and bSPECT/CT images were also compared. Digital PET/CT consistently provided better visual image quality and 90Y-to-background image contrast while depicting 90Y biodistribution than bSPECT/CT. Isocontour volumetric assessment using a 1% threshold precisely outlined 90Y activity and the treatment volume on dPET/CT images, whereas a more restrictive 20% threshold on bSPECT/CT images was needed to obtain comparable treatment volumes. The use of a less restrictive 10% threshold isocontour on bSPECT/CT images grossly overestimated the treatment volume when compared with the 1% threshold on dPET/CT images. Digital PET/CT is clinically feasible for the assessment of 90Y microsphere biodistribution following radioembolization, and provides better visual image quality and image contrast than routine bSPECT/CT with comparable acquisition times. With further optimization and clinical validation, dPET technology may allow faster and more accurate imaging-based assessment of 90Y microsphere biodistribution.

Prognostic value of pretreatment diffusion-weighted magnetic resonance imaging for outcome prediction of colorectal cancer liver metastases undergoing 90Y-microsphere radioembolization

To investigate the clinical potential of pretreatment apparent diffusion coefficient (ADC) on diffusion-weighted magnetic resonance imaging (DWI) for therapy response and outcome prediction in patients with liver-predominant metastatic colorectal cancer (CRC) undergoing radioembolization with 90Yttrium-microspheres (90Y-RE). Forty-six consecutive patients with unresectable CRC liver metastases underwent standardized clinical DWI on a 1.5T MR scanner prior to and 4-6 weeks after 90Y-RE. Pretreatment clinical parameters, ADC values derived from region-of-interest analysis, and the corresponding tumor sizes of three treated liver metastases per subject were recorded. Long-term tumor response to radioembolization was categorized into response (partial remission) and nonresponse (stable disease, progressive disease) according to Response Evaluation Criteria in Solid Tumors v1.1 (RECIST) 3 months after treatment. Associations between long-term tumor response and the clinical and imaging parameters were evaluated. The impact of pretreatment clinical and imaging parameters on progression-free survival (PFS) and overall survival (OS) was further assessed by Kaplan-Meier and multivariate Cox-regression analyses. Nonresponders had higher hepatic tumor burden (p = 0.021) and lower ADC values than patients responding to 90Y-RE, both pretreatment (986 ± 215 vs. 1162 ± 178; p = 0.036) and posttreatment (1180 ± 350 vs. 1598 ± 225; p = 0.002). ADC values higher than 935 × 10-6 mm2 (5 vs. 3 months; p = 0.022) and hepatic tumor burden ≤25% (6 vs. 3 months; p = 0.014) were associated with longer median PFS, whereas ADC >935 × 10-6 mm2 (14 vs. 6 months; p = 0.02), hepatic tumor burden ≤25% (14 vs. 6 months; p = 0.048), size of the largest metastasis <4.7cm (18 vs. 7 months; p = 0.024), and Eastern Cooperative Oncology Group (ECOG) score <1 (8 vs. 5 months; p = 0.045) were associated with longer median OS. On multivariate analysis, ADC >935 × 10-6 mm2 and hepatic tumor burden ≤25% remained prognostic factors for PFS, and ADC >935 × 10-6 mm2 and size of the largest metastasis <4.7cm were independent predictors of OS. Pretreatment ADC on DWI represents a valuable prognostic biomarker for predicting both the therapeutic efficacy and survival prognosis in CRC liver metastases treated by 90Y-RE, allowing risk stratification and potentially optimizing further treatment strategies.

Baseline hemoglobin and liver function predict tolerability and overall survival of patients receiving radioembolization for chemotherapy-refractory metastatic colorectal cancer.

Patients with liver metastatic colorectal cancer (mCRC) often benefit from receiving 90Y-microsphere radioembolization (RE) administered via the hepatic arteries. Prior to delivery of liver-directed radiation, standard laboratory tests may assist in improving outcome by identifying correctable pre-radiation abnormalities. A database containing retrospective review of consecutively treated patients of mCRC from July 2002 to December 2011 at 11 US institutions was used. Data collected included background characteristics, prior chemotherapy, surgery/ablation, radiotherapy, vascular procedures, 90Y treatment, subsequent adverse events and survival. Kaplan-Meier estimates compared the survival of patients across lines of chemotherapy. The following values were obtained within 10 days prior to each RE treatment: haemoglobin (HGB), albumin, alkaline phosphatase (Alk phosph), aspartate aminotransferase (AST), alanine transaminase (ALT), total bilirubin and creatinine. Common Terminology Criteria Adverse Events (CTCAEs) 3.0 grade was assigned to each parameter and analysed for impact on survival by line of chemotherapy. Consensus Guidelines were used to categorize the parameter grades as either within or outside guidelines for treatment. A total of 606 patients (370 male; 236 female) were studied with a median follow-up was 8.5 mo. (IQR 4.3-15.6) after RE. Fewer than 11% of patients were treated outside recommended RE guidelines, with albumin being the most common, 10.5% grade 2 (<3-2.0 g/dL) at time of RE. All seven parameters showed statistically significant decreased median survivals with any grade >0 (P<0.001) across all lines of prior chemotherapy. Compared to grade 0, grade 2 albumin decreased overall survival 67%; for grade 2 total bilirubin a 63% drop occurred, and grade 1 HGB resulted in 66% lower median survival. Review of pre-RE laboratory parameters may aid in improving median survivals if correctable grade >0 values are addressed prior to radiation delivery. HGB <10 g/dL is a well-known negative factor in radiation response and is easily corrected. Improving other parameters is more challenging. These efforts are important in optimizing treatment response to liver radiotherapy.

Administered activity and outcomes of glass versus resin (90)Y microsphere radioembolization in patients with colorectal liver metastases.

Given the differences in size, specific activity, and dosing methods for glass yttrium-90 microspheres ((90)Y-glass) and resin (90)Y microspheres ((90)Y-resin), these therapies may expose the liver to different amounts of radiation, thereby affecting their efficacy and tolerability. We aimed to compare the prescribed activity of (90)Y-glass and (90)Y-resin for real-world patients undergoing selective internal radiation therapy (SIRT) for liver-dominant metastatic colorectal cancer (mCRC) and to assess efficacy and safety outcomes in these patients. We examined the records of 28 consecutive patients with unresectable colorectal liver metastases treated with SIRT between June 2008 and May 2011 at our institution. Using baseline CT and MR images, we calculated a projected activity as if we had used the other product and compared it to the actual prescribed activity of (90)Y-glass and (90)Y-resin for each SIRT treatment per manufacturer guidelines. Progression and adverse events were evaluated at follow up visits. Survival was analyzed by the Kaplan-Meier method. For (90)Y-glass treatments with a mean prescribed (90)Y activity of 1.77 GBq, the mean projected (90)Y-resin activity was 0.84 GBq. For (90)Y-resin treatments with a mean prescribed (90)Y activity of 1.05 GBq, the mean projected (90)Y-glass activity was 2.48 GBq. The median survival was 9.3 months versus 18.2 months for (90)Y-glass and (90)Y-resin, respectively (P=0.292). During the second year after SIRT, the hazard ratio of death for patients treated with (90)Y-glass versus (90)Y-resin was 4.0 (95% CI: 1.3, 12.3; P=0.017). No significant difference in progression, adverse events or liver toxicity was observed. Using manufacturer recommended guidelines, (90)Y-resin delivers significantly less activity than (90)Y-glass to patients with liver-dominant mCRC undergoing SIRT with no significant difference in adverse events and a trend toward improved survival.

Yttrium-90 radioembolization for the treatment of chemorefractory colorectal liver metastases: Technical results, clinical outcome and factors potentially influencing survival

Background: The purpose of this study was to retrospectively assess the technical and clinical outcomes, overall survival and prognostic factors for prolonged survival after yttrium-90 (90Y) radioembolization as a salvage therapy for patients with chemorefractory liver-only or liver-dominant colorectal metastases.Material and methods: From January 2005 to January 2014, all the patients selected for 90Y radioembolization to treat chemorefractory colorectal liver metastases were identified. Demographic, laboratory, imaging and dosimetry data were collected. Post-treatment technical and clinical outcomes were analyzed as well as overall survival; finally several factors potentially influencing survival were analyzed.Results: In total 88 patients were selected for angiographic workup; 71 patients (81%) finally underwent catheter-directed 90Y microsphere infusion into the hepatic artery 25 days (standard deviation 13 days) after angiographic workup. Median infused activity was 1809 MBq; 30-day toxicity included: fatigue (n = 39; 55%), abdominal discomfort (n = 33; 47%), nausea (n = 5; 7%), fever (n = 14; 20%), diarrhea (n = 6; 9%), liver function abnormalities and elevated bilirubin (transient) (n = 3; 4%). Gastric ulcer was found in five patients (7%). A late complication was radioembolization-induced portal hypertension (REIPH) in three patients (4%). Median time to progression in the liver was 4.4 months. Estimated survival at six and 12 months was 65% and 30%, respectively, with a 50% estimated survival after 8.0 months in this group of chemorefractory patients. Prognostic factors for worse survival were high preprocedural bilirubin, alkaline phosphatase and tumor volume levels.Conclusion: 90Y microsphere radioembolization for chemorefractory colorectal liver metastases has an acceptable safety profile with a 50% estimated survival after 8.0 months. Pretreatment high bilirubin, alkaline phosphatase and tumor volume levels were associated with early death.

Survival in patients with hepatocellular carcinoma treated with 90Y-microsphere radioembolization. Prediction by 18F-FDG PET.

This retrospective study aims to evaluate the predictive value of FDG PET/CT in patients with unresectable hepatocellular carcinoma (HCC) undergoing radioembolization with yttrium-90 labeled microspheres (RE). The study cohort comprised 33 patients who were treated with RE at our institution and underwent FDG PET/CT at baseline and four weeks after radioembolization. According to the baseline FDG metabolic status of the HCC lesions, patients were divided into two groups: FDG-negative (n = 12) and FDG-positive (n = 21) HCC. FDG-positive patients were further divided into early metabolic responders and non-responders according to the relative change in SUVmax of the treated lesions. Survival analyses were performed with the Kaplan-Meier method (log-rank test, p < 0.05). Multivariate analysis was performed to assess the influence of prognostic factors on overall survival (OS). FDG-negative patients had a significantly longer OS (13 months, 95%CI 7-19) than FDG-positive patients (9 months, 95%CI 7-11; p = 0.010). Among FDG-positive patients, metabolic responders survived significantly longer than metabolic non-responders (10 months, 95%CI 8-12 vs. 5 months, 95%CI 4-6; p = 0.003). From the other baseline factors (including performance status, hepatic tumour burden, presence of extra-hepatic disease, administered activity) only the BCLC stage had a significant impact on OS (p = 0.028). Pre- and post-therapeutic FDG PET independently predicts overall survival in patients with HCC undergoing radioembolization. Interestingly, early metabolic response seems to be assessable as early as four weeks post-treatment.

Complications after 90Y microsphere radioembolization for unresectable hepatic tumors: An evaluation of 112 patients

The aim of this study was to estimate the incidence of complications after (90)Y microsphere radioembolization for unresectable hepatic tumors and evaluate risk factors for late complications. A cohort of 112 consecutive patients from two institutions underwent (90)Y microsphere radioembolization for unresectable hepatic tumors. Complications were graded according to the Common Terminology Criteria for Adverse Events, version 3.0. Symptoms secondary to postradioembolization syndrome occurring within 30days were recorded as early complications, and all other complications were considered late complications. Seventy-eight patients (70%) experienced postradioembolization syndrome, including fatigue, abdominal pain, nausea, vomiting, anorexia, or fever. Three patients (3%) experienced a Grade 3 early complication; no Grade 4 or 5 early toxicity occurred. Two patients (2%) experienced clinically significant liver dysfunction; 13 patients (12%), 27 patients (24%), and 9 patients (8%) had an elevation of bilirubin, aspartate aminotransferase, and alanine aminotransferase, respectively. Eleven patients (10%) experienced gastrointestinal ulceration, including two Grade 3 complications and one Grade 4 complication. Cholecystitis occurred in 7 patients (6%), including two Grade 3 complications. Grade 2 pancreatitis occurred in 1 patient (1%). No radiation pneumonitis was observed. The cumulative incidence of late Grade 3 or 4 complications at 12months after radioembolization was 8%. No Grade 5 toxicity occurred. (90)Y microsphere radioembolization is a well-tolerated treatment for unresectable hepatic tumors with a low risk of Grade 3 or higher early or late toxicity.

Clinical outcomes with yttrium-90 resin microsphere radioembolization for hepatocellular carcinoma in a multiethnic southeast Asian population.

e15137 Background: Treatment options for unresectable hepatocellular carcinoma (HCC) are limited. Intra-arterial yttrium-90 (90Y) microsphere radioembolization is an emerging treatment option with good outcomes among Caucasian patients. We report clinical outcomes in a multi-ethnic south-east Asian population treated with 90Y microspheres. Methods: A single-centre, retrospective, observational cohort study was conducted on patients who received 90Y microsphere radioembolization at Singapore General Hospital between January 2008 and June 2012. Patients were followed from the date of treatment until January 30, 2013, or until the date of death. Disease was staged by Barcelona Clinic Liver Cancer (BCLC) and Child-Pugh class. Patient survival was estimated using the Kaplan-Meier method. Response rate was determined by RECIST criteria. Prognostic factors for survival were identified using Cox proportional hazards regression. Results: 103 patients comprising 40.8% Chinese, 30.1% Myanmar, 14.6% Indonesian, 6.8% Indochinese and 7.7% others were treated with 90Y microspheres. Hepatitis B or C was recorded as the etiology in 47.6% and 23.3% of patients, respectively. The median overall survival (OS) was 14.4 months [95% CI 11.3-22.2 months] (BCLC B, 23.8 months ; BCLC C, 13.6 months; P = 0.048); (Child-Pugh A, 21.7 months; Child-Pugh B, 10.1 months; P &lt; 0.0001). Median OS in patients with portal vein thrombosis (PVT) was poorer than those without PVT (PVT, 11.0 months; No PVT, 18.1 months; P = 0.024). Overall disease control rate by RECIST was 64.7%, while target lesions response rate was 98.3%. Progression of disease was mainly due to new lesions (69.2%). Significant prognostic factors for survival were serum albumin levels, presence of ascites and PVT. Conclusions: Survival outcomes in south-east Asian patients treated with 90Y microsphere radioembolization for HCC are comparable to Western populations in spite of the different etiologies. While target lesions response was good, new lesions are common and suggest that concomitant systemic therapy may have a role in disease control.

New Imaging Techniques for 90Y Microsphere Radioembolization

Adequate patient selection and treatment planning is crucial for a safe and cost-effective administration of selective internal radiotherapy (SIRT) of malignant liver disease using 90Y-labelled microspheres. It requires the implementation of multimodality imaging, integrating metabolic, functional and structural characteristics. A multidisciplinary approach is a prerequisite for SIRT, bringing together the knowhow and expertise of radiologists, nuclear medicine physicians, medical physicists, imaging engineers, and radiotherapists. This review discusses the available radiologic (CT/MRI) and nuclear (SPECT/PET) imaging modalities and their specific utility in the different diagnostic phases related to SIRT: whole body and intrahepatic pre-treatment disease staging, CT and MRI-based angiography, liver-lung shunt assessment, treatment simulation, predictive dosimetry, post-treatment imaging, and SIRT response assessment.

Experience with SIR-Spheres 90Y Microsphere Radio-Embolization for Liver Metastases

Experience with SIR-Spheres 90Y Microsphere Radio-Embolization for Liver Metastases

Yttrium-90 Microsphere Radioembolotherapy of Hepatic Metastatic Neuroendocrine Carcinomas after Hepatic Arterial Embolization

Hepatic artery radioembolization was performed in a cohort of patients with unresectable neuroendocrine hepatic metastases who exhibited hepatic progression or toxicity despite technically adequate embolization procedures without other reasonable therapeutic options. Eight patients (five men) with a median age of 55.5 years met the study criteria. Infusions of yttrium-90 resin microspheres were performed in a lobar fashion. Standard clinical, laboratory, and imaging follow-up was performed. Median hepatic parenchyma replacement by tumor was 55% (range, 25%-60%). Twelve (90)Y resin microsphere infusions were performed, and the median delivered activity was 33.25 mCi (range, 23-55 mCi). One partial response, four cases of disease stabilization, and three cases of progressive disease were noted. No cases of radiation-induced liver disease occurred. Median survival times were 14 months (range, 3-15 months) from the time of (90)Y microsphere treatment and 36.5 months (range, 16-105 months) from the time of diagnosis of hepatic metastases. In this cohort, (90)Y microsphere radioembolization of neuroendocrine hepatic metastases was not precluded by previous nonradioactive embolization procedures, but the effectiveness in this population requires further investigation.