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Significant improvements within radioembolization imaging and dosimetry permit the development of an accurate and personalized pretreatment plan with technetium 99 m –labeled macroaggregated albumin single-photon emission computed tomography (99m Tc-MAA SPECT/CT). Despite these potential advantages, the clinical transition to pretreatment protocols with SPECT/CT is hindered by its unknown safety constraints. This study aimed to address this issue by establishing novel dose limits for 99m Tc-MAA SPECT/CT to enable quantitative pretreatment planning. Stratification criteria to determine images most viable for dosimetry analysis were created from a cohort of 85 patients. SPECT/CT, cone beam CT, and activity calculations derived from the local deposition method were used to create an accurate pretreatment protocol. Planar and SPECT/CT images were compared using linear regression and modified Bland-Altman analyses to convert accepted planar dose limits to SPECT/CT. To validate these new dose limits, activity calculations based on SPECT/CT were compared with those calculated with the body surface area and planar methods for 3 treatment plans. A total of 38 of 85 patients were deemed viable for dosimetry analysis. SPECT lung shunt fractions (LSFs) yielded greater values than planar imaging when LSFs were <4.89%, whereas planar imaging was greater than SPECT when LSFs were >4.89. Planar to SPECT/CT dose safety conversions were 0.76 ×, 0.70 ×, and 0.55 × for the whole liver, normal liver, and lungs, respectively. Patients with SPECT LSFs <4.89% were safely treated with the direct application of planar lung dose limits. Activity calculations with SPECT/CT were greater than the body surface area method by a median of 33.1% to 61.9% and were lower than planar-based activity calculations by 12.5% to 13.7% for the whole liver and by 29.4% to 32.2% for the normal liver. A generalized method to establish safety dose limits between 2 modalities was used to translate safety dose limits from planar imaging to 99m Tc-MAA SPECT/CT. An accurate 99m Tc-MAA SPECT/CT treatment protocol was developed guided by the current knowledge in the field. Established SPECT/CT dose limits safely treated 97.5% of patients and permitted the application of independent pretreatment planning with 99m Tc-MAA SPECT/CT. [ABSTRACT FROM AUTHOR]

Background: The goal of this study was to evaluate efficacy and safety of 90Y radioembolization for neuroendocrine liver metastases (NELM) in a multicenter registry.Methods: One hundred-seventy patients with NELM were enrolled in the registry (NCT02685631). Prior treatments included hepatic resection (n = 23, 14%), arterial therapy (n = 62, 36%), octreotide (n = 119, 83%), cytotoxic chemotherapy (n = 58, 41%), biologic therapy (n = 49, 33%) and immunotherapy (n = 10, 6%). Seventy-seven (45%) patients had extrahepatic disease. Seventy-eight (48%), 61 (37%), and 25 (15%) patients were Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or ≥ 2. Tumor grade was known in 81 (48%) patients: 57 (70%) were well-, 12 (15%) moderate-, and 12 (15%) poorly-differentiated. Kaplan-Meier analysis and log rank tests were performed to compare overall and progression-free survival (OS/PFS) by tumor location and grade. Toxicities were reported using Common Terminology Criteria for Adverse Events v.5. Cox Proportional Hazards were calculated for pancreatic primary, performance status, extrahepatic disease at treatment, unilobar treatment, baseline ascites, and > 25% tumor burden.Results: One, 2, and 3-year OS rates were 75, 62 and 46%, respectively. Median OS was 33 months [(95% CI: 25-not reached (NR)]. The longest median OS was in patients with pancreatic (42 months, 95% CI: 33-NR) and hindgut 41 months, 95% CI: 12-NR) primaries. The shortest OS was in foregut primaries (26 months; 95% CI: 23-NR; X2 = 7, p = 0.1). Median OS of well-differentiated tumors was 36 months (95% CI: 10-NR), compared to 44 (95% CI: 7-NR) and 25 (95% CI: 3-NR) months for moderate and poorly differentiated tumors. Median progression-free survival (PFS) was 25 months with 1, 2, and 3-year PFS rates of 70, 54, and 35%, respectively. Thirteen patients (7.6%) developed grade 3 hepatic toxicity, most commonly new ascites (n = 8, 5%) at a median of 5.5 months. Performance status of ≥2 (HR 2.7, p = 0.01) and baseline ascites (HR 2.8, P = 0.049) predicted shorter OS.Discussion: In a population with a high incidence of extrahepatic disease, 90Y was effective and safe in treatment of NELM, with median OS of 41 months for well differentiated tumors. Grade 3 or greater hepatic toxicity was developed in 7.6% of patients.Trial Registration: NCT02685631 . [ABSTRACT FROM AUTHOR]

Thoughtful and accurate dosimetry is critical to obtain the safest and most efficacious yttrium-90 (Y90) radioembolization of primary and secondary liver cancers. Three dosimetry models are currently used in clinical practice, namely, body surface area model, medical internal radiation dose model, and the partition model. The objective of this review is to briefly outline the history behind Y90 dosimetry and the difference between the aforementioned models. When applying these three models to a single case, the differences between them are further demonstrated. Each dosimetry model in clinical practice has its own benefits and limitations. Therefore, it is incumbent upon practicing interventional radiologists to be aware of these differences to optimize treatment outcomes for their patients. [ABSTRACT FROM AUTHOR]

Y90 radioembolization is an alternative to transarterial chemoembolization for the intra-arterial treatment of hepatocellular carcinoma (HCC). However, the optimal treatment of HCC varies by tumor stage, underlying liver function and functional status, and local expertise. Therefore, the appropriate selection of patients for Y90 radioembolization is of paramount importance for optimal outcomes. Data on the role of Y90 radioembolization for HCC are most robust in the palliative treatment of inoperable, liver-confined disease. However, data are also present on the role of Y90 radioembolization as a bridge to or to downstage patients for transplant. Outcomes for radiation segmentectomy (ablative radiation doses) with curative intent or prior to resection are also discussed. [ABSTRACT FROM AUTHOR]

Treatment paradigms for primary and metastatic malignancies involving the liver have evolved in recent years to include targeted liver therapies. Transarterial radioembolization is at the forefront of therapy in many treatment algorithms. However, due to significant hepatopulmonary shunting, some patients are excluded from this proven treatment due to the possibility of radiation-induced lung injury. In this article, we review techniques to mitigate hepatopulmonary shunts to improve the likelihood of inclusion and successful treatment in these patients. [ABSTRACT FROM AUTHOR]