For Hepatocellular Carcinoma Treated with Yttrium-90 Microspheres, Dose Volumetrics on Post-Treatment Bremsstrahlung SPECT/CT Predict Clinical Outcomes.

In transarterial radioembolization (TARE) of hepatocellular carcinoma (HCC) with Yttrium-90 (Y-90) microspheres, recent studies correlate dosimetry from bremsstrahlung single photon emission tomography (SPECT/CT) with treatment outcomes; however, these studies focus on measures of central tendency rather than volumetric coverage metrics commonly used in radiation oncology. We hypothesized that three-dimensional (3D) isodose coverage of gross tumor volume (GTV) is the driving factor in HCC treatment response to TARE and is best assessed using advanced dosimetry techniques applied to nuclear imaging of actual Y-90 biodistribution. We reviewed 51 lobar TARE Y-90 treatments of 43 HCC patients. Dose prescriptions were 120 Gy for TheraSpheres and 85 Gy for SIR-Spheres. All patients underwent post-TARE Y-90 bremsstrahlung SPECT/CT imaging. Commercial software was used to contour gross tumor volume (GTV) and liver on post-TARE SPECT/CT. Y-90 dose distributions were calculated using the Local Deposition Model based on post-TARE SPECT/CT activity maps. Median gross tumor volume (GTV) dose; GTV receiving less than 100 Gy, 70 Gy and 50 Gy; minimum dose covering the hottest 70%, 95%, and 98% of the GTV (D70, D95, D98); mean dose to nontumorous liver, and disease burden (GTV/liver volume) were obtained. Clinical outcomes were collected for all patients by chart and imaging review. HCC treatment response was assessed according to the modified response criteria in solid tumors (mRECIST) guidelines. Kaplan-Meier (KM) survival estimates and multivariate regression analyses (MVA) were performed using STATA. Median survival was 22.5 months for patients achieving objective response (OR) in targeted lesions (complete response (CR) or partial response (PR) per mRECIST) vs. 7.6 months for non-responders (NR, stable disease or disease progression per mRECIST). On MVA, the volume of underdosed tumor (GTV receiving less than 100 Gy) was the only significant dosimetric predictor for CR (p = 0.0004) and overall survival (OS, p = 0.003). All targets with less than CR (n = 39) had more than 20 cc of underdosed tumor. D70 (p = 0.038) correlated with OR, with mean D70 of 95 Gy for responders and 60 Gy for non-responders (p = 0.042). On MVA, mean dose to nontumorous liver trended toward significant association with grade 3+ toxicity (p = 0.09) and correlated with delivered activity (p < 0.001) and burden of disease (p = 0.05). Dosimetric models supplied area under the curve estimates of > 0.80 predicting CR, OR, and ≥grade 3 acute toxicity. Dosimetric parameters derived from the retrospective analysis of post-TARE Y-90 bremsstrahlung SPECT/CT after lobar treatment of HCC suggest that volumetric coverage of GTV, not a high mean or median dose, is the driving factor in treatment response and that this is best assessed through the analysis of actual Y-90 biodistribution.

The development, commercialization, and clinical context of yttrium-90 radiolabeled resin and glass microspheres.

Selective internal radiation therapy has emerged as a well-accepted therapeutic for primary and metastatic hepatic malignancies. This therapeutic modality requires the combined efforts of multiple medical disciplines to ensure the safe delivery of yttrium-90 (90Y)-labeled microspheres. The development of this therapy followed decades of clinical research involving tumor vascularity and microsphere development. Today, it is essential that treating physicians have a thorough understanding of hepatic tumor vascularity and 90Y microsphere characteristics before undertaking this complex intervention. This review explores the contributions of early investigators of this therapy, as well as the development, US Food and Drug Administration approval, manufacturing process, and attributes of the 2 commercially available 90Y radiolabeled microsphere device to clarify the key physical differences between the products.

Indications for inferior vena cava filter placement: do physicians comply with guidelines?

PURPOSE: Inferior vena cava (IVC) filter placement has increased significantly over the past few decades, but indications for filter placement vary widely depending on which professional society recommendations are followed, and it is uncertain how compliant physicians are in adhering to guidelines. This study assessed documented indications for IVC filter placement and evaluated compliance with standards set by the American College of Chest Physicians (ACCP) and the Society of Interventional Radiology (SIR). MATERIALS AND METHODS: A single-center, retrospective medical record review in a metropolitan, 652-bed, acute care, teaching hospital. Inpatient filter placement over a 26-month period was reviewed. The study measured compliance with established guidelines, relationship of medical specialty to filter placement, and evaluation of self-referral patterns among physicians. RESULTS: Compliance with established ACCP guidelines was poor regardless of whether the IVC filter insertion was performed by interventional radiology (IR; 43.5%), vascular surgery (VS; 39.9%), or interventional cardiology (IC; 33.3%) staff. Compliance with the less restrictive SIR guidelines was better (77.5%, 77.1%, and 80% for IR, VS, and IC, respectively). There was a greater degree of guideline compliance when filter placement was recommended by internal medicine (IM)-trained physicians than by non-IM-trained physicians: 46.3% of IR-placed filters requested by IM physicians met ACCP criteria whereas only 24.0% of filters recommended by non-IM specialties were compliant with criteria (P = .03). In the VS group, these compliance rates were 45.8% and 31.5%, respectively (P = .03). Among IR-placed filters, 84.0% of IM-recommended filter placements were compliant with SIR guidelines, versus only 48.0% of non-IM-recommended placements (P ≤ .001). In the VS group, these compliance rates were 87.8% and 69.6%, respectively (P ≤ .001). CONCLUSIONS: There is poor physician compliance with guidelines for IVC filter placement. Most filter indications meeting SIR guidelines are for patients classified as "falls risks," failures of anticoagulation, patients with limited cardiopulmonary reserve and patients non compliant with anticoagulation medications. This single-center study suggests a need for harmonization of current guidelines espoused by professional societies.