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The risk of electromagnetic interference between microwave (MW) ablation and cardiac implantable electronic devices (CIEDs), ie, pacemakers and defibrillators, has not been fully evaluated. Fourteen MW ablations (kidney, n = 8; liver, n = 5; lung, n = 1) were performed in 13 patients with CIEDs in normal operating mode. Electrocardiography tracings, cardiovascular complications, tumor size, tumor-to-CIED distance, and tumor-to-device lead distance were recorded. Mean tumor size was 2.9 cm, mean tumor-to-CIED distance was 26.4 cm (range, 9–30 cm), and mean tumor-to-lead distance was 12.1 cm (range, 3.5–20 cm). No device-based cardiovascular complications or class C or higher complications per Society of Interventional Radiology criteria were identified. MW ablation appears to be safe in select patients with CIEDs.

Purpose To determine the feasibility of using time-resolved 3D-digital subtraction angiography (4D-DSA) for quantifying changes in hepatic arterial blood flow and velocity during transarterial embolization. Materials and Methods Hepatic arteriography and selective transarterial embolization were performed in 4 female domestic swine (mean weight, 54 kg) using 100–300-μm microspheres. Conventional 2D and 4D-DSA were performed before, during, and after each embolization. From the 4D-DSA reconstructions, blood flow and velocity values were calculated for hepatic arterial branches using a pulsatility-based algorithm. 4D-DSA velocity values were compared to those measured using an intravascular Doppler wire with a linear regression analysis. Paired t-tests were used to compare data before and after embolization. Results There was a weak-to-moderate but statistically significant correlation of flow velocities measured with 4D-DSA and the Doppler wire (r = 0.35, n = 39, P = .012). For vessels with high pulsatility, the correlation was higher (r = 0.64, n = 11, P = .034), and the relationship between 4D-DSA and the Doppler wire fit a linear model with a positive bias toward the Doppler wire (failed to reject at 95% confidence level, P = .208). 4D-DSA performed after partial embolization showed a reduction in velocity in the embolized hepatic arteries compared to pre-embolization (mean, 3.96 ± 0.74 vs 11.8 2± 2.15 cm/s, P = .006). Conclusion Quantitative 4D-DSA can depict changes in hepatic arterial blood velocity during transarterial embolization in a swine model. Further work is needed to optimize 4D-DSA acquisitions and to investigate its applicability in humans.

Purpose To evaluate safety and efficacy of percutaneous hepatic microwave (MW) ablation performed near the heart. Materials and Methods This study reviewed 118 consecutive peripheral (ablation zone margins within 5 mm of liver capsule) percutaneous MW hepatic ablations performed between June 2010 and August 2015. Ablation zones of 27 tumors (22.8%) extended to ≤ 5 mm from myocardium, and these ablations comprised the study group; the remaining ablations formed the control group. The study cohort included 14 men and 10 women (mean age, 59 y) with 16 hepatocellular carcinomas, 9 metastases, and 2 hemangiomas. Periprocedural imaging was used to evaluate tumor size and distance from the heart, ablation zone size, and complications. Mean tumor size and distance to myocardium were 2.6 cm ± 1.7 and 1.1 cm ± 1.1, respectively. The electronic medical record was used to retrospectively assess local tumor progression (LTP) and electrocardiogram and hemodynamic alterations during and after ablation. Statistical analysis was performed with Fisher exact test and t test. Results Median follow-up was 13.6 months (range, 1.2–38.7 months). No arrhythmias occurred during or after ablation in the follow-up period (0/27). There was no difference between groups in frequency of alterations in periprocedural blood pressure (25.9% vs 29.6%, p=0.81) or heart rate (18.5% vs 24.2%, P = .61) or rate of LTP (12.0% vs 10.8%, P = 1.0). Conclusions Percutaneous MW ablation near the heart may be safe and effective, without increased risk of cardiac complications and with similar rates of LTP, compared with a control group of peripheral liver ablations.

Purpose To retrospectively review the results of hepatocellular carcinoma (HCC) treatment with a high-power, gas-cooled, multiantenna-capable microwave device. Materials and Methods A total of 107 HCCs in 75 patients (65 men) with a mean age of 61 years (range, 44–82 y) were treated via percutaneous approach. Combination microwave ablation and transarterial chemoembolization was performed for 22 tumors in 19 patients with tumors larger than 4 cm (n = 10), tumors larger than 3 cm with ill-defined margins (n = 7), or lesions not identified with ultrasonography (n = 5). Mean tumor size was 2.1 cm (range, 0.5–4.2 cm), with median follow-up of 14 months, for ablation alone; compared with 3.7 cm (range, 1.0–7.0 cm) and 12 months, respectively, for combination therapy. All procedures were performed with a single microwave system (Certus 140) with one to three 17-gauge antennas. Results Mean ablation time was 5.3 minutes (range, 1–11.5 min). All treatments were considered technically successful in a single session. Primary technique effectiveness rates were 91.6% (98 of 107) overall, 93.7% (89 of 95) for tumors 4 cm or smaller, and 75.0% (nine of 12) for tumors larger than 4 cm; and 91.8% (78 of 85) for ablation alone and 90.9% (20 of 22) for combination therapy. There was no major complication or procedure-related mortality. The overall survival rate was 76.0% at a median 14-month clinical follow-up, with most deaths related to end-stage liver disease (n = 11) or multifocal HCC (n = 5). Conclusions Treating HCC with a gas-cooled, multiantenna-capable microwave ablation device is safe, with promising treatment effectiveness.

Purpose To determine whether microwave ablation with high-power triaxial antennas creates significantly larger ablation zones than radiofrequency (RF) ablation with similarly sized internally cooled electrodes. Materials and Methods Twenty-eight 12-minute ablations were performed in an in vivo porcine kidney model. RF ablations were performed with a 200-W pulsed generator and either a single 17-gauge cooled electrode ( n = 9) or three switched electrodes spaced 1.5 cm apart ( n = 7). Microwave ablations were performed with one ( n = 7), two ( n = 3), or three ( n = 2) 17-gauge triaxial antennas to deliver 90 W continuous power per antenna. Multiple antennas were powered simultaneously. Temperatures 1 cm from the applicator were measured during two RF and microwave ablations each. Animals were euthanized after ablation and ablation zone diameter, cross-sectional area, and circularity were measured. Comparisons between groups were performed with use of a mixed-effects model with P values less than .05 indicating statistical significance. Results No adverse events occurred during the procedures. Three-electrode RF (mean area, 14.7 cm 2 ) and single-antenna microwave (mean area, 10.9 cm 2 ) ablation zones were significantly larger than single-electrode RF zones (mean area, 5.6 cm 2 ; P = .001 and P = .0355, respectively). No significant differences were detected between single-antenna microwave and multiple-electrode RF. Ablation zone circularity was similar across groups ( P > .05). Tissue temperatures were higher during microwave ablation (maximum temperature of 123°C vs 100°C for RF). Conclusions Microwave ablation with high-power triaxial antennas created larger ablation zones in normal porcine kidneys than RF ablation with similarly sized applicators.

Purpose To determine the effect of selective intubation on ablation zone size during pulmonary cryoablation. Materials and Methods Selective bronchial intubation and aeration was performed in three domestic swine. A total of 20 cryoablations (ventilated, n = 10; nonventilated, n = 10) were performed. The animals were immediately sacrificed, and their lungs were removed and sectioned along the axis of ablation in 5-mm intervals. The diameter and area of the ablation zone were recorded, and the isoperimetric ratio (measure of circularity) and estimated volume were calculated. Results There was no significant difference in maximum diameter, minimum diameter, area, circularity, or estimated volume of the ablation zones between the aerated and nonaerated groups (mean diameter, 2.4 cm vs 2.4 cm, respectively, P = .99; area, 4.6 cm 2 vs 4.8 cm 2 , P = .7; circularity, 0.94 vs 0.94, P = .99; estimated volume, 11.5 cm 3 vs 11.3 cm 3 , P = .99). Conclusions In contrast to radiofrequency ablation, selective bronchial intubation did not have a significant effect on the resulting ablation zones. This suggests that selective intubation may not be warranted in the setting of pulmonary cryoablation.