Relationship of Antenna Work and Ablation Cavity Volume Following Percutaneous Microwave Ablation of Hepatic Tumors

PurposeTo formulate a statistical model relating ablation time, power, and work with posttreatment cavity volume following percutaneous microwave ablation of hepatic tumors in vivo.Materials and MethodsA retrospective review (October 2015 to October 2018) yielded 122 hepatic tumors treated with microwave ablation. Ablation cavity dimensions were measured at 1-month follow-up examination and calculated using an ellipsoid volume formula. The antenna manufacturer (Neuwave Medical, Madison, Wisconsin) provided the activation time and energy used to calculate the antenna work. Generalized estimating equations with ordinary least-squares regression models were obtained to relate tumor volume with cumulative antenna work. Coefficient of determination (R²) and mean square error were used as statistical measures of model prediction performance.ResultsThere is a logarithmic relationship between postablation cavity volume (cm³) and cumulative work (kJ), represented by the formula: log₁₀ cm³ = ?0.4583 + 0.9887 × cumulative work (log10 kJ) (R² = 0.41, mean square error, 0.102). Ablation volumes were predicted as a function of antenna work, calculated using an antilog transformation. When a single antenna was used, ablation cavity volume was predicted using a generalized estimating equation ordinary least-squares regression model of power and time: log₁₀cm³= ?0.0546 + 0.0485 × total time (min) + 0.0107 × power (W) (R² = 0.30; mean square error, 0.106). Using this model, a nomogram was developed to predict the postablation cavity volume based on total activation time and target power.ConclusionThere is a logarithmic relationship between the ablation work and posttreatment ablation cavity volume, which can be expressed in a nomogram when using a single probe.     

Computed Tomography‒Guided Microwave Ablation Combined with Osteoplasty for the Treatment of Bone Metastases: A Multicenter Clinical Study

PurposeTo evaluate the efficacy and safety of combined microwave ablation (MWA) and osteoplasty as a palliative therapy for painful bone metastases.Materials and MethodsAs an extension of a previous limited single-center study, a retrospective review was conducted for 147 patients (77 male, 70 female) with painful bone metastases who underwent MWA combined with osteoplasty. In total, 102 (69.4%), 41 (27.9%), and 4 (2.7%) patients had spinal metastases, extraspinal metastases, and both, respectively. Treatment efficacy was determined by comparing visual analog scale (VAS) scores, daily morphine equivalent opioid consumption, and Oswestry disability index (ODI) scores before treatment and during the follow-up period (mean follow-up, 9.8 months; range 3–16).ResultsThe mean VAS score significantly declined from 6.4 ± 2.3 before treatment to 3.2 ± 2.1, 1.9 ± 1.6, 1.8 ± 1.6, 1.8 ± 1.6, and 1.9 ± 1.6 at 24 hours, 1 week, 4 weeks, 12 weeks, and 24 weeks after treatment, respectively (P < .01). Furthermore, the mean daily morphine equivalent opioid consumption was significantly reduced from 81.5 ± 32.8 mg before treatment to 40.0 ± 20.6, 32.4 ± 10.2, 26.4 ± 10.0, 21.5 ± 8.3, and 19.3 ± 7.4 mg. The mean ODI score also declined after treatment (P < .0001). Major complications occurred in 4 of 147 patients, with 1 pathologic fracture, 1 nerve injury, and 2 mild skin infections. Minor cement leakages were observed at 69 sites (32.8%).ConclusionsMWA combined with osteoplasty is an effective and safe treatment for painful bone metastases.     

Creation of an Ex Vivo Renal Perfusion Model to Investigate Microwave Ablation

This study hypothesized that an ex vivo renal perfusion model can create smaller microwave ablation (MWA) measurements during perfused states compared with nonperfused states across multiple device settings. Nine bovine kidneys, a fluoroscopic compatible perfusion model, and a commercially-available clinical MWA system were used to perform 72 ablations (36 perfused and 36 nonperfused) at 9 different device settings. Comparing perfused and nonperfused ablations at each device setting, significant differences in volume existed for 6 of 9 settings (P < .05). Collapsed across time settings, the ablation volumes by power were the following (perfused and nonperfused, P value): 60 W, 2.3 cm³ ± 1.0 and 7.2 cm³ ± 2.7, P < .001; 100 W, 5.4 cm³ ± 2.1 and 11.5 cm³ ± 5.6, P < .01; and 140 W, 11.2 cm³ ± 3.7 and 18.7 cm³ ± 6.3, P < .01. Applied power correlated with ablation volume: perfused, 0.021 cm³/W and R = 0.462, P = .004, and nonperfused, 0.029 cm³/W and R = 0.565, P < .001. These results support that an ex vivo perfused organ system can evaluate MWA systems and demonstrate heat sink perfusion effects of decreased ablation size.     

Combination of Microwave Ablation and Percutaneous Osteoplasty for Treatment of Painful Extraspinal Bone Metastasis

PurposeTo evaluate the efficacy and safety of microwave (MW) ablation combined with percutaneous osteoplasty (POP) on painful extraspinal bone metastases.Materials and MethodsIn this retrospective study, 50 adult patients with 56 extraspinal bone metastasis lesions, who suffered from refractory moderate to severe pain, were treated with MW ablation and POP. Changes in quality of life were evaluated based on the Visual Analog Scale (VAS), daily morphine consumption, and the Oswestry Disability Index (ODI) before and immediately after the procedure and during follow-up times.ResultsTechnical success was achieved in all patients. Mean preoperative VAS score and morphine dose were 7.0 ± 2.6 (range, 3–10) and 66.7 ± 33.2 mg (range, 10–120 mg), respectively. Mean postoperative VAS scores and daily morphine doses were as follows: 1 day, 3.5 ± 2.1 and 36.1 ± 25.8 mg (P < .05); 1 week, 1.5 ± 1.7 and 12.2 ± 14.8 mg (P < .001); 1 month, 0.9 ± 1.4 and 5.7 ± 10.0 mg (P < .001); and 3 months, 0.6 ± 1.2 and 4.7 ± 8.4 mg (P < .001). A significant decrease in the ODI score was also observed (P < .05). Periprocedural death was not observed. A pathologic fracture occurred in 1 (2%) patient with femoral metastasis, and local infection was observed in 2 (4%) patients. Minor cement leakage occurred in 4 (8%) patients with no symptomatic or intra-articular extravasation. No local tumor progression occurred in patients with imaging follow-up.ConclusionsMW ablation combined with POP is an effective and safe treatment for painful extraspinal bone metastases, which can significantly relieve pain and improve quality of life.     

Hypertensive Crisis during Microwave Ablation of Adrenal Neoplasms: A Retrospective Analysis of Predictive Factors

PurposeTo identify risk factors for hypertensive crisis (HC) during ultrasound-guided percutaneous microwave (MW) ablation of adrenal neoplasms.Materials and MethodsPatients who underwent MW ablation for adrenal tumors between April 2006 and November 2017 were retrospectively identified for this study (51 consecutive patients; 35 males, 16 females; mean age, 55 years; range, 15–85 years). A total of 77 MW ablation treatments were performed for 67 tumors (24 primary [9 pheochromocytomas, 8 adenomas, and 7 cortical carcinomas]; and 43 metastases [22 hepatocellular carcinoma, 8 renal cell carcinoma, 5 non-small cell lung cancer, 4 colorectal cancer, 3 liposarcoma, and 1 malignant fibrous histiocytoma]). The mean diameter of the adrenal tumors was 4.6 cm (range, 1.2–16.2 cm). Information about patient demographics, imaging studies, pathology and laboratory results, procedure records, and clinical outcomes was retrieved and analyzed. Statistical analysis was then performed to determine potential risk factors for HC.ResultsOf the 77 MW ablation procedures, HC occurred in 13 (16.9%). A significantly higher risk of HC was observed in patients with pheochromocytoma (odds ratio [OR], 9.037; 95% confidence interval [CI], 1.731–47.172; P = .009), body mass index <24 kg/m² (OR, 5.167; 95% CI, 1.060–25.194; P = .042), dominant tumor size ≤4.5 cm (OR, 4.023; 95% CI, 1.011–16.005; P = .048), and pre-procedural systolic blood pressure ≥130 mmHg (OR, 0.242; 95% CI, 0.068–0.861; P = .029).ConclusionHC can occur during MW ablation in patients with either primary or metastatic adrenal tumors. Pheochromocytoma, body mass index, tumor size, and pre-procedural systolic blood pressure appear to be significant risk factors for the occurrence of HC.     

Ablation of Cervical Lymph Nodes in Patients with Thyroid Cancer: A Comparison between Cryoablation and Percutaneous Ethanol Injection

The purpose of this study was to retrospectively evaluate the safety and efficacy of cryoablation and compare the outcomes with those of percutaneous ethanol injection (PEI) for the treatment of metastatic cervical lymph nodes (CLNs) in patients with thyroid cancer. The study included 24 patients with 47 CLNs treated with PEI and 7 patients with 11 CLNs treated with cryoablation. Three of 7 (42.9%) patients did not respond to PEI and progressed to cryoablation. There were more local recurrences in CLNs treated with PEI (7/47, 14.9%) compared with cryoablation (0/11, 0%), but this did not reach significance (P = .33). There was no difference in mild/moderate (3/24, 12.5% vs 2/7, 28.6%; P = .31) or severe (1/24, 4.2% vs 0/7, 0%; P = 1) adverse events in the PEI and cryoablation cohorts. The number of treatments required for CLNs treated with PEI (2 ± 1.1) was significantly greater than those for CLNs treated with cryoablation (1 ± 0) (P = .002). These limited data suggest that the treatment of metastatic CLNs with cryoablation or PEI may both be safe and effective; however, further data are needed to confirm superiority of cryoablation.     

External Validation of the Percutaneous Renal Ablation Complexity Scoring System in Patients Undergoing Percutaneous Cryoablation or Microwave Ablation of Renal Tumors

PurposeTo assess the ability of the Percutaneous Renal Ablation Complexity (P-RAC) scoring system to predict procedural complexity or adverse events (AEs) in adult patients undergoing percutaneous thermal ablation of renal tumors.Materials and MethodsA retrospective review of 240 consecutive adult patients who underwent percutaneous thermal renal ablation from 2004 to 2018 was conducted. The P-RAC score was calculated for each renal tumor and procedural complexity recorded. A correlation coefficient was calculated for the P-RAC score and both the number of probes used and procedural duration. Receiver operating characteristic curves assessed the score’s ability to predict the use of adjunctive techniques and/or major AEs, classified according to the Society of Interventional Radiology guidelines.ResultsFor the entire cohort, there was a weak correlation between P-RAC scores and both the number of probes used (r = 0.31; P < .001) and procedural duration (r = 0.18; P = .03). When evaluating only patients treated with microwave ablation (MWA), no correlation between P-RAC scores and either the number of probes (P = .7) used or procedural duration (P = .4) was found. The area under the curve (AUC) for the P-RAC score to predict the use of adjunctive techniques was 0.55 and 0.53 for the entire cohort and MWA group, respectively. The AUC for the P-RAC score to predict major AEs was 0.70, 0.71, and 0.73 for the entire cohort, MWA group, and cryoablation group, respectively.ConclusionsThe P-RAC scoring system is limited in its ability to predict percutaneous thermal renal tumor ablation procedural complexity, especially in patients treated with MWA. The scoring system may have a role in identifying patients at risk of major AEs.     

Microwave Ablation versus Stereotactic Body Radiotherapy for Stage I Non–Small Cell Lung Cancer: A Cost-Effectiveness Analysis

PurposeTo assess the cost effectiveness of microwave ablation (MWA) and stereotactic body radiotherapy (SBRT) for patients with inoperable stage I non–small cell lung cancer (NSCLC).Materials and MethodsA literature search was performed in MEDLINE with broad search clusters. A decision-analytic model was constructed over a 5-year period. The model incorporated treatment-related complications and long-term recurrence. All clinical parameters were derived from the literature with preference to long-term prospective trials. A healthcare payers’ perspective was adopted. Outcomes were measured in quality-adjusted life years (QALYs) extracted from prior studies and U.S. dollars from Medicare reimbursements and prior studies. Base case calculations, probabilistic sensitivity analysis with 10,000 Monte Carlo simulations, and multiple 1- and 2-way sensitivity analyses were performed.ResultsMWA yielded a health benefit of 2.31 QALYs at a cost of $195,331, whereas SBRT yielded a health benefit of 2.33 QALYs at a cost of $225,271. The incremental cost-effectiveness ratio was $1,480,597/QALY, indicating that MWA is the more cost-effective strategy. The conclusion remains unchanged in probabilistic sensitivity analysis with MWA being the optimal cost strategy in 99.84% simulations. One-way sensitivity analyses revealed that MWA remains cost effective when its annual recurrence risk is <18.4% averaged over 5 years, when the SBRT annual recurrence risk is >1.44% averaged over 5 years, or when MWA is at least $7,500 cheaper than SBRT.ConclusionsMWA appears to be more cost effective than SBRT for patients with inoperable stage I NSCLC.     

4D Flow MR Imaging to Improve Microwave Ablation Prediction Models: A Feasibility Study in an In Vivo Porcine Liver

PurposeTo characterize the effect of hepatic vessel flow using 4-dimensional (4D) flow magnetic resonance (MR) imaging and correlate their effect on microwave ablation volumes in an in vivo non-cirrhotic porcine liver model.Materials and MethodsMicrowave ablation antennas were placed under ultrasound guidance in each liver lobe of swine (n = 3 in each animal) for a total of 9 ablations. Pre- and post-ablation 4D flow MR imaging was acquired to quantify flow changes in the hepatic vasculature. Flow measurements, along with encompassed vessel size and vessel-antenna spacing, were then correlated with final ablation volume from segmented MR images.ResultsThe linear regression model demonstrated that the preablation measurement of encompassed hepatic vein size (β = –0.80 ± 0.25, 95% confidence interval [CI] –1.15 to –0.22; P = .02) was significantly correlated to final ablation zone volume. The addition of hepatic vein flow rate found via 4D flow MRI (β = –0.83 ± 0.65, 95% CI –2.50 to 0.84; P = .26), and distance from antenna to hepatic vein (β = 0.26 ± 0.26, 95% CI –0.40 to 0.92; P = .36) improved the model accuracy but not significantly so (multivariate adjusted R² = 0.70 vs univariate (vessel size) adjusted R² = 0.63, P = .24).ConclusionsHepatic vein size in an encompassed ablation zone was found to be significantly correlated with final ablation zone volume. Although the univariate 4D flow MR imaging-acquired measurements alone were not found to be statistically significant, its addition to hepatic vein size improved the accuracy of the ablation volume regression model. Pre-ablation 4D flow MR imaging of the liver may assist in prospectively optimizing thermal ablation treatment.     

Computed Tomography-Guided Microwave Ablation of Cystic Renal Cell Carcinoma: Assessment of Technique and Complications

This report evaluates the techniques and complications of microwave ablation of cystic renal cell carcinoma. Five patients with cystic renal cell carcinoma were treated with microwave ablation between October 2015 and June 2020. Medical records were reviewed to evaluate technique and complications. Technical success and primary technique efficacy both were 100%. There were no complications. Mean follow-up time was 18 months (range, 6–36 months). No local recurrence was identified during the follow-up period. Renal function remained stable at 1 month and the last follow-up. Percutaneous microwave ablation is promising for the nonsurgical management of cystic renal cell carcinoma.     

Safety and Efficacy of Radiofrequency Ablation for Nonfunctioning Benign Thyroid Nodules in Children and Adolescents in 14 Patients over a 10-Year Period

PurposeTo evaluate the efficacy and safety of radiofrequency (RF) ablation for nonfunctioning benign thyroid nodules in children and adolescents.Materials and MethodsFourteen pediatric patients (10 female, 4 male; mean age 15.7 ± 2.3 years, range 12–19 years) with nonfunctioning benign thyroid nodules (mean longest diameter 3.7 ± 1.1 cm, range 2.0–5.6 cm) treated with the use of RF ablation from 2005 to 2015 were evaluated. The inclusion criteria for RF ablation therapy were (i) age <20 years, (ii) benign cytological confirmation by ≥2 separate fine-needle aspiration or core needle biopsies, (iii) pressure symptoms or cosmetic problems caused by thyroid nodules, (iv) absence of any suspicious feature as determined with the use of ultrasound (US), (v) normal serum levels of thyroid hormone and thyrotropin, and (vi) follow-up of >6 months. RF ablation was performed with the use of an RF generator and an 18-gauge internally cooled electrode. RF ablation was performed under local anesthesia without conscious sedation or general anesthesia. Changes in nodules on follow-up US, changes in symptomatic and cosmetic scores, and complications arising during or after RF ablation were evaluated.ResultsMean follow-up period was 36.9 ± 21.7 months (range 6–69 months). At last follow-up visits, mean longest nodule diameter and volume had decreased significantly (3.7 ± 1.1 cm vs 1.4 ± 0.9 cm and 14.6 ± 13.3 mL vs 1.7 ± 4.4 mL; P < 0.001). Both cosmetic and compressive symptoms significantly improved (3.8 ± 0.6 vs 1.4 ± 0.6 and 3.4 ± 1.0 vs 0.1 ± 0.4; P < 0.001). The mean number of ablation sessions was 2.1 ± 1.2 (range 1–5 sessions) and no major complication was encountered during or after RF ablation.ConclusionsRF ablation might be a safe and effective treatment modality for nonfunctioning benign thyroid nodules in children and adolescents.     

Microwave Ablation as Bridging to Liver Transplant for Patients with Hepatocellular Carcinoma: A Single-Center Retrospective Analysis

PurposeTo evaluate the efficacy and safety of microwave (MW) ablation as first-line locoregional therapy (LRT) for bridging patients with hepatocellular carcinoma (HCC) to liver transplant.Materials and MethodsThis retrospective study evaluated 88 patients who received percutaneous MW ablation for 141 tumors as first-line LRT for HCC and who were listed for liver transplantation at a single medical center between 2011 and 2019. The overall survival (OS) rate statuses after liver transplant, waitlist retention, and disease progression were evaluated using the Kaplan-Meier techniques.ResultsAmong the 88 patients (72 men and 16 women; mean age, 60 years; Model for End-Stage Liver Disease score, 11.2) who were listed for transplant, the median waitlist time was 9.4 months (interquartile range, 5.5–18.9). Seventy-one (80.7%) patients received transplant after a median waitlist time of 8.5 months. Seventeen (19.3%) patients were removed from the waitlist; of these, 4 (4.5%) were removed because of tumors outside of the Milan criteria (HCC-specific dropout). No difference in tumor size or alpha-fetoprotein was observed in the transplanted versus nontransplanted patients at the time of ablation (2.1 vs 2.1 cm and 34.4 vs 34.7 ng/mL for transplanted vs nontransplanted, respectively; P > .05). Five (5.1%) of the 88 patients experienced adverse events after ablation; however, they all recovered. There were no cases of tract seeding. The local tumor progression (LTP) rate was 7.2%. The OS status after liver transplant at 5 years was 76.7%, and the disease-specific survival after LTP was 89.6%, with a median follow-up of 61 months for all patients.ConclusionsMW ablation appears to be safe and effective for bridging patients with HCC to liver transplant without waitlist removal from seeding, adverse events, or LTP.     

A Comparative Study of Cavitary and Noncavitary Non–small Cell Lung Cancer Patients Treated with CT-Guided Microwave Ablation

PurposeTo explore the outcomes of computed tomography‒guided microwave (MW) ablation in patients with cavitary non–small cell lung cancer (NSCLC) and to compare the outcomes of cavitary and noncavitary NSCLC treated with MW ablation.Materials and MethodsA total of 317 patients with NSCLC (194 men and 123 women) treated with MW ablation were include: 19 patients with cavitary NSCLC and 298 patients with noncavitary NSCLC. Complications, progression-free survival (PFS), and overall survival (OS) were evaluated and compared between the 2 groups. The Kaplan-Meier method was used to investigate the correlation of cavity and OS in patients with NSCLC.ResultsA total of 364 MW ablation procedures were performed. Adenocarcinoma was the predominant histopathological subtype in patients with cavitary NSCLC (73.7%). Cavitary NSCLC had an incidence rate of 57.9% in overall complications, which was significantly higher than that of 34.6% for noncavitary NSCLC (P = .040). In a mean follow-up of 27.2 months ± 11.9, the median PFS and OS for cavitary NSCLC were 9.0 months ± 8.5 and 14.0 months ± 10.8, respectively, and those for noncavitary NSCLC were 13.0 months ± 10.7 and 17.0 months ± 10.9, respectively. There was no significant difference in PFS (P = .180) or OS (P = .133) between cavitary and noncavitary NSCLC. In addition, the local recurrence rates for cavitary and noncavitary NSCLC were 15.8% and 21.5%, respectively, and no significant difference was found (P = .765). The Kaplan-Meier method revealed no association between the cavity and OS in patients with NSCLC treated with MW ablation.ConclusionsMW ablation was an effective and safe approach for cavitary NSCLC treatment. Compared with noncavitary NSCLC, cavitary NSCLC manifested with more complications but a comparable outcome after MW ablation.     

Radiofrequency Ablation for the Palliative Treatment of Bone Metastases: Outcomes from the Multicenter OsteoCool Tumor Ablation Post-Market Study (OPuS One Study) in 100 Patients

PurposeTo evaluate the effectiveness of radiofrequency (RF) ablation as measured by change in worst pain score from baseline to 3 mo after RF ablation for the palliative treatment of painful bone metastases.Materials and MethodsOne hundred patients (mean age, 64.6 y) underwent RF ablation for metastatic bone disease and were followed up to 6 mo. Subjects’ pain and quality of life were measured before RF ablation and postoperatively by using the Brief Pain Index and European Quality of Life questionnaires. Opioid agent use and device-, procedure-, and/or therapy-related adverse events (AEs) were collected.ResultsEighty-seven patients were treated for tumors involving the thoracolumbar spine and 13 for tumors located in the pelvis and/or sacrum. All ablations were technically successful, and 97% were followed by cementoplasty. Mean worst pain score decreased from 8.2 ± 1.7 at baseline to 3.5 ± 3.2 at 6 mo (n = 22; P < 0.0001 for all visits). Subjects experienced significant improvement for all visits in average pain (P < .0001), pain interference (P < .0001), and quality of life (P < .003). Four AEs were reported, of which 2 resulted in hospitalization for pneumonia and respiratory failure. All 30 deaths reported during the study were attributed to the underlying malignancy and not related to the study procedure.ConclusionsResults from this study show rapid (within 3 d) and statistically significant pain improvement with sustained long-term relief through 6 mo in patients treated with RF ablation for metastatic bone disease.     

Radiofrequency Ablation for Benign Symptomatic Thyroid Nodules in the Netherlands: Successful Introduction of a Minimally Invasive Treatment Option Improving Quality of Life

PurposeTo determine whether adoption of radiofrequency (RF) ablation in patients with symptomatic benign thyroid nodules (SBTNs) in a Dutch regional thyroid network resulted in clinical success and improvement in health-related and thyroid-related quality of life (QoL).Materials and MethodsThe eligibility criteria for RF ablation were as follows: (a) nodule size between 2.0 and 5.0 cm, (b) solid component >20%; (c) benign cytology in 2 separate cytological assessments, and (d) symptoms unequivocally related to mechanical compression. The primary end point of this study was volume reduction 1 year after ablation. The secondary outcomes were health-related and thyroid-related QoL, measured using the short form health survey questionnaire (SF-36) and thyroid-specific patient-reported outcome questionnaire (ThyPRO-39), respectively, as well as adverse event rates.ResultsA total of 72 SBTNs in 67 patients were included. Median age was 50.0 (interquartile range, 41.0–56.0) years, and 91.0% were women. The median volume reduction at 6 weeks, 6 months, 1 year, 2 years, and 3 years was 51.0%, 63.9%, 65.2%, 81.3%, and 90.3%, respectively. The patients showed a significant improvement on the SF-36 physical component scale and ThyPRO-39 overall QoL-impact scale. An absolute improvement was seen in goiter and cosmetic complaints, determined using ThyPRO-39. The overall adverse event rate was 9.0%, of which 4.5% were considered major.ConclusionsRF ablation is an effective treatment option for SBTNs, with a significant volume reduction and improvement in health-related and thyroid-related QoL.     

Dual-Applicator MR Imaging–Guided Microwave Ablation with Real-Time MR Thermometry: Phantom and Porcine Tissue Model Experiments

PurposeTo investigate the effect of simultaneous use of dual applicators on the image quality of real-time magnetic resonance (MR) thermometry and to characterize the dual-applicator treatment zone pattern during MR imaging–guided microwave ablation (MWA).Materials and MethodsMWA experiments were performed on a 1.5-T MR scanner with 2 commercial microwave systems (902–928 MHz). Phantom experiments were first performed to evaluate the effect of dual-applicator MWA on the image quality of MR. Then, porcine tissue model experiments were conducted with real-time MR thermometry using either a single applicator or dual applicators inserted 2.6, 3.6, and 4.6 cm apart. Fiberoptic thermal probes were used to measure the temperature changes at the tissue surface.ResultsSimultaneous use of dual applicators resulted in a decrease in the relative signal-to-noise ratio (SNR) in the MR thermometry images to 55% ± 2.9% when compared with that of a single applicator (86.2% ± 2.0%). Despite the lower SNR, the temperature and ablation zone maps were of adequate quality to allow visualization of the ablation zone(s). The extents of increase in the temperature at the tissue surface using dual applicators (19.7 °C ± 2.6 °C) and a single applicator (18.2 °C ± 3.3 °C) were not significantly different (P = .40). Treatment zones were significantly larger (P < .05) in dual-applicator ablations (29.4 ± 0.4, 39.9 ± 0.6, and 42.6 ± 0.9 cm² with 2.6-, 3.6-, and 4.6-cm spacing, respectively) at the end of the ablation procedure than in the single-applicator MWA (18.6 ± 0.9 cm²).ConclusionsMR imaging–guided dual-applicator MWA produced larger ablation zones while allowing adequate real-time MR thermometry image quality for monitoring the evolution of the treatment zone.     

Radiofrequency Ablation,Cryoablation, and Microwave Ablation for T1a Renal Cell Carcinoma: A Comparative Evaluation of Therapeutic and Renal Function Outcomes

PurposeTo compare the therapeutic and renal function outcomes of radiofrequency (RF) ablation, cryoablation, and microwave (MW) ablation for treatment of T1a renal cell carcinoma (RCC).Materials and MethodsA retrospective assessment of 297 patients (mean age 72 years range 24–90 years) with biopsy-proven RCC treated with image-guided percutaneous thermal ablation was performed between October 2006 and December 2016. Mean tumor size was 2.4 cm; mean radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, hilar tumor touching the main renal artery or vein, and location relative to polar lines; Preoperative Aspects and Dimensions Used for an Anatomical; and c-centrality scores were 6.0, 7.0, and 2.8, respectively. Assessments of adverse events, treatment efficacy, and therapeutic outcomes were performed among RF ablation, cryoablation, and MW ablation. The 2-year disease-free, metastatic-free, and cancer-specific survival rates were tabulated. Estimated glomerular filtration rate was used to assess for treatment related changes in renal function.ResultsA total of 297 T1aN0M0 biopsy-proven RCCs measuring 1.2–3.9 cm were treated with computed tomography–guided RF ablation (n = 244, 82%), cryoablation (n = 26, 9%), and MW ablation (n = 27, 9%). There were no significant differences in patient demographics among the 3 groups (P = .09). Technical success rates were similar among the 3 treatments (P = .33). Primary efficacy at 1 month postablation was more likely to be achieved with RF ablation and MW ablation than with cryoablation. At 2 years’ follow-up, there was no local recurrence, metastatic progression, or RCC-related death observed in the 3 groups. There was no significant change in estimated glomerular filtration rate among the 3 ablation groups compared with baseline at 2-year follow-up (P = .71).ConclusionRF ablation, cryoablation, and MW ablation are equivalent at 2 years for treatment of T1a RCC for therapeutic outcome, stability of renal function, and low adverse event rate.     

Ablation Therapy for Advanced Stage Non-Small Cell Lung Cancer: A National Cancer Database Study

PurposeTo compare overall survival (OS) of ablation with no treatment for patients with advanced stage non-small cell lung cancer.MethodsPatients with clinical stage IIIB (T_1–4N₃M₀, T₄N₂M₀) and stage IV (T_1–4N_0–3M₁) non-small cell lung cancer, in accordance with the American Joint Committee on Cancer, 7th edition, who did not receive treatment or who received ablation as their sole primary treatment besides chemotherapy from 2004 to 2014, were identified from the National Cancer Data Base. OS was estimated using the Kaplan-Meier method and evaluated by log-rank test, univariate and multivariate Cox proportional hazard regression, and propensity score-matched analysis. Relative survival analyses comparing age- and sex-matched United States populations were performed.ResultsA total of 140,819 patients were included. The 1-, 2-, 3- and 5-year survival rates relative to age- and sex-matched United States population were 28%, 18%, 12%, and 10%, respectively, for ablation (n = 249); and 30%, 15%, 9%, and 5%, respectively for no treatment (n = 140,570). Propensity score matching resulted in 249 patients in the ablation group versus 498 patients in the no-treatment group. After matching, ablation was associated with longer OS than that in the no-treatment group (median, 5.9 vs 4.7 months, respectively; hazard ratio, 0.844; 95% confidence interval, 0.719–0.990; P = .037). These results persisted in patients with an initial tumor size of ≤3 cm.ConclusionsPreliminary results suggest ablation may be associated with longer OS in patients with late-stage non-small cell lung cancer than survival in those who received no treatment.     

Utility of the RENAL Nephrometry Scoring System in Predicting Adverse Events and Outcomes of Percutaneous Microwave Ablation of Renal Tumors

PurposeTo assess the utility of the radius, exophytic/endophytic, nearness to collecting system or sinus, anterior/posterior, and location relative to polar lines (RENAL) nephrometry scoring system at predicting adverse events and outcomes in percutaneous microwave ablation (MWA) of renal tumors.Materials and MethodsA retrospective review of 116 patients who underwent MWA from 2004 to 2018 at 2 large university hospitals was conducted. Patient demographics and tumor characteristics were collected. The RENAL nephrometry scores were calculated, and procedure-related adverse events were stratified into minor and major (the Society of Interventional Radiology classification of class C or higher). Technical and oncologic outcomes were based on follow-up magnetic resonance imaging and computed tomography scans after ablation.ResultsThe mean RENAL score was 6.6 (range, 4–11), and the mean tumor size was 24 mm. Follow-up ranged between 16 and 161 weeks (median, 50 weeks; mean, 65 weeks). Oncologic control was achieved in 96% (n = 111) of patients. The major and minor adverse event rates were 8.6% (n = 10) and 17% (n = 19), respectively. The mean RENAL score for patients with recurrent and/or residual tumor (8.2 ± 2.7) was higher than that for patients without disease recurrence (6.5 ± 3.5, P = .05). However, in a multivariate analysis, the RENAL score was not found to be an independent predictor of oncologic outcomes (odds ratio, 1.548; P = .092).ConclusionsThe RENAL nephrometry score has minimal utility for predicting outcomes and adverse events in MWA of renal tumors. The inconsistent nature of RENAL nephrometry scoring in percutaneous ablation procedures underscores the need for an ablation-specific risk stratification system.     

Long-term Outcomes of Patients with Hepatocellular Carcinoma Who Underwent Microwave Ablation after Downstaging with Transarterial Chemoembolization to Barcelona Clinic Liver Cancer Stage A

PurposeTo compare the clinical results of microwave ablation (MWA) between patients downstaged to Barcelona Clinic Liver Cancer (BCLC) Stage A with transarterial chemoembolization (TACE) and those initially classified as BCLC Stage A.Materials and MethodsFrom January 2012 to May 2017, 1,087 patients were reviewed retrospectively using propensity score matching (1:1): 86 patients underwent MWA as a curative treatment after downstaging to BCLC Stage A by TACE (downstaging group) and 86 patients initially classified as BCLC Stage A underwent MWA (control group). The overall survival (OS) and disease-free survival (DFS) between the 2 groups were compared.ResultsThe 1-, 3-, and 5-year OS rates were 95.3%, 79.1%, and 58.1%, respectively, in the downstaging group and 93.0%, 81.4%, and 61.6%, respectively, in the control group (hazard ratio [HR], 0.75; 95% CI, 0.50–1.13; P = .162). The 1-, 3-, and 5-year DFS rates were 80.2%, 50.0%, and 24.4%, respectively, in the downstaging group and 77.9%, 52.3%, and 27.9%, respectively, in the control group (HR, 1.08; 95% CI, 0.76–1.53; P = .678). No significant differences were found in OS and DFS.ConclusionsThe long-term prognosis in patients with HCC who underwent MWA after downstaging to BCLC Stage A using TACE was similar to that in patients with initial BCLC Stage A.