Thermal Ablation of Thyroid Nodules, From the AJR "How We Do It" Special Series.

Ablation has been shown to be an effective option for treatment of well-selected patients with thyroid nodules, particularly benign nodules, and thermal ablation is being increasingly used for this purpose. The general approach to thermal ablation of the thyroid will be familiar to interventional radiologists who perform ablation in other tissues; however, thermal ablation of the thyroid has additional unique considerations. In this review, we provide evidence-based and real-world guidance on the performance of thermal ablation for the treatment of patients with thyroid nodules, drawing on our collective experience and clinical practice. We describe patient selection, ablation modalities, equipment, general procedural approach, additional technical considerations, and postprocedural follow-up. We discuss various clinical scenarios; give tips on performing specific portions of the procedure and highlight a range of relevant anatomic, biochemical, and clinical factors, as a guide for interventional radiologists in establishing a successful thyroid ablation practice.

Fixed-node diffusion Monte Carlo shows promise for modeling reaction thermochemistry of hydrocarbon-based radicals.

Reliable thermodynamic and kinetic properties of free radical polymerization reactions are essential for synthesizing both primary polymeric materials and specialty polymers. The computational generation of these data from quantum chemistry requires a time-efficient method capable of capturing the essential physics. One such method, fixed-node diffusion Monte Carlo (FN-DMC) (using single Slater-Jastrow trial wavefunctions), has demonstrated the capability to recover 90%-95% of missing dynamic correlation energy for typical systems. In this study, methyl radical addition to ethylene serves as a simple model to test FN-DMC's ability to calculate enthalpies of reaction and activation energies with different time steps, antisymmetric trial wavefunctions, basis set sizes, and effective core potentials. The FN-DMC computational protocol thus defined for methyl radical addition to ethylene is subsequently benchmarked against Weizmann-1 and experimental reaction enthalpies from Lin et al.'s test set of 21 radical addition and 28 hydrogen abstraction enthalpies. Our findings reveal that FN-DMC consistently generates reaction enthalpies with chemical accuracy, exhibiting mean absolute deviation of 3.5(7) and 1.4(8) kJ/mol from the Weizmann-1 reference for radical addition and hydrogen abstraction reactions, respectively. Given its favorable computational scaling and high degree of parallelizability, we, therefore, recommend more comprehensive testing of FN-DMC with effective core potentials to address more extensive and intricate polymerization reactions and reactions with other radicals.

Radiofrequency Ablation for Benign Thyroid Nodules: Radiology In Training.

Two patients, one with benign nonfunctioning nodules and one with functioning thyroid nodules, both of whom underwent radiofrequency ablation, are presented. Preprocedural evaluation, procedural considerations, and follow-up care of thyroid radiofrequency ablation, as well as published evidence on the topic, are discussed.

Uterine Fibroid Embolization or Myomectomy: How Much Marketing Is Enough? Comparative Analysis of Public Search Trends in Google and Medical Publications in PubMed.

To compare public popularity and volume of scientific publications regarding uterine fibroid embolization (UFE) and myomectomy. Google Trends and PubMed data were queried to assess temporal variations in online public search volumes and number of research publications for UFE and myomectomy. Time series analysis was used to identify meaningful temporal trends and forecast a future trend. Compared with UFE, myomectomy had significantly higher volumes of public online search and research publications, with an increasing trend over time (P < .0001). The forecasting models predicted a continuing increase in both public search volumes and number of research publications for myomectomy and static future trends in these metrics for UFE. This study signals significantly lower public popularity and research efforts for UFE compared with myomectomy for uterine fibroids. More effective marketing strategies and further research support will be needed to fill this gap.

Double-Barrel Nitinol Stent Placement for Iliocaval Reconstruction: The Effect of Deployment Sequence and Direction on Final Configuration.

Double-barrel stent placement across the iliocaval confluence is commonly used for the treatment of chronic bilateral iliocaval occlusion. The difference in the deployment outcomes of synchronous parallel stent deployment versus asynchronous or antiparallel deployment and the underlying stent interactions are poorly understood. In this study, 3 strategies of double-barrel nitinol self-expanding stent deployment across the iliocaval confluence (synchronous parallel, asynchronous parallel, and synchronous antiparallel) were contrasted in vivo in 3 swine followed by assessment of the explanted stent construct. Synchronous parallel stent deployment achieved a desired double-barrel configuration. The asynchronous parallel and antiparallel deployment strategies both resulted in a crushed stent despite subsequent simultaneous balloon angioplasty. These animal model results suggested that in patients who undergo double-barrel iliocaval reconstruction, synchronous parallel stent deployment may provide the desired stent conformation and increase the chance for clinical success.

Rendezvous Technique for Advanced Pancreatic Duct Interventions.

Interventional radiology can be used to perform complex pancreatic duct (PD) interventions in cases in which PD abnormalities limit the feasibility of an endoscopic approach. A multidisciplinary approach with gastroenterology using the rendezvous technique can improve procedural success. The establishment of through-and-through access to the PD via a combined percutaneous and endoscopic approach can be used when endoscopy alone fails. In this study, 3 cases are presented in which the rendezvous technique was successfully employed to access the PD for subsequent interventions.

Multicenter assessment of augmented reality registration methods for image-guided interventions.

PURPOSE: To evaluate manual and automatic registration times and registration accuracies on HoloLens 2 for aligning a 3D CT phantom model onto a CT grid, a crucial step for intuitive 3D navigation during CT-guided interventions; to compare registration times between HoloLens 1 and 2. METHODS: Eighteen participants in various stages of clinical training across two academic centers performed registration of a 3D CT phantom model onto a CT grid using HoloLens 2. Registration times and accuracies were compared among different registration methods, clinical experience levels, and consecutive attempts. Registration times were also compared retrospectively to prior HoloLens 1 results. RESULTS: Mean aggregate manual registration times were 27.7 s, 24.3 s, and 72.8 s for one-handed gesture, two-handed gesture, and Xbox controller, respectively; mean automatic registration time was 5.3 s (ANOVA p < 0.0001). No significant difference in registration times was found among attendings, residents and fellows, and medical students (p > 0.05). Significant improvements in registration times were detected across consecutive attempts using hand gestures (p < 0.01). Compared to prior HoloLens 1 data, hand gesture registration was 81.7% faster with HoloLens 2 (p < 0.05). Registration accuracies were not significantly different across manual registration methods, measuring at 5.9 mm, 9.5 mm, and 8.6 mm with one-handed gesture, two-handed gesture, and Xbox controller, respectively (p > 0.05). CONCLUSIONS: Manual registration times decreased significantly on HoloLens 2, approaching those of automatic registration and outperforming Xbox controller registration. Fast, adaptive, and accurate registration of holographic models of cross-sectional imaging is paramount for the implementation of augmented reality-assisted 3D navigation during CT-guided interventions.

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

PURPOSE: To 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 METHODS: A 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. RESULTS: There 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. CONCLUSION: There 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.

Analysis of Costs and Payments for Inferior Vena Cava Filter Retrieval in the Medicare Population.

Over the past decade, inferior vena cava (IVC) filter retrieval has been increasing, in part due to Food and Drug Administration recommendations and legal pressure. The costs and margin of IVC filter removal are poorly understood. Medicare claims data from 2016 for the 103 highest volume centers for IVC filter retrieval were examined. Pooled mean charges, costs, payments, and margin were calculated by institution. Mean ± SD charges, costs, and payments were $14,138.00 ± $8,400.48, $3,693.28 ± $2,294.27, and $1,949.82 ± $702.91, respectively. Average (range) margin was -$1,706.18 (-$7,509.93 to $362.77). The margin was negative in 99 of the 103 (96%) institutions evaluated. The most significant contributors to the total procedure cost were operating room, supplies, and recovery (44.5%, 23.5%, and 10.4%, respectively). While IVC filter retrieval is often medically indicated, it is typically associated with a financial loss under current reimbursement structure.

Predictors of All-Cause Mortality after Endovascular Aneurysm Repair: Assessing the Role of Psoas Muscle Cross-Sectional Area.

PURPOSE: To evaluate psoas muscle area (PMA) as a predictor of all-cause mortality after endovascular aneurysm repair (EVAR) and compare it with other predictor variables. MATERIAL AND METHODS: Retrospective review of 407 patients who underwent EVAR over a 7-year period was performed. Demographics, comorbidity variables, and outcomes were collected. Preprocedure computed tomography scans were used to measure the PMA. Descriptive statistics summarized the demographic information and predictor variables. Kaplan-Meier analysis and univariate and multivariate Cox proportional regression analyses were performed. The main outcome measure was survival time. RESULTS: Median survival time for patients with PMA in the lowest quartile of the distribution (≤1442 mm2) was 65.5 months (95% confidence interval [95% CI] 37.7-78.9) vs 91.2 months (95% CI 77.9-110.0 when PMA >1442 mm2). Multivariate analysis revealed lower PMA was associated with decreased survival (adjusted hazard ratio [AHR] 1.68; 95% CI 1.15-2.40, P = .006). Similarly, the presence of coronary artery disease (AHR 1.54, 95% CI 1.01-2.35, P = .045) and statin use after EVAR were associated with decreased survival (AHR 2.36, 95% CI 1.24-4.49, P = .009). Hyperlipidemia was associated with increased survival after EVAR (AHR 0.51, 95% CI 0.33-0.81, P = .004). Compared with patients with low body mass index (BMI) (<18.5), a normal BMI was associated with increased survival (AHR 0.21, 95% CI 0.08-0.53, P = .001). CONCLUSIONS: Although PMA is a risk factor for decreased survival time, other factors such as patient hyperlipidemia, presence of coronary artery disease, post-EVAR statin use, and BMI are also predictive of postoperative mortality.

Developing an Interactive Data Visualization Tool to Assess the Impact of Decision Support on Clinical Operations.

Due to mandates from recent legislation, clinical decision support (CDS) software is being adopted by radiology practices across the country. This software provides imaging study decision support for referring providers at the point of order entry. CDS systems produce a large volume of data, providing opportunities for research and quality improvement. In order to better visualize and analyze trends in this data, an interactive data visualization dashboard was created using a commercially available data visualization platform. Following the integration of a commercially available clinical decision support product into the electronic health record, a dashboard was created using a commercially available data visualization platform (Tableau, Seattle, WA). Data generated by the CDS were exported from the data warehouse, where they were stored, into the platform. This allowed for real-time visualization of the data generated by the decision support software. The creation of the dashboard allowed the output from the CDS platform to be more easily analyzed and facilitated hypothesis generation. Integrating data visualization tools into clinical decision support tools allows for easier data analysis and can streamline research and quality improvement efforts.

The Role of Interventional Radiologists in the Use of Extracorporeal Membranous Oxygenation in the Catheter-Directed Treatment of Pulmonary Embolism.

Patients with pulmonary embolism who are in hemodynamically unstable condition present a special challenge to the interventionalist. When treating such patients, extracorporeal membranous oxygenation (ECMO) can help to stabilize these patients' condition; however, specific criteria for its use do not exist. Two patients are presented here to familiarize the reader with the use of ECMO and to demonstrate its utility for the interventional radiologist.

Midterm Follow-up of Ureteral Embolization Using Vascular Plugs and N-Butyl Cyanoacrylate Glue.

This is a retrospective study of 9 consecutive female patients who underwent ureteral embolization via a "sandwich" technique with two vascular plugs and N-butyl cyanoacrylate glue for ureteral fistulae unresponsive to urinary diversion. Average age was 61 years (range, 39-77 y), average duration of diversion was 48 days (range, 2-120 d), and average follow-up was 11 months (range, 4-23 mo). Seven patients (78%) experienced immediate resolution of urinary leakage, and the other 2 (22%) required unilateral repeat treatment for resolution of leakage. Symptom resolution lasted throughout the follow-up period for all patients. Bilateral internal iliac artery pseudoaneurysms developed in 1 patient and were treated with embolization and stent placement.

Meta-Analysis of Prostatic Artery Embolization for Benign Prostatic Hyperplasia.

PURPOSE: To perform meta-analysis of available data on prostatic artery embolization (PAE). MATERIALS AND METHODS: Meta-analysis was conducted on articles published between November 2009 and December 2015. Peer-reviewed studies with > 5 patients and standard deviations and/or individual-level data on one or more of the following outcomes were included: prostate volume (PV), peak flow rate (Qmax), postvoid residual (PVR), International Prostate Symptom Score (IPSS), quality of life (QOL) score, International Index of Erectile Function (IIEF) score, and prostate-specific antigen (PSA) level. A random-effects meta-analysis was performed on the outcomes at 1, 3, 6, and 12 months after PAE compared with baseline values, with a P < .05 decision rule as the null hypothesis rejection criterion. RESULTS: Nineteen of 268 studies were included in data collection, with 6 included in the meta-analysis. At 12 months, PV decreased by 31.31 cm3 (P < .001), PSA remained unchanged (P = .248), PVR decreased by 85.54 mL (P < .001), Qmax increased by 5.39 mL/s (P < .001), IPSS improved by 20.39 points (P < .001), QOL score improved by -2.49 points (P < .001), and IIEF was unchanged (P = 1.0). There were a total of 218 adverse events (AEs) among 662 patients (32.93%), with 216 being Society of Interventional Radiology class A/B (99%). The most common complications were rectalgia/dysuria (n = 60; 9.0%) and acute urinary retention (n = 52; 7.8%). No class D/E complications were reported. CONCLUSIONS: PAE provided improvement in Qmax, PVR, IPSS, and QOL endpoints at 12 months, with a low incidence of serious AEs (0.3%), although minor AEs were common (32.93%). There was no adverse effect on erectile function.

Transcaval Aortic Access for Percutaneous Thoracic Aortic Aneurysm Repair: Initial Human Experience.

Transcaval aortic access has been used for deployment of transcatheter aortic valves in patients in whom conventional arterial approaches are not feasible. The present report describes its use for thoracic endovascular aortic repair (TEVAR) in a 61-year-old man with a descending thoracic aneurysm. Transcaval access was performed in lieu of a surgical iliac conduit in view of small atherosclerotic pelvic arteries. TEVAR was successfully performed, followed by intervascular tract occlusion with the use of a ventricular septal occluder. Computed tomography 2 d later demonstrated no extravasation. At 1 mo, the aneurysm was free of endoleaks, the aortocaval tract had healed, and the patient had returned to baseline functional status.

General Principles for the Safe Performance, Training, and Adoption of Ablation Techniques for Benign Thyroid Nodules: An American Thyroid Association Statement.

Background: The primary goal of this interdisciplinary consensus statement is to provide a framework for the safe adoption and implementation of ablation technologies for benign thyroid nodules. Summary: This consensus statement is organized around three key themes: (1) safety of ablation techniques and their implementation, (2) optimal skillset criteria for proceduralists performing ablative procedures, and (3) defining expectations of success for this treatment option given its unique risks and benefits. Ablation safety considerations in pre-procedural, peri-procedural, and post-procedural settings are discussed, including clinical factors related to patient selection and counseling, anesthetic and technical considerations to optimize patient safety, peri-procedural risk mitigation strategies, post-procedural complication management, and safe follow-up practices. Prior training, knowledge, and steps that should be considered by any physician who desires to incorporate thyroid nodule ablation into their practice are defined and discussed. Examples of successful clinical practice implementation models of this emerging technology are provided. Conclusions: Thyroid ablative procedures provide valid alternative treatment strategies to conventional surgical management for a subset of patients with symptomatic benign thyroid nodules. Careful patient and nodule selection are critical to the success of these procedures as is extensive pre-procedural patient counseling. Although these emerging technologies hold great promise, they are not without risk and require the development of a unique skillset and environment for optimal, safe performance and consistent outcomes.

Review of the Korean Society of Interventional Radiology and European Thyroid Association Guidelines Regarding the Role of Radiofrequency Ablation for Benign and Malignant Thyroid Tumors.

While radiofrequency ablation (RFA) for the treatment of symptomatic thyroid nodules has been gaining more widespread adoption in the United States, there is limited societal guidance for its role, and safe adoption. As many of the first adopters of thyroid nodule RFA developed their practices, they looked to the Korean Society of Interventional Radiology (KSIR), and European Thyroid Association (ETA) guidelines as a framework. Currently, efforts are underway from the American Thyroid Association to create updated guidelines for US providers. International consensus guidelines are also underway. Until these guidelines are available, a thorough understanding of the current available guidelines is key for interventionalists building a thyroid nodule RFA program.