Search

We present single-and dual-frequency antennas based on the shorted helical slot in hepatic microwave ablation. The single-frequency antenna is designed by lathing a helical slot on shorted traditional semi-rigid coaxial cable, which is expected to be operated at the frequency of 2450 MHz, and the dual-frequency antenna is designed with the combination of an annular slot and a helical slot, which can be operated at 915 and 2450 MHz. We use full-wave electromagnetic simulation and transient thermal simulation to analyze the performance of proposed ablation antennas. Both proposed antennas are fabricated, and used in ex vivo ablation experiments at different frequencies with a power level of 23 W for 2 or 5 minutes. We observe that proposed single-frequency antenna with helical slot has more concentrated specific absorption rate (SAR) pattern than those antennas with conventional slots does at 2450 MHz, and the dual-frequency one has the capability to control the roundness of ablation zone from 0.34 to 0.63, under the different combination of frequencies and operation times. Proposed microwave ablation antennas are expected to lead to a potential solution of curing the liver cancers with various characteristic.

Purpose The purpose of this study was to evaluate the feasibility and safety of transbronchial cryoablation with a novel flexible cryoprobe using nitrogen as the refrigerant in an in vivo porcine model of lung parenchyma. Materials and methods A novel flexible cryoprobe using nitrogen as the refrigerant was used for transbronchial cryoablation of lung parenchyma in six normal female pigs. The cryoprobe was delivered to the distal bronchus in the bilateral porcine lungs via the bronchoscopic working channel under virtual bronchoscopy guidance. The position was confirmed with real-time computed tomography (CT). The whole procedure included two freeze-thaw cycles (15 min and 2 min, respectively). CT images were obtained during cryoablation and at 24 h, one week, two weeks and four weeks after the treatment to assess the effectiveness and safety of the procedure. Ablation zone tissue samples were obtained at 24 h and four weeks after the cryoablation for further histopathological analysis. Results All ablation procedures (12/12; 100%) were performed successfully. No major complications occurred during the procedure or the observation period. The ablation zones were clearly depicted on CT with a maximal ablation zone volume at 24 h (21.88 ± 12.61 [SD] cm3) compared to 3.64 ± 2.06 (SD) cm3 and 10.73 ± 3.84 (SD) cm3 at the end of the 1st and 2nd freeze-thaw cycles, respectively (P Conclusion The novel flexible bronchoscopy-guided cryoablation is a feasible, safe and effective modality in an in vivo porcine model of peripheral normal lung parenchyma, suggesting potential capabilities for the treatment of peripheral lung cancer in humans.

Image-guided thermal ablation is a minimally invasive treatment option for patients with early stage non-small cell lung cancer or metastatic disease to the lungs. Percutaneous ablation treats malignant tumours in situ, which precludes histopathological evaluation of the ablated tumours. Imaging studies are used as surrogates to assess technical and clinical success. Although it is not universally accepted, a common protocol for surveillance imaging includes contrast-enhanced computed tomography (CT) at 1, 3, 6, 9, 12, 18, 24 months, and yearly thereafter. Integrated 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography (PET)/CT imaging is recommended at 3 and 12 months and when recurrent disease is suspected. There is a complex evolution of the ablation zone on CT and PET imaging studies. The zone of ablation, initially larger than the ablated tumour, undergoes gradual involution. In the process, it may cavitate and resemble a lung abscess. Different contrast-enhancement and radionuclide uptake patterns in and around the ablation zone may indicate a wide range of diagnostic possibilities from a normal physiological response to local progression. Ultimately, the zone of ablation may be replaced by a variety of findings including linear bands of density, pleural thickening, or residual necrotic tumour. Diagnostic and interventional radiologists interpreting post-ablation imaging studies must have a clear understanding of the ablation process and imaging findings on surveillance studies. Accurate and timely recognition of complications and/or local recurrence is necessary to guide further therapy. The purpose of this article is to review imaging protocols and salient imaging findings after thermal ablation of lung malignancies.

The goal of this study was to optimize a lung-tuned monopole antenna to deliver microwave energy at 2.45 GHz into a novel ventilator-controlled ex vivo lung model. An analytic\approach was utilized to create an optimized monopole antenna that was impedance-matched to aerated lung tissue. This lung-tuned antenna was then fabricated using a copper 0.085” semi-rigid copper coaxial cable. For validation, the lung-tuned antenna was inserted centrally into lobes of a ex vivo porcine lung that was fully inflated to physiologically appropriate volumes. Microwave ablations were then created at 50 and 100 W for 1 minute and 5 minutes. Reflected power, cross sectional ablation sizes and spherical shape of the lung-tuned antenna were compared against a liver-tuned antenna in the ventilator-controlled ex vivo lung tissue. The study showed that the lung-tuned antennas delivered energy significantly more efficiently, with less reflected power, compared to the conventionally-used liver-tuned antennas at 50 W at 1 minute (11.8 ${\pm }$ 3.0 vs 16.3 ${\pm }$ 3.1 W; p value = 0.03) and 5 minutes (16.2 ${\pm }$ 2.8 vs 19.4 ${\pm }$ 2.9 W; p value = 0.04), although this was only true using 100 W at the 1 min time point (29.0 ${\pm }$ 3.5 vs 38.0 ${\pm }$ 5.3 W; p value = 0.02). While overall ablation zone sizes were comparable between the two types of antenna, the lung-tuned antenna did create a significantly more spherical ablation zone compared to the liver-tuned antenna at the 1 minute, 50 W setting (aspect ratio: 0.43 ${\pm }$ 0.07 vs 0.38 ${\pm }$ 0.04; p value = 0.04). In both antenna groups, there was a significant rise in the ablation zone aspect ratio between 1 and 5 minutes, indicating that higher power and time settings can increase the spherical shape of ablation zones when using tuned antennas. Adapting this combined analytic and parametric approach to antenna design can be implemented in adaptive tissue-tuning for real-time microwave ablation optimization in lung tissue.

Small hepatic malignancies scheduled for CT-guided percutaneous ablation may have been identified in the hepatobiliary phase of liver MRI or in a specific phase of multi-phase CT but may be occult on unenhanced CT used to guide the ablation. We investigated whether the detectability of the target lesion would impact the efficacy of CT-guided hepatic tumor ablations.We included 69 patients with 99 malignant liver lesions (25 primary, 44 metastases) who underwent IRE (n = 35), RFA (n = 41), or MWA (n = 23) between 01/2015 and 06/2018. All procedures were performed under CT guidance. Lesions not detectable on CT (NDL) were targeted through identification of anatomical landmarks on preinterventional contrast-enhanced CT or MRI. Rates of incomplete ablation, size of ablation zone, local tumor recurrence, intrahepatic progression-free survival (ihPFS), and adverse event rates were compared for detectable lesions (DL) vs. NDL.40 lesions were NDL, and 59 lesions were DL on unenhanced CT. The mean follow-up was 16.2 months (14.8 for DL and 18.2 for NDL). The mean diameter of NDL and DL was similar (12.9 mm vs. 14.9 mm). The mean ablation zone size was similar (37.1 mm vs. 38.8 mm). Incomplete ablation did not differ between NDL vs. DL (5.0 % [2/40; 0.6-16.9 %] vs. 3.4 % [2/59; 0.4-11.7 %]), nor did local tumor recurrence (15.4 % [6/39; 5.7 %-30.5 %] vs. 16.9 % [10/59; 8.4-29.0 %]), or median ihPFS (15.5 months vs. 14.3 months).Target lesion detectability on interventional CT does not have a significant impact on outcome after percutaneous liver ablation when anatomical landmarks are used to guide needle placement.· Liver tumors can be successfully ablated even if they are not detectable on the navigational CT scan.. · Anatomical landmarks should be used and compared to preinterventional imaging..· Barzakova E, Senthilvel N, Bruners P et al. Detectability of Target Lesion During CT-Guided Tumor Ablations: Impact on Ablation Outcome . Fortschr Röntgenstr 2022; 194: 515 - 520.ZIEL: Intrahepatische maligne Läsionen, geplant für CT-gesteuerte perkutane Ablation, können MR-tomographisch oder CT-graphisch in einer bestimmten Kontrastmittelphase abgrenzbar sein, jedoch okkult in der nativen CT-Untersuchung, genutzt zur Planung der Ablation. Ziel dieser Studie ist zu untersuchen, ob die Abgrenzbarkeit der Zielläsion in der Planungsuntersuchung einen Einfluss auf das kurz- und mittelfristige Ablationsergebnis hat.Es wurden 69 Patienten mit insgesamt 99 malignen Leberläsionen (25 Primärtumoren, 44 Metastasen) eingeschlossen, die zwischen 01/2015 und 06/2018 irreversibler Elektroporation (n = 35), Radiofrequenzablation (n = 41) oder Mikrowellenablation (n = 23) unterzogen wurden. Alle Verfahren wurden unter CT-Führung durchgeführt. Läsionen, die in der Planungs-CT nicht nachweisbar waren (NDL), wurden durch die Korrelation zu anatomischen Landmarken in der kontrastverstärkten CT oder MRT-Voruntersuchung lokalisiert. Es wurden die Raten unvollständiger Ablation, lokalen Tumorrezidivs, die Größe der Ablationszone, das intrahepatische progressfreie Überleben (ihPFS) und die Komplikationsraten für nachweisbare Läsionen (DL) gegenüber NDL verglichen.40 Läsionen waren NDL, 59 Läsionen waren DL auf die native Planungs-CT. Die mittlere Beobachtungsdauer war 16,2 Monate (14,8 für DL und 18,2 für NDL). Die mittleren Durchmesser von NDL und DL waren ähnlich (12,9 mm vs. 14,9 mm). Die mittleren Ablationszonengrößen waren ähnlich (37,1 mm vs. 38,8 mm). Es zeigten sich keine wesentlichen Unterschiede zwischen NDL und DL bezüglich der Häufigkeit unvollständiger Ablationen (5,0 % [2/40; 0,6 %–16,9 %] gegenüber 3,4 % [2/59; 0,4 %–11,7]), des Auftretens eines lokalen Tumorrezidivs (15,4 % [6/39; 5,7 %–30,5 %] gegenüber 16,9 % [10/59; 8,4 %–29,0]) oder des medianen ihPFS (15,5 Monate gegenüber 14,3 Monate).Die Nachweisbarkeit der Zielläsion in dem periinterventionellen Planungs-CT hat keinen signifikanten Einfluss auf das Ergebnis nach perkutanen Leberablationen, wenn anatomische Landmarken zur Nadelplatzierung genutzt werden.· Lebertumoren können erfolgreich abladiert werden, auch wenn sie in dem nativen Planungs-CT nicht nachweisbar sind.. · Anatomische Landmarken sollten verwendet und mit der präinterventionellen Bildgebung verglichen werden..

To evaluate utility of advanced CT techniques including HighlY constrained back-projection and dual-energy CT for intra- and post-procedure hepatic microwave ablation zone monitoring. 8 hepatic microwave ablations were performed in 4 adult swine (5 min/65 W). Low-dose routine CECT and dual-energy CT images were obtained every 1 min during ablation. Images were reconstructed ± HYPR. Image quality and dose metrics were collected. 21 MWA were performed in 4 adult swine. Immediate post-procedure CECT was performed in the arterial, portal venous, and delayed phases using both routine and DECT imaging with full-dose weight-based IV contrast dosing. An additional 16 MWA were subsequently performed in 2 adult swine. Immediate post-procedure CT was performed with half-dose IV contrast using routine and DECT. 12 patients (10 M/2F, mean age 62.4 yrs) with 14 hepatic tumors (4 HCC, 10 metastatic lesions) treated with MWA were prospectively imaged with DECT 1 month post-procedure. 120 kV equivalent images were compared to DECT [51 keV, iodine material density]. Image quality and dose metrics were collected. Gas created during MWA led to high CNR in all intraprocedural CT datasets. Optimal CNRs were noted at 4 min with CNR 6.7, 15.5,15.9, and 21.5 on LD-CECT, LD-CECT + HYPR, DECT, and DECT + HYPR, respectively (p

One of the significant weaknesses of excimer laser-based vision correction devices is the difficulty of achieving a required change in the refractive properties of the cornea to sharply focus the image on the retina with distance from the working area (ablation zone) center to the periphery due to a change in the laser beam incidence angle. The study is aimed at improving the quality of laser action on the eye cornea by introducing an optical corrective system into the existing excimer laser vision correction equipment, ensuring the coincidence of the direction of the laser beam incidence on the corneal surface with the normal.It has been shown that the greater the reflection coefficient, the lower the absorbed energy, and the shallower the laser radiation penetration and ablation depths, which reduces the laser action opportunities and quality. When using excimer laser vision correction devices, it has been proposed to change the angle of the laser beam incidence on the cornea with a distance from the working area (ablation zone) center to the periphery during the surgery by introducing an optical corrective system based on a lightweight controllable and movable mirror, which allows achieving the coincidence of the direction of the laser beam incidence on the corneal surface with the normal.The studies have shown that the coincidence of the laser beam incidence on the corneal surface at any point with the normal when using a priori data on the specifics of the patient's eye allows expanding the functional opportunities of excimer laser photoablation, i. e., expand the ablation zone by 30 % and eliminate the possibility of errors caused by the human factor. The technique proposed can be used for excimer laser vision correction according to PRK, LASIK, Femto-LASIK, and other methods. To implement this approach, a patented excimer laser vision correction unit has been proposed with a PCcontrolled optical shaping system comprising galvo motor platforms and galvo mirrors installed on them.

ObjectiveChanges in ultrasound backscatter energy (CBE) imaging can monitor thermal therapy. Catheter-based ultrasound (CBUS) can treat deep tumors with precise spatial control of energy deposition and ablation zones, of which CBE estimation can be limited by low contrast and robustness due to small or inconsistent changes in ultrasound data. This study develops a multi-spatiotemporal compounding CBE (MST-CBE) imaging approach for monitoring specific to CBUS thermal therapy.MethodsEx vivo thermal ablations were performed with stereotactic positioning of a 180° directional CBUS applicator, temperature monitoring probes, endorectal US probe, and subsequent lesion sectioning and measurement. Five frames of raw radiofrequency data were acquired throughout in 15s intervals. Using window-by-window estimation methods, absolute and positive components of MST-CBE images at each point were obtained by the compounding ratio of squared envelope data within an increasing spatial size in each short-time window.ResultsCompared with conventional US, Nakagami, and CBE imaging, the detection contrast and robustness quantified by tissue-modification-ratio improved by 37.2 ± 4.7 (p < 0.001), 37.5 ± 5.2 (p < 0.001), and 6.4 ± 4.0 dB (p < 0.05) in the MST-CBE imaging, respectively. Correlation coefficient and bias between cross-sectional dimensions of the ablation zones measured in tissue sections and estimated from MST-CBE were up to 0.91 (p < 0.001) and -0.02 mm2, respectively.ConclusionThe MST-CBE approach can monitor the detailed changes within target tissues and effectively characterize the dimensions of the ablation zone during CBUS energy deposition.SignificanceThe MST-CBE approach could be practical for improved accuracy and contrast of monitoring and evaluation for CBUS thermal therapy.

Objective.To evaluate the effectiveness of preoperative coagulation of the vein adjacent to a tumor nodule in sonographically-guided percutaneous radiofrequency thermal ablation of perivascular liver metastases of colorectal cancer.Materials and methods.To address the issue, we compared the results of sonographically-guided percutaneous radiofrequency thermal ablation of perivascular liver metastases of colorectal cancer in 27 patients (aged 60.5 (58; 68) years) without prior coagulation of the adjacent vein (control group) and 26 patients (62.0 (60; 74)) with prior coagulation of the adjacent vein (experimental group).Results.Lower incidence of residual tumor in the ablation area in the patients with prior coagulation of the adjacent vein (14.3 % vs. 29 % of the patients in the control group) and a higher relapse-free survival of such patients (65.2 % vs. 53.6 % and 55.6 % vs. 33.3 %) were reported as compared to the group without prior coagulation of the adjacent vein (after 6 and 12 months, respectively).Conclusion.Preoperative coagulation of the vein adjacent to colorectal cancer liver metastasis allows reducing the effect of heat removal from the RFA zone, thereby contributing to higher radicality of the treatment and resulting both in a lower incidence of residual tumor in the ablation zone and a higher relapse-free survivalof patients, notably without signifcant concomitant changes in the affected part of the liver (segment atrophy).

Ablation behaviors of laminated carbon fiber reinforced plastics (CFRP) subjected to intense continuous wave laser in the supersonic wind tunnel are investigated experimentally. Comparable laser ablation tests in other environments, i.e., static air, static nitrogen and open airflow, are also carried out. Laser ablation rate in the supersonic wind tunnel is significantly larger than those of the other environments, in particular, at least twice of that in an open tangential airflow condition. The ablation morphology can be classified into two regions, coupled ablation zone (CAZ) and downstream affected zone (DAZ). Coupled thermal-fluid-solid analysis including thermochemical ablation and thermomechanical erosion models reveals that the contribution of each laser mechanisms is distinctive at the different positions of the laser ablation pit.

Purpose Patients with Von Hippel-Lindau disease often develop multifocal, metachronous renal cell carcinomas which require therapy. The purpose of this retrospective single-center study is to evaluate the outcomes of radiofrequency ablation (RFA) in the treatment of renal cell carcinomas in patients with Von Hippel-Lindau disease. Materials and Methods 9 patients (4 male, 5 female, 47.9 ± 10.7 y/o) with Von Hippel-Lindau disease underwent 18 CT-guided percutaneous RFA procedures for the treatment 21 renal cell carcinomas (largest diameter: 32.9 ± 8.6 mm, cT1a: 16, cT1b: 5). Seven patients were previously treated either by partial or radical nephrectomy. Technical success, effectiveness, safety, progression-free survival, overall survival and tumor characteristics were analyzed. Results All RFA procedures were technically successful without major complications. There were 5 minor complications. No residual or recurrent tumor was seen in the ablation zone during a follow-up of 34.0 ± 18.1 months (0–58 months). No patient required dialysis during follow-up. One patient died after 63 months after the first treatment due to complications from a cerebellar hemangioblastoma. No endpoint was reached for overall or progression-free survival. Conclusions The results from this limited case series suggest that RFA of RCCs in patients with VHL is a safe and effective therapy, which can preserve sufficient renal function even after renal surgery.

Preclinical studies have shown that modulation of the tumor microvasculature with anti-angiogenic agents decreases tumor perfusion and may increase the efficacy of radiofrequency ablation (RFA) in hepatocellular carcinoma (HCC). Retrospective studies suggest that sorafenib given prior to RFA promotes an increase in the ablation zone, but prospective randomized data are lacking. We conducted a randomized, double-blind, placebo-controlled phase II trial to evaluate the efficacy of a short-course of sorafenib prior to RFA for HCC tumors sized 3.5–7 cm (NCT00813293). Treatment consisted of sorafenib 400 mg twice daily for 10 days or matching placebo, followed by RFA on day 10. The primary objectives were to assess if priming with sorafenib increased the volume and diameter of the RFA coagulation zone and to evaluate its impact on RFA thermal parameters. Secondary objectives included feasibility, safety and to explore the relationship between tumor blood flow on MRI and RFA effectiveness. Twenty patients were randomized 1:1. Priming with sorafenib did not increase the size of ablation zone achieved with RFA and did not promote significant changes in thermal parameters, although it significantly decreased blood perfusion to the tumor by 27.9% (p = 0.01) as analyzed by DCE-MRI. No subject discontinued treatment owing to adverse events and no grade 4 toxicity was observed. Priming of sorafenib did not enhance the effect of RFA in intermediate sized HCC. Future studies should investigate whether longer duration of treatment or a different antiangiogenic strategy in the post-procedure setting would be more effective in impairing tumor perfusion and increasing RFA efficacy.

To determine whether histotripsy can create human-scale transcostal ablations in porcine liver without causing severe thermal wall injuries along the beam path. Histotripsy was applied to the liver using a preclinical prototype robotic system through a transcostal window in six female swine. A 3.0 cm spherical ablation zone was prescribed. Duration of treatment (75 min) was longer than a prior subcostal treatment study (24 min, 15 s) to minimize beam path heating. Animals then underwent contrast-enhanced MRI, necropsy, and histopathology. Images and tissue were analyzed for ablation zone size, shape, completeness of necrosis, and off-target effects. Ablation zones demonstrated complete necrosis with no viable tissue remaining in 6/6 animals by histopathology. Ablation zone volume was close to prescribed (13.8 ± 1.8 cm3 vs. prescribed 14.1 cm3). Edema was noted in the body wall overlying the ablation on T2 MRI in 5/5 (one animal did not receive MRI), though there was no gross or histologic evidence of injury to the chest wall at necropsy. At gross inspection, lung discoloration in the right lower lobe was present in 5/6 animals (mean size: 1 × 2 × 4 cm) with alveolar hemorrhage, preservation of blood vessels and bronchioles, and minor injuries to pneumocytes noted at histology. Transcostal hepatic histotripsy ablation appears feasible, effective, and no severe injuries were identified in an acute porcine model when prolonged cooling time is added to minimize body wall heating.

Background Microwave ablation (MWA) and radiofrequency ablation (RFA) have recently attracted interest as minimally invasive treatment modalities for papillary thyroid carcinoma (PTC). However, the ablation outcomes of T1N0M0 PTC are not well characterized. Purpose To evaluate the efficacy and safety of thermal ablation (MWA or RFA) of solitary T1N0M0 PTC in patients who were ineligible for (due to presence of comorbid cardiovascular disease, renal failure, other malignancy, etc) or who refused surgery. Materials and Methods This was a retrospective multicenter study of 847 patients (660 women) who underwent thermal ablation for PTC (673 T1a, 174 T1b) between March 2015 and March 2020; of these patients, 645 underwent MWA and 202 underwent RFA. The mean age of patients was 46 years ± 11 (standard deviation) (age range, 18-81 years); the mean follow-up time was 22 months ± 13 (range, 6-60 months). Changes in tumor size and volume and the rates of technical success, tumor disappearance, disease progression, and complications were assessed. Results The technical success rate was 100%. Relative to preablation measurements, the maximum diameter and volume of the ablation zone increased during the 1st month after ablation (P < .001), whereas there was no difference by the 3rd month; subsequently, the tumors showed reduction in size at 6, 9, and 12 months (all P < .001). Complete disappearance of tumors occurred in 68% of patients (577 of 847; 69% [466 of 673] in the T1a group vs 64% [111 of 174] in the T1b group; P < .001). The postablation disease progression rate was 1.1% (nine of 847 patients; 0.9% [six of 673 patients] in the T1a group vs 1.7% [three of 174 patients] in the T1b group; P = .54). The overall complication rate was 3.4% (29 of 847 patients; 2.7% [18 of 673 patients] in the T1a group vs 6.3% [11 of 174 patients] in the T1b group; P = .02). Conclusion This multicenter study provided evidence that thermal ablation is an effective and safe treatment option in selected -patients with solitary T1N0M0 papillary thyroid carcinoma. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Baek and Cho in this issue.

Purpose Microwave ablation (MWA) is a clinically established modality for treatment of lung tumors. A challenge with existing application of MWA, however, is local tumor progression, potentially due to failure to establish an adequate treatment margin. This study presents a robust simulation-based treatment planning methodology to assist operators in comparatively assessing thermal profiles and likelihood of achieving a specified minimum margin as a function of candidate applied energy parameters. Methods We employed a biophysical simulation-based probabilistic treatment planning methodology to evaluate the likelihood of achieving a specified minimum margin for candidate treatment parameters (i.e., applied power and ablation duration for a given applicator position within a tumor). A set of simulations with varying tissue properties was evaluated for each considered combination of power and ablation duration, and for four different scenarios of contrast in tissue biophysical properties between tumor and normal lung. A treatment planning graph was then assembled, where distributions of achieved minimum ablation zone margins and collateral damage volumes can be assessed for candidate applied power and treatment duration combinations. For each chosen power and time combination, the operator can also visualize the histogram of ablation zone boundaries overlaid on the tumor and target volumes. We assembled treatment planning graphs for generic 1, 2, and 2.5 cm diameter spherically shaped tumors and also illustrated the impact of tissue heterogeneity on delivered treatment plans and resulting ablation histograms. Finally, we illustrated the treatment planning methodology on two example patient-specific cases of tumors with irregular shapes. Results The assembled treatment planning graphs indicate that 30 W, 6 min ablations achieve a 5-mm minimum margin across all simulated cases for 1-cm diameter spherical tumors, and 70 W, 10 min ablations achieve a 3-mm minimum margin across 90% of simulations for a 2.5-cm diameter spherical tumor. Different scenarios of tissue heterogeneity between tumor and lung tissue revealed 2 min overall difference in ablation duration, in order to reliably achieve a 4-mm minimum margin or larger each time for 2-cm diameter spherical tumor. Conclusions An approach for simulation-based treatment planning for microwave ablation of lung tumors is illustrated to account for the impact of specific geometry of the treatment site, tissue property uncertainty, and heterogeneity between the tumor and normal lung.

Radiofrequency ablation (RFA) of lung metastases of colorectal origin can improve patient survival and quality of life. Our aim was to identify pre- and per-RFA features predicting local control of lung metastases following RFA. This case-control single-center retrospective study included 119 lung metastases treated with RFA in 48 patients (median age: 60 years). Clinical, technical, and radiological data before and on early CT scan (at 48 h) were retrieved. After CT scan preprocessing, 64 radiomics features were extracted from pre-RFA and early control CT scans. Log-rank tests were used to detect categorical variables correlating with post-RFA local tumor progression-free survival (LTPFS). Radiomics prognostic scores (RPS) were developed on reproducible radiomics features using Monte-Carlo cross-validated LASSO Cox regressions. Twenty-six of 119 (21.8%) nodules demonstrated local progression (median delay: 11.2 months). In univariate analysis, four non-radiomics variables correlated with post-RFA-LTPFS: nodule size (> 15 mm, p < 0.001), chosen electrode (with difference between covered array and nodule diameter < 20 mm or non-expandable electrode, p = 0.03), per-RFA intra-alveolar hemorrhage (IAH, p = 0.002), and nodule location into the ablation zone (not seen or in contact with borders, p = 0.005). The highest prognostic performance was reached with the multivariate model including a RPS built on 4 radiomics features from pre-RFA and early revaluation CT scans (cross-validated concordance index= 0.74) in which this RPS remained an independent predictor (cross-validated HR = 3.49, 95% confidence interval = [1.76 – 6.96]). Technical, radiological, and radiomics features of the lung metastases before RFA and of the ablation zone at 48 h can help discriminate nodules at risk of local progression that could benefit from complementary local procedure. • The highest prognostic performance to predict post-RFA LTPFS was reached with a parsimonious model including a radiomics score built with 4 radiomics features. • Nodule size, difference between electrode diameter, use of non-expandable electrode, per-RFA hemorrhage, and a tumor not seen or in contact with the ablation zone borders at 48-h CT were correlated with post-RFA LTPFS.

Context Ultrasound (US)-guided thermal ablation has generated recent interest as minimally invasive treatments of primary hyperparathyroidism (pHPT). But definitive evidence for the efficacy of thermal ablation in treating pHPT is not well characterized. Objective This work aims to evaluate the effectiveness and safety of thermal ablation for pHPT. Methods From January 2015 to March 2020, data pertaining to patients who received thermal ablation for pHPT at 4 centers were retrospectively analyzed. The median follow-up duration was 18.1 months (interquartile range, 6.5-42.2 months). A cure referred to the reestablishment of normal values of serum calcium and intact parathyroid hormone throughout the entire follow-up period, at least more than 6 months. The technical success, effectiveness, and safety of treatment were analyzed. Results A total of 119 patients (mean age, 57.2 ± 16.3 years; 81 female) with 134 parathyroid nodules were enrolled. The mean maximum diameter of the parathyroid glands was 1.6 ± 0.9 cm. Ninety-six patients underwent microwave ablation (MWA), and 23 patients underwent radiofrequency ablation (RFA). The technical success rate was 98.3% and the cure rate was 89.9%. Significant differences were found in the maximum diameter between the cured patients and the patients who did not undergo ablation of the target lesions. Except for cases with pHPT nodules less than 0.6 cm in diameter, the cure rate was 95%. There were no difference in cure rates at 6 months between the MWA and RFA groups (MWA vs RFA, 90.6% vs 87.0%; χ 2 = 0.275, P = .699). The volume reduction rate of the ablation zone was 94.6% at 12 months. The complication rate was 6.7% (8/119). With the exception of one patient with persistent voice impairment, other symptoms spontaneously resolved within 6 months. Conclusion Thermal ablation is effective and safe for pHPT.

Microwave (MW) antenna is a key element in microwave ablation (MWA) treatments as the means that energy is delivered in a focused manner to the tumor and its surrounding area. The energy delivered results in a rise in temperature to a lethal level, resulting in cell death in the ablation zone. The delivery of energy and hence the success of MWA is closely dependent on the structure of the antennas. Therefore, three design criteria, such as expected ablation zone pattern, efficiency of energy delivery, and minimization of the diameter of the antennas have been the focus along the evolution of the MW antenna. To further improve the performance of MWA in the treatment of various tumors through inventing novel antennas, this article reviews the state-of-the-art and summarizes the development of MW antenna designs regarding the three design criteria.

PURPOSE To evaluate refractive and visual outcomes of single-step transepithelial photorefractive keratectomy (transPRK) in the treatment of mixed astigmatism with the use of an aberration-neutral profile and large ablation zone. SETTING Nicolaus Copernicus University and Oftalmika Eye Hospital, Bydgoszcz, Poland. DESIGN Retrospective, observational case series. METHODS This study included patients who underwent transPRK to correct mixed astigmatism and completed the 3-year follow-up. Procedures were performed with an Amaris 750S excimer laser using an aberration-neutral profile and optical zone of 7.2 mm or more. RESULTS A total 48 eyes of 39 patients were included. Preoperatively, mean spherical manifest refraction was +1.37 ± 0.98 diopter (D) (0.25 to 4.00 D), and astigmatism was -4.00 ± 0.76 D (-2.25 to -6.00 D). Three years postsurgery, it was -0.17 ± 0.26 D and -0.41 ± 0.44 D, respectively. Attempted spherical equivalent correction within ±0.50 D was achieved in 45 eyes (94%) and cylindrical correction in 34 (71%). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 38 eyes (79%), and postoperative uncorrected was 20/20 or better in 29 eyes (60.0%). No eye had lost 2 or more Snellen lines of CDVA, whereas 3 eyes (6%) gained 2 or more lines. In 4 eyes (8%), haze of low intensity was observed at the periphery, with scores between 0.5 and 1.0, and only 1 eye getting a score of 2 in 0- to 4-degree scale. CONCLUSIONS Mixed astigmatism correction with large-ablation-zone transPRK provided good results for efficacy, safety, predictability, and visual outcomes in a 3-year follow-up.

Importance Hepatocellular carcinoma (HCC) is usually accompanied by liver cirrhosis, which makes treatment of this disease challenging. Liver transplantation theoretically provides an ultimate solution to the disease, but the maximal surgical stress and the scarcity of liver graft make this treatment option impossible for some patients. In an ideal situation, a treatment that is safe and effective should provide a better outcome for patients with the dilemma. Objective This article aims to give a comprehensive review of various types of loco-ablative treatment for HCC. Evidence review Loco-ablative treatment bridges the gap between surgical resection and transarterial chemotherapy. Various types of ablative therapy have their unique ability, and evidence-based outcome analysis is the most important key to assisting clinicians to choose the most suitable treatment modality for their patients. Findings Radiofrequency ablation (RFA) has a relatively longer history and more evidence to support its effectiveness. Microwave ablation (MWA) is gaining momentum because of its shorter ablation time and consistent ablation zone. High-intensity focused ultrasound (HIFU) ablation is a relatively new technology that provides non-invasive treatment for patients with HCC. It has been carried out at centers of excellence and it is a safe and effective treatment option for selected patients with HCC and liver cirrhosis. Conclusion and relevance Selective use of different loco-ablative therapies will enhance clinicians' treatment options for treatment of HCC.

Electrical ablation (EA) is a non-thermal ablation technique that causes less damage to the tissue surrounding the targeted area than conventional thermal ablation. EA induces immunogenic cell death (ICD) and can potentially synergize with cancer immunotherapy. In this study, the optimal voltage and pulse conditions for the induction of ICD were identified. Finite element analysis was used to estimate the ablation zone under a variety of voltage and pulse conditions. Cancer cells were cultured in vitro under two- and three-dimensional conditions to assess cell viability under different voltage and pulse conditions. Additionally, the expression of damage-associated molecular pattern (DAMP) markers of ICD was measured to identify an optimal voltage condition. Tumor volume, body weight, and survival after EA treatment were measured in vivo to identify the optimal pulse conditions. The optimal conditions to induce ICD by EA identified in this study are suitable to be combined with cancer immunotherapy.

This study assesses the temporal changes of Swetvarn and Thelu glaciers between 1968 and 2019 in Rakvarn glacial valley of Bhagirathi basin. Here we utilized high-resolution satellite images of CORONA KHA (1968), LISS IV (2012) and SENTINEL-2 MSI (2019), along with medium resolution images of LANDSAT TM (1990) and SRTM (2000) to carry out the research work. Analytical viewed strongly convinced that the selected glaciers receding continuously with non homogeneous retreat rate since 1968. During 1968 to 2019 the snout of the Swetvarn glacier lost ∼623m total length with 12.21ma−1 retreat rate, while the snout of Thelu glacier lost ∼590m total length (11.56ma−1). Results further confirmed that about 16.60% glaciated area of Swetvarn glacier and 24.50% glaciated area of Thelu glacier also vanished completely between 1968 and 2019. During this tenure the ablation zone shows 160m upward shift for Swetvarn glacier and 145m for Thelu glacier respectively. Overall analysis explains that three climatic trends of Garhwal Himalayan region; (1) catastrophic variation between rainfall and temperature during 1960–1990, (2) gradual increase in temperature and decrease in precipitation, (3) increased liquid precipitation and decreased solid precipitation highly influences the process of melting of the study region.

Background The purpose of this case series is to assess the safety and efficacy, as well as the overall survival (OS) and progression free survival (PFS) of patients with intrahepatic cholangiocarcinoma (ICC) treated with percutaneous ablation, transarterial arterial chemoembolization (TACE) or a combination of both at our institution. Methods Ten patients with pathological diagnosis of adenocarcinoma treated at out institution between January 1st 2013 and January 1st 2019 were reviewed. Three patients received a combined TACE and ablation treatment, three patients received TACE without ablation and four patients were treated with ablation only. Ablation technical success was determined by absence of residual tumor in the ablation zone on follow-up imaging one-month post-ablation. TACE response was assessed using the Modified Response Evaluation Criteria in Solid Tumors (mRECIST). Technical success was defined as injection of chemoembolic material in the involved liver lobes. PFS and OS were calculated from the date of diagnosis. Results In the TACE and radiofrequency ablation (RFA) group, OS was 12, 55 and 56 months; PFS was 5, 6 and 32 months, one patient died and two others remain alive. In the TACE group, OS was 29, 10 and 5 months; PFS was 15, 10 and 4 months. All three patients remain alive. In the ablation group, OS and PFS were 16, 31, 30 and 40 months. All patients remain alive. Overall, 9 of 10 patients are alive, with a Median OS and PFS of 29.5 and 15.5 months, respectively, with some patients remain alive over four years following initial presentation. Conclusions Our study shows that ablation and TACE in combination with more traditional modalities such as chemoradiation and surgical resection can extend survival in patients with ICC significantly. Locoregional therapy is well tolerated with only minor adverse events. The use of stereotactic body radiation therapy (SBRT) with ablation demonstrated the synergistic nature of using multiple lines of interventions.

To evaluate the effect of intravenous iodinated contrast on estimated glomerular filtration rate (eGFR) when administered immediately after thermal ablation of clinically localized T1a (cT1a) renal cell carcinoma (RCC). This HIPAA-compliant, dual-center retrospective study was performed under a waiver of informed consent. Three hundred forty-two consecutive patients with cT1a biopsy-proven RCC were treated with percutaneous ablation between January 2010 and December 2017. Immediate post-ablation contrast-enhanced CT was the routine standard of care at one institution (contrast group), but not the other (control group). One-month pre- and 6-month post-ablation eGFR were compared using the Wilcoxon signed-rank test or the Kruskal-Wallis test. Multivariate linear regression was used to determine the effect of contrast on eGFR. A 1:1 propensity score matching was performed for all patients with a logistic model using patient, tumor, and procedural covariates. In total, 246 patients (158 M; median age 69 years, IQR 62–74) were included. Median tumor diameter (2.4 vs 2.5, p = 0.23) and RENAL nephrometry scores (6 vs 6, p = 0.92), surrogates for ablation zone size, were similar. Baseline kidney function was similar for the control and contrast groups, respectively (median eGFR: 70 vs 74 mL/min/1.73 m2, p = 0.29). There was an expected mild decline in eGFR after ablation (control: 70 vs 60 mL/min/1.73 m2, p < 0.001; contrast: 75 vs 71 mL/min/1.73 m2, p = 0.001). Intravenous iodinated contrast was not associated with a decline in eGFR on multivariate linear regression (1.91, 95% CI - 3.43–7.24, p = 0.46) or 1:1 propensity score-matched model (- 0.33, 95% CI - 6.81–6.15, p = 0.92). Intravenous iodinated contrast administered during ablation of cT1a RCC has no effect on eGFR. • Intravenous iodinated contrast administered during thermal ablation of clinically localized T1a renal cell carcinoma has no effect on kidney function. • Thermal ablation of clinically localized T1a renal cell carcinoma results in a mild decline in kidney function. • A decline in kidney function is similar for radiofrequency and microwave ablation of clinically localized T1a renal cell carcinoma.

Curative treatment of oligometastatic pulmonary disease aims at eradication of all metastases. Radiofrequency ablation (RFA) has been shown to be an efficient method and the frequency of local tumor progression (LTP) should be minimized. The objective of this study was to determine the morphological and treatment-related risk factors for LTP after RFA of pulmonary metastases. All patients treated with RFA for pulmonary metastases from 2002 to 2014 were reviewed. All LTPs from 2011 to 2014 were individually matched on the basis of tumor size, number, and histology. In total, 48 LTPs and 112 controls were blindly analyzed for morphological factors including vicinity of bronchus and vessels as well as treatment-related factors such as the size of the ablation zone and ablation margins. In the simple regression analysis, the significant predictive variables were ≤ 5-mm distance to a large bronchus (OR = 4.94; p = 0.0095) or large vessel (OR = 7.09; p 0.36 (OR = 13.83; p = 0.013). In the multiple regression model, only a minimal ablation margin ≤ 5 mm remained a significant risk factor for LTP. Only the minimal ablation margin remains significant in the multiple regression analysis; the other factors are presumably surrogates of an insufficient ablation margin. Improvement of lung RFA outcomes can probably be obtained by immediate post RFA evaluation of ablation margins to ensure a minimal ablation margin of at least 5 mm. • A distance 5 mm after pulmonary RFA is associated with significantly less local tumor progression and should be looked for at the end of treatment session before needle removal in order to decrease local tumor progression. • Tumor location, pleural contact, occurrence of intra-alveolar hemorrhage, pulmonary atelectasis, and pneumothorax are not associated with an increased risk of local tumor progression.

Background Microwaves (MWs) deliver relatively high temperatures into biological tissue and cover a large ablation zone. This study aims to evaluate the efficacy and effectiveness of water-cooled double-needle MW ablation arrays in assisting the hepatic transection of an in vivo pig model. Methods Our research program comprised computer modeling, tissue-mimicking phantom experiments, and in vivo pig liver experiments. Computer modeling was based on the finite element method (FEM) to evaluate ablation temperature distributions. In tissue-mimicking phantom and in vivo pig liver ablation experiments, the performances of the water-cooled MW ablation array and conventional clamp crushing liver resection were compared. Results FEM showed that the maximum lateral ablation diameter at 100 W output and a duration of 60 s was 3 cm (assessed at 50 °C isotherm). In the phantom, the maximum transverse ablation diameter of the double-needle MW ablation increased rapidly to 3 cm in 60 s at 50 W. The blood loss and blood loss per transection area in Group A were significantly lower than those in Group B (18 (7–26) ml vs. 34 (19–57) ml, and 2.4 (2–3.1) ml/cm2 vs. 6.9 (3.2–8.3) ml/cm2, respectively) (p

Introduction Radiofrequency ablation (RFA) is one of the best curative treatments for hepatocellular carcinoma in selected patients, and this procedure can be applied either percutaneously or laparoscopically. Laparoscopic RFA has the benefit of direct visual control of the RFA procedure. Cluster electrodes (Octopus RF electrodes) can create a common ablation zone. Aim Using these two methods (laparoscopic approach and no touch technique), this present study evaluated the technical and clinical outcomes of early experience with laparoscopic RFA and a no-touch technique. Material and methods Between November 2015 and November 2018, 21 patients underwent laparoscopic RFA for hepatocellular carcinoma with a no-touch technique using cluster electrodes. Laparoscopic RFA is recommended for patients with a contraindication for surgical resection, patients wants and a relative contraindication for conventional percutaneous RFA, such as lesions adjacent to the gastrointestinal tract, gallbladder, bile duct, or heart. Results In the 21 tumors, 2 were treated with a single electrode, 12 with 2 electrodes, and 7 tumors with 3 electrodes. The mean time of ablation per lesion was 20.43 ±8.77 min. There was no mortality, local tumor progression, delayed destructive biliary damage, or liver abscess at the follow-up computed tomography. No technical failures occurred. Conclusions Laparoscopic RFA can access lesions for which percutaneous RFA is contraindicated or risky. Cluster electrodes can create sufficient ablation zones without contact and can achieve a sufficient margin with a low complication rate and no tumor dissemination. Therefore, laparoscopic RFA with a no-touch technique might be a safe and feasible treatment for HCC tumor in selected patients.

International audience; Purpose: Radiofrequency ablation (RFA) is a safe and effective minimally invasive treatment for pulmonary tumors. Patterns on chest computed tomography (CT) after RFA are classified into five types; however, the follow-up has not been fully described. The objectives of this study were to describe (1) the CT pattern 3 years after RFA and (2) its evolution over 7 years. Materials and methods: Lesions treated with RFA between 2009 and 2017 and with !3 years of follow-up CT data were included. Lesions with local recurrences were excluded from the study. The morphology of the ablation zone was classified as nodular, fibrotic, atelectatic, cavitary, and disappeared. Other initial anatomical parameters were recorded. Kruskal-Wallis or Chi-square tests were used to compare the groups. Results: One hundred lung RFA scars were included, and a retrospective longitudinal study was performed. Three years after RFA, nodular, fibrotic, atelectatic, and cavitary scars, and disappearance were observed in 49%, 36%, 5%, 3%, and 6% of the scars, respectively. Evolution over 7 years showed that the fibrosis, atelectasis, and disappearance remained stable over time, whereas 28% of nodular scars evolved into fibrotic scars. Additionally, 45% of cavitary scars evolved into nodular scars. Pleural contact was associated with disappearance, and the use of a 20-mm needle was associated with atelectasis. Conclusion: Follow-up after RFA showed that fibrosis, disappearance, and atelectasis remained stable over time. Nodular scars could evolve into fibrotic scars, and cavitary scars could evolve into nodular scars.

Purpose Intra-procedural monitoring and post-procedural follow-up is necessary for a successful ablation treatment. An imaging technique which can assess the ablation geometry accurately is beneficial to monitor and evaluate treatment. In this study, we developed an automated ablation segmentation technique for serial low-dose, noisy ablation computed tomography (CT) or contrast-enhanced CT (CECT). Methods Low-dose, noisy temporal CT and CECT volumes were acquired during microwave ablation on normal porcine liver (four with non-contrast CT and eight with CECT). Highly constrained backprojection (HYPR) processing was used to recover ablation zone information compromised by low-dose noise. First-order statistic features and normalized fractional Brownian features (NBF) were used to segment ablation zones by fuzzy c-mean clustering. After clustering, the segmented ablation zone was refined by cyclic morphological processing. Automatic and manual segmentations were compared to gross pathology with Dice's coefficient (morphological similarity), while cross-sectional dimensions were compared by percent difference. Results Automatic and manual segmentations of the ablation zone were very similar to gross pathology (Dice Coefficients: Auto.-Path. = 0.84 ± 0.02; Manu.-Path. = 0.76 ± 0.03, P = 0.11). The differences in ablation area, major diameter and minor diameter were 17.9 ± 3.2%, 11.1 ± 3.2% and 16.2 ± 3.4%, respectively, when comparing automatic segmentation to gross pathology, which were lower than the differences of 32.9 ± 16.8%, 13.0 ± 9.8% and 21.8 ± 5.8% when comparing manual segmentation to gross pathology. Manual segmentations tended to overestimate gross pathology when ablation area was less than 15 cm2 , but the automated segmentation tended to underestimate gross pathology when ablation zone is larger than 20 cm2 . Conclusion Fuzzy c-means clustering may be used to aid automatic segmentation of ablation zones without prior information or user input, making serial CT/CECT has more potential to assess treatments intra-procedurally.

Percutaneous image guided thermal ablation has become a cornerstone of therapy for patients with oligometastatic disease and primary liver malignancies. Evolving from percutaneous ethanol injection (PEI), thermal ablation utilizing radiofrequency ablation (RFA) and microwave ablation (MWA) have become the standard approach in the treatment of isolated lesions that fit within the size criteria for curative intent therapy (typically 3-4cm). With the evolution of more intense thermal ablation, such as MWA, the dramatic increase in both the size of ablation zone and intensity of heat generation have extended the limits of this technique. As a result of these innovations, intra-procedural and post-procedural pain have also significantly increased, requiring either higher levels of intravenous sedation or, in some institutions, general anesthesia. In addition to the increase in therapeutic intensity, the use of intravenous sedation during aggressive ablation procedures carries the risk of over-sedation when the noxious insult (i.e. the ablation) is removed, adding further difficulty to post-procedural recovery and management. Furthermore, high subdiaphragmatic lesions become challenging in this setting due to issues relating to sedation and compliance with breath hold/breathing instructions. Although general anesthesia may mitigate these complications, the added resources associated with providing general anesthesia during ablation is not cost effective and may result in substantial delays in treatment. The reduction of Aerosol Generating Medical Procedures (AGMP), such as intubation due to the COVID-19 Pandemic, must also be taken into consideration. Due to the potential increased risk of infection transmission, alternatives to general anesthesia should be considered when safe and possible. Upper abdominal regional nerve block techniques have been used to manage pain related to trauma, surgery, and cancer; however, blocks of this nature are not well described in the interventional radiology literature. The McGill University group has developed experience in using such blocks as splanchnic, celiac and hepatic hilar nerve blocks to provide peri-procedural pain control [1]. Since incorporating these techniques (along with hydrodissection with tumescent anesthesia), we have also observed in our high volume ablation center a dramatic decrease in the amount of sedatives administered during the procedure, a decrease in patient discomfort during localization and ablation, as well as decreased pain post-procedure. Faster time to discharge and overall reduction in room procedural time serve as added benefits. The purpose of this publication is to outline and illustrate the practical application and use of nerve block/regional anesthesia techniques with respect to percutaneous hepatic thermal ablation.

As Alpine glaciers become snow-free in summer, more dark, bare ice is exposed, decreasing local albedo and increasing surface melting. To include this feedback mechanism in models of future deglaciation, it is important to understand the processes governing broadband and spectral albedo at a local scale. However, few in situ reflectance data have been measured in the ablation zones of mountain glaciers. As a contribution to this knowledge gap, we present spectral reflectance data (hemispherical–conical–reflectance factor) from 325 to 1075 nm collected along several profile lines in the ablation zone of Jamtalferner, Austria. Measurements were timed to closely coincide with a Sentinel-2 and Landsat 8 overpass and are compared to the respective ground reflectance (bottom-of-atmosphere) products. The brightest spectra have a maximum reflectance of up to 0.7 and consist of clean, dry ice. In contrast, reflectance does not exceed 0.2 for dark spectra where liquid water and/or fine-grained debris are present. Spectra can roughly be grouped into dry ice, wet ice, and dirt or rocks, although gradations between these groups occur. Neither satellite captures the full range of in situ reflectance values. The difference between ground and satellite data is not uniform across satellite bands, between Landsat and Sentinel, and to some extent between ice surface types (underestimation of reflectance for bright surfaces, overestimation for dark surfaces). We highlight the need for further, systematic measurements of in situ spectral reflectance properties, their variability in time and space, and in-depth analysis of time-synchronous satellite data.

Background Ultrasound-guided thermal ablation plays an important role in the management of thyroid disease. The objective of this study was to evaluate the feasibility, efficacy, and safety of thermal ablation for patients with solitary T1bN0M0 papillary thyroid carcinoma (PTC) who are ineligible for or unwilling to undergo surgery. Materials and Methods Data pertaining to 172 patients (38 males and 134 females) who received thermal ablation therapy at 12 hospitals between April 2015 and March 2020 were retrospectively analyzed. The mean duration of follow-up was 24.9 ± 14.1 months (range, 12–60). The technical feasibility, technical success, efficacy, and safety of treatment were analyzed. Postablation tumor size at various time points was compared with preablation measurement. Results All patients selected for thermal ablation received enlarged ablation, according to contrast-enhanced ultrasound postablation. The maximum diameter and volume of ablation zone at 6, 12, 18, 24, 36, and 48 months postablation were significantly smaller than those recorded preablation (P Conclusion Thermal ablation may be a feasible, effective, and safe treatment option for patients with solitary T1bN0M0 PTC who are ineligible for or unwilling to undergo surgery. It may provide a novel treatment option for selected patients.

To evaluate the coagulative performance of a 21-gauge (G) internally cooled radiofrequency (RF) electrode using ex vivo and in vivo rat liver. We developed a prototype of 21-G internally cooled monopolar RF electrode with 5.0 mm active tip length. The ablative zone size created by this electrode was evaluated in ex vivo and in vivo rat liver. Five RF powers (3 W, 5 W, 7 W, 9 W, and 11 W) were applied with and without circulation of chilled water within the electrode. The ablation zone sizes were compared. Histopathological evaluation of the ablation zone was also performed at 24 h and at 7 days after RF ablation. From ex vivo experiments, the ablation volume was found to increase significantly when RF energy was applied with the chilled water circulation. Results of in vivo experiments demonstrate that the ablation volume reached its maximum value when RF power of 7 W was applied (532.3 ± 110.3 mm3). Histopathological examination showed delineated coagulation necrosis at 24 h after RF ablation, which clarified the ablation zone border. Fibrotic change was also observed at 7 days after RF ablation. RF ablation using a 21-gauge electrode produced coagulation necrosis in the rat liver. The ablation volume became maximum when RF power of 7 W was applied with chilled water circulation.

Close-range (CR) L-band radiometry and quasi-simultaneous in situ snow characterizations were conducted in May 2019 at the Swiss Camp research site in the ablation zone of the western Greenland ice sheet. Snow liquid-water and its melt/refreeze are retrieved from microwave antenna temperatures measured with the ground-based L-band radiometer ELBARA-III. The emission model (EM) used in the retrieval is a two-layer configuration of the ‘L-Band Specific Microwave Emission Model of Layered Snowpack’. Consistent snow wetness retrievals were achieved from both single- and multi-angle CR observations of L-band antenna temperatures. This suggests that multi-angle observation is not a pre-requisite for snow wetness retrieval. Therefore, in addition to soil moisture and ocean salinity (SMOS) multi-angle measurements, snow wetness can be estimated from spaceborne L-band brightness temperatures measured at a single observation angle, such as from NASA's SMAP satellite. Our results provide partial validation of a recently presented snow wetness retrieval approach based on the same EM and applied over Greenland using multi-angle SMOS brightness temperatures. Agreement between measured CR antenna temperatures and SMOS brightness temperatures is found to be within the 95% confidence intervals of ELBARA-III and SMOS measurement uncertainties. Our measurements confirm the modeled response of antenna temperatures to diurnal variations of snow wetness.

The purpose of this study is to assess the impact of MRI findings on management of symptomatic patients following RFA of OO. Retrospective review of 43 patients with RFA for OO between June 2010 and June 2017 was performed. Patient, nidus, and ablation data were reviewed. Pre- and 6–8 weeks post-procedural MRI (n = 32) were compared for coverage of nidus by ablation zone, bone marrow edema, nidus hyperintensity, and other findings. Baseline pain levels and analgesic use were compared with post-procedural follow-up visit at 6–8 weeks. Three groups of clinical and MRI outcomes of complete (CR), partial (PR), and no response (NR) were defined. A weighted kappa statistic was used to assess for agreement. Clinical responses were CR in 34/43 (79.1%, 95% CI: 64.0–90.0%), PR in 8/43 (18.6%), and NR in 1/43 (2.3%) patients. All 19/32 patients with MRI CR experienced clinical CR. One patient with MRI NR had clinical NR. All 7/32 patients with clinical PR had MRI PR. All 4/43 complications were in MRI PR or NR groups. Substantial agreement was observed between MRI and clinical outcomes (kappa: 0.69, 95% CI: 0.45–0.95). MRI helped determine etiologies in all symptomatic patients and their management (n = 8). MRI is recommended for symptomatic patients after ablation.

Understanding the impact of climatic variations on Himalayan-Karakoram glaciers has now become a necessity for planning water resources of Indus-Ganga–Brahmaputra basins. One of the most important parameters to assess this is the mass balance of glaciers. Besides ground-based studies of mass balance, differencing of Digital Elevation Models (DEMs) is now commonly employed for estimating the long-term changes for this purpose. Before applying this approach, it is necessary to evaluate the accuracy of elevation changes of glacier surfaces with respect to terrain parameters and the DEMs used. This study demonstrates the factors governing DEM differencing using an example of four glaciers of Zanskar region by comparing DEMs extracted from Cartosat-1 stereo data of ablation season of the years 2005 and 2015. A strong relation has been observed between slope of the terrain and elevation changes between the two DEMs on non-glaciated stable terrain (R2 = 0.8144). The regression equation thus developed has been used to correct elevation changes on glacier surface. Lowering of ablation zone of the four sample glaciers over a period of ten years has been of the order of 3.92, 11.17, 4.99 and 4.39 m. The results obtained by using Cartosat-I DEMs have also been validated using ASTER DEMs of similar time interval.

Purpose The aim of this study was to investigate the diagnostic accuracy of computed tomography (CT) for the prediction of ablation zones from microwave ablation (MWA) and cryoablation (CA) in an ex vivo porcine liver model. Methods Sequential (30 seconds) CT scans were acquired during and after MWA and CA in an ex vivo porcine liver model. We generated 120-kVp equivalent reconstructions of generic dual-energy CT data sets, and comprehensive region-of-interest measurements were statistically correlated with invasive temperature monitoring using Pearson correlation coefficient. Binary logistic regression was performed for prediction of successful ablation. Results With the use of pooled data from 6 lesions in 2 separate experiments, correlation analysis of attenuation in Hounsfield units (HU) and temperature yielded r = -0.79 [confidence interval (CI), -0.85 to -0.71] for MWA and r = 0.62 (CI, 0.55 to 0.67) for CA.For MWA, there was a linear association between attenuation and temperature up to 75°C; thus, linear regression yielded a slope of -2.00 HU/°C (95% CI, -1.58 to -2.41). For CA, a linear association between attenuation and temperature was observed in the cooling phase with a slope of 2.11 HU/°C (95% CI, 1.79 to 2.58). In MWA treatment, binary logistic regression separated less than 70°C and greater than 70°C with 89.2% accuracy. Within the ice ball, temperatures above and below -20°C were distinguished with 65.3% accuracy. Conclusions Our experiments reveal several difficulties in predicting ablation zone temperature from CT attenuation. Microwave ablation leads to gas production in the tissue, which degrades the accuracy of noninvasive temperature measurement, especially at higher temperatures. In CA, CT thermometry is limited by ice ball formation, which leads to homogeneous attenuation, nearly independent of temperature. Further research is needed to define the role of CT thermography in ablation zone monitoring in liver malignancies.

Radiofrequency ablation (RFA) is a non-invasive image-guided procedure where tumors are heated in the body with electrical current. RFA procedures are commonly indicated for patients with limited local disease or who are not surgical candidates. Current methods of RFA use multiple cords and wires that ergonomically complicate the procedure and present the risk of cutting or shorting the circuit if they are damaged. A wireless RFA technique based on electromagnetic induction is presented in this paper. The transmitting and receiving coils were coupled to resonate at the same frequency to ensure the highest power output. The receiving coil was connected to two insulated electrodes on a catheter, which allowed the current to flow to the targeted tissue. The prototype system was tested with ex-vivo bovine tissue, which has similar thermal and electrical properties to human tissue. The setup can monitor the received power, efficiency, temperature, and ablation zone during ablation procedures. The maximum received power was 15 W, and the average maximum efficiency was 63.27%. The novel system was also able to ablate up to a 2 cm ablation zone in non-perfused tissue. This proof of concept for performing RFA wirelessly with electromagnetic induction may merit further optimization.

Purpose To determine the effects of a thermal accelerant gel on temperature parameters during microwave liver ablation. Materials and Methods Sixteen consecutive liver ablations were performed in 5 domestic swine under general anesthesia with (n = 8) and without (n = 8) administration of thermal accelerant gel. Ablation zone temperature was assessed by real-time MR thermometry, measured as maximum temperature (Tmax) and the volume of tissue ≥ 60°C (V60). Tissue heating rate, ablation zone shape, and thermal energy deposition using the temperature degree-minutes at 43°C (TDM43) index were also measured. Differences between groups were analyzed using generalized mixed modeling with significance set at P = .05. Results Mean peak ablation zone temperature was significantly greater with thermal accelerant use (mean Tmax, thermal accelerant: 120.0°C, 95% confidence interval [CI] 113.0°C–126.9°C; mean Tmax, control: 80.3°C, 95% CI 72.7°C–88.0°C; P Conclusions Thermal accelerant use is associated with higher microwave ablation zone temperatures, greater thermal energy deposition, and faster and more spherical tissue heating compared with control ablations.

The Himalayan glaciers contribute significantly to regional water resources. However, limited field observations restrict our understanding of glacier dynamics and behaviour. Here, we investigated the long-term in situ mass balance, meteorology, ice velocity and discharge of the Chhota Shigri Glacier. The mean annual glacier-wide mass balance was negative, −0.46 ± 0.40 m w.e. a−1 for the period 2002–2019 corresponding to a cumulative wastage of −7.87 m w.e. Winter mass balance was 1.15 m w.e. a−1 and summer mass balance was −1.35 m w.e. a−1 over 2009–2019. Surface ice velocity has decreased on average by 25–42% in the lower and middle ablation zone (below 4700 m a.s.l.) since 2003; however, no substantial change was observed at higher altitudes. The decrease in velocity suggests that the glacier is adjusting its flow in response to negative mass balance. The summer discharge begins to rise from May and peaks in July, with a contribution of 43%, followed by 38% and 19% in August and September, respectively. The discharge pattern closely follows the air temperature. The long-term observation on the ‘Chhota Shigri – a benchmark glacier’, shows a mass wastage which corresponds to the slowdown of the glacier in the past two decades.

Management of residual or recurrent disease following thermal ablation of renal cortical tumors includes surveillance, repeat ablation, or surgical extirpation. We present a multicenter experience with regard to the management of this clinical scenario. Prospectively maintained databases were reviewed to identify 1265 patients who underwent cryoablation (CA) or radiofrequency ablation (RFA) for enhancing renal masses. Disease persistence or recurrence was classified into one of the three categories: (i) residual disease in ablation zone; (ii) recurrence in the ipsilateral renal unit; and (iii) metastatic/extra-renal disease. Seventy seven patients (6.1%) had radiographic evidence of disease persistence or recurrence at a median interval of 13.7 months (range, 1–65 months) post-ablation. Distribution of disease included 47 patients with residual disease in ablation zone, 29 with ipsilateral renal unit recurrences (all in ablation zone), and one with metastatic disease. Fourteen patients (18%) elected for surveillance, and the remaining underwent salvage ablation (n = 50), partial nephrectomy (n = 5), or radical nephrectomy (n = 8). Salvage ablation was successful in 38/50 (76%) patients, with 12 failures managed by observation (3), tertiary ablation (6), and radical nephrectomy (3). At a median follow-up of 28 months, the actuarial cancer-specific survival and overall survival in this select cohort of patients was 94.8 and 89.6%, respectively.

Objective: Accurate prospective modeling of microwave ablation (MWA) procedures can provide powerful planning and navigational information to physicians. However, patient-specific tissue properties are generally unavailable and can vary based on factors such as relative perfusion and state of disease. Therefore, a need exists for modeling frameworks that account for variations in tissue properties. Methods: In this study, we establish an inverse modeling approach to reconstruct a set of tissue properties that best fit the model-predicted and observed ablation zone extents in a series of phantoms of varying fat content. We then create a model of these tissue properties as a function of fat content and perform a comprehensive leave-one-out evaluation of the predictive property model. Furthermore, we validate the inverse-model predictions in a separate series of phantoms that include co-recorded temperature data. Results: This model-based approach yielded thermal profiles in close agreement with experimental measurements in the series of validation phantoms (average root-mean-square error of 4.8 °C). The model-predicted ablation zones showed compelling overlap with observed ablations in both the series of validation phantoms (93.4 ± 2.2%) and the leave-one-out cross validation study (86.6 ± 5.3%). These results demonstrate an average improvement of 17.3% in predicted ablation zone overlap when comparing the presented property-model to properties derived from phantom component volume fractions. Conclusion: These results demonstrate accurate model-predicted ablation estimates based on image-driven determination of tissue properties. Significance: The work demonstrates, as a proof-of-concept, that physical modeling parameters can be linked with quantitative medical imaging to improve the utility of predictive procedural modeling for MWA.

The glacier mass balance (GMB) is an important link between climate and water re-sources and has remarkable regulatory functions in river runoff. To simulate changes of the GMB and to analyze the recharge rates of glacier meltwater to runoff in the Manas River Basin (MRB) during 2000-2016, MOD11C3, TRMM 3B43 and other multi-source remote sensing data were used to drive the degree-day model. The results showed that: (1) the accuracy of the remote sensing meteorological data can be corrected effectively by constructing the temperature and precipitation inversion models, and the characteristics of glacial climate can be finely described through downscaling. The average annual temperature was −7.57 °C and the annual precipitation was 410.71 mm in the glacier area of the MRB. The zone at an altitude of about 4200 m was a severe climate change zone, and above and below that zone, the temperature drop rates were −0.03°C/100 m and −0.57°C/100 m, respectively, while precipitation gradients were −2.66 mm/100 m and 4.89 mm/100 m, respectively. (2) The overall GMB was negative with a cumulative GMB of up to −9811.19 mm w.e. and the average annual GMB fluctuated between −464.85 and −632.19 mm w.e. Besides, the glacier melted slowly during 2000–2002 and 2008-2010, but rapidly for 2002–2008 Sand 2010–2016, while the most serious loss of the glacier occurred in 2005-2009. Moreover, the vertical changes of the GMB increased at 244.83 mm w.e./100 m in the ablation zone but only at 18.77 mm w.e./100 m in the accumulation zone. (3) The intraannual runoff strongly responded to the change of the GMB especially in July and August when the loss of the GMB accounted for 75.4% of the annual loss, and when runoff accounted for 55.1% of the annual total. Due to differences in the annual precipitation and snow meltwater outside the glacier, the interannual glacier meltwater recharge rates fluctuated between 19% and 31%. The recharge rate of glacier meltwater to runoff in the MRB was close to that for other basins in the Tianshan Mountains, which may be used as a basis to confirm the reliability of the estimated GMB results. Furthermore, based on the present findings, it is recommended that the research community pursue studies on the GMB in other alpine river basins.

Radiofrequency ablation (RFA) is now a widely used minimally invasive treatment method for hepatic tumors. Preoperative planning plays a vital role in RFA therapy. With increasing tumor size, multiple overlapping ablations are needed, which are challenging to optimize while considering clinical constraints. In this paper, we present a new automatic RFA planning method. First, a 2-steps set cover-based model is formulated, which can integrate multiple clinical constraints for optimization of overlapping ablations. To ensure that the planning model can be solved in a reasonable time, a search space reducing strategy is then proposed. We also developed an algorithm for automatic RFA electrode selection, which provides a proper electrode ablation zone for the planning model. The proposed method was evaluated with 20 tumors of varying sizes (0.92 cm3 to 28.4 cm3). Results showed that the proposed method can generate clinical feasible RFA plans with a minimum number of RFA electrodes and ablations, complete tumor coverage and minimized ablation of normal tissue.

To evaluate the ablation zone diameter (AZD) using six modes of corneal topography after small-incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for myopia and to compare the programmed and postoperative AZDs This retrospective comparative study included 86 right eyes in 86 patients who underwent SMILE or FS-LASIK at the Shandong Eye Institute between June 2016 and August 2017. Data were collected preoperatively and at 1, 3, and 6 months postoperatively using the Pentacam system. The AZD was determined using six modes of corneal topography: postoperative axial curvature topography (PACT), postoperative tangential curvature topography (PTCT), difference-axial curvature topography (DACT), difference-tangential curvature topography (DTCT), postoperative front elevation topography (PFET), and difference-corneal thickness topography (DCTT). The difference between the programmed and postoperative AZDs was compared between the groups of two surgical procedures. At 3 months, the AZDs measured by PTCT, DTCT, and PFET after SMILE showed a significant decrease, while the AZD by DACT revealed an increase (P 0.75). In the treatment of myopia, the achieved topographic ablation zones after FS-LASIK were smaller than the theoretically designed ones. The AZDs after SMILE were larger than those after FS-LASIK, with an equivalent programmed value. The DACT may be more suitable for measuring postoperative ablation zones in clinic with clearer borders and favorable repeatability. This method may be potential for the measurement of ablation zones and further research on the visual quality after refractive surgery.

To compare manufacturer provided predictions and realized ablation dimensions in the liver using one 2450MHz 100 Watt generator model microwave ablation (MWA) system.Between 1/1/2015 and 2/1/2018, MWAs were performed in 86 patients who underwent a total of 103 MWAs with a single MWA system. There were 64 men and 22 women with a mean age of 63.9±9.9 (SD) years (range: 30-88 years). Demographic, procedural, and outcomes data was recorded. The manufacturer predicted ablation zone sizes in three dimensions (anterior-posterior [AP], transverse [TR], and cranial caudal [CC]) were recorded and then compared to the actual ablation zone sizes at one month follow-up imaging.MWAs were most commonly performed to treat hepatocellular carcinoma (92/103, 89.3%). Dividing the actual ablation size by the manufacturer prediction in the AP, TR, and CC directions resulted in a mean of 88.3±20.6 (SD) % (range: 33.3-156.4%), 80.2±26.5 (SD) % (range: 29.6-182.9%), and 86.7±25.1 (SD) % (range: 37-186.1%), respectively. The realized AP direction was statistically closer to the manufacturer prediction than the TR (P0.01). Ablation Watt setting of 100 Watts resulted in more accurate predictions than the 75 or 45 Watt settings in the AP direction (P=0.03).This 2450MHz 100 Watt generator MWA system manufacturer provided model fairly accurately predicts ablation zone dimensions, but tends to over predict realized dimensions in this mainly hepatocellular carcinoma, and therefore cirrhotic, cohort. The TR is the most inaccurately predicted dimension and manufacturer predictions appear to be best in the 100W setting, important aspects for interventionalists to consider during ablation planning and execution.

The aim of this study was to describe ultrasound (US) and contrast-enhanced ultrasound (CEUS) findings immediately and 1 d after percutaneous irreversible electroporation (IRE) of hepatic malignant tumors. Immediately after IRE, the ablation zone was shown to be a gradually expanding hypo-echoic area around the electrodes. The microcirculation of the ablation zone was markedly reduced on CEUS (before vs. immediately after, p0.001), and the macrocirculation within the ablation zone was preserved. At 1 d after IRE, the ablation zones lost their hypo-echogenicity to become iso-echoic or hyper-echoic (before vs. 1 d after, p = 0.004; immediately after vs. 1 d after, p = 0.002). At this time, further elimination of microcirculation was confirmed on CEUS (before vs. 1 d after, p0.001; immediately after vs. 1 d after, p = 0.003). The size of the ablation zone, which measured by US, was strongly correlated with that measured by CEUS (length: r: = 0.929, width: r = 0.940, p0.001), was significantly enlarged immediately after IRE and shrunk 1 d after IRE.

Objective To explore various microwave (MW) time/power combinations to achieve maximum single-probe system performance in a live pig liver model. Methods Fifty-one microwave ablations performed in 12 female pigs using the following time/power combinations: 65 W for 10 min (65W 10MIN), ramped from 20 to 65 W (RAMPED), 95 W pulses with cooling periods (95W PULSED), 40 W for 16 min 15 s (LOW POWER), 1 min 95 W pulse then 8 min 65 W then a second 1 min 95 W pulse (BOOKEND 95W) and 65 W for 15 min (65W 15MIN). Temperatures 1.5 cm from the antenna were measured. Livers were excised, and ablations were measured and compared. Results At fixed overall energy, LOW POWER produced ablation zones with the smallest volume compared to 65W 10MIN, RAMPED and 95W PULSED. At a fixed time of 10-min, BOOKEND 95W protocol achieved wider and larger ablation zones than 65W 10MIN (p = 0.038, p = 0.008) and 95W PULSED (p = 0.049, p = 0.004). The 65W 15MIN combination had significantly larger diameters (p = 0.026), larger lengths (p = 0.014) and larger volumes (p = 0.005) versus 65W 10MIN. Maximum temperatures were highest with BOOKEND 95W (62.9 °C) and 65 W 15 MIN (63.0 °C) and lowest with LOW POWER (45.9 °C), p = 0.009. Conclusions Low power ablations, even if controlled for total energy delivery, create small ablation zones. High peak powers are associated with larger ablation zones and high margin temperatures if cooling pauses are avoided. Ramping and pulsing protocols with interleaved cooling appear to be of no benefit versus continuous 65 W for creating large ablation zones.

Purpose The aims of this study were to evaluate a semi-automatic segmentation software for assessment of ablation zone geometry in computed tomography (CT)-guided microwave ablation (MWA) of liver tumors and to compare two different MWA systems. Material and Methods 27 patients with 40 hepatic tumors (primary liver tumor n = 20, metastases n = 20) referred for CT-guided MWA were included in this retrospective IRB-approved study. MWA was performed using two systems (system 1: 915 MHz; n = 20; system 2: 2.45 GHz; n = 20). Ablation zone segmentation and ellipticity index calculations were performed using SAFIR (Software Assistant for Interventional Radiology). To validate semi-automatic software calculations, results (2 perpendicular diameters, ellipticity index, volume) were compared with those of manual analysis (intraclass correlation, Pearson’s correlation, Mann–Whitney U test; p