Ablation Volume Research Articles

MP23-08 SHORT PULSE VS. LONG PULSE ABLATION WITH THE THULIUM FIBER LASER, AN IN VITRO STUDY

You have accessJournal of UrologyCME1 Apr 2023MP23-08 SHORT PULSE VS. LONG PULSE ABLATION WITH THE THULIUM FIBER LASER, AN IN VITRO STUDY Francois Soto Palou, Robert Medairos, Junqin Chen, Jodi Antonelli, Michael Lipkin, Glenn Preminger, and Pei Zhong Francois Soto PalouFrancois Soto Palou More articles by this author , Robert MedairosRobert Medairos More articles by this author , Junqin ChenJunqin Chen More articles by this author , Jodi AntonelliJodi Antonelli More articles by this author , Michael LipkinMichael Lipkin More articles by this author , Glenn PremingerGlenn Preminger More articles by this author , and Pei ZhongPei Zhong More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003248.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The thulium fiber laser (TFL) is becoming of interest to Urologists due to its unique properties. The TFL pulse profile consists of rectangular pulses, designed for enhancing photothermal ablation. Energy for each pulse may be modified by altering pulse duration or peak power. Our aim for this study is to compare short pulse (SP) versus long pulse (LP) for common 10 W dusting settings using the TFL platform. METHODS: All tests were conducted using an IPG Photonics TLR-50 W TFL system and a 200 μm fiber on “soft” (5:2) Begostone phantoms. The most popular 10 W dusting settings (Figure 1) among endourologists familiar with TFL were evaluated.[1] Four different standoff distances (0.2 mm, 0.5 mm 1 mm, 2 mm), and a clinically significant scanning speed of 1 mm/sec was used. The pulse profiles were altered for each energy setting to produce a short pulse (SP) and a long pulse (LP) design. The laser fiber was scanned in a 15 mm straight line with a 3D positioning system across a polished and submerged Begostone surface. Ablation volumes were quantified by optical coherence tomography (OCT). RESULTS: Overall, SP provided greater ablation volume when compared to LP. The greatest difference observed between SP and LP was at 1J/10 Hz and SD of 0.2 mm (2.51 mm3 vs. 0.35 mm3) and this difference was statistically significant (p<0.005). Out of the 20 performed trials there were only two instances in which LP outperformed SP in terms of ablation volume: 0.4J/25 Hz at SD of 2 mm (0 mm3 vs. 0.15 mm3) and 0.2J/50 Hz at SD of 0.2 mm (0.79 mm3 vs 0.81 mm3). In the latter case, however, the difference was not found to be statistically significant (p=0.7). CONCLUSIONS: TFL short pulse profile offers superior trough ablation volumes than long pulse during dusting under clinically relevant scanning speed of 1 mm/s with a time average power of 10 W. [1] Sierra A, Corrales M, Piñero A, Traxer O. Thulium fiber laser pre-settings during ureterorenoscopy: Twitter's experts' recommendations. World J Urol. 2022;40(6):1529-1535. doi:10.1007/s00345-022-03966-9. Source of Funding: N/A © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e308 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Francois Soto Palou More articles by this author Robert Medairos More articles by this author Junqin Chen More articles by this author Jodi Antonelli More articles by this author Michael Lipkin More articles by this author Glenn Preminger More articles by this author Pei Zhong More articles by this author Expand All Advertisement PDF downloadLoading ...

PD45-06 DUSTING EFFICIENCY FOR THULIUM FIBER LASER: WHEN IT COMES TO FREQUENCY, LESS IS MORE

You have accessJournal of UrologyCME1 Apr 2023PD45-06 DUSTING EFFICIENCY FOR THULIUM FIBER LASER: WHEN IT COMES TO FREQUENCY, LESS IS MORE Francois Soto Palou, Robert Medairos, Junqin Chen, Jodi Antonelli, Michael Lipkin, Glenn Preminger, and Pei Zhong Francois Soto PalouFrancois Soto Palou More articles by this author , Robert MedairosRobert Medairos More articles by this author , Junqin ChenJunqin Chen More articles by this author , Jodi AntonelliJodi Antonelli More articles by this author , Michael LipkinMichael Lipkin More articles by this author , Glenn PremingerGlenn Preminger More articles by this author , and Pei ZhongPei Zhong More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003358.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Data from Holmium laser studies has taught us that optimal dusting generally require low energy and high frequency settings. In assessing thulium fiber laser (TFL) technology urologists have often relied on “traditional” dusting settings obtained from Holmium laser trials and experiments. However, these two platforms are fundamentally different in their pulse profile and energy (Ep) delivery. Clinical TFL platforms have an energy range of 0.025J-6J and a frequency (F) range of 1Hz-2400Hz. With the seemingly endless combination of settings and lack of scientific evidence to support one over the other, we aim to provide guidance to the practicing urologists and assess the efficiency of the TFL platform in an automated in vitro “dusting model”. METHODS: All tests were conducted using an IPG Photonics TLR-50W TFL system and a 200μm fiber on “soft” (5:2) Begostone phantoms. We selected the most popular dusting settings (Figure 1) among endourologists familiar with TFL1 and tested each combination of Ep and F settings at four different standoff distances (SD) (0.2mm, 0.5mm 1mm, 2mm) and at clinically significant scanning speeds of 1mm/sec or 2mm/sec, under the same total laser energy delivered to the stone (i.e., 40 J). All pulses were adjusted to maximum peak power and the corresponding pulse duration. The laser fiber was scanned in a 15mm straight line with a 3D positioning system across a polished and submerged Begostone surface. Ablation volumes were quantified by optical coherence tomography (OCT). RESULTS: The maximum stone ablation was achieved at the combination of high energy and low frequency settings (p<0.005). Overall, the settings that produced the greatest ablation volume were 1J/10Hz (2.51mm3) and 1J/20Hz (2.55mm3). For the rectangular pulse profile typically used in TFL, as SD increased ablation volume decreased. CONCLUSIONS: The most efficient dusting settings for dusting using the current TFL occur at high energy, low frequency, and at a short SD of 0.2mm. Further studies are warranted to compare dusting efficiency produced by these settings using human kidney stones. Reference: 1. Sierra A, Corrales M, Piñero A, Traxer O. Thulium fiber laser pre-settings during ureterorenoscopy: Twitter's experts' recommendations. World J Urol. 2022;40(6):1529-1535. doi:10.1007/s00345-022-03966-9 Source of Funding: N/A © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1164 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Francois Soto Palou More articles by this author Robert Medairos More articles by this author Junqin Chen More articles by this author Jodi Antonelli More articles by this author Michael Lipkin More articles by this author Glenn Preminger More articles by this author Pei Zhong More articles by this author Expand All Advertisement PDF downloadLoading ...

MP68-05 STONE ABLATION CHARACTERISTICS OF THULIUM FIBER LASER WHEN WORKING FROM DISTANCE: MIND THE GAP

You have accessJournal of UrologyCME1 Apr 2023MP68-05 STONE ABLATION CHARACTERISTICS OF THULIUM FIBER LASER WHEN WORKING FROM DISTANCE: MIND THE GAP Ron Marom, William W. Roberts, Timothy L. Hall, John Robinson, Adam J. Matzger, and Khurshid R. Ghani Ron MaromRon Marom More articles by this author , William W. RobertsWilliam W. Roberts More articles by this author , Timothy L. HallTimothy L. Hall More articles by this author , John RobinsonJohn Robinson More articles by this author , Adam J. MatzgerAdam J. Matzger More articles by this author , and Khurshid R. GhaniKhurshid R. Ghani More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003331.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The Thulium Fiber Laser (TFL) is a novel laser technology. Its wavelength has a higher absorption in water than the Ho:YAG laser, which could affect its ablative capabilities when working from distance. In this bench study, we assessed stone ablative crater characteristics of TFL at various pulse lengths and laser fiber to stone distances. METHODS: Using a commercially available TFL (Fiber Dust, Quanta), a single pulse of 1J at the shortest and longest pulse durations (SP and LP) were delivered through a 200µm laser fiber placed at various distances from a flat BegoStone model using a 3D positioning system. Pulses were activated at 0, 0.5, 1, 2, and 3 mm from stone. 10 trials were performed for each pulse/distance combination; at least 4 trials had to result in ablation to be included. Each ablation crater was scanned using an optical microscope and a height map was calculated with FIJI using the Extended Depth of Field plugin (Fig 1A). The volume, depth, and area of the crater were calculated using MATLAB (Fig 1B). Statistical analysis was carried in R. RESULTS: Both SP and LP exhibited a reduction in the ablation volume with increasing distance of the fiber from stone surface (Fig 2A). LP did not result in any ablation at greater than 1 mm distance. Ablation volume of 1J SP was larger than 1J LP for all distances (p<0.00001) with up to 350% increased crater volume at contact. The same trend was seen for ablation crater depth with a mean depth of 0.38 mm and 0.2 mm at contact in SP and LP, respectively (Fig 2B). Surface area of the ablation crater was larger for SP at all distances; however, it showed different trend than volume and depth with a peak at distance of 0.5mm and then began to decline (Fig 2C). CONCLUSIONS: At 1J setting on contact, SP leads to at least three times more stone ablation volume in comparison to LP at contact. No ablation occurs with LP at greater than 1 mm distance. Further investigation is needed to understand why large differences exist between the same powered pulses at different pulse durations. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e954 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ron Marom More articles by this author William W. Roberts More articles by this author Timothy L. Hall More articles by this author John Robinson More articles by this author Adam J. Matzger More articles by this author Khurshid R. Ghani More articles by this author Expand All Advertisement PDF downloadLoading ...

MP09-17 EFFICACY AND SAFETY OF CT-GUIDED MICROWAVE ABLATION IN PATIENTS WITH LOCALIZED SMALL RENAL MASSES

You have accessJournal of UrologyCME1 Apr 2023MP09-17 EFFICACY AND SAFETY OF CT-GUIDED MICROWAVE ABLATION IN PATIENTS WITH LOCALIZED SMALL RENAL MASSES Shivani Jain, Ashley Foret, Chelsea Baumgartner, Megan Escott, Benjamin Henderson, Sean O'Brien, Scott Delacroix, Jessie Gills, and Mary Westerman Shivani JainShivani Jain More articles by this author , Ashley ForetAshley Foret More articles by this author , Chelsea BaumgartnerChelsea Baumgartner More articles by this author , Megan EscottMegan Escott More articles by this author , Benjamin HendersonBenjamin Henderson More articles by this author , Sean O'BrienSean O'Brien More articles by this author , Scott DelacroixScott Delacroix More articles by this author , Jessie GillsJessie Gills More articles by this author , and Mary WestermanMary Westerman More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003224.17AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: CT-guided microwave ablation (MWA) is increasingly used for the treatment of localized small renal masses, especially in patients with co-morbidities that increase the risks of traditional nephrectomy. The main advantages of a percutaneous ablative approach over surgery include less invasiveness and lower reported complication rates. We report patient characteristics and outcomes following MWA of clinically localized small renal masses. METHODS: A retrospective chart review of our institution’s biopsy database was conducted to identify all patients with clinically localized renal masses 3 cm or less on abdominal imaging and who underwent a subsequent renal mass biopsy (RMB) and MWA between the years of 2012 and 2022. RESULTS: 135 patients met inclusion criteria. MWA was technically successful in 98.4% of patients. The majority of patients were male (59.9%) and Caucasian (82.5%). Median (IQR) tumor size was 2.2 cm (0.7,3). The median (IQR) for age and BMI was 70 (38,94) and 30.7 (15.0,52.7), respectively. These parameters for MWA ablation time in minutes and watts were 10 (1,20) and 65 (65,140), respectively. 36% of lesions biopsied were benign oncocytomas. In those with biopsy-proven clear cell RCC, 4.3% of patients had complications following MWA. Complications requiring readmission, albeit rare, included urosepsis, lung collapse, and retroperitoneal hematoma. Renal function was conserved in all except 2 patients. Local recurrence requiring repeat ablation (4, 3.27%) or surgery (partial nephrectomy (2, 1.64%), radical nephrectomy (5, 4.10%) was rare. Metastatic-free survival was 95.6% at 24 months for patients who underwent MWA (95% CI 93.4 – 98.7). CONCLUSIONS: In this retrospective review of renal masses 3 cm or less that subsequently underwent RMB and MWA, procedural complication requiring admission or readmission was rare. Local control rates were 98.3% for cT1a malignancies. Complication and local control rates found in this large contemporary study are lower than those reported in previously published data. A majority of research on thermal ablation for renal masses focuses on cryoablation and RFA, and AUA 2021 guidelines on renal mass evaluation and management consider MWA an investigational technique. Nonetheless, MWA has potential advantages of higher ablation volume and shorter ablation time compared against other thermal techniques. MWA for renal masses 3 cm or less should be further investigated as a safe and efficacious option for patients who have co-morbidities that increase the risk of surgical complications. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e112 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Shivani Jain More articles by this author Ashley Foret More articles by this author Chelsea Baumgartner More articles by this author Megan Escott More articles by this author Benjamin Henderson More articles by this author Sean O'Brien More articles by this author Scott Delacroix More articles by this author Jessie Gills More articles by this author Mary Westerman More articles by this author Expand All Advertisement PDF downloadLoading ...

151 Intracranial Magnetic Resonance Guided Laser Interstitial Thermal Therapy for Epilepsy: A Single Institution’s Experience of 226 Cases

INTRODUCTION: Magnetic resonance guided laser interstitial thermal therapy (MRg-LITT) is a minimally invasive alternative to open surgical resection for epilepsy. Patient and technical factors associated with outcomes remain unclear. METHODS: We performed a retrospective review of consecutive patients undergoing MRg-LITT surgery at a single high-volume epilepsy center. Medical and surgical history, trajectory number per patient, adverse events, and outcomes up to 24 months were obtained and statistically analyzed. RESULTS: 203 patients underwent a total of 226 MRg-LITT procedures for epilepsy between 2011-2020. 52% and 55% of patients experienced seizure freedom at 12 and 24 months after ablation, respectively. Overall, patients with lesional epileptogenic foci were more likely to have better seizure control at 12- and 24-months after surgery (p &lt; 0.05). Of cases performed with curative intent, patients with mesial temporal sclerosis (MTS) were most likely to maintain long-term seizure freedom. Ablations performed for disconnection (corpus callosotomy) or palliation of multifocal epilepsy were unlikely to provide complete seizure freedom. 6 cases (2.7%) were complicated by intra- or post-operative hemorrhage. 3 patients (1.5%) experienced persistent post-operative complaints including cranial nerve palsy and headaches. The odds of complication (minor or major vs none) were multiplied by 1.43 for each additional trajectory (95% CI [1.16, 1.76]), and by 1.04 for each additional 1cm3 of volume ablated (95% CI [1.008, 1.076]). CONCLUSIONS: MRg-LITT, a safe and effective approach to distinct epilepsy types, appears most persistently beneficial for lesional epilepsy, particularly MTS. Although serious complications were infrequent, adverse events were statistically correlated with multiple stereotaxic trajectories and larger ablation volumes. Our results provide additional guidance for patient counseling and surgical planning.

Highlighting the effect of heterogeneous blood perfusion on radio-frequency ablation of human brain tumors: An image-based numerical investigation

Radio-frequency ablation (RFA) is a minimally invasive treatment that can provide highly localized and precise cancer therapy. Despite these advantages, its application in clinical practice remains limited. This is primarily due to the insufficient ablation volume, where blood perfusion plays a significant role. In this study, computational modeling is applied to examine the effects of heterogeneous blood perfusion on the tissue temperature, resultant thermal damage, and ablation volume in the RFA treatment. Two patients' heterogeneous blood perfusion and 3D brain tumor geometry are extracted from their dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) data. This patient-specific information is imported into the bioheat transfer model developed in OpenFOAM to predict thermal effects. Results show that the heterogeneous blood perfusion leads to deeper heat penetration in the tumor tissue compared to the simulation in which blood perfusion is assumed to be uniform across the entire tumor. On average, the predicted tissue temperature and ablation volume are 10–11% and 30–38% higher for both patients, respectively, when the heterogeneous blood perfusion is adopted. In addition, the ablation volume is highly susceptible to the applied RF voltage and coolant temperature. These two factors can be optimized to maximize the treatment. However, the optimal settings vary for each patient, highlighting the demand for patient-specific design. Results obtained from this study can assist clinicians and surgeons in optimizing RFA parameters for a specific patient that can improve the treatment efficacy.

Fundamental study of a femtosecond laser ablation mechanism in gold and the impact of the GHz repetition rate and number of pulses on ablation volume

In this work, we performed an experimental investigation supported by a theoretical analysis of single-shot laser ablation of gold to study the laser-matter interaction for predicting the ablation morphology and optimizing the process parameters. A set of coupled partial differential equations of the two-temperature model with dynamic optical properties and a phase explosion mechanism were used to determine the temporal and spatial evolution of the electron and lattice temperatures. The primary research focus of this work is to use the GHz frequency to investigate the ablation performance because the irradiated material is still far from thermal equilibrium during the laser-matter interaction. In contrast to conventional single-pulse laser ablation, intra-burst frequencies and the number of pulses are important factors in optimizing ablation efficiency and quality for fast material processing. Theoretical investigation revealed that the ablation volume increased due to heat accumulation, but the ablation quality decreased as the intra-burst frequencies decreased from 1000 GHz to 10 GHz. Moreover, the specific ablation volume increases with a higher burst number and lower intra-burst frequency at the expense of ablation quality.

Computational Re-Entry Vulnerability Index Mapping to Guide Ablation in Patients With Postmyocardial InfarctionVentricular Tachycardia.

Ventricular tachycardias (VTs) in patients with myocardial infarction (MI) are often treated with catheter ablation. However, the VT induction during this procedure does not always identify all of the relevant activationpathways or may not be possible or tolerated. The re-entry vulnerability index (RVI) quantifies regional activation-repolarization differences and can detect multiple regions susceptible to re-entry without the need to inducethe arrhythmia. This study aimed to further develop and validate the RVI mapping in patient-specific computational models of post-MI VTs. Cardiac magnetic resonance imaging data from 4 patients with post-MI VTs were used to induce VTs inacomputational electrophysiological model by pacing. The RVI map of a premature beat in each patient modelwasused to guide virtual ablations. We compared our results with those of clinical ablation in the same patients. Single-site virtual RVI-guided ablation prevented VT induction in 3 of 9 cases. Multisite virtual ablations guided by RVI mapping successfully prevented re-entry in all cases (9 of 9). Overall, virtual ablation required 15-fold fewer ablation sites (235.5 ± 97.4 vs 17.0 ± 6.8) and 2-fold less ablation volume (5.34 ± 1.79mL vs 2.11 ± 0.65mL) than the clinical ablation. RVI mapping allows localization of multiple regions susceptible to re-entry and may help guide VT ablation. RVI mapping does not require the induction of arrhythmia and may result in less ablated myocardial volumeswith fewer ablation sites.

Abstract No. 7 ▪ FEATURED ABSTRACT Pulsed Electric Field (PEF) Ablation Invokes Stronger Immune Cytokine Profile and Tumor Response than Radiofrequency Thermal Ablation for Matched Ablation Volumes

Focal tumor ablation may cause secondary immunogenic upregulation that enhances local and distant tumor responses, with profiles that are unique to each modality., Pulsed electric fields (PEFs) use short duration-high voltage electrical pulses to destabilize and kill cells through various biochemical processes. Because it does not rely on thermal effects PEF does not damage interstitial proteins, fostering improved antigen integrity and immune signaling which may lead to lesion resolution. This study compared whether cell death and subsequent interstitial effects caused by PEF and radiofrequency ablation (RFA) result in differentiated primary tumor responses. Thirty female Balb/c mice, divided into sham, PEF, and RFA treatment groups (n = 10/group) were transplanted with EMT6 cells in the left mammary fat pad. Eight days after challenge (d = 0), mice in the PEF and RFA groups received treatment with doses selected to achieve similar subtotal ablation volumes. Three mice from each group were euthanized at day 4 for H&E analysis of ablation zone. The remainder were survived to 10-days post-ablation to monitor tumor growth. Serum was collected on Days -1, +1, +4 and +10 for cytokine analysis. Four-day histology demonstrated comparable subtotal ablation areas between PEF and RFA treatment. While RFA-treated tumors presented immune cells accumulating at the tumor-treatment zone boundary, PEF-treated tumors showed immune cell infiltration throughout the tumor. Further, PEF treatment slowed tumor growth compared with RFA or sham treatments, with day 10 average tumor volumes of 335, 791, and 857 mm3 for PEF, RFA, and sham group, respectively. Ingenuity Pathway Analysis (IPA) of 32 serum cytokines revealed most notable differences between groups on day 4 post-ablation. The PEF-treated group had a significant decrease in the levels of CSF1, CSF2, CSF3, CCL2, IL1β, IL6, IL13, and TNF, and an increase in the levels of IL4. These changes suggest that PEF is associated to 1) decreased accumulation of myeloid derived suppressor cells (MDSCs), 2) decreased the proliferation of tumor-associated macrophages (TAMs), 3) decreased proliferation, survival and invasion of tumor cells. Conversely, these changes were all the opposite for the RFA group. PEF treatment may cause a stronger EMT6 tumor response in mice compared with RFA treatment. These data suggest that PEF may have a greater local and distant tumor response benefit versus RFA thermal ablation. Further studies should explore potential abscopal effects.

Early mortality after inpatient versus outpatient catheter ablation in patients with atrial fibrillation

Rates of early mortality and complications after catheter ablation (CA) of atrial fibrillation (AF) vary across health care settings. The purpose of this study was to identify the rate and predictors of early mortality (within 30 days) after CA in the inpatient and outpatient settings. Using the Medicare Fee for Service database, we analyzed 122,289 patients who underwent CA for treatment of AF between 2016 and 2019 to define 30-day mortality in both inpatients and outpatients. Odds of adjusted mortality were assessed with several methods, including inverse probability of treatment weighting. Mean age was 71.9 ± 6.7 years, 44% were women, and mean CHA2DS2-VASc score was 3.2 ± 1.7. Overall, 82% underwent AF ablation as an outpatient. Mortality rate 30 days after CA was 0.6%, with inpatients accounting for 71.5% of deaths (P <.001). Early mortality rates were 0.2% for outpatient procedures and 2.4% for inpatient procedures. The prevalence of comorbidities was significantly higher in patients with early mortality. Patients with early mortality had significantly higher rates of postprocedural complications. After adjustment, inpatient ablation was significantly associated with early mortality (adjusted odds ratio [aOR] 3.81; 95% confidence interval [CI] 2.87-5.08; P <.001). Hospitals with high overall ablation volume had 31% lower odds of early mortality (highest vs lowest tertile: aOR 0.69; 95% CI 0.56-0.86; P <.001). AF ablation conducted in the inpatient setting is associated with a higher rate of early mortality compared with outpatient AF ablation. Comorbidities are associated with enhanced risk of early mortality. High overall ablation volume is associated with a lower risk of early mortality.

Spacer-Supported Thermal Ablation to Prevent Carbonisation and Improve Ablation Size: A Proof of Concept Study.

Thermal ablation offers a minimally invasive alternative in the treatment of hepatic tumours. Several types of ablation are utilised with different methods and indications. However, to this day, ablation size remains limited due to the formation of a central non-conductive boundary layer. In thermal ablation, this boundary layer is formed by carbonisation. Our goal was to prevent or delay carbonisation, and subsequently increase ablation size. We used bovine liver to compare ablation diameter and volume, created by a stand-alone laser applicator, with those created when utilising a spacer between laser applicator and hepatic tissue. Two spacer variants were developed: one with a closed circulation of cooling fluid and one with an open circulation into hepatic tissue. We found that the presence of a spacer significantly increased ablation volume up to 75.3 cm3, an increase of a factor of 3.19 (closed spacer) and 3.02 (open spacer) when compared to the stand-alone applicator. Statistical significance between spacer variants was also present, with the closed spacer producing a significantly larger ablation volume (p < 0.001, MDiff = 3.053, 95% CI[1.612, 4.493]) and diameter (p < 0.001, MDiff = 4.467, 95% CI[2.648, 6.285]) than the open spacer. We conclude that the presence of a spacer has the potential to increase ablation size.

Surgical volume and outcomes of surgical ablation for atrial fibrillation: a nationwide population-based cohort study

BackgroundAtrial fibrillation is the most common cardiac arrythmia and causes many complications. Sinus rhythm restoration could reduce late mortality of atrial fibrillation patients. The Maze procedure is the gold standard for surgical ablation of atrial fibrillation. Higher surgical volume has been documented with favorable outcomes of various cardiac procedures such as mitral valve surgery and aortic valve replacement. We aimed to determine the volume–outcome relationship (i.e., association between surgical volume and outcomes) for the concomitant Maze procedure during major cardiac surgeries.MethodsThis nationwide population-based cohort study retrieved data from the Taiwan National Health Insurance Research Database. Adult patients undergoing concomitant Maze procedures during 2010–2017 were identified; consequently, 2666 patients were classified into four subgroups based on hospital cumulative surgery volumes. In-hospital outcomes and late outcomes during follow-up were analyzed. Logistic regression and Cox proportional hazards model were used to analyze the volume–outcome relationship.ResultsPatients undergoing Maze procedures at lower-volume hospitals tended to be frailer and had higher comorbidity scores. Patients in the highest-volume hospitals had a lower risk of in-hospital mortality than those in the lowest-volume hospitals [adjusted odds ratio, 0.30; 95% confidence interval (CI), 0.15–0.61; P < 0.001]. Patients in the highest-volume hospitals had lower rates of late mortality than those in the lowest-volume hospitals, including all-cause mortality [adjusted hazard ratio (aHR) 0.53; 95% CI 0.40–0.68; P < 0.001] and all-cause mortality after discharge (aHR 0.60; 95% CI 0.44–0.80; P < 0.001).ConclusionsA positive hospital volume–outcome relationship for concomitant Maze procedures was demonstrated for in-hospital and late follow-up mortality. The consequence may be attributed to physician skill/experience, experienced multidisciplinary teams, and comprehensive care processes. We suggest referring patients with frailty or those requiring complicated cardiac surgeries to high-volume hospitals to improve clinical outcomes.Trial registration: the institutional review board of Chang Gung Memorial Hospital approved all data usage and the study protocol (registration number: 202100151B0C502).

Global sensitivity study for irreversible electroporation: Towards treatment planning under uncertainty.

Electroporation-based cancer treatments are minimally invasive, nonthermal interventional techniques that leverage cell permeabilization to ablate the target tumor. However, the amount of permeabilization is susceptible to the numerous uncertainties during treatment, such as patient-specific variations in the tissue, type of the tumor, and the resolution of imaging equipment. These uncertainties can reduce the extent of ablation in the tissue, thereby affecting the effectiveness of thetreatment. The aim of this work is to understand the effect of these treatment uncertainties on the treatment outcome for irreversible electroporation (IRE) in the case of colorectal liver metastasis (CRLM). Understanding the nature and extent of these effects can help us identify the influential treatment parameters and build better models for predicting the treatmentoutcome. This is an in silico study using a static computational model with a custom applicator design, spherical tissue, and tumor geometry. A nonlinear electrical conductivity, dependent on the local electric field, is considered. Morris analysis is used to identify the influential treatment parameters on the treatment outcome. Seven treatment parameters pertaining to the relative tumor location with respect to the applicator, the tumor growth pattern, and the electrical conductivity of tissue are analyzed. The treatment outcome is measured in terms of the relative tumor ablation with respect to the target ablation volume and total ablationvolume. The Morris analysis was performed with 800 model evaluations, sampled from the seven dimensional input parameter space. Electrical properties of the tissue, especially the electrical conductivity of the tumor before ablation, were found to be the most influential parameter for relative tumor ablation and total ablation volume. This parameter was found to be about 4-15 times more influential than the least influential parameter, depending on the tumor size. The tumor border configuration was identified as the least important parameter for treatment effectiveness. The most desired treatment outcome is obtained by a combination of high healthy liver conductivity and low tumor conductivity. This information can be used to tackle worst-case scenarios in treatment planning. Finally, when the safety margins used in the clinical applications are accounted for, the effects of uncertainties in the treatment parameters reducedrastically. The results of this work can be used to create an efficient surrogate estimator for uncertainty quantification in the treatment outcome, that can be utilized in optimal real-time treatment planning solutions.

Efficacy and preliminary dose studies of ultrasound-guided sclerotherapy with lauromacrogol for the treatment of implanted hepatic tumors in rabbits.

To study the curative effect of sclerotherapy with lauromacrogol on a rabbit VX2 implanted liver tumor model, the effect of ultrasound-guided sclerotherapy with different doses of lauromacrogol in the treatment of the rabbit VX2 implanted liver tumor model and the degree of damage to the surrounding liver tissue was compared and observed. The relationship between the sclerosing effect and drug dose of lauromacrogol in the treatment of liver cancer is preliminarily discussed. Thirty rabbit models of liver cancer were randomly divided into 5 groups. Control Group A was injected with normal saline, control Group B was injected with absolute ethanol, experimental Group C was injected with lauromacrogol (Z =2.885D); the injection volume in experimental Group D was 1.5-fold higher than that in Group C; and the injection volume in experimental Group E was 2-fold higher than that in Group C. Changes in tumor volume were followed up by ultrasound before and 7 and 14 days after the operation; contrast-enhanced ultrasonography was used to measure the volume of the ablation area and volume rate. For pathological anatomy, hematoxylin and eosin (H&E) staining were used to observe tumor cell necrosis and the degree of damage to surrounding normal liver cells. The expression levels of the apoptosis-related protein cleaved-caspase 3 and the cell proliferation antigen Ki67 were examined by immunohistochemistry. The volumes in Groups A and C increased significantly. The volumes in Groups B, D, and E remained the same or slightly expanded, tumor growth in the three groups was significantly inhibited after sclerotherapy. Contrast-enhanced ultrasonography showed that the ablation volume and ablation volume rate in Groups B, D, and E were similar. Group C were smaller than those in the other treatment groups. Large coagulative necrotic foci were observed in the central area of tumors in Groups B, D, and E. The experiment demonstrates that lauromacrogol can inhibit tumor growth in the rabbit VX2 tumor model and cause VX2 tumor cell apoptosis. The sclerosing effect of the 1.5-fold amount of lauromacrogol is equivalent to that of absolute ethanol, with little effect on normal liver tissue.

Optimization of breast cancer ablation volume by ultrasonic pressure field characterization

In order to favor the potential in improving both oncologic and cosmetic results in breast cancer therapy, an Ultrasound (US) probe that increases cancer ablation volume and preserves neighboring healthy tissues in a modeled realistic breast from being ablated is designed using a finite element analysis (FEA) tool in this work. The acoustic pressure field and focal point of the Focused Ultrasound (FUS) are characterized by optimizing the transducer's frequency at 1.3 MHz and the initial water temperature at 20 °C. These optimal conditions yield qualitative properties of the FUS at the focal point, which are extended to wider areas to achieve quantitative results by displacing the probe at reduced time intervals of less than 60s. An elliptical focal volume of 10.2 mm (along the beam axis) × 4 mm (in the transverse direction) at 50s of dosing for a tumor diameter of 10 mm has been generated. Furthermore, a fractional healthy tissue damage of 2.1%, a rise in temperature of 99 °C above the ablation threshold temperature (42 °C) at 100 s of sonication, and an increase in pressure oscillation (favoring cavitation) at the focus are achieved. The optimal conditions of the setup are subjected to sensitivity tests and are found to be mostly sensitive to variations of the transducer frequency on which depend the attenuation coefficient and thermal conductivity of the tissue as well as the surface intensity of the transducer.

Comparative Analysis of Temperature Rise between Convective Heat Transfer Method and Computational Fluid Dynamics Method in an Anatomy-Based Left Atrium Model during Pulsed Field Ablation: A Computational Study.

The non-thermal effects are considered one of the prominent advantages of pulsed field ablation (PFA). However, at higher PFA doses, the temperature rise in the tissue during PFA may exceed the thermal damage threshold, at which time intracardiac pulsatile blood flow plays a crucial role in suppressing this temperature rise. This study aims to compare the effect of heat dissipation of the different methods in simulating the pulsatile blood flow during PFA. This study first constructed an anatomy-based left atrium (LA) model and then applied the convective heat transfer (CHT) method and the computational fluid dynamics (CFD) method to the model, respectively, and the thermal convective coefficients used in the CHT method are 984 (W/m2*K) (blood-myocardium interface) and 4372 (W/m2*K) (blood-catheter interface), respectively. Then, it compared the effect of the above two methods on the maximum temperature of myocardium and blood, as well as the myocardial ablation volumes caused by irreversible electroporation (IRE) and hyperthermia under different PFA parameters. Compared with the CFD method, the CHT method underestimates the maximum temperature of myocardium and blood; the differences in the maximum temperature of myocardium and blood between the two methods at the end of the last pulse are significant (>1 °C), and the differences in the maximum temperature of blood at the end of the last pulse interval are significant (>1 °C) only at a pulse amplitude greater than 1000 V or pulse number greater than 10. Under the same pulse amplitude and different heat dissipation methods, the IRE ablation volumes are the same. Compared with the CFD method, the CHT method underestimates the hyperthermia ablation volume; the differences in the hyperthermia ablation volume are significant (>1 mm3) only at a pulse amplitude greater than 1000 V, a pulse interval of 250 ms, or a pulse number greater than 10. Additionally, the hyperthermia ablation isosurfaces are completely wrapped by the IRE ablation isosurfaces in the myocardium. Thus, during PFA, compared with the CFD method, the CHT method cannot accurately simulate the maximum myocardial temperature; however, except at the above PFA parameters, the CHT method can accurately simulate the maximum blood temperature and the myocardial ablation volume caused by IRE and hyperthermia. Additionally, within the range of the PFA parameters used in this study, the temperature rise during PFA may not lead to the appearance of additional hyperthermia ablation areas beyond the IRE ablation area in the myocardium.

Analysis and Optimization of Crucial Factors Affecting Efficacy of Microwave Ablation

Abstract Microwave ablation (MA) has emerged as a better and more promising alternative to medicate the primitive stage of cancer. Significant advantages of MA include organ-specific treatment and the prospect of treating ≥3 cm diameter tumors with minimal pain and nominal cost. Past studies suggest that tissue properties and input parameters play a vital role during the MA process. Hence, an in-depth investigation has been made to inspect the influence of these crucial parameters: applied power, perfusion rate of blood, frequency, thermal conductivity (TC), electrical conductivity (EC), and relative permittivity (RP) on the dimension of ablation zone attained while treating with MA on Lungs. The finite element method (FEM)-based analysis with a numerical approach is considered to signify the parameters' sole effect on the ablation volume. Using the statistical tool, a regression equation was formulated, and the data derived from the Taguchi L27 orthogonal array helped to get the maximized ablation zone. The results infer that the applied power remarkably affects the response with a positive correlation. Additionally, frequency and blood perfusion rate were observed to significantly influence the treatment process. The following optimal settings, power3, frequency3, blood perfusion rate3, electrical conductivity3, thermal conductivity2, and relative permittivity2, were found along with the maximized ablation volume of 14.35 mm3. The results obtained from this work would be beneficial for the radiologist and the clinical practitioners to get pretreatment data during the initial phase.

Simulation Study of Microwave Ablation of Porous Lung Tissue

Microwave ablation, as an emerging method for treating lung cancer, has been widely used because of its advantages, such as being less invasive and having fewer side effects compared with other therapies, such as surgery and chemotherapy. The key to microwave ablation is to destroy the tumor tissue while minimizing the damage caused to the surrounding healthy tissues. Based on the heat transfer model of porous media, a two-dimensional simulation model of a spherical tumor surrounded by healthy tissue is established in this paper. The effects of tumor diameter, tumor porosity, and microwave ablation power on the highest temperature, ablation area, and volume of the tumor tissue were studied by using the software COMOSL Multiphysics. The results show that the porous heat transfer model is more practical than the Pennes biological heat transfer model. The tumor diameter and the tumor porosity have a great influence on the maximum temperature, the ablation area and volume. In this study, a more realistic model of microwave ablation of lung tumors was established, and the ablation results were predicted accurately, which provided the basic reference data for the selection of clinical therapeutic parameters of microwave ablation of lung tumors. To a certain extent, it can ensure that the ablation area completely covers the tumor and reduces the risk of tumor recurrence, which is of great significance in the accurate treatment of pulmonary tumors by microwave ablation.

The Effect of Thermal and Electrical Conductivities on the Ablation Volume during Radiofrequency Ablation Process

Radiofrequency ablation (RFA) is the treatment of choice for certain types of cancers, especially liver cancer. However, the main issue with RFA is that the larger the tumor volume, the longer the ablation period. That causes more pain for the patient, so the surgeons perform a larger number of ablation sessions or surgeries. The current commonly used electrode material, nickel-titanium alloy, used in RFA is characterized by low thermal and electrical conductivities. Using an electrode material with higher electrical conductivity and thermal conductivity provides more thermal energy to tumors. In this paper, we design two models: a cool-tip RF electrode and a multi-hook RF electrode, which aim to study the effect of the thermal and electrical conductivities of the electrode material on ablation volume. Gold, silver, and platinum have higher thermal and electrical conductivity than nickel and titanium alloy, and therefore we studied the effect of these materials on the ablation volume using two different designs, which are the RF cooling tip electrode and the multi-hook electrode. The proposed model reduces the ablation time and damages healthy tissue while increasing the ablation volume with values ranging from 2.6 cm3 to 15.4 cm3. The results show ablation volume increasing with materials characterized by higher thermal and electrical conductivities and thus reducing patient pain.

Comparison of Ablation Performance between Octopus Multipurpose Electrode and Conventional Octopus Electrode.

To compare Octopus multipurpose (MP) electrodes, which are capable of saline instillation and direct tissue temperature measurement, and conventional electrodes for radiofrequency ablation (RFA) in porcine livers in vivo. Sixteen pigs were used in this study. In the first experiment, RFA was performed in the liver for 6 minutes using Octopus MP electrodes (n = 15 ablation zones) and conventional electrodes (n = 12 ablation zones) to investigate the effect of saline instillation. The ablation energy, electrical impedance, and ablation volume of the two electrodes were compared. In the second experiment, RFA was performed near the gallbladder (GB) and colon using Octopus MP electrodes (n = 12 ablation zones for each) with direct tissue temperature monitoring and conventional electrodes (n = 11 ablation zones for each). RFA was discontinued when the temperature increased to > 60℃ in the Octopus MP electrode group, whereas RFA was performed for a total of 6 minutes in the conventional electrode group. Thermal injury was assessed and compared between the two groups by pathological examination. In the first experiment, the ablation volume and total energy delivered in the Octopus MP electrode group were significantly larger than those in the conventional electrode group (15.7 ± 4.26 cm3 vs. 12.5 ± 2.14 cm3, p = 0.027; 5.48 ± 0.49 Kcal vs. 5.04 ± 0.49 Kcal, p = 0.029). In the second experiment, thermal injury to the GB and colon was less frequently noted in the Octopus MP electrode group than that in the conventional electrode group (16.7% [2/12] vs. 90.9% [10/11] for GB and 8.3% [1/12] vs. 90.9% [10/11] for colon, p < 0.001 for all). The total energy delivered around the GB (2.65 ± 1.07 Kcal vs. 5.04 ± 0.66 Kcal) and colon (2.58 ± 0.57 Kcal vs. 5.17 ± 0.90 Kcal) were significantly lower in the Octopus MP electrode group than that in the conventional electrode group (p < 0.001 for all). RFA using the Octopus MP electrodes induced a larger ablation volume and resulted in less thermal injury to the adjacent organs compared with conventional electrodes.