Interaction Between Microbubbles and Microwave Ablation: A Phantom and Rabbit Model

OBJECTIVES

This study aimed to explore the interactions between microbubbles and microwave ablation (MWA).

METHODS

The study employed custom-made phantoms (in vitro) and white New Zealand rabbits (in vivo). MWA was performed with or without microbubbles in the phantoms (2 × 105 particles mL-1) and rabbit livers (intravenous injection of 0.05 mL/kg SonoVue). During the MWA, K-type thermocouple probes were used to monitor the MWA-induced temperature increase. Contrast-enhanced ultrasound imaging (CEUS) was used to monitor and analyze the microbubbles signal intensity. After MWA, the ablation-zone volumes were evaluated and compared between the groups with and without microbubbles.

RESULTS

In both the phantom models and rabbits, microbubbles showed no significant influence on MWA, including the ablation range and MWA-induced temperature increase. In phantoms and rabbit livers filled with microbubbles, MWA caused the formation of a gradually expanding microbubble-defect region over the ablation time. An increase in the temperature caused microbubble destruction.

CONCLUSIONS

Microbubbles had no significant influence on MWA. However, MWA induced the destruction of microbubbles in a temperature-dependent manner. Thus, the poor thermotolerance of microbubbles is a non-negligible barrier when using CEUS to monitor the ablation range during MWA in real-time.

Optimal parameters for the efficient microwave ablation of liver tumor from the 3D-IRCADb-01 database

Purpose: Microwave ablation is a minimally invasive thermal modality for cancer treatment with high survival and low recurrence rates. Despite the unquestionable benefits of microwave ablation, the interaction between the medical instruments and the tissue may cause damage to the healthy tissue around the tumor. Such damages can be removed by clarifying the conditions for their development. In addition to clinical methods, computer simulations have become very effective tools for optimizing microwave ablation performance. Methods: The study was focused on the determination of the optimal input power for complete microwave tumor ablation with an ade-quate safety margin avoiding injury to the surrounding healthy tissue. In three-dimensional simulations, the liver tumor model was based on a real tumor (1.74 cm × 2.40 cm × 1.43 cm) from the 3D-IRCADb-01 database. Calculations were performed for a 10-slot antenna proven to achieve a higher degree of ablation zone localization than a standard single-slot antenna. The temperature-dependent dielectric and thermal properties of healthy and tumoral liver tissue, blood perfusion, and water content were included in the model. Results: The obtained simulation results revealed that the proper choice of input power ensures that necrotic tissue is mainly located in the tumor with minimal damage to the surrounding healthy tissue. Conclusions: This study may represent a step forward in the planning of individual microwave ablation treatment for each patient.

A Preliminary Study on the Microwave Ablation of Multifocal Papillary Thyroid Microcarcinoma

RATIONALE AND OBJECTIVES

To evaluate the feasibility, efficiency, and safety of microwave ablation (MWA) for multifocal papillary thyroid microcarcinoma (PTMC).

METHODS

This was a retrospective study, and the data of patients who underwent MWA for multifocal PTMC from October 2016 to December 2021 were reviewed. After ablation, the changes in tumor size and volume, as well as the rates of technical success, tumor disappearance, disease progression, and complications, were assessed. According to the tumor location, the cases were further divided into a unilateral multifocal disease (UMD) subgroup and a bilateral multifocal disease (BMD) subgroup. Further analyses were carried out.

RESULTS

There was a total of 94 cases enrolled in the present study, which included 24 males and 70 females. The median age was 40 years (22-66 years); the median follow-up time was 14 months (6-48 months). Complete ablation was achieved in all enrolled cases. Therefore, the technical success rate was 100%. Due to expanding ablation, the MD and volume of the ablation zone increased at the 1st and 3rd months after ablation and decreased from the 12th month after ablation (p < 0.05 for all). The total complete tumor disappearance rates were 45/94 (47.87%) overall, 40.625% (13/32) in the UMD subgroup and 51.61% (32/62) in the BMD subgroup (p = 0.312). The total disease progression rates were 4.26% (4/94) overall, 6.25% (2/32) in the UMD subgroup and 3.23% (2/62) in the BMD subgroup (p = 0.881). The overall complication rate was 4.26% (4/94).

CONCLUSION

This preliminary study indicates that MWA is a safe and effective treatment for multifocal PTMC.

Percutaneous Microwave Ablation versus Cryoablation for Small Renal Masses (≤4 cm): 12-Year Experience at a Single Center

PURPOSE

To determine whether microwave ablation (MWA) has equivalent outcomes to those of cryoablation (CA) in terms of technical success, adverse events, local tumor recurrence, and survival in adult patients with solid enhancing renal masses ≤4 cm.

MATERIALS AND METHODS

A retrospective review was performed of 279 small renal masses (≤4 cm) in 257 patients (median age, 71 years; range, 40-92 years) treated with either CA (n = 191) or MWA (n = 88) between January 2008 and December 2020 at a single high-volume institution. Evaluations of adverse events, treatment effectiveness, and therapeutic outcomes were conducted for both MWA and CA. Disease-free, metastatic-free, and cancer-specific survival rates were tabulated. The estimated glomerular filtration rate was employed to examine treatment-related alterations in renal function.

RESULTS

No difference in patient age (P = .99) or sex (P = .06) was observed between the MWA and CA groups. Cryoablated lesions were larger (P < .01) and of greater complexity (P = .03). The technical success rate for MWA was 100%, whereas 1 of 191 cryoablated lesions required retreatment for residual tumor. There was no impact on renal function after CA (P = .76) or MWA (P = .49). Secondary analysis using propensity score matching demonstrated no significant differences in local recurrence rates (P = .39), adverse event rates (P = .20), cancer-free survival (P = .76), or overall survival (P = .19) when comparing matched cohorts of patients who underwent MWA and CA.

CONCLUSIONS

High technical success and local disease control were achieved for both MWA and CA. Cancer-specific survival was equivalent. Higher adverse event rates after CA may reflect the tendency to treat larger, more complex lesions with CA.

Endovenous Microwave Ablation Versus Laser Ablation for Small Saphenous Vein Varicosis

INTRODUCTION

Laser and radiofrequency ablation are two thermal ablation methods currently widely used to treat lower limb venous insufficiency. However, very few studies have been conducted on the use of microwaves, a form of thermal ablation, for the treatment of small saphenous vein (SSV) insufficiency. This study aimed to examine the efficacy and safety of endovenous microwave ablation (EMA) for the treatment of SSV insufficiency.

METHODS

The clinical data of 126 patients (126 lower limbs) with SSV insufficiency (SSV trunk reflux time ≥ 500 ms on lower limb color Doppler ultrasound) treated at the Surgery Department of The Sixth People's Hospital of Zhuji from January 2020 to June 2022 were analyzed retrospectively; 64 patients underwent EMA and 62 underwent endovenous laser ablation (EVLA). The perioperative marker data [duration of surgery, duration of hospitalization, length of thermal ablation, duration of thermal ablation, number of incisions, and numerical pain rating scale (NPRS)], complication data [skin ecchymosis, skin burns, surgical site infection, paresthesia, deep vein thrombosis (DVT), and heat-induced thrombosis (EHIT)], venous clinical severity score (VCSS), chronic venous disease quality of life questionnaire (CIVIQ-20) before and 1, 3, 12 months after surgery, and SSV trunk occlusion rate at 12 months after surgery were compared between the two groups.

RESULTS

No significant differences in the surgery or hospitalization durations were observed between the two groups. There were no significant differences in the length of the SSV that required thermal ablation between the two groups; however, the thermal ablation time was shorter in the EMA group than that in the EVLA group (6.14 ± 1.47 min vs 7.05 ± 1.16 min, P < 0.001). There were no statistical differences in the number of incisions, volume of tumescent solution used, or quantity of sclerosing foam used. The NPRS scores of the EMA group at 24 h and 72 h after surgery were significantly greater than those of the EVLA group (4.03 ± 0.98 vs 3.52 ± 1.28, P = 0.013; 3.78 ± 1.06 vs 3.15 ± 1.03, P = 0.001). Moreover, the two groups showed no significant difference in the NPRS score at 1 month (1.14 ± 0.84 vs 1.07 ± 0.75, P = 0.623). The EMA and EVLA group patients experienced similar postoperative complications. The VCSS and CIVIQ-20 score significantly improved at 1, 3, and 12 months after surgery. The VCSS and CIVIQ-20 scores were compared between the two groups at 12 months after surgery, and there were no significant differences (1.44 ± 0.63 vs 1.56 ± 0.56, P = 0.261; 24.24 ± 4.96 vs 25.19 ± 5.36, P = 0.304). There was no significant difference in the incidence of SSV trunk occlusion at 12 months after surgery between the two groups (95.31% vs 96.77%, OR 1.475; 95% CI 0.238-9.146, P = 1.000).

CONCLUSION

EMA and EVLA are equally effective treatment methods for SSV insufficiency. EMA is associated with higher NPRS scores in the early postoperative period.

Safety and efficacy of microwave ablation for symptomatic benign thyroid nodules in children

OBJECTIVE

To evaluate the efficacy and safety of microwave ablation (MWA) for the treatment of symptomatic benign thyroid nodules in children.

METHODS

A retrospective study of MWA for the treatment of 34 symptomatic benign thyroid nodules in 25 children was conducted. Volume reduction ratio (VRR), technique efficacy, symptom score, cosmetic score, and thyroid function were used to evaluate the efficacy of the technique. The associated complications and side effects were recorded.

RESULTS

The participants were followed for at least 6 months (median 12 months, range 6-48 months). After MWA treatment, the volumes of the targeted nodules decreased gradually (median volume 5.86 mL before MWA and 0.34 mL at the final follow-up assessment), the VRR achieved was up to 85.03% at the final follow-up assessment, and the technical efficacy at this time was 91.2%. The subjective and objective nodule-related symptoms were also ameliorated. The circulating hormone concentrations reflecting thyroid function remained within their normal ranges in all the participants after one month of follow-up. The procedure had no major complications.

CONCLUSIONS

MWA seems to be an effective and safe technique for the treatment of symptomatic benign thyroid nodules in pediatric patients.

CLINICAL RELEVANCE STATEMENT

Microwave ablation is a safe and effective method to treat symptomatic benign thyroid nodules in pediatric patients. This treatment may be selected if the patient or parents are not suitable or refuse to undergo surgery.

KEY POINTS

• Microwave ablation is effective in reducing the volume of benign thyroid nodules and ameliorating nodule-related symptoms in pediatric patients. • Microwave ablation is a safe method in children, with low complications. • Microwave ablation does not affect the circulating thyroid hormone concentrations of children.

Hepatic Ablation Technology: Assessment of Conflicts of Interest in Recent Literature

INTRODUCTION

Collaboration between the health care industry and surgeons is critical in modern medicine. Conflict of interest (COI) has the risk of introducing bias into research studies. We investigated the accuracy of self-disclosed COI for studies that researched the use of microwave ablation for liver metastasis.

METHODS

A literature search identified studies that investigated the use of microwave ablation for liver cancer between 2016 and 2022. We utilized the Open Payments Database to query individual authors' financial contributions from the industry. The accuracy of the disclosure statement and financial contribution for each study and author was calculated. We compared the amount of financial contribution authors received based on the accuracy of their COI statement.

RESULTS

Twenty-five studies of interest were identified. The mean number of authors was 8.24. A disclosure statement was present in 52% of studies. Of those, 28% had an incongruent disclosure statement. 9/25 (36%) of studies had a conflict of interest based on financial payments provided by industry. Overall, authors received an average of $440,483.41 (SD $1,889,375.34). We did not find a difference in the financial contribution's value based on the disclosure statement's accuracy (P = .55).

CONCLUSIONS

Over a quarter of studies in our review of microwave ablation literature had discrepancies in the reporting of conflicts of interest, highlighting the need for improved reporting of potential conflicts of interest to protect the integrity of clinical research. Compared to other fields of surgery, we found a lower rate of undisclosed COI, suggesting that the scope of cancer-directed surgery may be more resistant to industry influence.

[Ablation of liver tumors : From pre-interventional imaging to post-interventional assessment]

The aim of this article is to provide an overview on the most frequently applied image-guided, percutaneous, local ablative techniques for treatment of primary and secondary liver tumors. The technical procedures of microwave ablation (MWA) and radiofrequency ablation (RFA) are presented. The pre-interventional diagnostics, indications and feasibility are also discussed, taking the current national guidelines into consideration. Finally, treatment outcomes and recommendations on post-interventional imaging following local tumor ablation are presented.

Glycolysis inhibition induces anti-tumor central memory CD8+T cell differentiation upon combination with microwave ablation therapy

Minimally invasive thermal therapy is a successful alternative treatment to surgery in solid tumors with high complete ablation rates, however, tumor recurrence remains a concern. Central memory CD8+ T cells (TCM) play important roles in protection from chronic infection and cancer. Here we find, by single-cell RNA analysis of human breast cancer samples, that although the memory phenotype of peripheral CD8+ T cells increases slightly after microwave ablation (MWA), the metabolism of peripheral CD8+ T cells remains unfavorable for memory phenotype. In mouse models, glycolysis inhibition by 2-deoxy-D-glucose (2DG) in combination with MWA results in long-term anti-tumor effect via enhancing differentiation of tumor-specific CD44hiCD62L+CD8+ TCM cells. Enhancement of CD8+ TCM cell differentiation determined by Stat-1, is dependent on the tumor-draining lymph nodes (TDLN) but takes place in peripheral blood, with metabolic remodeling of CD8+ T cells lasting the entire course of the the combination therapy. Importantly, in-vitro glycolysis inhibition in peripheral CD8+ T cells of patients with breast or liver tumors having been treated with MWA thrice leads to their differentiation into CD8+ TCM cells. Our work thus offers a potential strategy to avoid tumor recurrence following MWA therapy and lays down the proof-of-principle for future clinical trials.

Identifying symptom clusters and temporal interconnections in patients with lung tumors after CT-guided microwave ablation: A network analysis

PURPOSE

To explore symptom clusters and interrelationships using a network analysis approach among symptoms in patients with lung tumors who underwent computed tomography (CT)-guided microwave ablation (MWA).

METHODS

A longitudinal study was conducted, and 196 lung tumor patients undergoing MWA were recruited and were measured at 24 h, 48 h, and 72 h after MWA. The Chinese version of the MD Anderson Symptom Inventory and the Revised Lung Cancer Module were used to evaluate symptoms. Network analyses were performed to explore the symptom clusters and interrelationships among symptoms.

RESULTS

Four stable symptom communities were identified within the networks. Distress, weight loss, and chest tightness were the central symptoms. Distress, and weight loss were also the most key bridge symptoms, followed by cough. Three symptom networks were temporally stable in terms of symptom centrality, global connectivity, and network structure.

CONCLUSION

Our findings identified the central symptoms, bridge symptoms, and the stability of symptom networks of patients with lung tumors after MWA. These network results will have important implications for future targeted symptom management intervention development. Future research should focus on developing precise interventions for targeting central symptoms and bridge symptoms to promote patients' health.

Preoperative MRI radiomic analysis for predicting local tumor progression in colorectal liver metastases before microwave ablation

PURPOSE

Radiomics may aid in predicting prognosis in patients with colorectal liver metastases (CLM). Consistent data is available on CT, yet limited data is available on MRI. This study assesses the capability of MRI-derived radiomic features (RFs) to predict local tumor progression-free survival (LTPFS) in patients with CLMs treated with microwave ablation (MWA).

METHODS

All CLM patients with pre-operative Gadoxetic acid-MRI treated with MWA in a single institution between September 2015 and February 2022 were evaluated. Pre-procedural information was retrieved retrospectively. Two observers manually segmented CLMs on T2 and T1-Hepatobiliary phase (T1-HBP) scans. After inter-observer variability testing, 148/182 RFs showed robustness on T1-HBP, and 141/182 on T2 (ICC > 0.7).Cox multivariate analysis was run to establish clinical (CLIN-mod), radiomic (RAD-T1, RAD-T2), and combined (COMB-T1, COMB-T2) models for LTPFS prediction.

RESULTS

Seventy-six CLMs (43 patients) were assessed. Median follow-up was 14 months. LTP occurred in 19 lesions (25%).CLIN-mod was composed of minimal ablation margins (MAMs), intra-segment progression and primary tumor grade and exhibited moderately high discriminatory power in predicting LTPFS (AUC = 0.89, p = 0.0001). Both RAD-T1 and RAD-T2 were able to predict LTPFS: (RAD-T1: AUC = 0.83, p = 0.0003; RAD-T2: AUC = 0.79, p = 0.001). Combined models yielded the strongest performance (COMB-T1: AUC = 0.98, p = 0.0001; COMB-T2: AUC = 0.95, p = 0.0003). Both combined models included MAMs and tumor regression grade; COMB-T1 also featured 10th percentile of signal intensity, while tumor flatness was present in COMB-T2.

CONCLUSION

MRI-based radiomic evaluation of CLMs is feasible and potentially useful for LTP prediction. Combined models outperformed clinical or radiomic models alone for LTPFS prediction.

Long-Term Safety and Efficacy of Transcatheter Microwave and Radiofrequency Denervation in a Chronic Ovine Model

BACKGROUND

Transcatheter renal denervation (RDN) has had inconsistent efficacy and concerns for durability of denervation. We aimed to investigate long-term safety and efficacy of transcatheter microwave RDN in vivo in normotensive sheep in comparison to conventional radiofrequency ablation.

METHODS AND RESULTS

Sheep underwent bilateral RDN, receiving 1 to 2 microwave ablations (maximum power of 80-120 W for 240 s-480 s) and 12 to 16 radiofrequency ablations (180 s-240 s) in the main renal artery in a paired fashion, alternating the side of treatment, euthanized at 2 weeks (acute N=15) or 5.5 months (chronic N=15), and compared with undenervated controls (N=4). Microwave RDN produced substantial circumferential perivascular injury compared with radiofrequency at both 2 weeks [area 239.8 (interquartile range [IQR] 152.0-343.4) mm2 versus 50.1 (IQR, 32.0-74.6) mm2, P <0.001; depth 16.4 (IQR, 13.9-18.9) mm versus 7.5 (IQR, 6.0-8.9) mm P <0.001] and 5.5 months [area 20.0 (IQR, 3.4-31.8) mm2 versus 5.0 (IQR, 1.4-7.3) mm2, P=0.025; depth 5.9 (IQR, 1.9-8.8) mm versus 3.1 (IQR, 1.2-4.1) mm, P=0.005] using mixed models. Renal denervation resulted in significant long-term reductions in viability of renal sympathetic nerves [58.9% reduction with microwave (P=0.01) and 45% reduction with radiofrequency (P=0.017)] and median cortical norepinephrine levels [71% reduction with microwave (P <0.001) and 72.9% reduction with radiofrequency (P <0.001)] at 5.5 months compared with undenervated controls.

CONCLUSIONS

Transcatheter microwave RDN produces deep circumferential perivascular ablations without significant arterial injury to provide effective and durable RDN at 5.5 months compared with radiofrequency RDN.

Laparoscopic-assisted microwave ablation in treatment of small hepatocellular carcinoma: safety and efficacy in comparison with laparoscopic hepatectomy

Laparoscopic-assisted microwave ablation (LAMWA), as one of the locoregional therapies, has been employed to treat hepatocellular carcinoma (HCC). This study aims to compare the efficacy and safety of LAMWA and laparoscopic hepatectomy in the treatment of small HCC.This study included 140 patients who met the inclusion criteria. Among them, 68 patients received LAMWA and 72 patients underwent laparoscopic hepatectomy. The perioperative condition, liver function recovery, the alpha fetoprotein (AFP) level, morbidities, hospitalization time, overall survival (OS), disease-free survival (DFS) and recurrence rate between the two groups were compared. The rate of complete elimination of tumor tissue was 100% and the AFP level was returned to normal within 3 months after surgery in both groups (P > 0.05). The mean alanine transaminase (ALT) and aspartate transaminase (AST) peak in the LAMWA group was lower than that in the laparoscopic hepatectomy group (259.51 ± 188.75 VS 388.9 ± 173.65, P = 0.000) and (267.34 ± 190.65 VS 393.1 ± 185.67, P = 0.000), respectively. The mean operation time in the LAMWA group was shorter than that in the laparoscopic hepatectomy group (89 ± 31 min VS 259 ± 48 min, P = 0.000). The blood loss in the LAMWA group was less than that in the laparoscopic hepatectomy group (58.4 ± 64.0 ml VS 213.0 ± 108.2 ml, P = 0.000). Compared with the laparoscopic hepatectomy group, patients in the LAMWA group had lower mean hospital stay (4.8 ± 1.2d VS 11.5 ± 2.9d, P = 0.000). The morbidities of the LAMWA group and the hepatectomy group were 14.7%(10/68) and 34.7%(25/72), respectively (P = 0.006). The one-, three-, and five-year OS rates were 88.2%, 69.9%, 45.6% for the LAMWA group and 86.1%, 72.9%, 51.4% for the laparoscopic hepatectomy group (P = 0.693). The corresponding DFS rates for the two groups were 76.3%, 48.1%, 27.9% and 73.2%, 56.7%, 32.0% (P = 0.958). Laparoscopic-assisted microwave ablation is a safe and effective therapeutic option for selected small HCC.

Comparison of Microwave and Radiofrequency Ablation for the Treatment of Small- and Medium-Sized Hepatocellular Carcinomas in a Prospective Randomized Trial

PURPOSE

 To compare the therapeutic response and clinical outcome of CT-guided percutaneous microwave (MWA) and radiofrequency ablation (RFA) for the treatment of small- and medium-sized HCC.

MATERIALS AND METHODS

 In this prospective trial, 50 patients with HCC were randomly assigned to MWA or RFA treatment. MRI was performed 24 h before and after ablation and subsequently in 3-month intervals. Ablation volumes, ablation durations, adverse events (AE), technique efficacy, technical success, local tumor progression (LTP), disease-free survival (DFS), intrahepatic distant recurrence (IDR), and overall survival (OS) rates were evaluated.

RESULTS

 The mean ablation volume was 66.5 cm³ for MWA and 29.2  cm³ for RFA (p < 0.01). The mean ablation durations for MWA and RFA were 11.2 ± 4.0 min and 16.3 ± 4.7 min, respectively (p < 0.01). Six mild AEs were documented (p > 0.05). All treatments had a technical success rate and a technique efficacy rate of 100 % (50/50, p = 1.00). LTP within 2 years occurred in 1/25 (4 %) in the MWA group and in 4/25 (16 %) in the RFA group (p = 0.06). IDR within 2 years was 8/25 (32 %) for MWA and 14/25 (56 %) for RFA (p < 0.05). The median DFS was 24.5 months and 13.4 months for MWA and RFA, respectively (p = 0.02). The 1-, 2-, 3-year OS rates were 100 %, 80 %, 72 % in the MWA group and 72 %, 64 %, 60 % in the RFA group, respectively (p ≥ 0.14).

CONCLUSION

 The clinical outcome after MWA or RFA for HCC treatment was very similar with no significant differences in LTP or OS. However, MWA shows a trend toward better DFS with fewer IDRs than RFA.

KEY POINTS

  · MWA allows for larger ablation volumes and a shorter treatment duration compared to RFA in patients with HCC.. · MWA shows a trend toward better disease-free survival and fewer intrahepatic distant recurrences compared to RFA.. · The three-year survival rates show no significant difference between the two methods..

Microwave Energy for the Treatment of Painful Intractable Plantar Keratosis: A Retrospective Medical Record Review of Nine Patients

BACKGROUND

Plantar keratoma are common hyperkeratinized, deep-seated lesions, often located on weightbearing areas of the foot. Such lesions are frequently associated with pain and disability. Intractable plantar keratomata (IPK) are highly recurrent and, in most patients, require regular, palliative treatment visits with a significant impact on patient time, cost, and quality of life.

METHODS

We undertook a retrospective chart review of 9 patients (with a total of 21 lesions) who underwent a minimum of two treatments using microwave therapy to their IPK. Pain levels were assessed at each of their treatments using a 10-point scale and patients were invited for review for follow-up in the following year. A total of seven patients undertook four treatments and were included in the final analysis.

RESULTS

Mean baseline pain scores significantly dropped with each subsequent treatment, equating to a 90.4% mean reduction in pain between the first and fourth visits, with 71.4% of patients reporting a zero-pain rating at their final treatment visit.

CONCLUSIONS

The use of microwave therapy has been shown to be effective in producing significant and prolonged pain reduction in a cohort of patients with painful IPK.

Achievement of textbook outcome after hepatectomy combined with thermal ablation for colorectal liver metastases

BACKGROUND

Hepatic resection combined with intraoperative ablation has been described as a technical solution potentially widening the resectability rate of patients with colorectal liver metastases (CRLM). Nevertheless, the perioperative and oncological benefit provided by this combined approach remains unclear. We hypothesized that textbook outcome (TO), which is a composite measure achieved for patients for whom some desired health indicators are met, may help to refine the indications of this approach.

METHODS

Patients submitted to hepatectomy with curative intent in combination with radiofrequency ablation or microwave ablation for CRLM ≤ 3 cm in two tertiary referral centers were included. TO was defined according to a recent definition for liver surgery based on a Delphi process including also the achievement of complete radiological response of the ablated lesion/s at 4 weeks.

RESULTS

Between 2015 and 2022, 112 patients were enrolled. Among them, 63 (56.2%) achieved a TO. According to multivariate analysis, minimally invasive (MI) approach (OR 2.72, 95% CI 0.99-7.48, p = 0.050), simultaneous CR resection (OR 0.28, 95% CI 0.11-0.70, p = 0.007), tumor burden score (OR 0.89, 95% CI 0.82-0.96, p = 0.004), and major hepatectomy (OR 0.12, 95% CI 0.03-0.52, p = 0.004) were significantly associated with the achievement of TO. Median overall survival was longer in those patients who were able to achieve a TO compared to those who did not.

CONCLUSIONS

The combination of hepatectomy and ablation constitutes a valuable solution in patients affected by multiple CRLM and it may provide, also using a MI approach, adequate perioperative and oncological outcomes, allowing to achieve TO, however, in a selected number of patients and depending on several factors including the burden of disease.

Discrepancy Between Achieved and Vendor-Predicted Ablation Zones in the Lung: Contributing Factors

PURPOSE

Several factors are known to affect lung ablation zones. Questions remain as to why there are discrepancies between achieved and vendor-predicted ablation zones and what contributing factors can be modified to balance therapeutic effects with avoidance of complications. This retrospective study of lung tumour microwave ablation analyses day 1 post-treatment CT to assess the effects of lesion-specific and operator-dependent factors on ablation zones.

METHODS AND MATERIALS

Consecutive patients treated at a tertiary centre from 2018 to 2021 were included. All ablations were performed using a single microwave ablation device under lung isolation. The lung tumours were categorised as primary or secondary, and their "resistance" to ablation was graded according to their locations. Intraprocedural pulmonary inflation was assessed as equal to or less than the contralateral non-isolated lung. Ablation energy was categorised as high, medium, or low. Ablation zone dimensions were measured on day 1 CT and compared to vendor reference charts. Ablations with multiple needle positions or indeterminate boundaries were excluded.

RESULTS

A total of 47 lesions in 31 patients were analysed. Achieved long axes are longer than predicted by 5 mm or 14% (p < 0.01) without overall short axis discrepancy. Secondary tumours (p = 0.020), low-resistance location (p < 0.01), good lung inflation (p < 0.01), low (p = 0.003) and medium (p = 0.038) total energy produce lengthened long axes by 4-6 mm or 10-19%. High total energy results in shorter than predicated short axes by 6 mm or 18% (p = 0.010).

CONCLUSION

We identified several factors affecting ablation zone dimensions which may have implications for ablation planning and the avoidance of complications.

Clinical safety and efficacy of microwave ablation for small renal masses

PURPOSE

CT-guided MWA is a safe and effective tool that should be utilized in the treatment of small renal masses (SRMs). We aim to clarify the utility of CT-guided MWA by examining patient outcomes such as recurrence, treatment success, changes in renal function, and complications.

METHODS

A retrospective review of consecutive patients with SRMs who underwent same day renal mass biopsy (RMB) and CT-guided MWA between 2015 and 2022 was performed. Treatment safety was assessed by 30-day complications according to the Clavien-Dindo system and change in eGFR >30 days post-procedure. Treatment efficacy was defined by local recurrence and incomplete treatment rates and calculated using the Kaplan-Meier method.

RESULTS

A total of 108 renal masses were found in 104 patients. The overall complication rate was 7.4% (8/108), of which 4 were major complications (3.7%). For those with renal function available >30 days post ablation, the median eGFR was 47.2 (IQR: 36.0, 57), compared to 52.3 (IQR: 43.7, 61.5) pre-ablation, p<0.0001. 5-year local recurrence free survival was 86%. Among those with biopsy proven malignancy (n= 66), there were five local recurrences (7.54%) occurring at a median of 25.1 months (IQR 19.9, 36.2) and one case (1.5%) of incomplete treatment.

CONCLUSIONS

As the medical field continues to evolve towards less invasive interventions, MWA offers a valuable tool in the management of renal masses. With low major complication and recurrence rates, our findings support the utility of CT-guided MWA as a tool for treatment of SRMs.

Cone-beam computed tomography image-guided percutaneous microwave ablation for lung nodules in a hybrid operating room: an initial experience

OBJECTIVES

The experience of thermal ablation of lung lesions is limited, especially performing the procedure under localisation by cone-beam CT in the hybrid operation room (HOR). Here, we present the experience of microwave ablation (MWA) of lung nodules in the HOR.

METHODS

We reviewed patients who underwent image-guide percutaneous MWA for lung nodules in the HOR under general anaesthesia between July 2020 and July 2022. The workflow in the HOR including the pre-procedure preparation, anaesthesia consideration, operation methods, and postoperative care was clearly described.

RESULTS

Forty lesions in 33 patients who underwent MWA under general anaesthesia (GA) in the HOR were analysed. Twenty-seven patients had a single pulmonary nodule, and the remaining six patients had multiple nodules. The median procedure time was 41.0 min, and the median ablation time per lesion was 6.75 min. The median global operation room time was 115.0 min. The median total dose area product was 14881 μGym2. The median ablation volume was 111.6 cm3. All patients were discharged from the hospital with a median postoperative stay of 1 day. Four patients had pneumothorax, two patients had pleural effusion during the first month of outpatient follow-up, and one patient reported intercostal neuralgia during the 3-month follow-up.

CONCLUSIONS

Thermal ablation of pulmonary nodules under GA in the HOR can be performed safely and efficiently if we follow the workflow provided. The procedure provides an alternative to managing pulmonary nodules in patients.

CLINICAL RELEVANCE STATEMENT

Thermal ablation of pulmonary nodules under GA in the HOR can be performed safely and efficiently if the provided workflow is followed.

KEY POINTS

• We tested the feasibility of microwave ablation of lung lesions performed in a hybrid operating room. • To this end, we provide a description of microwave ablation of the lung under cone-beam CT localisation. • We describe a workflow by which ablation of the pulmonary nodule can be performed safely under general anaesthesia.

Microwave ablation versus laparoscopic resection for hepatocellular carcinoma in patients with clinically significant portal hypertension: a propensity score-matched study of postoperative liver decompensation

OBJECTIVES

The study of postoperative liver decompensation after microwave ablation (MWA) for hepatocellular carcinoma (HCC) in patients with clinically significant portal hypertension (CSPH) is still lacking. The purpose of the present study was to compare the postoperative liver decompensation after MWA and laparoscopic resection (LR) for HCC in patients with CSPH.

METHODS

The present retrospective study enrolled 222 HCC patients with CSPH who underwent MWA (n = 67) or LR (n = 155). Postoperative liver decompensation, complications, postoperative hospital stays, and overall survival were analyzed. Factors associated with postoperative liver decompensation were identified.

RESULTS

After propensity score matching, the postoperative liver decompensation rate was significantly lower in the MWA group than that in the LR group (15.5% versus 32.8%, p = 0.030). The multivariable regression analysis identified that type of treatment (MWA vs. LR, odds ratio [OR] 0.44; 95% confidence interval [CI], 0.21-0.91; p = 0.026) and Child-Pugh B (OR, 2.86; 95% CI, 1.24-6.61; p = 0.014) were independent predictors for postoperative liver decompensation. The rate of complications for patients in the MWA group was significantly lower than that in the LR group (p < 0.001). And MWA showed shorter postoperative hospital stays than LR (3 days vs. 6 days, p < 0.001). Overall survival rate between the two groups was not significantly different (p = 0.163).

CONCLUSION

Compared with laparoscopic resection, microwave ablation has a lower rate of postoperative liver decompensation and might be a better option for HCC patients with CSPH.

CLINICAL RELEVANCE STATEMENT

Microwave ablation exhibited a lower incidence of postoperative liver decompensation in comparison to laparoscopic resection, thereby conferring greater advantages to hepatocellular carcinoma patients with clinically significant portal hypertension.

KEY POINTS

•Postoperative liver decompensation rate after microwave ablation was lower than that of laparoscopic resection for hepatocellular carcinoma in patients with clinically significant portal hypertension. •Microwave ablation showed shorter postoperative hospital stays than laparoscopic resection. •Microwave ablation had fewer complications than laparoscopic resection.

Microwave disinfection of facial silicone prostheses, Part 1: Color stability

STATEMENT OF PROBLEM

The choice of cleaning method is an important consideration for lengthening the serviceable time of facial prostheses as microbial organisms and biofilms could degrade facial prostheses and cause skin irritation. Whether microwave disinfection is a suitable cleaning method without degradation of the properties of a prosthesis is unclear.

PURPOSE

The purpose of this in vitro study was to measure the color stability of 6 commonly used facial silicone elastomers after microwave disinfection over a simulated 1.5-year period.

MATERIAL AND METHODS

Six different facial silicone elastomers: MDX4-4210, MDX4-4210/Type A, M511, A-2186, VST-50, and A-2000 were mixed with intrinsic silicone white opacifier (except for the control group) and subsequently combined with 4 silicone intrinsic pigment color groups: red (R), yellow (Y), burnt sienna (B), and a mixture of R+Y+B (M). The control group was a silicone elastomer without opacifier or pigment. Each of the 30 experimental groups consisted of 5 specimens (N=150). Five specimens were placed in a 250-mL Erlenmeyer flask filled with 160 mL of tap water. Seven flasks were then placed in a 660-W microwave oven. An exposure of 6 minutes was used according to the antimicrobial efficacy of microwave disinfection protocol on facial silicone prostheses with a final water temperature of 60 °C for 18 times (simulating 1.5 years of microwave disinfection with one 6-minute exposure monthly). A spectrophotometer was used to measure reflectance color change values (∆E). Color differences were calculated following CIELab (∆E*ab) and CIEDE2000 (∆E00) formulae. ∆E*ab and ∆E00 were statistically analyzed by a linear mixed effects model with 3 factors (silicone type, color shade, and time) using the R Statistical software program (α=.05).

RESULTS

Both ∆E*ab and ∆E00 of all silicone elastomers studied were less than the visual perceptibility thresholds (∆E*ab<1.1 and E00<0.7) and were considered clinically acceptable (∆E*ab<3.0 and E00<2.1) after the 1.5-year simulation of microwave disinfection. Yellow and blue pigments had more effect on MDX4-4210 and M511, while red pigment had more effect on MDX4-4210, MDX4-4210/Type A, and M511 (P<.05). Nevertheless, the values were still below the perceptibility threshold (∆E*ab≤1.0 and E00<0.6).

CONCLUSIONS

All 6 facial silicone elastomers maintained clinically acceptable color after 18 months of exposure to microwave disinfection.

Comparison of Micro-flow Imaging and Contrast-Enhanced Ultrasound in Ultrasound-Guided Microwave Ablation of Benign Thyroid Nodules

OBJECTIVE

The study described here was aimed at ascertaining the utility of micro-flow imaging (MFI) during ultrasound (US)-guided microwave ablation (MWA) of thyroid nodules by contrasting its effectiveness with that of contrast-enhanced ultrasound (CEUS).

METHODS

Seventy-three patients with eighty-eight thyroid nodules who underwent US-guided MWA were included in our study from January 2020 to June 2023. Thirty-five patients underwent CEUS during the MWA process, and thirty-eight patients underwent MFI during the MWA process. We compared the two groups' baseline characteristics, tumor volume (V), volume reduction rate (VRR), complications and clinical characteristics.

RESULTS

Both groups exhibited similar outcomes with respect to V and VRR at 1, 3, 6, 12 and 18 mo after MWA (p > 0.05). Consistency was observed with respect to post-operative complications, supplementary ablation times and surgical duration (p > 0.05). It is worth noting that the MFI group had lower treatment costs compared with the CEUS group (11,337.64 ± 80.93 yuan for the MFI group versus 12,971.23 ± 254.89 yuan for the CEUS group, p < 0.05).

CONCLUSION

In the MWA procedure for thyroid nodules, MFI is similar to CEUS with respect to safety and efficacy. Simultaneously, it offers the advantage of reducing surgical expenses, which lessens the economic burden for patients.