CT-guided microwave ablation through the lungs for treating liver tumors near the diaphragm

Comparison of Effectiveness and Safety of Microwave Ablation of Colorectal Liver Metastases Adjacent versus Nonadjacent to the Diaphragm

PURPOSE

To compare the effectiveness and safety of percutaneous microwave ablation (MWA) for colorectal liver metastasis (CLM) adjacent versus nonadjacent to the diaphragm.

MATERIALS AND METHODS

This was a retrospective analysis of a prospectively created MWA database, from 2 prospective clinical trials for patients with CLM treated in a single tertiary center from 2012 to 2023. CLM adjacent to the diaphragm was defined as a tumor located <1 cm from the diaphragm. Minimal ablation margin (MM) was calculated with 3-dimensional software using postablation contrast-enhanced computed tomography (CT). Adverse events were assessed with Common Terminology Criteria for Adverse Events (CTCAE) v5.0 classification for 6 months.

RESULTS

Two hundred nine CLMs underwent 191 MWA sessions in 143 patients. Mean tumor diameter was 1.52 cm (SD ± 0.53). Eighty-three of 209 (39.7%) CLMs were adjacent to the diaphragm. There was no difference in local tumor progression-free survival (LTPFS) between CLMs adjacent and nonadjacent to the diaphragm (hazard ratio [HR], 0.65; 95% CI, 0.37-1.16; P = .15). MMs of 5-10 mm and >10 mm were documented in 49.3% versus 46.8% (P = .83) and 21.6% versus 12.6% (P = .16) for CLMs adjacent versus nonadjacent to the diaphragm, respectively. Twelve-month LTPFS was similar between groups (HR, 0.65; 95% CI, 0.37-1.16; P = .15) without local tumor progression for MM of >10 mm. There were 3 Grade IV adverse events: 1 diaphragmatic perforation, 1 liver abscess, and 1 biloma. Pneumothorax was associated with location adjacent to the diaphragm (P < .001) and transpulmonary approach (P < .001). Median length of hospital stay was 2 days (interquartile range [IQR], 1-3 days) for patients who needed thoracostomy (n = 20, 9.6%) compared with 1 day (IQR, 1-8 days) for those who did not, without long-term sequelae.

CONCLUSIONS

MWA of CLM adjacent to the diaphragm is effective and safe, without difference in success and 12-month LTPFS. Pneumothorax was associated with location adjacent to the diaphragm and thoracostomy that resulted in longer hospitalization without long-term sequelae.

Simulation of Image-Guided Microwave Ablation Therapy Using a Digital Twin Computational Model

Emerging computational tools such as healthcare digital twin modeling are enabling the creation of patient-specific surgical planning, including microwave ablation to treat primary and secondary liver cancers. Healthcare digital twins (DTs) are anatomically one-to-one biophysical models constructed from structural, functional, and biomarker-based imaging data to simulate patient-specific therapies and guide clinical decision-making. In microwave ablation (MWA), tissue-specific factors including tissue perfusion, hepatic steatosis, and fibrosis affect therapeutic extent, but current thermal dosing guidelines do not account for these parameters. This study establishes an MR imaging framework to construct three-dimensional biophysical digital twins to predict ablation delivery in livers with 5 levels of fat content in the presence of a tumor. Four microwave antenna placement strategies were considered, and simulated microwave ablations were then performed using 915 MHz and 2450 MHz antennae in Tumor Naïve DTs (control), and Tumor Informed DTs at five grades of steatosis. Across the range of fatty liver steatosis grades, fat content was found to significantly increase ablation volumes by approximately 29-l42% in the Tumor Naïve and 55-60% in the Tumor Informed DTs in 915 MHz and 2450 MHz antenna simulations. The presence of tumor did not significantly affect ablation volumes within the same steatosis grade in 915 MHz simulations, but did significantly increase ablation volumes within mild-, moderate-, and high-fat steatosis grades in 2450 MHz simulations. An analysis of signed distance to agreement for placement strategies suggests that accounting for patient-specific tumor tissue properties significantly impacts ablation forecasting for the preoperative evaluation of ablation zone coverage.

Percutaneous microwave ablation‑induced hepatic artery‑pulmonary artery fistula: A rare case report

Microwave ablation (MWA) is safe and effective for patients with unresectable primary and secondary hepatic tumors, but it also has a series of complications. The present study reported on the case of a 60-year-old male patient with progression of solitary liver metastasis who underwent multiple courses and lines of chemotherapy. Hepatic artery-pulmonary artery fistula due to thermal damage may occur after MWA for hepatic tumor adjacent to the diaphragm. Symptomatic improvement was achieved by trans-arterial embolization and hepatic arteriography indicated complete occlusion of the fistula. The postoperative course was uneventful and the patient was discharged three days later. This rare complication should be taken into consideration in clinical treatment.

Fully Guided Tooth Bud Ablation in Pigs Results in Complete Tooth Bud Removal and Molar Agenesis

PURPOSE

Fully guided microwave tooth bud ablation has the potential to become a minimally invasive means for managing third molars in adolescent patients. If developed, this new modality could provide improved outcomes and reduced complications compared to traditional third molar management strategies. The purpose of this 28-day longitudinal characterization study was to determine if the healing response following fully guided microwave ablation of second molar tooth buds in juvenile pigs would result in the complete removal of targeted tooth bud tissues, molar agenesis, and no significant collateral tissue damage.

METHODS

Investigators performed fully guided microwave ablation on 24 mandibular second molar tooth buds (#18 and #31) in seven-week-old pigs. Postablation healing assessment consisted of radiographic and histological evaluation of 3 subcohorts (consisting of 4 animals each) at 7-, 14- and 28-days post ablation. Controls were untreated, opposing maxillary second molar tooth buds. Neurological assessment was performed to determine if there was any detectible loss of inferior alveolar nerve function.

RESULTS

Healing processes were nearly complete at 28 days post ablation. While one tooth bud was identified as partially ablated at 14 days post treatment, all treated tooth bud tissues were replaced with trabecular new bone formation by the end of this study. There was no detectible loss of inferior alveolar nerve function. The thermal dosing strategy used in this study appears to deliver prescribed ablation volumes and-within the context of this animal model-there was no detected collateral tissue damage.

CONCLUSIONS

The results of this study confirm the hypothesis that healing processes following fully guided tooth bud ablation resulted in removal of targeted tooth bud tissues, complete molar agenesis, and trabecular new bone growth at 28-days post treatment.

Current perspectives on microwave ablation of liver lesions in difficult locations

Microwave ablation (MWA) is becoming the standard of care in treating liver lesions smaller than 3 cm benefiting from a plethora of radiofrequency ablation (RFA) data in the literature. Some of the advantages of MWA compared to RFA are as follows: Faster ablations, more reproducible and predictable heating, better thermal conductivity in different liver tissue environments, and less susceptibility to heat-sink effect. Despite its many advantages, there are still concerns regarding MWA use in high-risk locations such as near portal veins, near the bile ducts, and near the heart. Some centers have historically considered these tumor locations as a contraindication to percutaneous thermal ablation. In this review, we summarize the current data on the safety of MWA of liver tumors in challenging locations. We also discuss several technical tips with examples provided.

CT-guided microwave ablation of hepatic malignancies via transpulmonary approach without ancillary techniques

OBJECTIVES

The objectives of the study were to determine the safety and efficacy of computed tomography (CT)-guided transpulmonary percutaneous microwave ablation (MWA) for hepatic malignancies without the use of ancillary techniques.

MATERIAL AND METHODS

A retrospective review was performed on patients who underwent MWA for hepatic malignancy between January 2014 and February 2020 at a single tertiary center. Imaging was reviewed for each procedure to identify MWA showing transpleural transgression on CT scans. For these patients, demographics, ablation data, pulmonary complication rate, and predictors of pneumothorax were analyzed.

RESULTS

A total of 71 consecutive sessions (62.1 ± 11.3 years, 79% of males) of MWA were performed to treat 71 tumors (1.90 ± 0.96 cm) via transpulmonary approach under CT guidance. Technical success was achieved in all cases immediately after the procedure. At 1-month follow-up, 65/69 (94.2%) patients had no residual disease (two patients were lost to follow-up). Pulmonary complications occurred in 26/71 (36.6%) sessions, and 15/26 (57.7%) were minor requiring no intervention. Pneumothorax occurred in 14/71 (19.7%) sessions, and the rate of major pneumothorax requiring chest tube was 8/71 (11.3%). Lesions on the left side of the liver (segments I-IV) and intraprocedural probe adjustment were found to be independent predictors of developing major pneumothorax (P = 0.007 and 0.028, respectively). There were no reported pulmonary complications at the 1-month follow-up.

CONCLUSION

CT-guided transpulmonary MWA is safe and effective in treating hepatic malignancies. Although it is associated with the risk of developing pulmonary complications, patients underwent successful ablation of their hepatic malignancies without life-threatening complications and mortality.

Adjunctive hydrodissection of the bare area of liver during percutaneous thermal ablation of sub-cardiac hepatic tumours

OBJECTIVE

To report the technique of hydrodissection of the sub-diaphragmatic bare area of the liver, in order to protect the diaphragm/heart during percutaneous thermal ablation (PTA) of sub-cardiac hepatic tumours.

MATERIALS AND METHODS

Between January 2016 and December 2018, five patients (four female, one male; mean age 56.2 years) with five sub-cardiac liver tumours (two hepatocellular carcinoma, three metastases; mean size 39 mm) abutting the bare area (segments II/IVA) with expected ablation zones ≤ 5 mm from the myocardium were treated with PTA and adjunctive hydrodissection. Time to perform hydrodissection, distance between superior hepatic and diaphragmatic/pericardial surfaces before and after hydrodissection, ablation efficacy, complications, and local tumour progression (LTP) at last imaging follow-up were recorded.

RESULTS

Technical feasibility was 100%, with mean hydrodissection-volume of 126 ml (range 80-200 ml) and median hydrodissection-time of 9 min (range 8-45 min). Liver-diaphragmatic and liver-pericardial distance increased, respectively, from 2.4 mm (range 0-8 mm) to 10.8 mm (range 6-19 mm) and from 4 mm (range 1-10 mm) to 12.6 mm (range 8-20 mm) post-hydrodissection. All procedures were performed at full-power with complete tumour ablation and without complications (including peri-procedural haemodynamic/electrocardiographic disturbances, pericardial effusion and diaphragmatic hernia) or evidence of LTP at mean 12.2-month (range 1-26 month) follow-up.

CONCLUSION

Hydrodissection of the sub-diaphragmatic bare area of the liver is technically feasible and may potentially optimize safety PTA of sub-cardiac hepatic tumours.

Microwave ablation of hepatic malignant tumors using 1.5T MRI guidance and monitoring: feasibility and preliminary clinical experience

Purpose: To evaluate the feasibility and therapeutic efficacy of 1.5-T MRI-guided and monitored microwave ablation in patients with hepatic malignant tumors.Materials and Methods: This retrospective study was approved by the ethics committee of the First Affiliated Hospital of Fujian Medical University. Thirty-five patients (32 men, three women) with 48 lesions (maximum diameter < 3 cm) underwent microwave ablation under the guidance and monitoring of a 1.5-T MRI. The MRI-compatible microwave generator was appended with a magnetic shield case, and the cable was combined with a choke coil for shielding the Larmor processing frequency. The average age of the patients was 56.51 ± 11.36 years (31-77 years). Twenty-eight patients (37 lesions) displayed hepatocellular carcinoma and seven patients (11 lesions) had metastatic liver carcinoma. The mean maximum tumor diameter was 12.31 ± 4.72 mm (range 5.0-25.7 mm).Results: MRI scans were performed simultaneously without electromagnetic interference during ablation. The average maximum diameter of the hypointense zone of the last monitored T2WI sequence, hypointense zone of post-procedure T2WI sequence, and hyperintense zone of post-procedure T1WI were 28.82 ± 7.58 mm, 29.79 ± 7.91 mm, and 28.28 ± 8.37 mm, respectively, with no observed statistical difference (F = 0.434, p = .649). The technical success rate was 100%. The average follow-up duration was 11.43 ± 5.29 (4-33) months. The technique efficacy rate was 100%.Conclusion: MRI-guided and monitored microwave ablation of hepatic malignant tumors is feasible and potentially safe and effective.Key pointsMRI-guided microwave ablation of hepatic malignant tumors is feasible.The MRI monitoring scan could accurately reflect the scope of ablation lesion.On T1WI, the ablation lesions of liver showed the 'target sign'.

3D visualization ablation planning system assisted microwave ablation for hepatocellular carcinoma (Diameter >3): a precise clinical application

Background

The aim of this retrospective study was to compare the feasibility and efficiency of ultrasound-guided percutaneous microwave ablation (US-PMWA) assisted by three-dimensional visualization ablation planning system (3DVAPS) and conventional 2D planning for hepatocellular carcinoma (HCC) (diameter > 3 cm).

Methods

One hundred thirty patients with 223 HCC nodules (5.0 ± 1.5 cm in diameter, [3.0–10.0 cm]) who met the eligibility criteria divided into 3D and 2D planning group were reviewed from April 2015 to August 2018. Ablation parameters and oncological outcomes were compared, including overall survival (OS), recurrence-free survival (RFS), and local tumor progression (LTP). Multivariate analysis was performed on clinicopathological variables to identify the risk factors for OS and LTP.

Results

The median follow-up period was 21 months (range 3–44). Insertion number (5.4 ± 1.2 VS. 4.5 ± 0.9, P = 0.034), ablation time (1249.2 ± 654.2 s VS. 1082.4 ± 584.7 s, P = 0.048), ablation energy (57,000 ± 11,892 J VS. 42,600 ± 10,271 J, P = 0.038) and success rate of first ablation (95.0% VS. 85.7%, P = 0.033) were higher in the 3D planning group compared with those in 2D planning group. There was no statistical difference in OS, and RFS between the two groups (P = 0.995, P = 0.845). LTP rate of 3D planning group was less than that of 2D planning group (16.5% VS 41.2%, P = 0.003). Multivariate analysis showed tumor maximal diameters (P < 0.001), tumor number (P = 0.003) and preoperative TACE (P < 0.001) were predictors for OS and sessions (P = 0.024), a-fetoprotein level (P = 0.004), and preoperative planning (P = 0.002) were predictors for LTP, respectively.

Conclusions

3DVAPS improves precision of US guided ablation resulting in lower LTP and higher 5 mm-AM for patients with HCC lesions larger than 3 cm in diameter.

Videolaparoscopic microwave ablation in patients with HCC at a European high-volume center: Results of 815 procedures

BACKGROUND

Videolaparoscopic (VL) microwave ablation (MWA) is not included in most of the international guidelines as a therapeutic option for hepatocellular carcinoma (HCC). Aim of this study was to assess the safety of VL MWA in patients with HCC for whom resection or percutaneous ablation is unsuitable.

METHODS

A retrospective analysis was performed on a prospective database of patients with HCC treated with VL MWA at our institution from 2009 to 2016. Patient demographics, operational characteristics, and complications were recorded. Statistical analysis was performed to identify safety profile, overall survival and recurrence rate.

RESULTS

A total of 815 VL MWA were performed in 674 patients with a mean age of 64 years. Patients had a mean Model for End-stage Liver Disease score of 10 (±3); 32.8% were Child B, 44.1% Barcelona Clinic Liver Cancer B-C. Perioperative mortality was 0.4%. Overall morbidity was 30.8%, with Dindo-Clavien complications ≥3 in 2%. The median length of stay was 2 days. In 43.1% VL MWA was the first-line therapy. Overall 1-, 3-, and 5-year survival rates were 81.9%, 54.9%, and 35.9%.

CONCLUSIONS

The present is the largest series of VL ablation and the bigger number of patients with HCC treated with MW reported nowadays. It confirms the safety of a minimally invasive procedure for patients with HCC when resection or percutaneous ablation is not feasible.