Microwave ablation compared with radiofrequency ablation for breast tissue in an ex vivo bovine udder model

Ultrasound-guided microwave ablation for the treatment of idiopathic granulomatous mastitis: comparison with surgical excision

BACKGROUND

Idiopathic granulomatous mastitis (IGM) results in notable clinical symptoms and breast deformity. This study aimed to evaluate the clinical feasibility of microwave ablation (MWA) for the treatment of IGM through comparison with surgical excision.

METHODS

From June 2016 to December 2020, a total of 234 consecutive patients admitted to the hospital were retrospectively included in this study. IGM was pathologically confirmed via breast biopsy in all included patients. These patients were divided into the MWA group (n = 91) and surgical group (n = 143) based on the type of treatment. Patients in both groups received oral prednisone prior to intervention. The clinical remission rate, recurrence rate, operative pain, complications, and BREAST Q score were compared between the two groups.

RESULTS

There were 340 lesions in the MWA group, and 201 lesions in the surgical group were ultimately included. Significant differences in the complete remission rate (96.7% vs. 86.7%, p = 0.020), recurrence rate (3.3% vs. 13.3%, p = 0.020), operation time (48.7±14.6 min vs. 68.1±36.4 min, p < 0.001), postoperative pain (p < 0.001) and postoperative BREAST Q score (p < 0.001) were observed between the MWA and surgical groups.

CONCLUSIONS

Microwave ablation is feasible for the treatment of IGM, due to its high curative rate and low recurrence rate. Because of the minimal invasiveness of MWA and sufficient preservation of the gland and contour of the breast, patients are more satisfied with the appearance of the breast. Therefore, for patients with complex conditions requiring surgery, MWA is a good alternative treatment.

Ultrasound-guided microwave ablation for multiple benign breast lesions: A prospective study

AIM

To provide medical evidence for the feasibility and clinical efficacy of microwave ablation (MWA) in the treatment of benign breast lesions, especially multiple benign breast lesions.

METHODS

We included patients with multiple benign breast lesions who were seen at our hospital during the period from June 2016 to December 2017. After signed informed consent had been obtained and core breast biopsy, all included patients who underwent MWA at 2450 MHz with 30 W power adjustment. Postoperative follow-up was performed for 1 year, at 3-month intervals. Ablation time, complications, volume-reduction ratio (VRR), and lesion residuals after ablation were analyzed.

RESULTS

We ultimately included 1274 lesions from 164 cases in the study with a median follow-up time of 13.6 months. For a single lesion, the median ablation time was 36 s. Pain, fat liquefaction, and skin scalding were the most common complications. The overall complete disappearance rate was 92.1% (1173/1274), with the highest complete disappearance rate observed among those patients with lesions <10 mm in diameter (942/968, 97.3%). For lesions that persisted at 12 months after MWA, the average the volume-reduction ratio (VRR) was 87.5%.

CONCLUSIONS

For multiple benign lesions of the breast, especially lesions with the longest diameter <10 mm, ultrasound guided MWA is a minimally invasive, relatively quick therapeutic strategy associated with accuracy in treatment and few complications.

Clinical application of ultrasound-guided percutaneous microwave ablation for benign breast lesions: a prospective study

BACKGROUND

Background: Benign breast lesions are the most common diseases in adult women, which have been treated with minimally invasive therapies in recent years. Little is known about the feasibility of Microwave ablation (MWA) for benign breast lesion treatment. The primary aim of this prospective study was to evaluate the safety and efficiency of MWA as a potential therapeutic option for benign breast lesions in a single-center cohort study.

METHODS

Women with possibly benign breast lesions based on an ultrasound (US) assessment who were scheduled to undergo MWA between November 2014 to July 2018 were included in the study. The patients underwent conventional US to measure the size of the lesion, Doppler US to assess the vascularity of the lesion, elastography to evaluate the stiffness of the mass, core needle biopsy of suspicious lesions, contrast-enhanced US to help determine the treatment plan and eventually MWA of the lesion. Lesions were followed at one, three, six, twelve and eighteen months after treatment to with the same imaging modalities.

RESULTS

A total of 314 women aged 17 to 69 years old (mean = 36.9 ± 9.9 years) with 725 benign breast lesions (mean of maximum diameter = 10.86 ± 5.40 mm) were included. The frequency of palpable mass, pain and nipple discharge significantly decreased after treatment. Complete ablation rate was 97.8%, immediately after ablation, which increased to 100% after supplementary ablation of the 15 cases with incomplete ablation. Blood flow classification and lesion's volume also showed a significant decrease, while both volume reduction ratio and disappearance rate significantly increased following treatment. The elasticity score of the lesions showed fluctuations across different follow-up intervals. None of the patients experienced major complications and the 1% who had mild symptoms were successfully treated.

CONCLUSION

MWA treatment is shown to be safe and efficient and has the potential to be considered as an alternative first line treatment for benign breast lesions.

A tumor map generated from three-dimensional visualization of image fusion for the assessment of microwave ablation of hepatocellular carcinoma: a preliminary study

PURPOSE

This study aimed to investigate the clinical value of a tumor map for assessing the ablative effect after ultrasound-guided percutaneous microwave ablation (US-PMWA) for hepatocellular carcinoma (HCC).

METHODS

The medical records of 68 patients (49 male and 19 female, 59.9±12.7 years) with HCC who underwent US-PMWA from May 2013 to May 2017 were reviewed. A tumor map was generated from the fusion of three-dimensional (3D) visualization images based on the preoperative target tumor and postoperative ablation area, to evaluate whether the ablation area covering the tumor has reached a 5 mm ablative margin (AM). The lesions were divided into two groups according to the tumor maps: group A (failed to achieve AM) and group B (achieved AM). The cumulative local tumor progression (LTP) rates of both groups were statistically analyzed using the log-rank test.

RESULTS

Success rate of tumor map generation was 100% (68/68), and no residual tumors were found. MWA-related 3D images, which included target tumor volume, ablation area volume, and residual liver ratio, were compared between groups A and B (P=0.295, P=0.772, and P=0.527, respectively). Technique effectiveness rate (91.7% vs 100%) was achieved in the two groups, showing no significant statistical differences (P=0.672). The 3-, 6-, 9-, and 12-month LTP rate was 8.3%, 16.7%, 20.8%, and 34%, respectively, for group A and 0%, 2.8%, 2.8%, and 2.8%, respectively, for group B, showing significant statistical differences (P<0.001) between the two groups.

CONCLUSION

The novel technology of tumor map generated from 3D visualization of image fusion is feasible and useful in evaluating the ablative effect of US-PMWA for HCC.

Ultrasound guided percutaneous microwave ablation of benign breast lesions

The benign breast lesions (BBLs) share a high incidence for women and therapy methods with minimal invasion and better cosmetic outcome are thirsted for. In this study, 122 patients with 198 biopsy-proved BBLs were enrolled. Ultrasound (US)-guided microwave ablation (MWA) was performed with local anesthesia from November, 2013 to April, 2016. The mean longest tumor size assessed was 1.6±0.7 cm (ranging 0.7-4.9 cm). MWA was successfully performed in all cases including 85 lesions adjacent to the skin, pectoralis and areola. The mean ablation time was 3.2mins (ranging 0.5-18.3 mins). 99.5% of BBLs showed complete ablation when assessed by magnetic resonance imaging and 100% of them by US. At the median 14-month follow-up, the BBLs were not palpable in 45.9 % of the cases (palpable in 90.2 % of the cases before MWA) and the mean volume reduction ratio was 78.4±33.5% for total lesions and 89.3±20.8%, 84.7±27.6% and 55.9±32.9% for ≤1.0 cm, 1.1-2.0cm and >2.0 cm lesions in 12-month follow-up, respectively. Cosmesis were reported as good or excellent in 100 % by physician and patients. No side effect was found. The MWA of the BBLs proved feasible and effective, while showing meaningful reduction in volume, palpability and cosmetic satisfying outcomes.

Microwave ablation: state-of-the-art review

This paper reviews state-of-the-art microwave ablation (MWA) of tumors. MWA is a novel method for treating inoperable tumors, ie, tumors that cannot be treated surgically. However, patients generally choose removal of the tumor by conventional techniques. A literature review of MWA for breast, liver, lung, and kidney tumors is reported here, with tabulation of our findings according to the type of technique used, with a detailed description of the time, type of microwave generator used, and number of patients treated with MWA. In some cases, the subjects were not human patients, but pig or bovine liver specimens. MWA is a technique that has proved to be promising and likely to be used increasingly in the ablation of cancerous tumors. However, MWA needs to be used more widely to establish itself as a common tool in the treatment of inoperable tumors.

Evaluation of the therapeutic efficacy of sequential therapy involving percutaneous microwave ablation in combination with 131I-hypericin using the VX2 rabbit breast solid tumor model

PURPOSE

Combination of percutaneous microwave ablation (PMWA) and intravenous injection of 131I-hypericin(IIIH) may bear potential as a mini-invasive treatment for tumor. The objective of this study was to assess the effect of PMWA and IIIH in breast tumor growth.

METHODS

Ten New Zealand White rabbits bearing VX2 breast carcinomas were randomly divided into two groups (each 5 examples) and processed using PMWA followed by IIIH and IIIH alone. The IIIH activity was evaluated using planar scintigraphy, autoradiography and biodistribution analysis. The maximum effective safe dose of IIIH was found through 48 rabbits with VX2 breast tumor, which were randomized into six groups (n=8 per group). Subsequently, a further 75 rabbits bearing VX2 breast solid tumors were randomly divided into five groups (each 15 examples) and treated as follows: A, no treatment group; B, PMWA alone; C, IIIH alone; D, PMWA+IIIH×1 (at 8 h post-PMWA); and E, PMWA+IIIH×2 (at 8 h and at 8 days post-PMWA). The therapeutic effect was assessed by measurement of tumor size and performation of positron emission tomography/computed tomograph (PET/CT) scans, liver and renal function tests and Kaplan-Meier survival analysis.

RESULTS

The planar scintigraphy findings suggested a significant uptake of 131I in necrotic tumor tissue. The autoradiography gray scales indicated higher selective uptake of IIIH by necrotic tissue, with significant differences between the groups with and those without necrotic tumor tissue (P<0.05). The maximum effective safe dose of IIIH was 1 mCi/kg. The PET/CT scans and tumor size measurement suggested improvements in treatment groups at all time points (P<0.01). Significant differences were detected among Groups A, B, D and E (P<0.05). Lower levels of lung metastasis were detected in Groups D and E (P<0.05). There were no abnormalities in liver and renal functions tests or other reported side effects.

CONCLUSION

IIIH exhibited selective uptake by necrotic tumor tissue. Sequential therapy involving PMWA+IIIH was successfully inhibiting tumor growth and prolonging survival.

Comparison of ablation zones among different tissues using 2450-MHz cooled-shaft microwave antenna: results in ex vivo porcine models

Background

For complete tumor ablation in different tissues, it is necessary to investigate the exact coagulation zone of microwave ablation in different tissues. The aim of this study was to compare the extent of microwave ablation zone in muscle, liver and adipose tissue in ex vivo porcine models and assess the shape of microwave coagulation zone among these tissues.

Materials and Methods

Microwave ablations were performed in ex vivo porcine muscle, liver and adipose tissue using 2450-MHz cooled-shaft microwave antenna. The content of water, fat and protein in these three tissues was determined. Two power increments (40 and 80 W) and five time increments (1, 3, 5, 7, and 10 minutes) were used in this study. Diameters and shapes of the ablation zones were assessed on gross specimens.

Results

The average percentages of water, fat and protein in these three tissues were significantly different (P < 0.001), respectively. The long-axis and short-axis diameters among these three tissues at each time-power combination were not significantly different (P > 0.05). The coagulation zones were all elliptical in muscle, liver and adipose tissue. When microwave ablation was performed in the tissue containing both muscle and adipose tissue, the coagulation zone was also elliptical. Regardless of the output power, the ellipticity index (EI) value of 1 minute treatment duration was higher than that of 10 minutes treatment duration (P < 0.05). Furthermore, the EI value did not decrease significantly when the treatment duration was more than 5 minutes (P > 0.05).

Conclusion

The extent of microwave ablation zones was not significantly different among completely different tissues. Microwave ablations with ≥ 5 minutes time duration can induce coagulation zones with clinical desirable shape. Future clinical studies are still required to determine the role of microwave ablation in different tissues.

Computational modelling of microwave tumour ablations

Microwave tissue heating is being increasingly utilised in several medical applications, including focal tumour ablation, cardiac ablation, haemostasis and resection assistance. Computational modelling of microwave ablations is a precise and repeatable technique that can assist with microwave system design, treatment planning and procedural analysis. Advances in coupling temperature and water content to electrical and thermal properties, along with tissue contraction, have led to increasingly accurate computational models. Developments in experimental validation have led to broader acceptability and applicability of these newer models. This review will discuss the basic theory, current trends and future direction of computational modelling of microwave ablations.

Ultrasound-guided microwave ablation for abdominal wall metastatic tumors: a preliminary study

AIM

To evaluate the feasibility, safety and efficacy of ultrasound-guided microwave (MW) ablation for abdominal wall metastatic tumors.

METHODS

From August 2007 to December 2010, a total of 11 patients with 23 abdominal wall nodules (diameter 2.59 cm ± 1.11 cm, range 1.3 cm to 5.0 cm) were treated with MW ablation. One antenna was inserted into the center of tumors less than 1.7 cm, and multiple antennae were inserted simultaneously into tumors 1.7 cm or larger. A 21 gauge thermocouple was inserted near important organs which required protection (such as bowel or gallbladder) for real-time temperature monitoring during MW ablation. Treatment outcome was observed by contrast-enhanced ultrasound and magnetic resonance imaging (MRI) [or computed tomography (CT)] during follow-up.

RESULTS

MW ablation was well tolerated by all patients. Six patients with 11 nodules had 1 thermocouple inserted near important organs for real-time temperature monitoring and the maximum temperature was 56 °C. Major complications included mild pain (54.5%), post-ablation fever (100%) and abdominal wall edema (25%). All 23 tumors (100%) in this group were completely ablated, and no residual tumor or local recurrence was observed at a median follow-up of 13 mo (range 1 to 32 mo). The ablation zone was well defined on contrast-enhanced imaging (contrast-enhanced CT, MRI and/or contrast-enhanced ultrasound) and gradually shrank with time.

CONCLUSION

Ultrasound-guided MW ablation may be a feasible, safe and effective treatment for abdominal wall metastatic tumors in selected patients.

Percutaneous microwave coagulation for eradication of VX2 tumors subcutaneously in rabbits

BACKGROUND

Percutaneous microwave coagulation (PMC) has been accepted as a promising modality in the treatment of tumors in well-vascularized tissues such as liver tumors and hysteromyoma. However, PMC for treatment of tumors in low blood-flow tissues has been seldom reported. The aim of this study was to determine the feasibility and safety of PMC for the treatment of tumors in low blood-flow tissues in a rabbit model.

METHODS

Fifteen rabbits with VX2 tumors implanted subcutaneously underneath the right second nipple were divided into a PMC group (n = 9) and a control group (n = 6). PMC was performed with output power of 40 W for one to two minutes. The therapeutic efficacy was evaluated by magnetic resonance imaging (MRI), physical examinations, survival rate, and histology. The cosmetic outcome after PMC was also assessed.

RESULTS

In the PMC group, tumor eradication was achieved in six rabbits (66.7%) without any evidence of tumor recurrence and metastasis as proven by MRI and histological examinations. The mean greatest and shortest tumor diameters of these six rabbits were 1.83 and 1.33 cm, respectively. Slight epidermal burns, which proved reversible, were found in seven rabbits (77.8%). The PMC group had a significantly longer survival than those in the control group (P = 0.0097). The four rabbits with coagulated tumors survived more than three months with their tumors becoming nonpalpable and undetectable by MRI and histological examinations.

CONCLUSIONS

PMC is feasible and safe in the treatment of tumors in low blood-flow tissues in a rabbit model. Attention should be paid to avoid skin burns with PMC.