Dosimetric analysis of ultrasound-guided high intensity focused ultrasound ablation for breast fibroadenomas: a retrospective study

Prediction of high-intensity focused ultrasound (HIFU)-induced lesion size using the echo amplitude from the focus in tissue

In the realm of high-intensity focused ultrasound (HIFU) therapy, the precise prediction of lesion size during treatment planning remains a challenge, primarily due to the difficulty in quantitatively assessing energy deposition at the target site and the acoustic properties of the tissue through which the ultrasound wave propagates. This study investigates the hypothesis that the echo amplitude originating from the focus is indicative of acoustic attenuation and is directly related to the resultant lesion size. Echoes from multi-layered tissues, specifically porcine tenderloin and bovine livers, with varying fat thickness from 0 mm to 35 mm were collected using a focused ultrasound (FUS) transducer operated at a low power output and short duration. Subsequent to HIFU treatment under clinical conditions, the resulting lesion areas in the ex vivo tissues were meticulously quantified. A novel treatment strategy that prioritizes treatment spots based on descending echo amplitudes was proposed and compared with the conventional raster scan approach. Our findings reveal a consistent trend of decreasing echo amplitudes and HIFU-induced lesion areas with the increasing fat thickness. For porcine tenderloin, the values decreased from 2541.7 ± 641.9 mV and 94.4 ± 17.9 mm2 to 385(342.5) mV and 24.9 ± 18.7 mm2, and for bovine liver, from 1406(1202.5) mV and 94.4 ± 17.9 mm2 to 502.1 ± 225.7 mV and 9.4 ± 6.3 mm2, respectively, as the fat thickness increases from 0 mm to 35 mm. Significant correlations were identified between preoperative echo amplitudes and the HIFU-induced lesion areas (R = 0.833 and 0.784 for the porcine tenderloin and bovine liver, respectively). These correlations underscore the potential for an accurate and dependable prediction of treatment outcomes. Employing the proposed treatment strategy, the ex vivo experiment yielded larger lesion areas in bovine liver at a penetration depth of 8 cm compared to the conventional approach (58.84 ± 17.16 mm2 vs. 44.28 ± 15.37 mm2, p < 0.05). The preoperative echo amplitude from the FUS transducer is shown to be a reflective measure of acoustic attenuation within the wave propagation window and is closely correlated with the induced lesion areas. The proposed treatment strategy demonstrated enhanced efficiency in ex vivo settings, affirming the feasibility and accuracy of predicting HIFU-induced lesion size based on echo amplitude.

A Comparison of Quality of Life, Cosmesis and Cost-Utility of Open Surgery, Vacuum-Assisted Breast Biopsy and High Intensity Focused Ultrasound for Breast Fibroadenoma

RATIONALE AND OBJECTIVES

To compare the quality of life (QOL), cosmesis and cost-utility of open surgery (OS), vacuum-assisted breast biopsy (VABB) and high intensity focused ultrasound (HIFU) for fibroadenoma (FA).

MATERIALS AND METHODS

A total of 162 patients with 267 FAs were enrolled. Baseline characteristics and treatment information were recorded. Patients were followed up at 3-, 6- and 12-month post-treatment. QOL was evaluated by health survey. Breast cosmesis was evaluated by self-rating survey and Harvard Scale. A decision-analytic model was established and incremental cost was calculated for cost-utility analysis.

RESULTS

For QOL evaluation, there was no difference of physical component summary (PCS) score in three groups (P > 0.05), while the mental component summary (MCS) score was significantly higher in HIFU group than the other two groups at 3- and 6-month post-treatment (P < 0.05). The proportion of patients satisfied with breast cosmesis was significantly higher in HIFU group (96.49%) than in VABB group (54.90%) and OS group (49.99%) (P < 0.05). By Harvard Scale, 27.78%, 78.42% and 100.00% of patients were rated as excellent and good in OS group, VABB group and HIFU group, respectively (P < 0.05). To acquire a quality-adjusted life year (QALY), cost of OS, VABB and HIFU was 1034.31 USD, 1776.96 USD and 1277.67 USD, respectively. When compared to OS, incremental cost analysis showed HIFU was cost-effective, while VABB was not.

CONCLUSION

OS, VABB and HIFU were all effective and safe for FA, but among these three treatments, HIFU had the best QOL improvement, breast cosmesis and cost-effectiveness.

Feasibility and efficacy of ultrasound-guided high-intensity focused ultrasound of breast fibroadenoma

OBJECTIVE

This nonrandomized prospective clinical trial aimed to assess the efficacy, safety and follow-up outcomes of ultrasound-guided high-intensity focused ultrasound (USgHIFU) surgery in patients with breast fibroadenoma.

METHODS

With the approval of the institutional ethics committee and written informed consent, a total of 113 patients diagnosed with breast fibroadenoma by core-needle biopsy in our hospital were recruited. USgHIFU surgery was performed under local anesthesia. Contrast-enhanced ultrasound (CEUS) or contrast-enhanced MRI (CEMRI) was performed to evaluate the nonperfused volume (NPV). The patients were followed up with physical examination and ultrasound imaging.

RESULTS

The clinical outcome of 85 patients with 147 fibroadenomas with a follow-up time of more than 3 months was analyzed in this study. Fifty-two patients had one lesion, twenty-one patients had two lesions and twelve patients had more than two lesions. During USgHIFU, the median localization time for all fibroadenomas was 3 (interquartile range: 1, 5) min, and the median treatment time was 9 (interquartile range: 5, 15) min. Under local anesthesia, all the patients tolerated the treatment well. No serious epidermal burns were observed in any of the patients. Based on CEUS or CEMRI imaging evaluation, the median NPV ratio was 100% (interquartile range: 79.2%, 116.8%). The VRR were 26.77 ± 50.05%, 50.22 ± 42.01% and 72.74 ± 35.39% at 3-6 months, 6-12 months and >12 months, respectively, which showed significant statistical difference (p < .001).

CONCLUSION

Ultrasound-guided HIFU surgery is an effective and safe noninvasive alternative technique for the treatment of breast fibroadenoma.

Evaluating the learning curve of high intensity focus ultrasound for breast fibroadenoma by CUSUM analysis: a multi-center study

OBJECTIVE

To explore the learning curve of high intensity focus ultrasound (HIFU) treatment for breast fibroadenoma.

METHODS

A database of 110 patients with 255 breast fibroadenomas who underwent HIFU treatment at two different clinical centers (Center 1 and 2) were retrospectively analyzed. The learning curves of HIFU treatment for breast fibroadenoma were drawn by CUSUM analysis in two centers, respectively. According to the inflection point of the learning curves, the treatment was divided into two groups: initial phase and consolidation phase. HIFU treatment parameters were compared between two groups. The effectiveness and safety results were also evaluated.

RESULTS

The inflection points of the learning curves were the 60^th treatment in Center 1 and the 65^th treatment in Center 2. The screening time, treatment time, sonication time and hyperechoic scale change time were significantly shorter in consolidation phase than those in initial phase of the two centers (p < 0.05). There were no differences in non-perfused volume (NPV) ratio and energy effect factor (EEF) between the two groups in Center 1, while in Center 2, these above-mentioned results in consolidation phase led to a greater improvement than those in initial phase. There was no difference of Visual Analogue Scale (VAS) scores and no adverse event observed in both centers.

CONCLUSION

HIFU treatment for breast fibroadenoma was effective and safe. The learning curve of HIFU treatment for breast fibroadenoma can be completed after treating 60-65 tumors without increasing the safety risk.