A feasibility study for non-invasive thermometry using non-linear ultrasound

Harmonic Motion Imaging-Guided Focused Ultrasound Ablation: Comparison of Three Focused Ultrasound Interference Filtering Methods

OBJECTIVE

Harmonic motion imaging (HMI) is an acoustic radiation force-based elasticity imaging technique, which can be used to monitor changes in tissue mechanical properties caused by focused ultrasound (FUS)-induced thermal ablation. In conventional HMI, the amplitude-modulated FUS sequence and imaging pulse are transmitted simultaneously. With this method, the high-amplitude FUS signal must be separated from the imaging data for tissue displacement estimation. Frequency domain notch filtering and bandpass filtering were previously used to filter FUS interference from imaging data. However, FUS interference becomes more pronounced at the increased intensities and durations necessary for thermal ablation, rendering frequency domain filtering challenging. In this study, three methods for FUS interference filtering during HMI-guided FUS ablation (HMIgFUS) were compared. The methods were notch filtering; interleaved HMIgFUS, with interleaved FUS and imaging pulses; and FUS-net, a convolutional neural network-based U-Net autoencoder developed by our group for FUS interference filtering in radiofrequency data. FUS-net was applied here for the first time for the purpose of ablation displacement monitoring.

METHODS

The three filtering methods were tested during 20 HMIgFUS acquisitions in an ex vivo canine liver using a range of peak positive pressures from 11 to 18 MPa and durations ranging from 60 to 180 seconds. The B-mode mean squared errors (MSEs) and displacement amplitude contrast-to-noise ratios (CNRs) of the three methods were calculated and compared.

RESULTS

The interleaved method for HMIgFUS was found to be significantly robust in avoiding FUS interference in all tested cases for FUS ablation monitoring, especially cases with high FUS pressure and long durations, as opposed to traditional notch filtering and FUS-net filtering. CNRs obtained from displacement amplitude maps in the interleaved data set were significantly higher in all cases than those obtained from the notch filtered and FUS-net data sets. There was not a significant trend in displacement CNR between the FUS-net and notch filtered data sets. However, B-mode MSE was found to be significantly higher when comparing the FUS-net and interleaved data sets as opposed to the notch filtered and interleaved data sets, suggesting further potential of FUS-net as an FUS interference filtering method.

CONCLUSION

These findings indicate the robustness of interleaved HMIgFUS in avoiding FUS interference during HMIgFUS monitoring and the advantages, limitations and future potential of FUS-net and notch filtering.

Statistical Analysis of Ultrasonic Scattered Echoes Enables the Non-invasive Measurement of Temperature Elevations inside Tumor Tissue during Oncological Hyperthermia

Non-invasive monitoring of temperature elevations inside tumor tissue is imperative for the oncological thermotherapy known as hyperthermia. In the present study, two cancer patients, one with a developing right renal cell carcinoma and the other with pseudomyxoma peritonei, underwent hyperthermia. The two patients were irradiated with radiofrequency current for 40 min during hyperthermia. We report the results of our clinical trial study in which the temperature increases inside the tumor tissues of patients with right renal cell carcinoma and pseudomyxoma peritonei induced by radiofrequency current irradiation for 40 min could be detected by statistical analysis of ultrasonic scattered echoes. The Nakagami shape parameter m varies depending on the temperature of the medium. We calculated the Nakagami shape parameter m by statistical analysis of the ultrasonic echoes scattered from the tumor tissues. The temperature elevations inside the tumor tissues were expressed as increases in brightness on 2-D hot-scale maps of the specific parameter α_mod, indicating the absolute values of the percentage changes in m values. In the α_mod map for each tumor tissue, the brightness clearly increased with treatment time. In quantitative analysis, the mean values of α_mod were calculated. The mean value of α_mod for the right renal cell carcinoma increased to 1.35 dB with increasing treatment time, and the mean value of α_mod for pseudomyxoma peritonei increased to 1.74 with treatment time. The increase in both α_mod brightness and the mean value of α_mod implied temperature elevations inside the tumor tissues induced by the radiofrequency current; thus, the acoustic method is promising for monitoring temperature elevations inside tumor tissues during hyperthermia.

Development of an ultrasonic nonlinear frequency compounding method with applications in tissue thermometry

Frequency compounding is an ultrasound imaging technique used to improve signal-to-noise ratio (SNR). In this work, a nonlinear frequency compounding (NLFC) method was introduced, and its application in noninvasive tissue thermometry investigated. The NLFC method was used to produce two-dimensional maps of the temperature sensitive change in backscattered energy of acoustic harmonics (hCBE), during heating of ex vivo porcine tissue with a low intensity focused ultrasound transducer. A hCBE-to-temperature calibration was performed, and temperature maps produced and compared with a theoretical COMSOL based model. Last, a comparative study of the NLFC and previously used nonlinear single frequency (NLSF) methods was completed to quantify the improvement in SNR of the produced hCBE maps. When using the NLFC method, a SNR of 6.06 ± 1.28 was found. SNR values of 3.70 ± 0.53 and 4.38 ± 0.84 were found while using central frequencies of 4.31 and 5.43 MHz, respectively, with the NLSF method. This translates to an improvement of (64.13 ± 4.16)% over the 4.31 MHz NLSF, and (38.72 ± 2.97)% over the 5.43 MHz NLSF methods overall. It was concluded that the NLFC method can produce hCBE and temperature maps with superior image SNR over the NLSF method.

Noninvasive calibrated tissue temperature estimation using backscattered energy of acoustic harmonics

PURPOSE

A real-time and non-invasive thermometry technique is essential in thermal therapies to monitor and control the treatment. Ultrasound is an attractive thermometry modality due to its relatively high sensitivity to change in temperature and fast data acquisition and processing capabilities. A temperature-sensitive acoustic parameter is required for ultrasound thermometry in order to track the changes in that parameter during the treatment. Currently, the main ultrasound thermometry methods are based on variation in the attenuation coefficient, the change in backscattered energy of the signal (CBE), the backscattered radio-frequency (RF) echo-shift due to change in the speed of sound and thermal expansion of the medium, and change in the amplitudes of the acoustic harmonics. In this work, an ultrasound thermometry method based on second harmonic CBE (CBE_h2) and combined fundamental and second harmonic CBE (CBE_comb) is used to produce 2D temperature maps, detect localized heated region generated by low intensity focused ultrasound (LIFU), and control temperature in the heated region.

MATERIALS AND METHODS

Ex vivo pork muscle tissue samples were exposed to localized LIFU heating source and 2D temperature maps were produced from the RF data acquired by a 4.2 MHz linear array probe using a Verasonics Vantage™ ultrasound scanner (Verasonics Inc., Redmond, WA) after the exposure. Calibrated needle thermocouples were also placed in the ex vivo tissue sample close to the LIFU focal zone for temperature calibration purposes. The estimated temperature maps were the established echo-shift technique. A tissue motion compensation algorithm was also used to reduce the susceptibility to motion artifacts.

RESULTS

2D temperature maps were generated using CBE of acoustic harmonic and echo-shift techniques. The results show a direct correlation between the CBE of acoustic harmonics and focal tissue temperature for a range of temperatures from 37 °C (baseline) to 47 °C.

CONCLUSIONS

The findings of this study show that the CBE of acoustic harmonics technique can be used to noninvasively estimate temperature change in tissue in the hyperthermia temperature range.

Techniques for Temperature Monitoring of Myocardial Tissue Undergoing Radiofrequency Ablation Treatments: An Overview

Cardiac radiofrequency ablation (RFA) has received substantial attention for the treatment of multiple arrhythmias. In this scenario, there is an ever-growing demand for monitoring the temperature trend inside the tissue as it may allow an accurate control of the treatment effects, with a consequent improvement of the clinical outcomes. There are many methods for monitoring temperature in tissues undergoing RFA, which can be divided into invasive and non-invasive. This paper aims to provide an overview of the currently available techniques for temperature detection in this clinical scenario. Firstly, we describe the heat generation during RFA, then we report the principle of work of the most popular thermometric techniques and their features. Finally, we introduce their main applications in the field of cardiac RFA to explore the applicability in clinical settings of each method.

Durability study of a gellan gum-based tissue-mimicking phantom for ultrasonic thermal therapy

Stability and duration of ultrasonic phantoms are still subjects of research. This work presents a tissue-mimicking material (TMM) to evaluate high-intensity therapeutic ultrasound (HITU) devices, composed of gellan gum (matrix), microparticles (scatterers), and chemicals. The ultrasonic velocity and attenuation coefficient were characterized as a function of temperature (range 20 °C-85 °C). The nonlinear parameter B/A was determined by the finite amplitude insertion substitution (FAIS) method, and the shear modulus was determined by a transient elastography technique. The thermal conductivity and specific heat were determined by the line source method. The attenuation was stable for 60 days, and in an almost linear frequency dependence (0.51f^0.96dB cm^-1), at 20 °C (1-10 MHz). All other evaluated physical parameters are also close to typical soft tissue values. Longitudinal ultrasonic velocities were between 1.49 and 1.75 mm μs^-1, the B/A parameter was 7.8 at 30 °C, and Young's modulus was 23.4 kPa. The thermal conductivity and specific heat values were 0.7 W(m K)^-1 and 4.7 kJ(kg K)^-1, respectively. Consistent temperature increases and thermal doses occurred under identical HITU exposures. Low cost, longevity, thermal stability, and thermal repeatability make TMM an excellent material for ultrasonic thermal applications. The TMM developed has the potential to assess the efficacy of hyperthermia devices and could be used to adjust the ultrasonic emission of HITU devices.

Toward development of PreVoid alerting system for nocturnal enuresis patients: A fuzzy-based approach for determining the level of liquid encased in urinary bladder

Preventive and accurate assessment of bladder voiding dysfunctions necessitates measuring the amount of liquid encapsulated within urinary bladder walls in a non-invasive and real-time manner. The real-time monitoring of urine levels helps patients with urological disorders such as Nocturnal Enuresis (NE) by preventing the occurrence of enuresis via a pre-void stage alerting system. Although some advances have been achieved toward developing a non-invasive approach for determining the amount of accumulated urine inside the bladder, there is still a lack of an easy-to-implement technique which is suitable to embed in a wearable pre-warning device. This study aims to develop a machine-learning empowered technique to quantify to what extent an individual's bladder is filled by observing the filling-voiding pattern of a patient over a training period. In this experiment, a pulse-echo sonar element is used to generate ultrasound pulses while the probe surface is positioned perpendicular to the bladder's position. From the reflected echoes, four features which show sufficient sensitiveness and therefore could be modulated noticeably by different levels of liquid encased in the bladder, are extracted. The extracted features are then fed into a novel intelligent decision support system- known as FECOC - which is based on hybridization of fuzzy inference systems (FIS) and error correcting output codes (ECOC). The proposed scheme tends to achieve better results when examined in real case studies.

A remote temperature sensor for an ultrasound hyperthermia system using the acoustic signal derived from the heating signals

We demonstrate a non-invasive technique, based on the modal frequency shift of a region insonified by a dual-beam ultrasound (US) transducer (region of interest, ROI), to remotely assess the temperature of the region in a tissue-mimicking object. The application is in ultrasound hyperthermia systems for controlled maintenance of tumour temperature during chemotherapy. Towards this, we have characterised the variation of the storage modulus with the temperature of two tissue-mimicking visco-elastic materials. Due to this variation in tissue storage modulus (and viscosity), we have observed a shift in the resonant modes of the ROI, vibrated remotely with a dual-beam focussed ultrasound transducer. A modal analysis of the vibrating ROI is done to identify the modes captured by the detector. A variation in this modal frequency with temperature is computed and matches reasonably well with the experimental measurements. Through this, we demonstrate that an ultrasound hyperthermia system can have a remote temperature sensor without using an additional imaging modality.

Human Brown Adipose Tissue Temperature and Fat Fraction Are Related to Its Metabolic Activity

BACKGROUND AND AIM

The metabolic activity of human brown adipose tissue (BAT) has been previously examined using positron emission tomography (PET). The aim of this study was to use proton magnetic resonance spectroscopy (1H MRS) to investigate whether the temperature and the fat fraction (FF) of BAT and white adipose tissue (WAT) are associated with BAT metabolic activity determined by deoxy-2-18F-fluoro-d-glucose (18F-FDG)-PET.

MATERIALS AND METHODS

Ten healthy subjects (four women, six men; 25 to 45 years of age) were studied using PET-magnetic resonance imaging during acute cold exposure and at ambient room temperature. BAT and subcutaneous WAT 1H MRS were measured. The tissue temperature and the FF were derived from the spectra. Tissue metabolic activity was studied through glucose uptake using dynamic FDG PET scanning during cold exposure. A 2-hour hyperinsulinemic euglycemic clamp was performed on eight subjects.

RESULTS

The metabolic activity of BAT associated directly with the heat production capacity and inversely with the FF of the tissue. In addition, the lipid-burning capacity of BAT associated with whole-body insulin sensitivity. During cold exposure, the FF of BAT was lower than at room temperature, and cold-induced FF of BAT associated inversely with high-density lipoprotein and directly with low-density lipoprotein cholesterol.

CONCLUSION

Both 1H MRS-derived temperature and FF are promising methods to study BAT activity noninvasively. The association between the lipid-burning capacity of BAT and whole-body insulin sensitivity emphasizes the role of BAT in glucose handling. Furthermore, the relation of FF to high-density lipoprotein and low-density lipoprotein cholesterol suggests that BAT has a role in lipid clearance, thus protecting tissues from excess lipid load.

Temperature dependence of acoustic harmonics generated by nonlinear ultrasound wave propagation in water at various frequencies

Ultrasound-based thermometry requires a temperature-sensitive acoustic parameter that can be used to estimate the temperature by tracking changes in that parameter during heating. The objective of this study is to investigate the temperature dependence of acoustic harmonics generated by nonlinear ultrasound wave propagation in water at various pulse transmit frequencies from 1 to 20 MHz. Simulations were conducted using an expanded form of the Khokhlov-Zabolotskaya-Kuznetsov nonlinear acoustic wave propagation model in which temperature dependence of the medium parameters was included. Measurements were performed using single-element transducers at two different transmit frequencies of 3.3 and 13 MHz which are within the range of frequencies simulated. The acoustic pressure signals were measured by a calibrated needle hydrophone along the axes of the transducers. The water temperature was uniformly increased from 26 °C to 46 °C in increments of 5 °C. The results show that the temperature dependence of the harmonic generation is different at various frequencies which is due to the interplay between the mechanisms of absorption, nonlinearity, and focusing gain. At the transmit frequencies of 1 and 3.3 MHz, the harmonic amplitudes decrease with increasing the temperature, while the opposite temperature dependence is observed at 13 and 20 MHz.

Thermometry and ablation monitoring with ultrasound

In this review we present the current status of ultrasound thermometry and ablation monitoring, with emphasis on the diverse approaches published in the literature and with an eye on which methods are closest to clinical reality. It is hoped that this review will serve as a guide to the expansion of sonographic methods for treatment monitoring and thermometry since the last brief review in 2007.

A survey of ultrasound elastography approaches to percutaneous ablation monitoring

Percutaneous thermal ablation has been widely used as a minimally invasive treatment for tumors. Treatment monitoring is essential for preventing complications while ensuring treatment efficacy. Mechanical testing measurements on tissue reveal that tissue stiffness increases with temperature and ablation duration. Different types of imaging methods can be used to monitor ablation procedures, including temperature or thermal strain imaging, strain imaging, modulus imaging, and shear modulus imaging. Ultrasound elastography demonstrates the potential to become the primary imaging modality for monitoring percutaneous ablation. This review briefly presented the state-of-the-art ultrasound elastography approaches for monitoring radiofrequency ablation and microwave ablation. These techniques were divided into four groups: quasi-static elastography, acoustic radiation force elastography, sonoelastography, and applicator motion elastography. Their advantages and limitations were compared and discussed. Future developments were proposed with respect to heat-induced bubbles, tissue inhomogeneities, respiratory motion, three-dimensional monitoring, multi-parametric monitoring, real-time monitoring, experimental data center for percutaneous ablation, and microwave ablation monitoring.

Tissue-mimicking gel phantoms for thermal therapy studies

Tissue-mimicking phantoms that are currently available for routine biomedical applications may not be suitable for high-temperature experiments or calibration of thermal modalities. Therefore, design and fabrication of customized thermal phantoms with tailored properties are necessary for thermal therapy studies. A multitude of thermal phantoms have been developed in liquid, solid, and gel forms to simulate biological tissues in thermal therapy experiments. This article is an attempt to outline the various materials and techniques used to prepare thermal phantoms in the gel state. The relevant thermal, electrical, acoustic, and optical properties of these phantoms are presented in detail and the benefits and shortcomings of each type are discussed. This review could assist the researchers in the selection of appropriate phantom recipes for their in vitro study of thermal modalities and highlight the limitations of current phantom recipes that remain to be addressed in further studies.

Mean scatterer spacing estimation in normal and thermally coagulated ex vivo bovine liver

The liver has been hypothesized to have a unique arrangement of microvasculature that presents as an arrangement of quasiperiodic scatterers to an interrogating ultrasound pulse. The mean scatterer spacing (MSS) of these quasiperiodic scatterers has been proposed as a useful quantitative ultrasound biomarker for characterizing liver tissue. Thermal ablation is an increasingly popular method for treating hepatic tumors, and ultrasonic imaging approaches for delineating the extent of thermal ablation are in high demand. In this work, we examine the distribution of estimated MSS in thermally coagulated bovine liver and normal untreated bovine liver ex vivo. We estimate MSS by detecting local maxima in the spectral coherence function of radio frequency echoes from a clinical transducer, the Siemens VFX 9L4 transducer operating on an S2000 scanner. We find that normal untreated bovine liver was characterized by an MSS of approximately 1.3 mm. We examined regions of interest 12 mm wide laterally, and ranging from 12 mm to 18 mm axially, in 2 mm increments. Over these parameters, the mode of the MSS estimates was between 1.25 and 1.37 mm. On the other hand, estimation of MSS in thermally coagulated liver tissue yields a distribution of MSS estimates whose mode varied between 0.45 and 1.0 mm when examining regions of interest over the same sizes. We demonstrate that the estimated MSS in thermally coagulated liver favors small spacings because the randomly positioned scatterers in this tissue are better modeled as aperiodic scatterers. The submillimeter spacings result from the fact that this was the most probable spacing to be estimated if the discretely sampled spectral coherence function was a uniformly random two-dimensional function.

Techniques for temperature monitoring during laser-induced thermotherapy: an overview

Laser-induced thermotherapy (LITT) is a hyperthermic procedure recently employed to treat cancer in several organs. The amount of coagulated tissue depends on the temperature distribution around the applicator, which plays a crucial role for an optimal outcome: the removal of the whole neoplastic tissue, whilst preventing damage to the surrounding healthy tissue. Although feedback concerning tissue temperature could be useful to drive the physician in the adjustment of laser settings and treatment duration, LITT is usually performed without real-time monitoring of tissue temperature. During recent decades, many thermometric techniques have been developed to be used during thermal therapies. This paper provides an overview of techniques and sensors employed for temperature measurement during tissue hyperthermia, focusing on LITT, and an investigation of their performances in this application. The paper focuses on the most promising and widespread temperature monitoring techniques, splitting them into two groups: the former includes invasive techniques based on the use of thermocouples and fibre-optic sensors; the second analyses non-invasive methods, i.e. magnetic resonance imaging-, computerised tomography- and ultrasound-based thermometry. Background information on measuring principle, medical applications, advantages and weaknesses of each method are provided and discussed.

Ultrasonic evaluation of microwave-induced thermal lesions based on wavelet analysis of mean scatterer spacing

The microwave ablation has become an important manner for tumor treatment. In this paper, we proposed a new method for evaluation of microwave-induced thermal lesions using the wavelet analysis of the mean scatterer spacing (MSS). First, the ultrasonic radiofrequency (RF) data of normal and coagulated porcine liver tissues was collected through the temperature-controlled water bath heating experiments. The convex array ultrasound probe with a center frequency of 3.5 MHz was used. Second, the wavelet analysis was used to compute the MSS of normal and coagulated porcine liver tissues, respectively. Finally, the microwave-induced thermal lesions were detected based on the differences in the MSS between normal tissues and thermal lesions. Eighteen cases of microwave ablation experiments and 20 cases of water bath heating experiments were conducted on fresh porcine liver samples. The MSS of normal porcine liver tissues was 1.15±0.12 mm, and the MSS of coagulated porcine liver tissues was 0.93±0.07 mm. Six cases of thermal lesions were compared between the MSS-detected area and the caliper-measured area, and the MSS-detected area had an error of (13.55±5.29) %. The experimental results indicated that the proposed method could be used in preliminary detection and evaluation of microwave-induced thermal lesions.

Surgery combined with intraoperative hyperthermic intraperitoneal chemotherapy (IHIC) for gastric cancer: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Adjuvant intraoperative hyperthermic intraperitoneal chemotherapy (IHIC) is a therapy which combines thermotherapy and intraperitoneal chemotherapy. It is theoretically powerful for patients with advanced gastric cancer (AGC), but is there evident advantage in clinical practice? We need evidence to guide our decision-making.

OBJECTIVES

Meta-analysis was performed to assess the effectiveness and safety of adjuvant intraoperative hyperthermic intraperitoneal chemotherapy (IHIC) for patients with resectable locally advanced gastric cancer, and to provide the reference for clinical practice and study.

METHODS

We searched the Cochrane Library, PubMed, Embase, Web of Science and Chinese databases (Chinese BioMedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI) and Wanfang) electronically and also retrieved papers from other sources (tracing related references and communication with other authors). All relevant randomised controlled trials (RCTs) were collected to compare surgery combined with IHIC to surgery without IHIC for AGC. There were no language restrictions. After independent quality assessment and data extraction by two reviewers, meta-analysis was conducted by RevMan 5.1 software.

RESULTS

16 RCTs involving 1,906 patients were included. Compared with surgery alone, combination therapy (surgery plus IHIC) was associated with a significant improvement in survival rate at 1 year (hazard ratio (HR) = 2.99; 95% confidence interval (CI) = 2.21 to 4.05; p < 0.00001), 2 years (HR = 2.43; 95%CI = 1.81 to 3.26; p < 0.00001), 3 years (HR = 2.63; 95%CI = 2.17 to 3.20; p < 0.00001), 5 years (HR = 2.49; 95%CI = 1.97 to 3.14; p < 0.00001), and 9 years (HR = 2.14; 95%CI = 1.38 to 3.32; p = 0.0007). Compared with surgery alone, combination therapy was associated with a significant reduction in recurrence rate at 2 years (RR = 0.42; 95%CI = 0.29 to 0.61; p < 0.00001), 3 years (RR = 0.35; 95%CI = 0.24 to 0.51; p < 0.00001) and 5 years (RR = 0.47; 95%CI = 0.39 to 0.56; p < 0.00001). IHIC was not found to be associated with higher risks of anastomotic leakage, ileus, bowel perforation, myelosuppression, gastrointestinal reaction and hypohepatia, but it increased the incidence of abdominal pain (RR = 21.46; 95%CI = 5.24 to 87.78; p < 0.00001).

CONCLUSIONS

Compared with surgery alone, surgery combined with IHIC can improve survival rate and reduce the recurrence rate, with acceptable safety. However, safety outcomes should be further evaluated by larger samples and high quality studies. Additionally, hyperthermia for the intraperitoneal chemotherapy needs more clinical research.

The effect of high-intensity focused ultrasound treatment on immune function in patients with uterine fibroids

PURPOSE

The aim of this study was to investigate the effect of high-intensity focused ultrasound (HIFU) on immune function in patients with uterine fibroids, in a randomised comparison to conventional myomectomy.

METHODS

The patients were assigned (1:1) to the HIFU group or the myomectomy (MY) group. Venous blood samples were collected 24 h before and 24 h and 72 h after operation. The percentages of CD4(+) and CD8(+) T cells and natural killer (NK) cells were quantified by flow cytometry (FCM). Serum levels of interleukin-2 (IL-2), IL-6 and IL-10 were determined using enzyme-linked immunosorbent assay.

RESULTS

HIFU was associated with early ambulation, fewer post-operative complications, and shorter hospital stay (p < 0.001). The percentages of CD4(+) and CD8(+) T cells and NK cells in the HIFU group were not significantly altered after treatment compared with before treatment. In contrast, the numbers of these cells in the MY group decreased significantly 24 h after conventional myomectomy (p < 0.001). The CD4(+)/CD8(+) T cell ratios were also decreased significantly 24 h and 72 h after conventional myomectomy (p < 0.001). Serum levels of IL-6 and IL-10 increased after treatment in both groups. Peak IL-6 and IL-10 levels were significantly lower in the HIFU group than in the MY group (p < 0.001). In contrast, IL-2 level decreased significantly in the MY group compared to the HIFU group at 24 h post-operation (p < 0.001).

CONCLUSIONS

Short-term post-operative immune function is better preserved after HIFU treatment. Better preserved immune function may reflect a reduction in tissue trauma after HIFU treatment and contribute to reduced post-operative complications.