Tissue Temperature Changes Research Articles

Evaluation of the impact of shockwave therapy on the functioning of a patient with a lower calcaneal spur

Introduction. A common cause of heel pain is the presence of a calcaneal spur. This condition may disrupt the posterior superficial fascia chain and can also lead to problems in distant areas of the body. Among the physical methods used, shockwave therapy is often applied. The aim of the study was to assess the effectiveness of shockwave therapy and its effect on the tension of the gastrocnemius muscle, which is part of the posterior fascia chain. Materials and Methods. A 52-year-old female patient diagnosed with a left lower calcaneal spur underwent a series of six radial shockwave therapy sessions, performed twice a week. The method for assessing the therapy’s effectiveness involved measuring pain on the Visual Analogue Scale (VAS) and changes in tissue temperature before, immediately after, and five minutes post-therapy. Electromyographic (EMG) examination was used to assess the tension of the gastrocnemius muscle. Results. An average decrease in temperature was observed immediately after the treatment (from 25.3°C to 24.45°C). After five minutes, the temperature increased to 27.05°C compared to the initial measurement. The resting tension of the gastrocnemius muscle, as measured by EMG, decreased as follows: channel 1: from 0.6 µV to 0.4 µV, channel 2: from 4.3 µV to 3.2 µV. Pain decreased from a level of 7 to 2 on the VAS scale. Conclusions. Shockwave therapy is an effective solution for alleviating pain in the case of a calcaneal spur. The reduction of resting tension in the gastrocnemius muscle leads to a decrease in elevated tension within the posterior myofascial chain, which may help reduce the risk of secondary pathologies in distant areas along the chain.

Transient Changes in Cerebral Tissue Oxygen, Glucose, and Temperature by Microstrokes: A Computational Study.

This study focuses on evaluating the disruptions in key physiological parameters during microstroke events to assess their severity. A mathematical model was developed to simulate the changes in cerebral tissue pO2, glucose concentration, and temperature due to blood flow interruptions. The model considers variations in baseline cerebral blood flow (CBF), capillary density, and blood oxygen/glucose levels, as well as ambient temperature changes. Simulations indicate that complete blood flow obstruction still allows for limited glucose availability, supporting nonoxidative metabolism and potentially exacerbating lactate buildup and acidosis. Partial obstructions decrease tissue pO2, with minimal impact on glucose level, which can remain almost unchanged or even slightly increase. Reduced CBF, capillary density, or blood oxygen due to aging or disease enhances hypoxia risk at lower obstruction levels, with capillary density having a significant effect on stroke severity by influencing both pO2 and glucose levels. Conditions could lead to co-occurrence of hypoxia/hypoglycemia or hypoxia/hyperglycemia, each worsening outcomes. Temperature effects were minimal in deep brain regions but varied near the skull by 0.2-0.8°C depending on ambient temperature. The model provides insights into the conditions driving severe stroke outcomes based on estimated levels of hypoxia, hypoglycemia, hyperglycemia, and temperature changes.

MODELING THE IMPACT OF LASER IRRADIATION ON TEMPERATURE CHANGES IN BIOLOGICAL TISSUES

Modeling the impact of laser irradiation (MILI) on biological tissues plays a crucial role in research and the development of laser technologies in biology and medicine. MILI opens a wide spectrum of knowledge for scientists and medical professionals, providing insights into how laser radiation interacts with different types of tissues and organs and determining optimal parameters to achieve the desired outcome. Models can account for various physical processes occurring during irradiation, such as energy absorption, heat propagation, changes in tissue structure, and functions. This enables the prediction of tissue responses to different laser exposure regimes, including intensity, wavelength, and exposure time. In medicine, modeling is used to determine optimal laser exposure parameters for specific diseases or procedures. For example, MILI helps identify the optimal radiation dose during laser therapy or surgical interventions. Additionally, modeling allows for the assessment of potential risks associated with laser radiation, such as tissue overheating or side effects. This, in turn, enhances the development of safer and more effective laser application methods. Moreover, optimizing laser irradiation parameters is relevant for minimizing the risk of damage to surrounding tissues. MILI can be used to develop new laser technologies and devices aimed at improving the outcomes of laser applications in medicine. It also facilitates the faster and more efficient implementation of new methods and technologies into clinical practice. Thus, modeling the impact of laser irradiation on temperature changes in biological tissues plays a vital role in enhancing understanding of processes in biological tissues and contributes to the development of new methods and technologies, as well as the optimization of laser application for achieving effective treatment outcomes and patient safety.

Breast Cancer Screening Using Inverse Modeling of Surface Temperatures and Steady-State Thermal Imaging.

Cancer is characterized by increased metabolic activity and vascularity, leading to temperature changes in cancerous tissues compared to normal cells. This study focused on patients with abnormal mammogram findings or a clinical suspicion of breast cancer, exclusively those confirmed by biopsy. Utilizing an ultra-high sensitivity thermal camera and prone patient positioning, we measured surface temperatures integrated with an inverse modeling technique based on heat transfer principles to predict malignant breast lesions. Involving 25 breast tumors, our technique accurately predicted all tumors, with maximum errors below 5 mm in size and less than 1 cm in tumor location. Predictive efficacy was unaffected by tumor size, location, or breast density, with no aberrant predictions in the contralateral normal breast. Infrared temperature profiles and inverse modeling using both techniques successfully predicted breast cancer, highlighting its potential in breast cancer screening.

Comparative analysis of non-invasive and invasive alternating electric fields therapy for malignant gliomas: a simulation study

Alternating electric fields (AEFs) at intermediate frequencies (100–300 kHz) and low intensities (1–3 V/cm) have shown promise as an effective approach for inhibiting cancer cell proliferation. However, a noticeable research gap exists in comparing the biophysical properties of invasive and non-invasive AEFs methods, and AEFs delivery strategies require further improvement. In this study, we constructed a realistic head model to simulate the effects of non-invasive and invasive AEFs on malignant gliomas. Additionally, a novel method was proposed involving the placement of a return electrode under the scalp. We simulated the electric field and temperature distributions in the brain tissue for each method. Our results underscore the advantages of invasive AEFs, showcasing their superior tumor-targeting abilities and reduced energy requirements. The analysis of brain tissue temperature changes reveals that non-invasive AEFs primarily generate heat at the scalp level, whereas invasive methods localize heat production within the tumor itself, thereby preserving surrounding healthy brain tissue. Our proposed invasive AEFs method also shows potential for selective electric field intervention. In conclusion, invasive AEFs demonstrate potential for precise and effective tumor treatment. Its enhanced targeting capabilities and limited impact on healthy tissue make it a promising avenue for further research in the realm of cancer treatment.

Quantifying tissue temperature changes induced by infrared neural stimulation: numerical simulation and MR thermometry.

Infrared neural stimulation (INS) delivered via short pulse trains is an innovative tool that has potential for us use for studying brain function and circuitry, brain machine interface, and clinical use. The prevailing mechanism for INS involves the conversion of light energy into thermal transients, leading to neuronal membrane depolarization. Due to the potential risks of thermal damage, it is crucial to ensure that the resulting local temperature increases are within non-damaging limits for brain tissues. Previous studies have estimated damage thresholds using histological methods and have modeled thermal effects based on peripheral nerves. However, additional quantitative measurements and modeling studies are needed for the central nervous system. Here, we performed 7 T MRI thermometry on ex vivo rat brains following the delivery of infrared pulse trains at five different intensities from 0.1-1.0 J/cm2 (each pulse train 1,875 nm, 25 us/pulse, 200 Hz, 0.5 s duration, delivered through 200 µm fiber). Additionally, we utilized the General BioHeat Transfer Model (GBHTM) to simulate local temperature changes in perfused brain tissues while delivering these laser energies to tissue (with optical parameters of human skin) via three different sizes of optical fibers at five energy intensities. The simulation results clearly demonstrate that a 0.5 second INS pulse train induces an increase followed by an immediate drop in temperature at stimulation offset. The delivery of multiple pulse trains with 2.5 s interstimulus interval (ISI) leads to rising temperatures that plateau. Both thermometry and modeling results show that, using parameters that are commonly used in biological applications (200 µm diameter fiber, 0.1-1.0 J/cm2), the final temperature increase at the end of the 60 sec stimuli duration does not exceed 1°C with stimulation values of 0.1-0.5 J/cm2 and does not exceed 2°C with stimulation values of up to 1.0 J/cm2. Thus, the maximum temperature rise is consistent with the thermal damage threshold reported in previous studies. This study provides a quantitative evaluation of the temperature changes induced by INS, suggesting that existing practices pose minimal major safety concerns for biological tissues.

Exploring Skin Interactions with 5G Millimeter-Wave through Fluorescence Lifetime Imaging Microscopy

The ongoing expansion of fifth-generation (5G) and future sixth-generation (6G) mobile communications is expected to result in widespread human exposure to millimeter-wave (mmWave) radiation globally. Given the short penetration depth of mmWaves and their high absorption by the skin, it is imperative to investigate the potential effects of 5G radiation not only in terms of temperature increase but also at the cellular level. To understand the biological mechanisms of mmWave effects, accurate methods for assessing mmWave absorption in the skin are crucial. In this study, we use fluorescence lifetime imaging microscopy (FLIM) to explore these effects. Employing a mmWave exposure system operating at 26 gigahertz (GHz), porcine skin is irradiated for varying durations (5, 10, 20, and 30 min). We investigate changes in tissue temperature and the autofluorescence of flavin adenine dinucleotide (FAD). Our findings suggest that operating our mmWave exposure systems at the configured power level of 26 GHz is unlikely to cause damage to FADs, even after a 30 min exposure duration.

Assessing renal tissue temperature changes and perfusion effects during laser activation in an in vivo porcine model.

High fluid temperatures have been seen in both in vitro and in vivo studies with laser lithotripsy, yet the thermal distribution within the renal parenchyma has not been well characterized. Additionally, the heat-sink effect of vascular perfusion remains uncertain. Our objectives were twofold: first, to measure renal tissue temperatures in response to laser activation in a calyx, and second, to assess the effect of vascular perfusion on renal tissue temperatures. Ureteroscopy was performed in three porcine subjects with a prototype ureteroscope containing a temperature sensor at its tip. A needle with four thermocouples was introduced percutaneously into a kidney with ultrasound guidance to allow temperature measurement in the renal medulla and cortex. Three trials of laser activation (40W) for 60s were conducted with an irrigation rate of 8ml/min at room temperature in each subject. After euthanasia, three trials were repeated without vascular perfusion in each subject. Substantial temperature elevation was observed in the renal medulla with thermal dose in two of nine trials exceeding threshold for tissue injury. The temperature decay time (t½) of the non-perfused trials was longer than in the perfused trials. The ratio of t½ between them was greater in the cortex than the medulla. High-power laser settings (40W) can induce potentially injurious temperatures in the in vivo porcine kidney, particularly in the medullary region adjacent to the collecting system. Additionally, the influence of vascular perfusion in mitigating thermal risk in this susceptible area appears to be limited.

Noninvasive Monitoring of Tissue Temperature Changes Induced by Focused Ultrasound Exposure using Sparse Expression of Ultrasonic Radio Frequency Echo Signals.

Noninvasive therapies such as focused ultrasound were developed to be used for cancer therapies, vessel bleeding, and drug delivery. The main purpose of focused ultrasound therapy is to affect regions of interest (ROI) of tissues without any injuries to surrounding tissues. In this regard, an appropriate monitoring method is required to control the treatment. This study is aimed to develop a noninvasive monitoring technique of focused ultrasound (US) treatment using sparse representation of US radio frequency (RF) echo signals. To this end, reasonable results in temperature change estimation in the tissue under focused US radiation were obtained by utilizing algorithms related to sparse optimization as orthogonal matching pursuit (OMP) and accompanying Shannon's entropy. Consequently, ex vivo tissue experimental tests yielded two datasets, including low-intensity focused US (LIFU) and high-intensity focused US (HIFU) data. The proposed processing method analyzed the ultrasonic RF echo signal and expressed it as a sparse signal and calculated the entropy of each frame. The results indicated that the suggested approach could noninvasively estimate temperature changes between 37°C and 47°C during LIFU therapy. In addition, it represented temperature changes during HIFU ablation at various powers, ranging from 10 to 130 W. The normalized mean square error of the proposed method is 0.28, approximately 2.15 on previous related methods. These results demonstrated that this novel proposed approach, including the combination of sparsity and Shanoon's entropy, is more feasible and effective in temperature change estimation than its predecessors.

Difference in tissue temperature change between two cryoballoons

BackgroundCryoballoon ablation, especially Arctic Front Advance Pro (AFA-Pro) (Medtronic, Minneapolis, Minnesota, USA), has been widely recognised as a standard approach to atrial fibrillation (AF). Recently, Boston Scientific has released a...

Thermographic Examination of the Horse

Abstract Thermography is a noninvasive diagnostic imaging technique that detects regions of the body surface with increased (or decreased) temperature by measuring infrared radiation. It reveals physiological and pathophysiological changes primarily related to blood flow and metabolic rate in the examined body regions, as well as altered heat production. These include physical stress, various physical injuries, medical conditions, and environmental factors. In equine medicine, thermography can be used for early detection of tissue temperature changes, allowing intervention at an early stage of a medical deterioration. Thermographic examination can be used to detect tissue abnormalities in all regions of the body. It is particularly useful for the detection of musculoskeletal disorders. Inflammatory processes are present in many diseases and injuries, which can be successfully detected with thermography. Thermography makes it possible to monitor the success of treatment. Often, thermographically visible disease changes are detected before clinical signs or other imaging techniques become visible in the animal. In physical therapy, it helps locate regions of the body in need of treatment and plays an important role in detecting illegal procedures (such as local analgesics) to improve competitive performance in horses. Thermography serves as a complementary diagnostic tool. However, in practice, it has some limitations. The method is not specific and cannot determine the etiology of pathological changes. Therefore, it is usually used together with other diagnostic methods (such as X-ray, ultrasound, computed tomography and magnetic resonance imaging) and can not replace them.

Thermal Profiles for Focal Pulsed Electric Field Ablation

BackgroundPulsed electrical field (PEF) ablation may cause tissue heating. These changes are reportedly small, but each PEF system and waveform will have a different behavior, and data are lacking. ObjectivesThis study sought to compare the temperature profile of focal point, monopolar biphasic PEF ablation versus radiofrequency (RF). MethodsAblation lesions were performed on perfused thigh muscle of swine. PEF lesions were performed with 3 compatible ablation catheters at the highest (25 amp) energy, and 1 catheter (Tacticath SE) was also used at the 22- and 19-amp levels. Temperature changes in the tissue were measured using fluoroptic temperature probes inserted at the muscle surface, as well as 3 mm and 7 mm below the surface. Temperatures were recorded continuously at baseline, during delivery, and after ablation. Muscle temperatures were compared with those of RF lesions performed with 1 catheter (Tacticath SE) at 30 W for 30 seconds. ResultsPEF ablation with 3energy settings produced small temperature changes. Maximum average temperature rise for PEF for the maximum (25-amp) energy setting (32 lesions) was 7.6 °C, 2.8 °C, and 0.9 °C at the surface, 3-mm depth, and 7-mm depth, respectively. The temperature rise was dose dependent, with lower energy settings yielding less temperature rise. RF ablations (10 lesions) produced temperature increases of 16.6 °C, 39.8 °C, and 9.5 °C at the surface, 3-mm depth, and 7-mm depth, respectively. ConclusionsPEF caused detectable temperature changes in muscle tissue, which never exceeded 2.8 °C at the 3-mm depth versus baseline. By contrast, RF produced substantial temperature rises. These data support that focal monopolar biphasic energy delivered by this PEF technology retains a favorable thermal safety profile.

Optimizing intra-arterial hypothermia scheme for acute ischemic stroke in an MCAO/R rat model

Hypothermia is a promising neuroprotective treatment. This study aims to explore and optimize the intervention scheme of intra-arterial hypothermia (IAH) in a middle cerebral artery occlusion and reperfusion (MCAO/R) rat model. The MCAO/R model was established with a thread that could be retracted 2 h after occlusion. Cold normal saline was injected into the internal carotid artery (ICA) through a microcatheter in different infusion conditions. Grouping followed an orthogonal design (L9[34]) based on three critical factors closely associated with IAH: perfusate temperature (4, 10, 15 °C), infusion flow rate (1/3, 1/2, 2/3 blood flow rate of ICA), and duration (10, 20, 30 min), resulting in 9 subgroups (H1, H2 to H9). A myriad of indexes were monitored, such as vital signs, blood parameters, changes in local ischemic brain tissue temperature (Tb), ipsilateral jugular venous bulb temperature (Tjvb), and the core temperature of the anus (Tcore). After 24 h and 72 h of cerebral ischemia, cerebral infarction volume, cerebral water content, and neurological function were assessed to explore the optimal IAH conditions. The results revealed that the three critical factors were independent predictors for cerebral infarction volume, cerebral water content, and neurological function. The optimal perfusion conditions were 4 °C, 2/3 RICA (0.50 ml/min) for 20 min, and there was a significant correlation between Tb and Tjvb (R = 0.994, P < 0.001). The vital signs, blood routine tests and biochemical indexes showed no significant abnormal changes. These findings revealed that IAH was safe and feasible with the optimized scheme in an MCAO/R rat model.

Microwave Radiometry for the Diagnosis and Monitoring of Inflammatory Arthritis

The ability of microwave radiometry (MWR) to detect with high accuracy in-depth temperature changes in human tissues is under investigation in various medical fields. The need for non-invasive, easily accessible imaging biomarkers for the diagnosis and monitoring of inflammatory arthritis provides the background for this application in order to detect the local temperature increase due to the inflammatory process by placing the appropriate MWR sensor on the skin over the joint. Indeed, a number of studies reviewed herein have reported interesting results, suggesting that MWR is useful for the differential diagnosis of arthritis as well as for the assessment of clinical and subclinical inflammation at the individual large or small joint level and the patient level. MWR showed higher agreement with musculoskeletal ultrasound, used as a reference, than with clinical examination in rheumatoid arthritis (RA), while it also appeared useful for the assessment of back pain and sacroiliitis. Further studies with a larger number of patients are warranted to confirm these findings, taking into account the current limitations of the available MWR devices. This may lead to the production of easily accessible and inexpensive MWR devices that will provide a powerful impetus for personalized medicine.

Computer Simulations of Dual-Antenna Microwave Ablation and Comparison to Experimental Measurements

Single-antenna microwave ablation (MWA) is mainly used to treat small tumors less than 3 cm in diameter. To obtain a larger coagulation zone in a single ablation, a dual-antenna ablation approach was proposed. A three-dimensional finite element method (FEM) simulation model of parallel dual-antennas was developed. Ex vivo experiments at 50 W for 8 min were performed to verify the model. Both the temperature changes in tissue and the size of the coagulation zone were recorded. The effects of dual-antenna spacing, heating power, and blood perfusion on the coagulation zone were analyzed. Fifteen experiments were carried out. The errors between the mean measurements and simulated results at the set temperature points were 1.08 °C, 0.95 °C, and 2.1 °C, respectively. For the same conditions, the blood perfusion of 1.0, 1.5, and 3.0 kg/(m3·s) can result in a reduction in the coagulation volume by 18.4%, 25.4%, and 42.5%. As the spacing increased, the coagulation zone of each antenna started to fuse together later and the resulting integral coagulation zone became larger. Dual-antenna MWA is expected to be used for the treatment of tumors larger than 5 cm in diameter.

Effects of Cryotherapy on Lower Leg Deep Tissue Temperature Changes: As Measured in Healthy Volunteers by Using MRI Technique.

Background: Since the 1950s, researchers have studied temperature changes in deep tissues caused by cooling stimuli. However, these changes have not been investigated non-invasively. Moreover, opinions are divided as to whether the temperature in the joints rises or falls. The present study investigated the effects of cooling on various tissues in the body, including muscles.Methods: Seven healthy subjects (four males and three females) were enrolled (age, 21.5 ± 0.8 years; height, 165.2 ± 10.7 cm; weight, 63.1 ± 12.17 kg). The research was conducted at the Department of Radiology, Okubo Hospital (Akashi, Hyogo, Japan) between March 2015 and December 2020. Magnetic resonance imaging (MRI) was performed on both lower legs in a noncooled resting state. The right lower leg was cooled for 15 minutes using an ice bath, then both legs were examined by MRI (Experiment 1). After two weeks, the left lower leg was cooled, and MRI was performed on both legs (Experiment 2). After the subsequent two weeks, MRI was performed on both legs without cooling (Experiment 3). The target areas were subcutaneous and adipose tissues, muscle, bone, and cartilage. T1 signal intensity changes after cooling were examined for each tissue. Normality was confirmed by the Shapiro-Wilk test in advance, and the effect size (Cohen's d) was calculated as a post-test when a significant difference was found.Results: In Experiments 1 and 2, T1 signal intensities in subcutaneous tissue, lateral inframalleolar fat pad, the extensor digitorum longus, and abductor hallucis muscles were significantly higher in the cooled than in the noncooled leg (P < 0.05). No significant differences were observed in tissues on the noncooled side.Conclusions: A 15-minute cold stimulation, such as that used for ankle sprains, reduced temperatures in subcutaneous adipose tissue, muscles, and the lateral inframalleolar fat pad. As the lateral inframalleolar fat pad was effectively cooled, the joint capsule and ligaments immediately below may have also been cooled. It is important to consider the tissue intended for cooling when performing cryotherapy. An ice bath below the lower leg is effective for promoting the recovery of damaged tissue.

Close-Range Thermography and Reflectance Spectroscopy Support InVitro and InVivo Characterization of Colletotrichum spp. Isolates from Mango Fruits.

Colletotrichum causing anthracnose in mango is known for its variable virulence that may have an effect on disease development and efficacy of management strategies. In this study, we characterized Colletotrichum spp. isolated from mango fruits under invitro and invivo conditions using close-range thermography and reflectance spectroscopy. Twenty-six isolates were phylogenetically characterized to ascertain species using the internal transcribed spacer sequence. Virulence, spectral (invivo and invitro), and thermographic responses (invivo) of these isolates were analyzed. Isolates were grouped into the Colletotrichum gloeosporioides species complex and classified into eight morphotypes. Mycelial growth, conidia production, sporulation abundance, and area under disease progress curve (AUDPC) varied largely among isolates. Disease symptoms were observed 4 days after inoculation (dai), and, for most morphotypes, changes in tissue temperature were registered at 11 dai, with the greatest decrease at 14 dai with pathogen sporulation. In vitro and invivo morphotypes shared changes in the spectrum range, and main variations were found in the number of informative spectral bands. In vivo average gross reflectance was higher in disease-inoculated tissue than in healthy uninoculated tissue. Morphotype responses varied depending on AUDPC values and postinoculation time. Discriminant analysis of the spectral response using principal component analysis and partial least squares regression explained 94 to 96.3 and 98 to 99.9% of the variance from invitro and invivo tests, respectively. Spectral markers were obtained for four distinct morphotype groups. We found three (550 to 650, 650.1 to 790, and 1,300 to 1,400 nm) and two (520 to 830 and 1,100 to 1,450 nm) regions with highly (P < 0.05) discriminant spectral bands for diseased fruits and morphotype characterization.

Robotic stray energy with constant-voltage versus constant-power regulating electrosurgical generators.

Stray energy from surgical energy instruments can cause unintended thermal injuries. There are no published data regarding electrosurgical generators and their influence on stray energy transfer during robotic surgery. There are two approved generators for the DaVinci Xi robotic platform: a constant-voltage regulating generator (cVRG) and a constant-power regulating generator (cPRG). The purpose of this study was to quantify and compare stray energy transfer in the robotic Xi platform using a cVRG versus a cPRG. An ex vivo bovine model was used to simulate a standard multiport robotic surgery. The DaVinci Xi (Intuitive Surgical, Sunnyvale, CA) robotic platform was attached to a trainer box using robotic ports. A 5s, open-air activation of the monopolar scissors was done with commonly used electrosurgical settings using a cPRG (ForceTriad, Covidien-Medtronic, Boulder, CO) or cVRG (ERBE VIO 300 dV 2.0, ERBE USA, Marietta, GA). Stray energy transfer was quantified as the change in tissue temperature (°C) nearest the tip of the assistance grasper (which was not in direct contact with the active monopolar scissors). Stray energy transfer occurred with both generators. Utilizing common, comparable settings for standard coagulation, significantly less stray energy was transferred with the cVRG versus cPRG (4.4 ± 1.6°C vs. 41.1 ± 13.0°C, p < 0.001). Similarly, less stray energy was transferred using cut modes with the cVRG compared to the cPRG (5.61 ± 1.79°C vs. 33.9 ± 18.4°C, p < 0.001). Stray energy transfer increases tissue temperatures more than 45C in the DaVinci Xi robotic platform. Low voltage modalities, such as cut or blend; as well as a cVRG generator, significantly reduces stray energy. Robotic surgeons can minimize the risk of stray energy injuries by using these low risk modes and/or generator.

Transcutaneous application of ultrasound enhances the effects of finasteride in a murine model of androgenic alopecia.

PurposeThe purpose of this study was to evaluate if transcutaneous application of low-intensity ultrasound can locally enhance the effects of finasteride on hair growth in a murine model of androgenic alopecia (AA).MethodsAA mice (injected twice per week with testosterone enanthate, n=11), under daily oral administration of finasteride, received 1-MHz ultrasound for 1 hour at the unilateral thigh area five times per week for 5 weeks. Non-thermal and non-cavitational ultrasound was delivered in a pulsed manner (55-ms pulse duration with a repetition frequency of 4 Hz). Skin temperature was measured during sonication, and the measurements were validated with numerical simulations of sonication-induced tissue temperature changes. Hair growth was assessed both photographically and histologically.ResultsWe found more hair growth on the sonicated thigh area than on the unsonicated thigh, beginning from week 3 through the end of the experiment. Histological analyses showed that the number of hair follicles doubled in the skin sections that received sonication compared to the unsonicated zone, with thicker follicular diameter and skin. An over five-fold increase was also observed in the anagen/telogen ratio in the sonicated area, suggesting an enhanced anagen phase. Skin temperature was unaltered by the administered sonication.ConclusionThe findings of the present study suggest that pulsed application of ultrasound promotes hair growth, potentially by disrupting the binding of albumin to finasteride. This may suggest further applications to enhance the pharmacological effects of other relevant drugs exhibiting high plasma protein binding.

Pilot study on the effects of low intensity focused ultrasound in a swine model of neuropathic pain.

The authors' laboratory has previously demonstrated beneficial effects of noninvasive low intensity focused ultrasound (liFUS), targeted at the dorsal root ganglion (DRG), for reducing allodynia in rodent neuropathic pain models. However, in rats the DRG is 5 mm below the skin when approached laterally, while in humans the DRG is typically 5-8 cm deep. Here, using a modified liFUS probe, the authors demonstrated the feasibility of using external liFUS for modulation of antinociceptive responses in neuropathic swine. Two cohorts of swine underwent a common peroneal nerve injury (CPNI) to induce neuropathic pain. In the first cohort, pigs (14 kg) were iteratively tested to determine treatment parameters. liFUS penetration to the L5 DRG was verified by using a thermocouple to monitor tissue temperature changes and by measuring nerve conduction velocity (NCV) at the corresponding common peroneal nerve (CPN). Pain behaviors were monitored before and after treatment. DRG was evaluated for tissue damage postmortem. Based on data from the first cohort, a treatment algorithm was developed, parameter predictions were verified, and neuropathic pain was significantly modified in a second cohort of larger swine (20 kg). The authors performed a dose-response curve analysis in 14-kg CPNI swine. Specifically, after confirming that the liFUS probe could reach 5 cm in ex vivo tissue experiments, the authors tested liFUS in 14-kg CPNI swine. The mean ± SEM DRG depth was 3.79 ± 0.09 cm in this initial cohort. The parameters were determined and then extrapolated to larger animals (20 kg), and predictions were verified. Tissue temperature elevations at the treatment site did not exceed 2°C, and the expected increases in the CPN NCV were observed. liFUS treatment eliminated pain guarding in all animals for the duration of follow-up (up to 1 month) and improved allodynia for 5 days postprocedure. No evidence of histological damage was seen using Fluoro-Jade and H&E staining. The results demonstrate that a 5-cm depth can be reached with external liFUS and alters pain behavior and allodynia in a large-animal model of neuropathic pain.