Soft Tissue Layer Research Articles

Efficacy, Safety, and Longevity of Hyaluronic Acid Filler Injection in Treating Temple Hollowness by Sonographic Identifying 17 Soft Tissue Layers.

Successful aesthetic interventions in upper-face aging require a profound understanding of the intricate anatomy of temporal. This study aimed to comprehensively evaluate the effect of hyaluronic acid (HA) injection in temple areas by combining quantitative analysis with detailed anatomical insights. Twenty-five women received HA injections for temple hollowness. The injections targeted the interfacial layer between superficial and deep temporal fascia. Three-dimensional scanning, hollowness examination, and sonographic measurements were conducted 3 and 6 months postprocedure. Sonography identified 17 soft tissue layers in the temple, each with distinct characteristics. The notable layers include the epidermis, dermis, superficial and deep temporal fasciae, innominate fasciae, and superficial and deep temporal fat compartments. Three-dimensional volume was 0.86 mL at 3 months and 0.72 mL at 6 months. The average thickness of HA was 3.82 mm (immediately), 3.00 mm (3 mo), and 2.51 mm (6 mo). The depression on the temple was 4.33 mm (preprocedure), 0.71 mm (3 mo), and 1.62 mm (6 mo). The grade improved by 2.41 and 1.74 levels at 3 and 6 months. Identifying detailed superficial and deep layers of the deep temporal fascia challenged traditional descriptions, with detailed dividing of superficial and deep temporal fascia in sonography. Innominate fascia was also distinguished. This study provided a comprehensive evaluation of the effects of HA injections in temple areas. Precise anatomical insights and quantitative assessments contribute to a deeper understanding of the structural changes induced by this procedure. Sonography is valuable for delineating distinct layers and guiding aesthetic interventions in the temporal region.

Cortical bone plate properties assessment using inversion of axially transmitted low frequency ultrasonic guided waves.

Over the past few decades, early osteoporosis detection using ultrasonic bone quality evaluation has gained prominence. Specifically, various studies focused on axial transmission using ultrasonic guided waves and have highlighted this technique's sensitivity to intrinsic properties of long cortical bones. This work aims to demonstrate the potential of low-frequency ultrasonic guided waves to infer the properties of the bone inside which they are propagating. A proprietary ultrasonic transducer, tailored to transmit ultrasonic guided waves under 500 kHz, was used for the data collection. The gathered data underwent two-dimensional fast Fourier transform processing to extract experimental dispersion curves. The proposed inversion scheme compares experimental dispersion curves with simulated dispersion curves calculated through the semi-analytical iso-geometric analysis (SAIGA) method. The numerical model integrates a bone phantom plate coupled with a soft tissue layer on its top surface, mimicking the experimental bone phantom plates. Subsequently, the mechanical properties of the bone phantom plates were estimated by reducing the misfit between the experimental and simulated dispersion curves. This inversion leaned heavily on the dispersive trajectories and amplitudes of ultrasonic guided wave modes. Results indicate a marginal discrepancy under 5% between the mechanical properties ascertained using the SAIGA-based inversion and those measured using bulk wave pulse-echo measurements.

Design and characterization of 3D-printed hollow microneedle arrays for transdermal insulin delivery

The delivery of insulin to diabetic patients remains a challenge due to the limitations of current insulin delivery paradigms, including painful cannula insertion, potential infections, interference with activity, embarrassment, and sometimes cost. To address this problem, we designed and fabricated nine prototypes of stereolithographic 3D-printed microneedle arrays (MNAs) appropriate for the minimally invasive delivery of insulin. We characterized their transdermal penetration performance by delivering fluid at a constant rate to porcine skin through these MNAs. Moreover, we characterized the force required for these MNAs to puncture porcine skin using a mechanical testing apparatus. We developed an improved method of mechanical testing for the MNAs against porcine skin by incorporating an imitation soft tissue layer under the skin and compared the MNA results with those using a single microneedle and a hypodermic needle. In addition, we investigated the mechanical flexural strength of the MNAs by performing a flexural failure load test on them. We confirmed that the prototype MNAs are mechanically robust and do not fracture during skin penetration, setting the stage for future trials in vitro and in vivo. The final, optimized designs are freely available in stereolithography (STL) file format.

Construction of multi-component finite element model to predict biomechanical behaviour of breasts during running and quantification of the stiffness impact of internal structure

This study aims to investigate the biomechanical behaviour and the stiffness impact of the breast internal components during running. To achieve this, a novel nonlinear multi-component dynamic finite element method (FEM) has been established, which uses experimental data obtained via 4D scanning technology and a motion capture system. The data are used to construct a geometric model that comprises the rigid body, layers of soft tissues, skin, pectoralis major muscle, fat, ligaments and glandular tissues. The traditional point-to-point method has a relative mean absolute error of less than 7.92% while the latest surface-to-surface method has an average Euclidean distance (d) of 7.05 mm, validating the simulated results. After simulating the motion of the different components of the breasts, the displacement analysis confirms that when the motion reaches the moment of largest displacement, the displacement of the breast components is proportional to their distance from the chest wall. A biomechanical analysis indicates that the stress sustained by the breast components in ascending order is the glandular tissues, pectoralis major muscle, adipose tissues, and ligaments. The ligaments provide the primary support during motion, followed by the pectoralis major muscle. In addition, specific stress points of the breast components are identified. The stiffness impact experiment indicates that compared with ligaments, the change of glandular tissue stiffness had a slightly more obvious effect on the breast surface. The findings serve as a valuable reference for the medical field and sports bra industry to enhance breast protection during motion.

Accuracy of cone-beam computed tomography in imaging the components of the periodontal phenotype.

The components and dimensions of the periodontal and peri-implant phenotype have a high relevance in contemporary dental research and should be taken into consideration in the decision-making process in the management of a variety of clinical scenarios to optimize the outcomes of therapy. Various assessment methods for quantifying and classifying the phenotypical dimensions have emerged and developed in recent decades. Nevertheless, the use of cone-beam computed tomography (CBCT) scans remains the most commonly used approach worldwide. However, the accuracy to adequately imaging and measuring the dimensions of the hard and soft tissue components around teeth may represent a significant challenge in different clinical scenarios due to factors such as the age of the patient and motion during the scan, presence of metallic artifacts causing streaks and gray-value distortion, overlapping of soft tissue structures, machine performance, file processing, and small voxel size among others. These factors pose a particular challenge when tiny structures are under investigation, for example, the buccal/lingual bony or soft tissue layer of lower/upper incisors. Therefore, this review addresses the underlying technical information of the use of CBCT scans, and suggests some recommendations on the utilization of this method of assessment to optimally use it despite its' system-inherent limitations.

Differences in scalp-to-cortex tissues across age groups, sexes and brain regions: Implications for neuroimaging and brain stimulation techniques

Aging affects the scalp-to-cortex distance (SCD) and the comprising tissues. This is crucial for noninvasive neuroimaging and brain stimulation modalities as they rely on traversing from the scalp to the cortex or vice versa. The specific relationship between aging and these tissues has not been comprehensively investigated. We conducted a study on 250 younger and older adults to examine age-related differences in SCD and its constituent tissues. We identified region-specific differences in tissue thicknesses related to age and sex. Older adults exhibit larger SCD in the frontocentral regions compared to younger adults. Men exhibit greater SCD in the inferior scalp regions, while women show similar-to-greater SCD values in regions closer to the vertex compared to men. Younger adults and men have thicker soft tissue layers, whereas women and older adults exhibit thicker compact bone layers. CSF is considerably thicker in older adults, particularly in men. These findings emphasize the need to consider age, sex, and regional differences when interpreting SCD and its implications for noninvasive neuroimaging and brain stimulation.

Influence of skeletal classes and facial patterns on the positioning of the craniovertebral junction, dimensions of the pharyngeal airway space, and pre-vertebral soft tissue thickness: A cone beam computed tomography study

This study employed cone beam computed tomography (CBCT) to assess the influence of skeletal classes and facial patterns on the craniovertebral complex, pharyngeal airway space (PAS) dimensions, and pre-vertebral soft tissue thickness. The analysis of 150 CBCTs involved measurements between various vertebrae and layers of soft tissue. Significant findings included a lower odontoid process in Class II and hyperdivergent individuals, while hypodivergent subjects exhibited a larger area and volume in the PAS. A negative correlation between PAS size and pre-vertebral soft tissue thickness was observed. Gender differences were noteworthy, with males consistently displaying higher values. Significant age-related variations were also identified, with the age groups of 18-30 and 31-45 exhibiting distinct characteristics. The study underscores the impact of facial patterns and skeletal classes on the craniovertebral complex, emphasizing an inverse relationship between PAS and pre-vertebral soft tissue thickness. The intricate connections between gender and age highlight their influence on anatomical characteristics. Understanding how facial patterns and skeletal classes affect the craniovertebral complex has implications for respiratory disorders, including Obstructive Sleep Apnea and Hypopnea Syndrome (OSAHS).

Cutaneous Layer and SMAS Suspension (CaSS) Lift as a Minimally Invasive Lateral Midface Lift.

In our prior study, the authors determined that pulling on the superficial adipose layer is more effective in lifting the skin than pulling on the superficial musculoaponeurotic system (SMAS). Applying this concept of using the superficial adipose layer to transmit the lifting force to the skin, this study examined improvements in patients who underwent lateral midface lifting using our minimally invasive multilayer lifting technique and measured the duration of those improvements. Along the hairline in front of the sideburns, a W-shaped zigzag incision of 3 to 8mm in width and 3 to 4cm in length was made. On the temporal scalp, 3 to 4cm away from the first incision, a second incision was made more lateral/posterior to the first incision, and an elliptical excision of 3 to 5mm in width and 3 to 4cm in length was made. From the medial cut margin of the anterior first incision, the superficial temporal fascia/SMAS (the deep layer), and the superficial adipose layer (the superficial layer) were purchased with 3-0 polyester sutures, tunneled under the soft tissue, and fixed to the deep temporal fascia of the second posterior temporal incision. Prior to the excised temporal scalp closure, the dermis in the medial cut margin of the second incision was pulled to the rear as much as possible and fixed to the deep temporal fascia. The effects of surgery were monitored for 6 to 42 months after surgery. The nasolabial folds were improved. Skin elasticity also showed significant improvements, which lasted throughout the follow-up period (up to 42mo). Unlike traditional wide dissection SMAS facelift, our method requires minimal incisions and does not require skin undermining. Therefore, the operating time is shorter, and postoperative swelling is minimized. In our technique, the superficial adipose layer, the superficial temporal fascia/SMAS, and the dermis were pulled individually to lift all layers of the lateral midface soft tissues. This results in a significant and long-lasting lateral midface rejuvenation.

Modeling and Simulation of Robotic Palpation to Detect Subsurface Soft Tissue Anomaly for Presurgical Assessment

Abstract Surgical Haptics is an emergent field of research to integrate and advance the sense of robotic touch in laparoscopic tools in robot-assisted minimally invasive surgery. Haptic feedback from the tooltip and soft tissue surface interaction during robotic palpation can be leveraged to detect the texture and contour of subsurface geometry. However, precise force modulation of the robotic palpating probe is necessary to determine stiff inclusions of the anatomy and maneuver successive manipulation tasks during surgery. This paper focuses on investigating the layered deformations associated with different force profiles involved in manipulating the superficial anatomy of soft tissues during dynamic robotic palpation to determine the underlying anomaly. A realistic three-dimensional (3D) cross-sectional soft tissue phantom with anatomical layers and tumor, as an anomaly, is designed, modeled, and analyzed to examine the effects of oriented palpating forces (0–5 N) of a 7 DOF robot arm equipped with a contoured palpation probe. Finite element static structural analysis of oriented robotic palpation on the developed 3D soft tissue phantoms (with and without anomaly) reveals the soft tissue layer deformations and associated strains needed to identify presence of stiffer inclusions or anomaly during Robotic palpation. The finite element analysis study shows that the difference in deformations of soft tissue layers (e.g., underlying myofascial layers) under stiffer inclusions at different force levels can facilitate haptic feedback to acquire information about subsurface tumors. The deformation variations are further compared to assess better palpation orientations for subsurface anomaly detection.

Cortical bone properties assessment using axially transmitted low frequency (<500 kHz) guided waves

The early diagnosis of osteoporosis through bone quality assessment has been extensively studied in the past decade. Research in axial transmission using ultrasonic guided waves has shown the method to be sensitive to intrinsic properties of long cortical bone. The aim of this work is, therefore, to show the capability of low frequency guided waves to enable the inversion of dispersion curves into bone properties. The proposed inversion scheme relies on dispersion curves simulated using the semi-analytical iso-geometric analysis (SAIGA) method. The model used in simulation comprised a bone phantom plate with a layer of soft tissue attached to the top surface in accordance with experimental bone phantom plates. A proprietary axial transmission multielement ultrasonic transducer specifically designed to excite ultrasonic guided waves under 500 kHz was used for measurements. Acquired data were processed using the 2-D Fast Fourier Transform to extract dispersion curves. The mechanical properties of the bone phantom plates were obtained by minimizing the difference between the experimental and simulated dispersion curves. The inversion was based on the dispersive properties of ultrasonic guided waves as well as their amplitudes. Results show a difference around 5% between the mechanical properties found with the SAIGA based inversion and those provided by the manufacturer of the plates.

Humeral Tissue Remodeling in Contact with Pyrocarbon Interposition Implant

The interactions between pyrocarbon (PyC) interposition implants and human humeral cancellous bone leads to the formation of a new interpositional tissue made a dense layer of cortical bone and a cartilage-like tissue. A sample of the tissue in contact with the PyC interposition implant was harvested on the humeral bone side from 6 patients undergoing a re-operation for implant removal due to staged surgery or clinical failure related to pain. The samples where then prepared for histology to evaluate the tissue morphology and immunohistology to assess for the presence of collagen I and collagen II within the matrix. For all the cases, a layer of dense cortical bone and a layer of soft tissue was observed between the PyC interpositional implant and the humeral cancellous bone. The nature of the interpositional soft tissue was different between the cases. While the hypothesis that a new tissue was modeled at PyC - humeral cancellous bone interface was confirmed, the nature of the soft interpositional tissue evolved from a fibrocellular to a cartilage-like tissue depending on the cases. The hypotheses for the different nature of the soft interpositional tissue observed between the different cases was based on humeral bone mechanobiological remodeling. The influence of the degree of attachment between the soft and bony interpositional-tissues and on the PISA geometry on the soft interpositional tissue nature are discussed. Further investigations on the role of humeral bone and on the PISA biomechanics should be performed to better understand this tissue remodeling.

The effect of subcutaneous fat and skin-to-lamina distance on complications and functional outcomes of minimally invasive lumbar decompression.

Minimally invasive lumbar decompression (MIS) in obese pzatients is technically challenging due to the use of longer tube retractors. The purpose of this study was to evaluate the impact of the thickness of the soft tissue and subcutaneous fat on complications, revisions, and patient-reported functional outcomes after MIS. This is a retrospective analysis of 148 consecutive patients who underwent minimally invasive lumbar decompression at our institute between 2013 and 2017 and had at least one year of follow-up. Analysis was performed five times, each time the study group was defined by another measure of adiposity: BMI > 30, skin to lamina distance at the site of surgery and at L4 > 6 cm, and subcutaneous fat thickness at the site of surgery and at L4 > 3 cm. Outcomes included intraoperative complications (durotomy or neurological deficit), possibly inadequate decompression (residual disc, reoperation), length of stay, return to the emergency room or readmission, postoperative medical complications, and functional outcomes: visual analog scores for back and leg pain, and Oswestry Disability Index (ODI). Patients with a thicker layer soft tissue had a significantly higher burden of comorbidities than controls, including higher prevalence of cardiovascular disease (p = 0.002), diabetes (p < 0.001), hypertension (p < 0.001) and higher ASA scores (p = 0.002). Nevertheless, there was no significant difference between the patient groups in surgical and medical complications, functional outcomes, and other assessed outcomes. Our results indicate that minimally invasive lumbar decompression is safe and effective for patients with a thick layer of soft tissue and subcutaneous fat.

Relationship between morphometric and mechanical properties of superficial lumbosacral soft tissue layers in healthy young adults.

Introduction: It is commonly considered that myotonometry is a non-invasive method capable of quantifying linear elastic and viscoelastic properties of the myofascial tissue through the application of a weak mechanical impulse to the surface of the skin. However, before the impulse can reach the myofascial tissue, it must cross more superficial tissues such as the skin and subcutaneous tissue (ST). All these superficial tissues have different distributions and organizations of structural components. Therefore, the study aimed to examine the potential relationships between the mechanical and morphometric properties of various superficial soft tissues surrounding the lumbar multifidus muscle (LM). Methods: Myotonometric measurements of dynamic stiffness, logarithmic decrement, and creep, and ultrasonographic measurements of thickness and echogenicity of cutaneous, subcutaneous, perimuscular tissue, and LM were obtained from 50 healthy individuals in the resting prone position and during contralateral arm lift. Results: The most important findings were that in both the relaxed and contracted LM state, the dynamic stiffness strongly negatively (r = -0.69; p < 0.001 in relaxation, r = -0.83; p < 0.001 in contraction) and creep strongly positively (r = 0.79; p < 0.001 in relaxation, r = 0.85; p < 0.001 in contraction) correlated with the thicknesses of the ST. Similar but weaker correlations were noticed between both these measures and the perimuscular tissue thickness. Elasticity was uncorrelated to the thicknesses of the tissues. With LM contraction (change from the relaxed to contracted state), the relative increase in dynamic stiffness was correlated with the relative decrease in dermis (r = -0.51; p < 0.001) and ST (r = -0.47; p = 0.001) thickness, and with the relative increase in LM (r = 0.36; p = 0.010) thickness. Moreover, the relative decrease (thinning) in the ST thickness was correlated with the relative increase in logarithmic decrement (i.e., decrease in soft tissue elasticity, r = -0.37, p = 0.011). The mechanical properties of the soft tissues were not related to their echogenicity. Discussion: In conclusion, the thicker the subcutaneous and perimuscular layers, the lesser the stiffness and the greater the time-dependent deformation to the external force of the tissues surrounding the LM during its relaxation and isometric contraction. Moreover, the greater the thinning of the ST and the thickening of the LM during its contraction, the higher the increase in lumbosacral tissue stiffness and the decrease in elasticity. Therefore, one should consider the thickness of the ST before planning or analyzing the outcomes of myotonometric or other external biomechanical measurements to avoid drawing the wrong conclusions about the mechanical properties of the myofascial tissue.

Role of multi-layer tissue composition of musculoskeletal extremities for prediction of in vivo surface indentation response and layer deformations.

Emergent mechanics of musculoskeletal extremities (surface indentation stiffness and tissue deformation characteristics) depend on the underlying composition and mechanics of each soft tissue layer (i.e. skin, fat, and muscle). Limited experimental studies have been performed to explore the layer specific relationships that contribute to the surface indentation response. The goal of this study was to examine through statistical modeling how the soft tissue architecture contributed to the aggregate mechanical surface response across 8 different sites of the upper and lower extremities. A publicly available dataset was used to examine the relationship of soft tissue thickness (fat and muscle) to bulk tissue surface compliance. Models required only initial tissue layer thicknesses, making them usable in the future with only a static ultrasound image. Two physics inspired models (series of linear springs), which allowed reduced statistical representations (combined locations and location specific), were explored to determine the best predictability of surface compliance and later individual layer deformations. When considering the predictability of the experimental surface compliance, the physics inspired combined locations model showed an improvement over the location specific model (percent difference of 25.4 +/- 27.9% and 29.7 +/- 31.8% for the combined locations and location specific models, respectively). While the statistical models presented in this study show that tissue compliance relies on the individual layer thicknesses, it is clear that there are other variables that need to be accounted for to improve the model. In addition, the individual layer deformations of fat and muscle tissues can be predicted reasonably well with the physics inspired models, however additional parameters may improve the robustness of the model outcomes, specifically in regard to capturing subject specificity.

Three-dimensional Computer-aided Design System used in Orthodontics and Orthognathic Surgery for Diagnosis and Treatment Planning- A Narrative Review

Three dimensional advancements in technology have made a profound impact on various fields, and dentistry, particularly the branch of orthodontics and orthognathic surgeries, which has not been exempt from this transformative influence. Among the cuttingedge technologies that have gained significant traction is Three-Dimensional (3D) printing, which has found its initial applications in orthodontics for producing dental casts. By integrating intraoral scanners, dentists now possess the remarkable ability to obtain dental impressions without subjecting patients to the discomfort associated with traditional methods. Furthermore, 3D planning techniques have emerged as a pivotal element in orthodontics, especially when striving for optimal aesthetic and occlusal outcomes. Precise treatment planning plays a vital role in ensuring successful orthognathic surgeries and other orthodontic interventions. The utilisation of 3D planning techniques facilitates the gathering of comprehensive data, thereby achieving two main objectives: an accurate diagnosis of the dentoskeletal deformity and the formulation of a treatment plan that can be faithfully replicated during the clinical procedure. Even 3D imaging technology, such as Computed Tomography (CT) and Cone Beam Computed Tomography (CBCT), has become an indispensable tool in dentistry. These imaging techniques provide volumetric images of a patient's facial anatomy, enabling the transformation of intricate details into precise 3D representations of the craniofacial skeleton and soft tissue layers. Consequently, this progress has led to the development of computerised resources dedicated to preoperative planning and the fabrication of surgical splints. The integration of advanced technologies, including 3D printing, 3D planning techniques, and 3D imaging technology, has revolutionised orthodontics, providing dentists with precise tools for accurate diagnosis, treatment planning, and ultimately, enhanced patient care. As this field continues to progress, the potential for further advancements and innovative applications utilising artificial intelligence becomes an exciting prospect in the ever-evolving landscape of modern dentistry.

Norms of soft tissue cephalometric in the 18-25 age demography in Vietnam.

The soft-tissue layer and facial skeleton influence the harmony and equilibrium of the face. The evaluation of the patient's structural and soft-tissue features is one of the most crucial steps in preparing for the diagnosis and treatment of oral-maxillofacial orthodontics. Clinicians can intervene with the proper treatment at the proper time to achieve the best results by being aware of the traits and variations of soft tissue at various developmental stages and in various races. To obtain a consistent treatment result in terms of function and aesthetically pleasing results, patients, and forecast, the growth that may take place after the orthopedic therapy has concluded. To examine the soft-tissue features of the oral-maxillofacial area in Vietnamese adults (aged 18-25 years) by evaluating cephalometric radiographs. In a cross-sectional descriptive study, 85 students from Can Tho University of Medicine and Pharmacy took part. Students' lateral cephalograms were taken in compliance with the sample requirements. Men's lip protrusion (4.30 ± 0.71) was higher than women's (3.88 ± 0.97) (P = 0.024 <.05) and men's (-4.88 ± 0.93) chin lip groove depth was higher than women's (-4.24 ± 0.93) (P = 0.002), both with a P value of. 05. The study identified a statistically significant difference in the protrusion of the top lip and the depth of the cleft lip between the male and female, demonstrating that the soft-tissue features of Vietnamese students were distinct from those of other races.

Pyramidal multiple‐theory (multi‐type, multi‐method and multi‐layer) for facial fat grafting

Age-related changes to the face pertinent anatomy and important aspects of autologous fat grafting have been widely applied in facial rejuvenation. Various types of autologous fat products (Macrofat, Microfat, SEFF, nanofat, and SVF-gel) with different properties and applicabilities have been introduced and available for surgeons. Key differences between common techniques for fat processing and infiltration. Develop a plan for patients based on site-specific facial anatomical zones, we suggested a pyramidal multiple-theory (multi-type, multi-method and multi-layer) for facial fat grafting. Based on the complicated mechanism of the face decrepitude in different layers of facial soft tissue, autologous fat products with various particle sizes and components into different layers. Fifty-eight patients underwent this facial fat grafting strategy from June 2020 to Jan 2022. All achieved cosmetic improvements, with higher patients' satisfaction, and minor complications. Our facial fat grafting strategy takes advantage of different fat products and is able to address the physiological tissue changes during aging, more properly and targetedly, than the traditional facial fat grafting. Fat grafting to the face aids in volume restoration and rejuvenation, thereby addressing soft-tissue atrophy associated with the aging face, acquired conditions, or congenital malformations. The technique described as "lipo-tumescence" has been successfully used in the breast and other regions of the body that have radiation damage and is discussed in this article specifically for the face and neck.

Radiation exposure to fetus from extremity CBCT examinations

PurposeTo evaluate fetal doses from extremity CBCT examinations at different stages of pregnancy and to investigate different methods of fetal dose optimization. MethodFetal doses were measured in an anthropomorphic phantom for two CBCT examination protocols – knee and elbow. The measurements were made at three different heights representing the three trimesters during pregnancy and three different depths in the phantom. The effect of soft tissue layer, tube voltage, add-on device shield and body angulation on fetal dose were investigated. ResultsThe fetal doses in clinical examination protocols were in the range of 3.4 to 6.0 µGy during knee examinations and 2.9 to 7.7 µGy during elbow examinations depending on the depth of the fetus and the stage of pregnancy. A soft tissue layer representing variative body composition above abdomen region decreased the fetal dose up to 19 % in knee and up to 21 % in elbow examinations. Using lower tube voltage decreased the fetal doses up to 45 % (knee) and 51 % (elbow). An add-on device shield decreased the fetal doses up to 91 % (knee) and up to 75 % (elbow). Turning the body away from the device bore reduced the fetal doses up to 62 %. The conversion factor to convert an entrance surface dose to the fetal dose ranged from 0.4 to 0.6. ConclusionsThe fetal doses from CBCT examinations of extremities are low and do not produce a concern about radiation detriment to the fetus. The most efficient way found to reduce the fetal dose was to use the add-on device shielding.

Thermal Modeling of Ultrasound Diathermy in Tissues with a Circular Inclusion near a Curved Interface

The influences of implants on the temperature field in tissues during ultrasound diathermy is controversial. In addition, most previous studies have focused on plate implants, and the effects of irregular implants and bones are seldom discussed. In this study, a hybrid computational framework per se is proposed to investigate the effects of double circular inclusions on the temperature distribution during ultrasound diathermy. The tissue–inclusion–bone structure is simplified as a two-dimensional bilayer composite model consisting of soft tissue and bone with a circular inclusion imbedded in the soft tissue. The interface between the bone layer and the soft-tissue layer is assumed as a convex surface for the incident ultrasonic waves. Multiply scattered waves originate between the two acoustic scatterers, i.e., the circular inclusion and the convex bone. The proposed computational framework consists of two kernels tackling ultrasound propagation and heat conduction problems, respectively. Making use of theoretical solutions of pressure fields, the transformed heat sources are efficiently obtained in the first kernel without sacrificing much computational burden. Temperature distributions in the composite media under ultrasound diathermy are evaluated via finite element numerical simulations in the second kernel. Numerical results indicate that the temperature distributions in the composite system obviously change when the bone layer changes from flat to convex. In addition, the inclusion size, location, material, and ultrasound operation frequency will also affect the temperature distribution and peak temperature during ultrasound diathermy. Pertinent findings could serve as a guide for clinical innovations in therapeutic ultrasounds.

Classifying Muscle States with One-Dimensional Radio-Frequency Signals from Single Element Ultrasound Transducers.

The reliable assessment of muscle states, such as contracted muscles vs. non-contracted muscles or relaxed muscles vs. fatigue muscles, is crucial in many sports and rehabilitation scenarios, such as the assessment of therapeutic measures. The goal of this work was to deploy machine learning (ML) models based on one-dimensional (1-D) sonomyography (SMG) signals to facilitate low-cost and wearable ultrasound devices. One-dimensional SMG is a non-invasive technique using 1-D ultrasound radio-frequency signals to measure muscle states and has the advantage of being able to acquire information from deep soft tissue layers. To mimic real-life scenarios, we did not emphasize the acquisition of particularly distinct signals. The ML models exploited muscle contraction signals of eight volunteers and muscle fatigue signals of 21 volunteers. We evaluated them with different schemes on a variety of data types, such as unprocessed or processed raw signals and found that comparatively simple ML models, such as Support Vector Machines or Logistic Regression, yielded the best performance w.r.t. accuracy and evaluation time. We conclude that our framework for muscle contraction and muscle fatigue classifications is very well-suited to facilitate low-cost and wearable devices based on ML models using 1-D SMG.