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Alginate cast visualization Axial 3D ultra-short echo time images of the alginate cast surrounding the rat leg, pre, during and post indentation. FLASH 3D rendering shows anatomical landmarks and location of selected 3D ultra-short echo time images.
Source publication
Deformation of skeletal muscle in the proximity of bony structures may lead to deep tissue injury category of pressure ulcers. Changes in mechanical properties have been proposed as a risk factor in the development of deep tissue injury and may be useful as a diagnostic tool for early detection. MRE allows for the estimation of mechanical propertie...
Citations
... Por todo esto, se hace necesario seguir investigando en el área puesto que las implicancias que podría alcanzar el uso de este dispositivo podrían no solo aportar en el ámbito de la prevención de las LPP, sino también en el comportamiento de este tipo de lesiones; en su evolución e incluso en los mecanismos de su cronicidad, aportando sustento al mecanismo de desarrollo de estas. Se espera por tanto que estudios futuros den cuenta de los procesos fisiopatológicos tras los cambios de las propiedades mecánicas musculo dañado y como estas generan cambios a corto y largo plazo(Nelissen et al., 2017;Febré-Vergara et al., 2023).Si bien ya desde el 2006, Quintavalle, planteó la posibilidad del uso de la HFUS a visualizar de forma temprana las lesiones por presión, aún los estudios son insuficientes y queda mucho por descubrir en el área.4 CONCLUSIÓNLas lesiones por presión (LPP) representan un desafío significativo en diversos entornos de atención en salud terciaria, especialmente entre pacientes críticos, quienes tienen una incidencia más altas en comparación con otros pacientes hospitalizados. ...
Las lesiones por presión son un evento adverso de gran prevalencia, que en la mayoría de los casos resulta prevenible, por lo que evitar su ocurrencia o detectarlas en etapas primarias en esencial. Objetivo: Determinar la importancia clínica del uso de la ultrasonografía en la detección precoz de las lesiones por presión. Método: Se realizó una revisión de la literatura científica disponible en las bases de datos: SCOPUS, Web of Science, CINHAL y Scielo. Los criterios que limitaron la búsqueda fueron que fueran ensayos clínicos controlados, revisiones sistemáticas y meta-análisis y el idioma inglés y/o español. No se aplicó límite de años de publicación de los artículos. Resultados: se seleccionaron 5 artículos que cumplían con los criterios propuestos de un total de 3829 artículos encontrados. Se establece la importancia clínica del ultrasonido de alta frecuencia para la detección temprana de lesiones por presión, con un alto nivel de precisión en comparación a otras tecnologías similares. Conclusión: Esta revisión permite determinar las implicancias del uso del ultrasonido de alta frecuencia, tanto en al ámbito de la prevención de las LPP, como en el comportamiento de este tipo de lesiones; en cuanto a su evolución y cronicidad. Por ello, el uso de esta tecnología es altamente relevante para la clínica.
... This can be done with Magnetic Resonance Elastography (MRE), a technique where the muscle is mechanically stimulated using an external actuator and the wave propagation is imaged using motionencoded MRI sequences, providing information on local tissue stiffness, which can be related to collagen content. 48,49 The presence of an increased amount of collagen is also expected to modify the diffusion processes of water molecules in the extracellular space, which can be detected using Diffusion MRI. Preliminary findings show a correlation between histology-determined fibrosis area and the membrane permeability obtained in diffusion MRI experiments at long diffusion times, 50 but additional validation is required to assess the specificity of DWI to fibrotic processes. ...
Due to its exceptional sensitivity to soft tissues, MRI has been extensively utilized to assess anatomical muscle parameters such as muscle volume and cross‐sectional area. Quantitative Magnetic Resonance Imaging (qMRI) adds to the capabilities of MRI, by providing information on muscle composition such as fat content, water content, microstructure, hypertrophy, atrophy, as well as muscle architecture. In addition to compositional changes, qMRI can also be used to assess function for example by measuring muscle quality or through characterization of muscle deformation during passive lengthening/shortening and active contractions. The overall aim of this review is to provide an updated overview of qMRI techniques that can quantitatively evaluate muscle structure and composition, provide insights into the underlying biological basis of the qMRI signal, and illustrate how qMRI biomarkers of muscle health relate to function in healthy and diseased/injured muscles. While some applications still require systematic clinical validation, qMRI is now established as a comprehensive technique, that can be used to characterize a wide variety of structural and compositional changes in healthy and diseased skeletal muscle. Taken together, multiparametric muscle MRI holds great potential in the diagnosis and monitoring of muscle conditions in research and clinical applications.
Evidence Level
5
Technical Efficacy
Stage 2
... As it stands, the direct measurement of overload thresholds in the context of occipital ulceration would involve applying and sustaining pressure until the development of an overload injury in the soft tissues at the back of the head. Similar methodologies have been successfully used in literature to study overload injury in the muscle of animal models of pressure ulceration [24][25][26] or in in vitro tissue engineering models. 27 However, this invasive approach is not applicable for human in vivo testing. ...
Introduction
The high prevalence of occipital ulcers in UK military casualties observed during the conflict in Afghanistan is a multifactorial phenomenon. However, the consensus is that ulceration is triggered by excessive pressure that is maintained for too long during the use of the general service military stretcher. Thresholds for capillary occlusion are accepted benchmarks to define excessive pressure, but similar thresholds for safe/excessive duration of pressure application do not exist. To address this gap in knowledge, we propose to use the time it takes for a healthy person to feel pain at the back of the head as an initial indication of safe exposure to pressure.
Methods
Healthy military personnel (16 male/10 female) were asked to lie motionless on a typical general service stretcher until they felt pain. Time-to-pain and the location of pain were recorded. To support the interpretation of results, baseline sensitivity to pain and pressure distribution at the back of the head were also measured. Independent samples t-test was used to assess differences between genders.
Results
Twenty participants felt pressure-induced soft-tissue pain at the back of the head. The remaining six participants terminated the test due to musculoskeletal pain caused by poor ergonomic positioning. On average, pain at the occiput developed after 31 min (±14 min). Female participants were significantly more sensitive to pain (t(24)=3.038,p=0.006), but time-to-pain did not differ significantly between genders (p>0.05).
Conclusions
When people lie motionless on a typical military stretcher, the back of the head is the first area of the body that becomes painful due to pressure. The fact that pain develops in ≈30 min can help healthcare providers decide how frequently to reposition their patients who are unable to do this on their own. More research is still needed to directly link time-to-pain with time-to-injury.
... The link between tissue damage and altered mechanical properties was previously demonstrated for muscle tissue using an animal model 9,10 . Nelissen et al. induced deep-tissue injury by applying large-strain indentation for two hours in the tibialis anterior muscle of anaesthetised rats 9 . ...
... Measurement of the tissue's mechanical behaviour before and after overloading revealed significant localised stiffening following overload injury. Even though the methods for overloading-induced tissue damage presented by Nelissen et al. are not transferable to in vivo human testing, their findings highlight tissue stiffening as a potential marker for soft tissue overloading 9,10 . ...
This proof-of-concept study demonstrates that repetitive loading to the pain threshold can safely recreate overloading-induced soft tissue damage and that localised tissue stiffening can be a potential marker for injury. This concept was demonstrated here for the soft tissue of the sole of the foot where it was found that repeated loading to the pain threshold led to long-lasting statistically significant stiffening in the overloaded areas. Loading at lower magnitudes did not have the same effect. This method can shed new light on the aetiology of overloading injury in the foot to improve the management of conditions such as diabetic foot ulceration and heel pain syndrome. Moreover, the link between overloading and tissue stiffening, which was demonstrated here for the first time for the plantar soft tissue, opens the way for an assessment of overloading thresholds that is not based on the subjective measurement of pain thresholds.
... 12,35,36 Experimental and numerical models indicate that large deformations over short periods of time represent the most important factor in the causal pathway for Deep Tissue Injury (DTI), which initiates in muscle tissues. 8,15,[31][32][33]39,40,53,54 By contrast, superficial pressure ulcers (PUs) are generally caused by external pressures and shear forces. The tissue tolerance to loading magnitude and duration varies between individuals, 19 and is influenced by many intrinsic factors. ...
... During periods of loading application, the magnitude and duration of mechanical strain is considered to represent the most important factor in the causal pathway for damage of soft tissue. 8,15,[31][32][33]39,40,53,54 The largest strains observed in this study were between 20 and 30%, applied over a 15 minute period. These conditions represent a lower range than that observed in examining tissue damage in model systems 17 and in clinical situations. ...
Despite the potential for biomechanical conditioning with prosthetic use, the soft tissues of residual limbs following lower-limb amputation are vulnerable to damage. Imaging studies revealing morphological changes in these soft tissues have not distinguished between superficial and intramuscular adipose distribution, despite the recognition that intramuscular fat levels indicate reduced tolerance to mechanical loading. Furthermore, it is unclear how these changes may alter tissue tone and stiffness, which are key features in prosthetic socket design. This study was designed to compare the morphology and biomechanical response of limb tissues to mechanical loading in individuals with and without transtibial amputation, using magnetic resonance imaging in combination with tissue structural stiffness. The results revealed higher adipose infiltrating muscle in residual limbs than in intact limbs (residual: median 2.5% (range 0.2-8.9%); contralateral: 1.7% (0.1-5.1%); control: 0.9% (0.4-1.3%)), indicating muscle atrophy and adaptation post-amputation. The intramuscular adipose content correlated negatively with daily socket use, although there was no association with time post-amputation. Residual limbs were significantly stiffer than intact limbs at the patellar tendon site, which plays a key role in load transfer across the limb-prosthesis interface. The tissue changes following amputation can have relevance in the clinical understanding of prosthetic socket design variables and soft tissue damage risk in this vulnerable group.
... Experimental and numerical models indicate that large deformations over short periods of time represent the most important factor in the causal pathway for Deep Tissue Injury (DTI), which initiates in muscle tissues [4]- [12]. By contrast, superficial pressure ulcers (PUs) are generally caused by external pressures and shear forces. ...
... During periods of loading application, the magnitude and duration of mechanical strain is considered to represent the most important factor in the causal pathway for damage of soft tissue [4]- [12]. The largest strains observed in this study were between 20 and 30%, applied over a 15 minute period. ...
Despite the potential for biomechanical conditioning with prosthetic use, the soft tissues of residual limbs following lower-limb amputation are vulnerable to damage. Imaging studies revealing morphological changes in these soft tissues have not distinguished between superficial and intramuscular adipose distribution, despite the recognition that intramuscular fat levels indicate reduced tolerance to mechanical loading. Furthermore, it is unclear how these changes may alter tissue tone and stiffness. This study was designed to compare the morphology and biomechanical response of limb tissues to mechanical loading in individuals with and without transtibial amputation, using magnetic resonance imaging in combination with tissue structural stiffness. The results revealed higher adipose infiltrating muscle in residual limbs than in intact limbs (residual: median 2.5% (range 0.2-8.9%); contralateral: 1.7% (0.1-5.1%); control: 0.9% (0.4-1.3%)), indicating muscle atrophy and adaptation post-amputation. The intramuscular adipose content correlated negatively with daily socket use, although there was no association with time post-amputation. Residual limbs were significantly stiffer than intact limbs at the patellar tendon site, which plays a key role in load transfer across the limb-prosthesis interface. The tissue changes following amputation can have relevance in the clinical understanding of prosthetic socket design variables and soft tissue damage risk in this vulnerable group.
... Des modèles de rats présentant des lésions au niveau des tissus musculaires profonds ont aussi montré l'efficacité du T 2 comme biomarqueur. En comparaison, des mesures d'élastographie ont été obtenues et montrent une piste prometteuse pour l'étude structurelle des tissus musculaires [91]. Des modèles de souris sarcopéniques ont permis d'observer un rallongement du T 2 dans le muscle gastrocnémien par rapport à de jeunes souris saines [92]. ...
Le syndrome gériatrique de fragilité est défini comme un état cliniquement reconnaissable de vulnérabilité accrue résultant du déclin associé au vieillissement. Bien que ce diagnostic soit délivré suite à des tests physiques, l’état des muscles n’est pas spécifiquement étudié alors qu’un des facteurs principaux de l’état de fragilité est la sarcopénie. Afin de poursuivre dans cette voie, il a été décidé d’étudier les muscles par Imagerie par Résonance Magnétique (IRM), méthode non-invasive favorisant les suivis longitudinaux et offrant de fortes résolutions spatiales. Étant donné la nécessité de développer de nouvelles méthodes IRM pour l’exploration des muscles, le choix s’est également porté sur l’utilisation de modèles animaux, et plus particulièrement le rat, car ils permettent de mimer de nombreuses pathologies humaines. Tout d’abord, un lit IRM-compatible a été développé afin de pouvoir placer le rat dans l’imageur, tout en permettant l’électrostimulation du muscle gastrocnémien. Ce lit possède également une pédale associée à un capteur de pression afin de mesurer la force exercée par la patte stimulée. S’ajoute à cela le développement d’une carte électronique permettant la synchronisation entre l’électrostimulateur et les séquences IRM.La mesure multi-paramétrique du muscle pendant l’effort a été réalisée grâce au développement d’une séquence Look-Locker à encodage radial, d’une séquence Multi-Slice Multi-Echo et l’utilisation de la spectroscopie du phosphore 31P pour mesurer les temps de relaxation T1, T2 et la consommation d’ATP/PCr.Grâce aux développements méthodologiques, aucun artefact de mouvement n’a été détecté sur les images, ce qui a permis d’appliquer ces séquences à une étude comparative de l’effort musculaire entre des rats jeunes et âgés. Les méthodes ont permis de montrer que, contrairement au T1, le T2 varie en fonction de l’intensité de stimulation. La spectroscopie a également permis d’établir une corrélation entre les variations de T2 avec la consommation de PCr.En parallèle, une étude clinique chez l’homme a permis de mesurer le T2 du muscle de patients fragiles et de le corréler aux dégénérescences cognitives liées à l’âge.
... © The Author(s)2019 ...
At present, there is a lack of well-validated protocols that allow for the analysis of the mechanical properties of muscle and tendon tissues. Further, there are no reports regarding characterization of mouse skeletal muscle and tendon mechanical properties in vivo using elastography thereby limiting the ability to monitor changes in these tissues during disease progression or response to therapy. Therefore, we sought to develop novel protocols for the characterization of mechanical properties in musculotendinous tissues using atomic force microscopy (AFM) and ultrasound elastography. Given that TIEG1 knockout (KO) mice exhibit well characterized defects in the mechanical properties of skeletal muscle and tendon tissue, we have chosen to use this model system in the present study. Using TIEG1 knockout and wild-type mice, we have devised an AFM protocol that does not rely on the use of glue or chemical agents for muscle and tendon fiber immobilization during acquisition of transversal cartographies of elasticity and topography. Additionally, since AFM cannot be employed on live animals, we have also developed an ultrasound elastography protocol using a new linear transducer, SLH20-6 (resolution: 38 µm, footprint: 2.38 cm), to characterize the musculotendinous system in vivo. This protocol allows for the identification of changes in muscle and tendon elasticities. Such innovative technological approaches have no equivalent to date, promise to accelerate our understanding of musculotendinous mechanical properties and have numerous research and clinical applications.
... Used with permission from Elsevier has demonstrated clinical success in the evaluation of liver disease [21,23,24]. Disadvantages of MRE mainly lie in its high cost, metal-free requirement, and time-consuming operational procedure [25,26]. ...
Tissue stiffness, shear stress, and interstitial pressure constitute major factors of the liver mechanical microenvironment that play a key regulatory role in controlling cell behavior in the liver and progression of liver diseases. In this review, we focus on the characteristics of the liver mechanical microenvironment and summarize cellular responses to mechanobiological changes during liver pathogenesis, especially in hepatic fibrosis and cirrhosis. A better understanding of the indispensable contribution of mechanical cues to liver homeostasis and pathogenesis is essential for identifying new therapeutic targets for liver diseases such as hepatic fibrosis or cirrhosis.
... Most of the current knowledge on changes in biomechanical properties related to deep tissue injury and pressure ulcers in general were obtained from controlled indentation experiments in animals and finite element analysis (FEA). [17][18][19][20][21][22][23][24][25][26][27] One of the well-established animal models of deep tissue injury involves the deformation of the rat tibialis anterior (TA) muscle with a custom loading device that can be placed in a MRI scanner for imaging during the development of the damage. 19,27 Several MRI and histopathologic readouts were employed to provide a comprehensive understanding of the damage development, recovery, and regeneration in this model. ...
... [17][18][19][20][21][22][23][24][25][26][27] One of the well-established animal models of deep tissue injury involves the deformation of the rat tibialis anterior (TA) muscle with a custom loading device that can be placed in a MRI scanner for imaging during the development of the damage. 19,27 Several MRI and histopathologic readouts were employed to provide a comprehensive understanding of the damage development, recovery, and regeneration in this model. 18,21,25,28,29 It was found that the initial tissue response to deformation started at some distance from the center of indentation, affecting a relatively large area. ...
... For this purpose, we employed the recently introduced rat magnetic resonance elastography (MRE) setup, which facilitates direct quantification of muscle shear modulus values. 27 This setup enables MRE estimations of local muscle tissue mechanical properties pre, during (not shown), and post-indentation of the rat TA muscle in the MRI scanner. 27 To review briefly, the setup consisted of an indentation and MRE part ( Figure 2). ...
The current state‐of‐the‐art diagnosis method for deep tissue injury in muscle, a subcategory of pressure ulcers, is palpation. It is recognized that deep tissue injury is frequently preceded by altered biomechanical properties. A quantitative understanding of the changes in biomechanical properties preceding and during deep tissue injury development is therefore highly desired. In this paper we quantified the spatial–temporal changes in mechanical properties upon damage development and recovery in a rat model of deep tissue injury.
Deep tissue injury was induced in nine rats by two hours of sustained deformation of the tibialis anterior muscle. Magnetic resonance elastography (MRE), T2‐weighted, and T2‐mapping measurements were performed before, directly after indentation, and at several timepoints during a 14‐day follow‐up.
The results revealed a local hotspot of elevated shear modulus (from 3.30 ± 0.14 kPa before to 4.22 ± 0.90 kPa after) near the center of deformation at Day 0, whereas the T2 was elevated in a larger area. During recovery there was a clear difference in the time course of the shear modulus and T2. Whereas T2 showed a gradual normalization towards baseline, the shear modulus dropped below baseline from Day 3 up to Day 10 (from 3.29 ± 0.07 kPa before to 2.68 ± 0.23 kPa at Day 10, P < 0.001), followed by a normalization at Day 14.
In conclusion, we found an initial increase in shear modulus directly after two hours of damage‐inducing deformation, which was followed by decreased shear modulus from Day 3 up to Day 10, and subsequent normalization. The lower shear modulus originates from the moderate to severe degeneration of the muscle. MRE stiffness values were affected in a smaller area as compared with T2. Since T2 elevation is related to edema, distributing along the muscle fibers proximally and distally from the injury, we suggest that MRE is more specific than T2 for localization of the actual damaged area.
