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Tecse A, Romero SE, Naemi R, Castaneda B. Characterisation of soft tissue viscous and elastic properties using ultrasound elastography and rheological models: validation and applications in plantar soft tissue assessment. Phys Med Biol 2023; 68. [PMID: 36996846 DOI: 10.1088/1361-6560/acc923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 03/30/2023] [Indexed: 04/01/2023]
Abstract
OBJECTIVE The mechanical behaviour of soft tissue is influenced by its elastic and viscous characteristics. Therefore, the aim of this study was to develop a protocol to characterise the viscoelastic properties of soft tissues based on ultrasound elastography data. APPROACH Plantar soft tissue was chosen as the tissue of interest, and gelatine-phantoms replicating its mechanical properties were manufactured for validation of the protocol. Both plantar soft tissue and the phantom were scanned using Reverberant shear wave elastography at 400-600 Hz. Shear wave speed (SWS) was estimated using the US particle velocity data. The viscoelastic parameters were extracted by fitting the shear wave dispersion data to the Young's modulus as a function of frequency derived from the constitutive equations of the eight rheological models (four classic and their fractional-derivative versions). Furthermore, stress-time functions derived from the eight rheological models were fitted to the phantom stress-relaxation data. MAIN RESULTS The viscoelastic parameters estimated using elastography data based on the fractional-derivative (FD) models were closer to those quantified using the mechanical test. In addition, the FD-Maxwell and FD-Kelvin-Voigt models can more effectively replicate the viscoelastic behaviour of the plantar soft tissue with minimum number of model parameters (R^2 = 0.72 for both models) . Hence the FD-KV and FD-Maxwell models can more effectively quantify the viscoelastic characteristics of the soft tissue compared to other models. SIGNIFICANCE In this study, a method for mechanical characterisation of the viscoelastic properties of soft tissue in ultrasound elastography was developed and validated. An investigation into the most valid rheological model and its applications in plantar soft tissue assessment were also presented. This approach for the characterisation of viscous and elastic mechanical properties of soft tissue has implications in assessing the soft tissue function where those can be used as markers for diagnosis or prognosis of tissue status.
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Affiliation(s)
- Aldo Tecse
- Engineering, Pontificia Universidad Catolica del Peru, 1801 Universitaria Avenue, San Miguel, Lima, Lima, Lima, 15038, PERU
| | - Stefano E Romero
- Pontificia Universidad Catolica del Peru, 1801 Universitaria Avenue, Lima, Lima, 15088, PERU
| | - Roozbeh Naemi
- Centre for Biomechanics and Rehabilitation Technologies, Staffordshire University, College Rd, Stoke-on-Trent, Staffordshire, ST4 2DE, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Benjamin Castaneda
- Department of Engineering, Pontificia Universidad Catolica del Peru, Av. Universitaria 1801, San Miguel, Lima 32-Perú, Lima, 32, PERU
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Patwari M, Chatzistergos P, Sundar L, Chockalingam N, Ramachandran A, Naemi R. A quantitative comparison of plantar soft tissue strainability distribution and homogeneity between ulcerated and non-ulcerated patients using ultrasound strain elastography. Proc Inst Mech Eng H 2022; 236:722-729. [PMID: 35199619 DOI: 10.1177/09544119221074786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The primary objective of this study was to develop a method that allows accurate quantification of plantar soft tissue stiffness distribution and homogeneity. The secondary aim of this study was to investigate if the differences in soft tissue stiffness distribution and homogeneity can be detected between ulcerated and non-ulcerated foot. Novel measures of individual pixel stiffness, named as quantitative strainability (QS) and relative strainability (RS) were developed. Strain Elastography data obtained from 39 (nine with active diabetic foot ulcers) patients with diabetic neuropathy. The patients with active diabetic foot ulcer had wound in parts of the foot other than the first metatarsal head and the heel where the elastography measures were conducted. RS was used to measure changes and gradients in the stiffness distribution of plantar soft tissues in participants with and without active diabetic foot ulcer. The plantar soft tissue homogeneity in superior-inferior direction in the left forefoot was found to be significantly (p < 0.05) higher in ulcerated group compared to non-ulcerated group. The assessment of homogeneity showed potentials to further explain the nature of the change in tissue that can increase internal stress. This can have implications in assessing the vulnerability to plantar soft tissue damage and ulceration in diabetes.
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Affiliation(s)
- Mayank Patwari
- Computer Aided Medical Procedures, Technische Universität München, Munich, Garching, Germany
| | - Panagiotis Chatzistergos
- Centre for Biomechanics and Rehabilitation Technologies, School of Health, Science and Wellbeing, Staffordshire University, Stoke on Trent, Staffordshire, UK
| | | | - Nachiappan Chockalingam
- Centre for Biomechanics and Rehabilitation Technologies, School of Health, Science and Wellbeing, Staffordshire University, Stoke on Trent, Staffordshire, UK
| | | | - Roozbeh Naemi
- Centre for Biomechanics and Rehabilitation Technologies, School of Health, Science and Wellbeing, Staffordshire University, Stoke on Trent, Staffordshire, UK
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Naemi R, Romero Gutierrez SE, Allan D, Flores G, Ormaechea J, Gutierrez E, Casado-Pena J, Anyosa-Zavaleta S, Juarez M, Casado F, Castaneda Aphan B. Diabetes Status is Associated With Plantar Soft Tissue Stiffness Measured Using Ultrasound Reverberant Shear Wave Elastography Approach. J Diabetes Sci Technol 2022; 16:478-490. [PMID: 33095039 PMCID: PMC8861805 DOI: 10.1177/1932296820965259] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION The purpose of this study was to investigate the association between the mechanical properties of plantar soft tissue and diabetes status. METHOD 51 (M/F: 21/30) participants with prediabetes onset (fasting blood sugar [FBS] level > 100 mg/dL), age >18 years, and no lower limb amputation were recruited after ethical approval was granted from Pontificia Universidad Catolica del Peru ethical review board. Ultrasound reverberant shear wave elastography was used to assess the soft tissue stiffness at the 1st metatarsal head (MTH), 3rd MTH, and the heel at both feet. RESULTS Spearman's rank-order correlation (rho) test indicated a significant (P < .05) positive correlations between FBS level and the plantar soft tissue shear wave speed at the 1st MTH: rho = 0.402 (@400 Hz), rho = 0.373 (@450 Hz), rho = 0.474 (@500 Hz), rho= 0.395 (@550 Hz), and rho = 0.326 (@600 Hz) in the left foot and rho = 0.364 (@450 Hz) in the right foot. Mann-Whitney U test indicated a significantly (P < .05) higher shear wave speed in the plantar soft tissue with the following effect sizes (r) at the 1st MTH of the left foot at all tested frequencies: r = 0.297 (@450 Hz), r = 0.345 (@500 Hz), r = 0.322 (@550 Hz), and r = 0.275 (@600 Hz), and at the 1st MTH of right foot r = 0.286 (@400 Hz) in diabetes as compared with the age and body mass index matched prediabetes group. CONCLUSION An association between fasting blood sugar level and the stiffness of the plantar soft tissue with higher values of shear wave speed in diabetes versus prediabetes group was observed. This indicated that the proposed approach can improve the assessment of the severity of diabetic foot complications with potential implications in patient stratification.
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Affiliation(s)
- Roozbeh Naemi
- Centre for Biomechanics and
Rehabilitation Technologies, School of Life Sciences and Education, Staffordshire
University, Staffordshire, UK
- Roozbeh Naemi, BSc, MSc, PhD, School of Life
Sciences and Education, Staffordshire University, Science Centre, Leek Road,
Stoke on Trent, Staffordshire, ST4 2DF, UK.
| | | | - David Allan
- Centre for Biomechanics and
Rehabilitation Technologies, School of Life Sciences and Education, Staffordshire
University, Staffordshire, UK
| | - Gilmer Flores
- Department of Engineering, Medical
Imaging Laboratory, Pontificia Universidad Catolica del Peru, Lima, Peru
| | - Juvenal Ormaechea
- Department of Engineering, Medical
Imaging Laboratory, Pontificia Universidad Catolica del Peru, Lima, Peru
- Department of Electrical and Computer
Engineering, University of Rochester, New York, USA
| | - Evelyn Gutierrez
- Department of Engineering, Medical
Imaging Laboratory, Pontificia Universidad Catolica del Peru, Lima, Peru
| | | | - Sharon Anyosa-Zavaleta
- Translational Unit, Institute of Omics
and Applied Biotechnology, Pontificia Universidad Catolica del Peru, Lima,
Peru
| | - Mauricio Juarez
- Department of Engineering, Medical
Imaging Laboratory, Pontificia Universidad Catolica del Peru, Lima, Peru
| | - Fanny Casado
- Department of Engineering, Medical
Imaging Laboratory, Pontificia Universidad Catolica del Peru, Lima, Peru
| | - Benjamin Castaneda Aphan
- Department of Engineering, Medical
Imaging Laboratory, Pontificia Universidad Catolica del Peru, Lima, Peru
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Balasubramanian G, Chockalingam N, Naemi R. A systematic evaluation of cutaneous microcirculation in the foot using post-occlusive reactive hyperemia. Microcirculation 2021; 28:e12692. [PMID: 33655651 DOI: 10.1111/micc.12692] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 02/22/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Cutaneous microcirculatory impairments are associated with skin injury to the foot. Post-Occlusive reactive hyperemia (PORH) is one of the quick and easy methods to assess microcirculatory function. However, there are variations in the protocols currently used. Hence, this study aimed to systematically investigate the reproducibility of PORH protocols with minimal occlusion time in the foot. METHODS Post-Occlusive reactive hyperemia was measured using 12 different protocols (three occlusion times, two occlusion sites and with or without temperature control) in 25 healthy adults. Each of the 12 different protocols was repeated three times, and the intraclass correlation coefficient (ICC) was calculated. RESULTS Intraclass correlation coefficient showed that that ankle level occlusion produced moderate to excellent reproducibility for most PORH measures. In the right foot, 30- and 60-s ankle level occlusion without temperature control showed ICC of >0.40 for all parameters except the area of hyperemia (ICC = -0.36) and biological zero to peak flow percent change (ICC = -0.46). In the left foot, 30-s ankle level occlusion without temperature control showed ICC of >0.40 for all parameters except time to latency (ICC = 0.29), after hyperemia (ICC = 0.37), and max (ICC = -0.01), and area of hyperemia (ICC = -0.36). But the 60-s protocol showed ICC > 0.40 for all except time to max (ICC = 0.38). In the hallux protocols, all three 10-, 30-, and 60-s protocols without temperature control showed moderate to excellent reproducibility (ICC > 0.40). In most cases, the temporal and area under the perfusion-time curve parameters showed poor reproducibility. CONCLUSION Post-Occlusive reactive hyperemia can be tested efficiently with a minimal occlusion time of 10 s with hallux occlusion and 30 s with ankle occlusion in the foot. This can suggest that microcirculatory assessment is feasible in routine practice and can potentially be included for routine assessment of foot in people with diabetes.
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Affiliation(s)
- Gayathri Balasubramanian
- Centre for Biomechanics and Rehabilitation Technologies, Staffordshire University, Stoke-on-Trent, UK
| | - Nachiappan Chockalingam
- Centre for Biomechanics and Rehabilitation Technologies, Staffordshire University, Stoke-on-Trent, UK.,Faculty of Health Sciences, University of Malta, Msida, Malta
| | - Roozbeh Naemi
- Centre for Biomechanics and Rehabilitation Technologies, Staffordshire University, Stoke-on-Trent, UK
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Allan D, Chockalingam N, Naemi R. Validation of a non-invasive imaging photoplethysmography device to assess plantar skin perfusion, a comparison with laser speckle contrast analysis. J Med Eng Technol 2021; 45:170-176. [PMID: 33750251 DOI: 10.1080/03091902.2021.1891309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Assessing skin perfusion is an established and reliable method to study impaired lower limb blood flow. Laser Speckle Contrast Analysis (LASCA) has been identified as the current gold standard to measure skin perfusion. Imaging photoplethysmography (iPPG) is a new low-cost imaging technique to assess perfusion. However, it is unclear how results obtained from this technique compare against that of LASCA at plantar skin. Therefore, the aim of this study was to investigate the association between the skin perfusion at the plantar surface of the foot using iPPG and LASCA. Perfusion at six plantar locations (Hallux, 1st 3rd 5th metatarsal heads, midfoot, heel) was simultaneously measured using LASCA and iPPG in 20 healthy participants. Skin thickness and skin temperature were also collected at the same plantar locations. Spearman's rank tests showed significant associations with medium strength between the perfusion values measured with LASCA and iPPG for most tested sites. No improvement in the relationship between iPPG and LASCA data was observed when controlling for either skin thickness or skin temperature. Skin perfusion values obtained using iPPG were found to be significantly associated with the corresponding values obtained using the gold standard LASCA device. Additionally, the measurement of perfusion using iPPG is shown to be robust.
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Affiliation(s)
- David Allan
- Centre for Biomechanics and Rehabilitation Technologies, Staffordshire University, Stoke-on-Trent, UK
| | - Nachiappan Chockalingam
- Centre for Biomechanics and Rehabilitation Technologies, Staffordshire University, Stoke-on-Trent, UK
| | - Roozbeh Naemi
- Centre for Biomechanics and Rehabilitation Technologies, Staffordshire University, Stoke-on-Trent, UK
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Abstract
BACKGROUND Diabetic foot ulceration has a complex and multifactorial etiology and can involve changes in the pathophysiology of the plantar soft tissue. In the current study, histomorphological analyses of diabetic and non-diabetic plantar tissue were performed. It was hypothesized that the diabetic tissue would have thicker skin (epidermis and dermis), less interdigitation between the dermis and epidermis, thicker elastic septa and decreased adipose cell size. MATERIALS AND METHODS Two locations of the foot (the heel and the first metatarsal) were examined, both of which have been reported to be locations with a high incidence of ulceration. Stereological methods and quantitative morphological techniques were used to evaluate the skin thickness, interdigitation index, elastic septae thickness and adipocyte cell size. RESULTS The diabetic donors had a greater body mass index (BMI) than the non-diabetic donors. The diabetic tissue had significantly thicker elastic septae and dermis. However, no significant difference was observed in the interdigitation index or adipocyte size. CONCLUSION These findings demonstrate that morphological changes can be evaluated histologically to give a better understanding of the pathological changes in the plantar soft tissue with diabetes. These evaluations can then be associated with biomechanical changes that occur in diabetes to provide new insight into how microstructural changes can alter macroscopic properties. CLINICAL RELEVANCE An understanding of the histomorphological changes in the soft tissue in relationship to the location on the foot could help to explain the biomechanical changes that occur in diabetes and the subsequent increase in susceptibility to breakdown.
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