Operative skill: quantifying surgeon's response to tissue properties

Ultrasound elastography is a constantly developing imaging technique which is capable of displaying the elastic properties of tissue. The measured characteristics could help to refine physiological tissue models, but also indicate pathological changes. Therefore, elastography data give valuable insights into tissue properties. This paper presents an algorithm that measures the spatially resolved Young’s modulus of inhomogeneous gelatin phantoms using a CINE sequence of a quasi-static compression and a load cell measuring the compressing force. An optical flow algorithm evaluates the resulting images, the stresses and strains are computed, and, conclusively, the Young’s modulus and the Poisson’s ratio are calculated. The whole algorithm and its results are evaluated by a performance descriptor, which determines the subsequent calculation and gives the user a trustability index of the modulus estimation. The algorithm shows a good match between the mechanically measured modulus and the elastography result—more precisely, the relative error of the Young’s modulus estimation with a maximum error 35%. Therefore, this study presents a new algorithm that is capable of measuring the elastic properties of gelatin specimens in a quantitative way using only the image data. Further, the computation is monitored and evaluated by a performance descriptor, which measures the trustability of the results.

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Prognostic utility of differential contrast-enhancement patterns on late gadolinium enhancement cardiac MRI (LGE-CMR) in patients with cancer-associated cardiac masses

European Heart Journal ◽

10.1093/ehjci/ehaa946.0223 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

A Chan ◽

W Dinsfriend ◽

J Kim ◽

R Steingart ◽

J.W Weinsaft

Keyword(s):

Contrast Enhancement ◽

Cancer Patients ◽

Cancer Type ◽

Tissue Properties ◽

All Cause Mortality ◽

Prognostic Utility ◽

Cardiac Masses ◽

Embolic Risk ◽

Lge Cmr

Abstract Background LGE-CMR tissue characterization is widely used to identify cardiac masses (CMASS) in cancer patients – including neoplasm (NEO) and thrombus (THR). Prognostic utility of their differential LGE patterns is unknown. Purpose To determine incremental prognostic utility of LGE patterns in CMASS Methods The population comprised of cancer patients with CMASS on LGE-CMR, for which etiology was classified based on presence (NEO) or absence (THR) of enhancement, and controls matched for cancer type/stage. LGE-CMR tissue properties of NEO was classified based on extent of contrast enhancement – diffusely enhancing (DE), mixed (ME), and predominantly avascular (PA). Clinical follow up was performed for embolic events within 6 months of CMR and all-cause mortality. Results 330 cancer patients (55% M; 55±16yo) with an array of cancer diagnoses (19% sarcoma, 17% GI, 13% GU) were studied. Among CMASS+ pts (n=190), 66% had NEO and 34% had THR on LGE. All THR were non-enhancing. Among NEO, LGE pattern was variable (46% DE, 41% ME, 13% PA); ME lesions were larger than other groups (Fig. 1A). Quantitative tissue properties were consistent with qualitative groups, as evidenced by stepwise variation in signal intensity and CNR. Cumulative embolic events were 3-fold higher in CMASS+ than controls (All: 20% vs. 7%, p=0.001; PE: 13% vs. 5%, p=0.02; CVA/systemic embolism: 10% vs. 3%, p=0.01). Median time to event was 1.3 months [IQR 0.1–2.3] from CMR. Aggregate events were similar between NEO and THR, reflecting similar rates of PE and CVA (p=NS). Among CMASS pts with embolic events, 56% were on anticoagulation at time of event (59% NEO, 50% THR, p=0.61). Regarding CMASS morphology, emboli were 3-fold higher among intracavitary (IC) or highly mobile (HM) CMASS (IC: 25% vs 7%, p<0.001; HM: 38% vs 12%, p=0.001). Regarding location, right sided CMASS were associated with a 3–5 fold increase in PE (IC: 19% vs 6%; HM: 35% vs 7%, both p<0.001) and similar CVA events among left sided CMASS (IC: 17% vs. 6%, p=0.02; HM: 33% vs 6%, p=0.05). Embolic events were similar when partitioned based on quantitative LGE patterns between patients with and without embolic events. As for all-cause mortality, NEO on CMR conferred increased mortality than THR (HR 3.06 [CI=1.84–5.1], p<0.001) and matched controls (HR 2.08 [CI=1.42–3.04], p<0.001) during a median follow-up of 9.4 months [IQR 3.6–23.2]. Among NEO subgroups (Fig. 1B), survival was lower in patients with heterogeneous LGE patterns vs matched controls: the lowest survival in ME (p=0.002) suggests increased vascularity and tumor hypoxia/necrosis associated with aggressive tumors and hence larger lesions. Conclusions Among cancer patients, CMR-evidenced CMASS confers high short-term embolic risk, which are equivalently common between NEO and THR. Intra-cavitary location and increased mobility augment embolic risk irrespective of CMASS tissue properties whereas differential LGE patterns on CMR strongly impact prognosis. Funding Acknowledgement Type of funding source: None

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Mechanical Enhancement of Cytocompatible 3D Scaffolds, Consisting of Hydroxyapatite Nanocrystals and Natural Biomolecules, Through Physical Cross-Linking

Bioengineering ◽

10.3390/bioengineering7030096 ◽

2020 ◽

Vol 7 (3) ◽

pp. 96

Author(s):

Despoina Brasinika ◽

Elias P. Koumoulos ◽

Kyriaki Kyriakidou ◽

Eleni Gkartzou ◽

Maria Kritikou ◽

...

Keyword(s):

Elastic Modulus ◽

Cell Attachment ◽

Great Promise ◽

Porous Network ◽

Mechanical Reinforcement ◽

Experimental Conditions ◽

Tissue Properties ◽

Human Osteosarcoma Cells ◽

Hydroxyapatite Nanocrystals ◽

Physical Crosslinking

Bioinspired scaffolds mimicking natural bone-tissue properties holds great promise in tissue engineering applications towards bone regeneration. Within this work, a way to reinforce mechanical behavior of bioinspired bone scaffolds was examined by applying a physical crosslinking method. Scaffolds consisted of hydroxyapatite nanocrystals, biomimetically synthesized in the presence of collagen and l-arginine. Scaffolds were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), microcomputed tomography, and nanoindentation. Results revealed scaffolds with bone-like nanostructure and composition, thus an inherent enhanced cytocompatibility. Evaluation of porosity proved the development of interconnected porous network with bimodal pore size distribution. Mechanical reinforcement was achieved through physical crosslinking with riboflavin irradiation, and nanoindentation tests indicated that within the experimental conditions of 45% humidity and 37 °C, photo-crosslinking led to an increase in the scaffold’s mechanical properties. Elastic modulus and hardness were augmented, and specifically elastic modulus values were doubled, approaching equivalent values of trabecular bone. Cytocompatibility of the scaffolds was assessed using MG63 human osteosarcoma cells. Cell viability was evaluated by double staining and MTT assay, while attachment and morphology were investigated by SEM. The results suggested that scaffolds provided a cell friendly environment with high levels of viability, thus supporting cell attachment, spreading and proliferation.

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Publisher Correction: Diattenuation Imaging reveals different brain tissue properties

Scientific Reports ◽

10.1038/s41598-019-42189-8 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Miriam Menzel ◽

Markus Axer ◽

Katrin Amunts ◽

Hans De Raedt ◽

Kristel Michielsen

Keyword(s):

Brain Tissue ◽

Tissue Properties

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Effect of Bone Tumor and Osteoporosis on Mechanical Properties of Bone and Bone Tissue Properties: A Finite Element Study

Volume 10: Mechanics of Solids and Structures, Parts A and B ◽

10.1115/imece2007-42389 ◽

2007 ◽

Author(s):

Vipul P. Gohil ◽

Paul K. Canavan ◽

Hamid Nayeb-Hashemi

Keyword(s):

Mechanical Properties ◽

Finite Element ◽

Bone Density ◽

Bone Tissue ◽

Bone Tumor ◽

Cellular Structure ◽

Bone Tumors ◽

World Health ◽

Tissue Stiffness ◽

Tissue Properties

This research is aimed to study the variations in the biomechanical behavior of bone and bone tissues with osteoporosis and bone tumors. Osteoporosis and bone tumors reduce the mechanical strength of bone, which creates a greater risk of fracture. In the United States alone, ten million individuals, eight million of whom are women, are estimated to already have osteoporosis, and almost 34 million more are estimated to have low bone mass (osteopenia) placing them at increased risk for osteoporosis. World Health Organization defines osteopenia, as a bone density between one and two and a half standard deviations (SD) below the bone density of a normal young adult. (Osteoporosis is defined as 2.5 SD or more below that reference point.). Together, osteoporosis and osteopenia are expected to affect an estimated 52 million women and men age 50 and older by 2010, and 61 million by 2020. The current medical cost of osteoporosis total is nearly about $18 billion in the U.S. each year. There is a dearth of literature that addresses the effects of osteoporosis on bone tissue properties. Furthermore, there are few studies published related to the effect of bone tumors such as Adamantinoma of long bones, Aneurysmal bone cyst, Hemangioma and others on overall behavior of bone. To understand the variations in bio-mechanical properties of internal tissues of bone with osteoporosis and bone tumor, a 2D finite element (FE) model of bone is developed using ANSYS 9.0 ® (ANSYS Inc., Canonsburg, PA). Trabecular bone is modeled using hexagonal and voronoi cellular structure. This finite element model is subjected to change in BVF (bone volume fraction) and bone architecture caused by osteoporosis. The bone tumor is modeled as finer multi-cellular structure and the effects of its size, location, and property variation of tumor on overall bone behavior are studied. Results from this analysis and comparative data are used to determine behavior of bone and its tissue over different stage of osteoporosis and bone tumor. Results indicate that both bone tumor and osteoporosis significantly change the mechanical properties of the bone. The results show that osteoporosis increases the bone tissue stiffness significantly as BVF reduces. Bone tissue stiffness is found to increase by 80 percent with nearly 55 percent reduction of BVF. The results and methods developed in this research can be implemented to monitor variation in bio-mechanical properties of bone up to tissue level during medication or to determine type and time for need of external support such as bracing.

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Site-matched assessment of structural and tissue properties of cortical bone using scanning acoustic microscopy and synchrotron radiation μCT

Physics in Medicine and Biology ◽

10.1088/0031-9155/51/3/017 ◽

2006 ◽

Vol 51 (3) ◽

pp. 733-746 ◽

Cited By ~ 63

Author(s):

K Raum ◽

I Leguerney ◽

F Chandelier ◽

M Talmant ◽

A Saïed ◽

...

Keyword(s):

Synchrotron Radiation ◽

Cortical Bone ◽

Acoustic Microscopy ◽

Scanning Acoustic Microscopy ◽

Tissue Properties

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On the Natural Lubrication of Synovial Joints: Normal and Degenerate

Journal of Lubrication Technology ◽

10.1115/1.3453003 ◽

1977 ◽

Vol 99 (2) ◽

pp. 163-172 ◽

Cited By ~ 28

Author(s):

Joseph M. Mansour ◽

Van C. Mow

Keyword(s):

Articular Cartilage ◽

Solid Phase ◽

Articular Surface ◽

Moving Load ◽

Frictional Resistance ◽

Elastic Solid ◽

Surface Load ◽

Two Phase ◽

Tissue Properties ◽

Synovial Joints

Fluid flow and mass transport mechanisms associated with articular cartilage function are important biomechanical processes of normal and pathological synovial joints. A three-layer permeable, two-phase medium of an incompressible fluid and a linear elastic solid are used to model the flow and deformational behavior of articular cartilage. The frictional resistance of the relative motion of the fluid phase with respect to the solid phase is given by a linear diffusive dissipation term. The subchondral bony substrate is represented by an elastic solid. The three-layer model of articular cartilage is chosen because of the known histological, ultrastructural, and biomechanical variations of the tissue properties. The calculated flow field shows that for material properties of normal healthy articular cartilage the tissue creates a naturally lubricated surface. The movement of the interstitial fluid at the surface is circulatory in manner, being exuded in front and near the leading half of the moving surface load and imbibed behind and near the trailing half of the moving load. The flow fields of healthy tissues are capable of sustaining a film of fluid at the articular surface whereas pathological tissues cannot.

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Bioprinted Nanoparticles for Tissue Engineering Applications

ASME 2009 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2009-206760 ◽

2009 ◽

Author(s):

Kivilcim Buyukhatipoglu ◽

Robert Chang ◽

Wei Sun ◽

Alisa Morss Clyne

Keyword(s):

Tissue Engineering ◽

Tissue Growth ◽

Bioactive Components ◽

Engineering Applications ◽

Tissue Properties ◽

Native Tissue ◽

3D Architecture

Tissue engineering may require precise patterning of cells and bioactive components to recreate the complex, 3D architecture of native tissue. However, it is difficult to image and track cells and bioactive factors once they are incorporated into the tissue engineered construct. These bioactive factors and cells may also need to be moved during tissue growth in vitro or after implantation in vivo to achieve the desired tissue properties, or they may need to be removed entirely prior to implantation for biosafety concerns.

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