Cardiac Motion Extraction from Images by Filtering Estimation Based on a Biomechanical Model

Abstract Background Cardiac PET has recently found novel applications in coronary atherosclerosis imaging using [18F]NaF as a radiotracer, highlighting vulnerable plaques. However, the resulting uptakes are relatively small, and cardiac motion and respiration-induced movement of the heart can impair the reconstructed images due to motion blurring and attenuation correction mismatches. This study aimed to apply an MR-based motion compensation framework to [18F]NaF data yielding high-resolution motion-compensated PET and MR images. Methods Free-breathing 3-dimensional Dixon MR data were acquired, retrospectively binned into multiple respiratory and cardiac motion states, and split into fat and water fraction using a model-based reconstruction framework. From the dynamic MR reconstructions, both a non-rigid cardiorespiratory motion model and a motion-resolved attenuation map were generated and applied to the PET data to improve image quality. The approach was tested in 10 patients and focal tracer hotspots were evaluated concerning their target-to-background ratio, contrast-to-background ratio, and their diameter. Results MR-based motion models were successfully applied to compensate for physiological motion in both PET and MR. Target-to-background ratios of identified plaques improved by 7 ± 7%, contrast-to-background ratios by 26 ± 38%, and the plaque diameter decreased by −22 ± 18%. MR-based dynamic attenuation correction strongly reduced attenuation correction artefacts and was not affected by stent-related signal voids in the underlying MR reconstructions. Conclusions The MR-based motion correction framework presented here can improve the target-to-background, contrast-to-background, and width of focal tracer hotspots in the coronary system. The dynamic attenuation correction could effectively mitigate the risk of attenuation correction artefacts in the coronaries at the lung-soft tissue boundary. In combination, this could enable a more reproducible and reliable plaque localisation.

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Estimation of Human Center of Mass Position through the Inertial Sensors-Based Methods in Postural Tasks: An Accuracy Evaluation

Sensors ◽

10.3390/s21020601 ◽

2021 ◽

Vol 21 (2) ◽

pp. 601 ◽

Cited By ~ 1

Author(s):

Marco Germanotta ◽

Ilaria Mileti ◽

Ilaria Conforti ◽

Zaccaria Del Prete ◽

Irene Aprile ◽

...

Keyword(s):

Inertial Sensors ◽

Center Of Mass ◽

Correlation Coefficients ◽

Biomechanical Model ◽

Lower Limbs ◽

Accuracy Evaluation ◽

Postural Tasks ◽

Single Sensor ◽

Using Data ◽

Displacement Based

The estimation of the body’s center of mass (CoM) trajectory is typically obtained using force platforms, or optoelectronic systems (OS), bounding the assessment inside a laboratory setting. The use of magneto-inertial measurement units (MIMUs) allows for more ecological evaluations, and previous studies proposed methods based on either a single sensor or a sensors’ network. In this study, we compared the accuracy of two methods based on MIMUs. Body CoM was estimated during six postural tasks performed by 15 healthy subjects, using data collected by a single sensor on the pelvis (Strapdown Integration Method, SDI), and seven sensors on the pelvis and lower limbs (Biomechanical Model, BM). The accuracy of the two methods was compared in terms of RMSE and estimation of posturographic parameters, using an OS as reference. The RMSE of the SDI was lower in tasks with little or no oscillations, while the BM outperformed in tasks with greater CoM displacement. Moreover, higher correlation coefficients were obtained between the posturographic parameters obtained with the BM and the OS. Our findings showed that the estimation of CoM displacement based on MIMU was reasonably accurate, and the use of the inertial sensors network methods should be preferred to estimate the kinematic parameters.

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Non-rigid image registration using a modified fuzzy feature-based inference system for 3D cardiac motion estimation

Computer Methods and Programs in Biomedicine ◽

10.1016/j.cmpb.2021.106085 ◽

2021 ◽

Vol 205 ◽

pp. 106085

Author(s):

Monire Sheikh Hosseini ◽

Mahammad Hassan Moradi ◽

Mahdi Tabassian ◽

Jan D'hooge

Keyword(s):

Image Registration ◽

Motion Estimation ◽

Cardiac Motion ◽

Inference System ◽

Feature Based

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Stability as a constraint in sagittal plane human force exertion modeling

Occupational Ergonomics ◽

10.3233/oer-1998-1104 ◽

1998 ◽

Vol 1 (1) ◽

pp. 23-39

Author(s):

Carter J. Kerk ◽

Don B. Chaffin ◽

W. Monroe Keyserling

Keyword(s):

Muscle Strength ◽

Ankle Joint ◽

Coefficient Of Friction ◽

Sagittal Plane ◽

Biomechanical Model ◽

Whole Body ◽

The Stability ◽

Joint Center ◽

Static Conditions ◽

Stability Limits

The stability constraints of a two-dimensional static human force exertion capability model (2DHFEC) were evaluated with subjects of varying anthropometry and strength capabilities performing manual exertions. The biomechanical model comprehensively estimated human force exertion capability under sagittally symmetric static conditions using constraints from three classes: stability, joint muscle strength, and coefficient of friction. Experimental results showed the concept of stability must be considered with joint muscle strength capability and coefficient of friction in predicting hand force exertion capability. Information was gained concerning foot modeling parameters as they affect whole-body stability. Findings indicated that stability limits should be placed approximately 37 % the ankle joint center to the posterior-most point of the foot and 130 % the distance from the ankle joint center to the maximal medial protuberance (the ball of the foot). 2DHFEC provided improvements over existing models, especially where horizontal push/pull forces create balance concerns.

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An index for back pain risk assessment in nursery activities

Occupational Ergonomics ◽

10.3233/oer-2004-4405 ◽

2005 ◽

Vol 4 (4) ◽

pp. 281-290

Author(s):

Silvia Taloni ◽

Giovanni Carlo Cassavia ◽

Giuseppe Luca Ciavarro ◽

Giuseppe Andreoni ◽

Giorgio Cesare Santambrogio ◽

...

Keyword(s):

Back Pain ◽

Biomechanical Model ◽

Risk Level ◽

Individual Risk ◽

Industrialized Countries ◽

Good Correspondence ◽

Gold Standard Method ◽

Trunk Inclination ◽

Leg Flexion ◽

The One

Back pain is one of the most significant socioeconomic problem in industrialized countries. Its origin is multifactorial, including physical, psychosocial and individual risk factors. Among the working population, nursery teachers are highly exposed to back pain diseases, but not many studies have dealt with this problem. So a suitable quantitative index is proposed, based on an unobtrusive video-analysis of established motor-tasks. In particular five nursery teachers were asked to perform lifting and lowering movements placing their feet at two different distances from a weight (a toy pet loaded with 8 kg, simulating a child) with different strategies (flexed, partially flexed and extended legs). The index is based on the idea that a greater trunk inclination angle determines increased loads on the lumbar spine, and so an augmented probability of spinal disorders. To validate our protocol, the same data were analyzed through a 3D biomechanical model (gold standard method), which computes the loads on L3-L4 intervertebral disc. Data show a good correspondence between the risk level suggested by the index and the one indicated by the mechanical loads: the antero-posterior shearing forces and the values of index coherently increase with the reduction of leg flexion.

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Reduced biomechanical models for precision-cut lung-slice stretching experiments

Journal of Mathematical Biology ◽

10.1007/s00285-021-01578-2 ◽

2021 ◽

Vol 82 (5) ◽

Author(s):

Hannah J. Pybus ◽

Amanda L. Tatler ◽

Lowell T. Edgar ◽

Reuben D. O’Dea ◽

Bindi S. Brook

Keyword(s):

Smooth Muscle ◽

Muscle Contraction ◽

Ex Vivo ◽

Finite Thickness ◽

Biomechanical Model ◽

Local Stress ◽

Smooth Muscle Contraction ◽

Biomechanical Models ◽

Cytokine Activation ◽

Asymptotic Reduction

AbstractPrecision-cut lung-slices (PCLS), in which viable airways embedded within lung parenchyma are stretched or induced to contract, are a widely used ex vivo assay to investigate bronchoconstriction and, more recently, mechanical activation of pro-remodelling cytokines in asthmatic airways. We develop a nonlinear fibre-reinforced biomechanical model accounting for smooth muscle contraction and extracellular matrix strain-stiffening. Through numerical simulation, we describe the stresses and contractile responses of an airway within a PCLS of finite thickness, exposing the importance of smooth muscle contraction on the local stress state within the airway. We then consider two simplifying limits of the model (a membrane representation and an asymptotic reduction in the thin-PCLS-limit), that permit analytical progress. Comparison against numerical solution of the full problem shows that the asymptotic reduction successfully captures the key elements of the full model behaviour. The more tractable reduced model that we develop is suitable to be employed in investigations to elucidate the time-dependent feedback mechanisms linking airway mechanics and cytokine activation in asthma.

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