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415 results on '"Link, T. M."'

4. Automated 3D trabecular bone structure analysis of the proximal femur—prediction of biomechanical strength by CT and DXA

Author

Baum, T., Carballido-Gamio, J., Huber, M. B., Müller, D., Monetti, R., Räth, C., Eckstein, F., Lochmüller, E. M., Majumdar, S., Rummeny, E. J., Link, T. M., and Bauer, J. S.

Subjects
Medicine & Public Health, Rheumatology, Endocrinology, Gynecology, Orthopedics, Computed tomography, Failure load, Osteoporosis, Proximal femur, Trabecular bone structure
Abstract

The standard diagnostic technique for assessing osteoporosis is dual X-ray absorptiometry (DXA) measuring bone mass parameters. In this study, a combination of DXA and trabecular structure parameters (acquired by computed tomography [CT]) most accurately predicted the biomechanical strength of the proximal femur and allowed for a better prediction than DXA alone.An automated 3D segmentation algorithm was applied to determine specific structure parameters of the trabecular bone in CT images of the proximal femur. This was done to evaluate the ability of these parameters for predicting biomechanical femoral bone strength in comparison with bone mineral content (BMC) and bone mineral density (BMD) acquired by DXA as standard diagnostic technique.One hundred eighty-seven proximal femur specimens were harvested from formalin-fixed human cadavers. BMC and BMD were determined by DXA. Structure parameters of the trabecular bone (i.e., morphometry, fuzzy logic, Minkowski functionals, and the scaling index method [SIM]) were computed from CT images. Absolute femoral bone strength was assessed with a biomechanical side-impact test measuring failure load (FL). Adjusted FL parameters for appraisal of relative bone strength were calculated by dividing FL by influencing variables such as body height, weight, or femoral head diameter.The best single parameter predicting FL and adjusted FL parameters was apparent trabecular separation (morphometry) or DXA-derived BMC or BMD with correlations up to r = 0.802. In combination with DXA, structure parameters (most notably the SIM and morphometry) added in linear regression models significant information in predicting FL and all adjusted FL parameters (up to R adj = 0.872) and allowed for a significant better prediction than DXA alone.A combination of bone mass (DXA) and structure parameters of the trabecular bone (linear and nonlinear, global and local) most accurately predicted absolute and relative femoral bone strength.

Published
2010

5. Automated simulation of areal bone mineral density assessment in the distal radius from high-resolution peripheral quantitative computed tomography

Author

Burghardt, A. J., Kazakia, G. J., Link, T. M., and Majumdar, S.

Subjects
Medicine & Public Health, Rheumatology, Endocrinology, Gynecology, Orthopedics, Bone mineral density, DXA, HR-pQCT, Osteoporosis, Simulation
Abstract

An automated image processing method is presented for simulating areal bone mineral density measures using high-resolution peripheral quantitative computed tomography (HR-pQCT) in the ultra-distal radius. The accuracy of the method is validated against clinical dual X-ray absorptiometry (DXA). This technique represents a useful reference to gauge the utility of novel 3D quantification methods applied to HR-pQCT in multi-center clinical studies and potentially negates the need for separate forearm DXA measurements.Osteoporotic status is primarily assessed by measuring areal bone mineral density (aBMD) using 2D dual X-ray absorptiometry (DXA). However, this technique does not sufficiently explain bone strength and fracture risk. High-resolution peripheral quantitative computed tomography (HR-pQCT) has been introduced as a method to quantify 3D bone microstructure and biomechanics. In this study, an automated method is proposed to simulate aBMD measures from HR-pQCT distal radius images.A total of 117 subject scans were retrospectively analyzed from two clinical bone quality studies. The distal radius was imaged by HR-pQCT and DXA on one of two devices (Hologic or Lunar). Areal BMD was calculated by simulation from HR-pQCT images (aBMDsim) and by standard DXA analysis (aBMDdxa).The reproducibility of the simulation technique was 1.1% (root mean-squared coefficient of variation). HR-pQCT-based aBMDsim correlated strongly to aBMDdxa (Hologic: R 2 = 0.82, Lunar: R 2 = 0.87), though aBMDsim underestimated aBMDdxa for both DXA devices (p

Published
2009

6. MR imaging of therapy-induced changes of bone marrow

Author

Daldrup-Link, H E, Henning, T, and Link, T M

Subjects
bone marrow, treatment effects, MR imaging, contrast agents
Abstract

MR imaging of bone marrow infiltration by hematologic malignancies provides non-invasive assays of bone marrow cellularity and vascularity to supplement the information provided by bone marrow biopsies. This article will review the MR imaging findings of bone marrow infiltration by hematologic malignancies with special focus on treatment effects. MR imaging findings of the bone marrow after radiation therapy and chemotherapy will be described. In addition, changes in bone marrow microcirculation and metabolism after anti-angiogenesis treatment will be reviewed. Finally, new specific imaging techniques for the depiction of regulatory events that control blood vessel growth and cell proliferation will be discussed. Future developments are directed to yield comprehensive information about bone marrow structure, function and microenvironment.

Published
2007

11. Subject‐specific biomechanical analysis to estimate locations susceptible to osteoarthritis:finite element modeling and MRI follow-up of ACL reconstructed patients

Author

Bolcos, P. O. (Paul O.), Mononen, M. E. (Mika E.), Roach, K. E. (Koren E.), Tanaka, M. S. (Matthew S.), Suomalainen, J. (Juha‐Sampo), Mikkonen, S. (Santtu), Nissi, M. J. (Mikko J.), Töyräs, J. (Juha), Link, T. M. (Thomas M.), Souza, R. B. (Richard B.), Majumdar, S. (Sharmila), Ma, C. B. (C. Benjamin), Li, X. (Xiaojuan), and Korhonen, R. K. (Rami K)

Subjects
osteoarthritis—posttraumatic, reconstruction, finite eelement analysis, cartilage, gait, biomechanics
Abstract

The aims of this case-control study were to: (1) Identify cartilage locations and volumes at risk of osteoarthritis (OA) using subject-specific finite element (FE) models; (2) Quantify the relationships between the simulated biomechanical parameters and T₂ and T1ρ relaxation times of magnetic resonance imaging (MRI). We created subject-specific FE models for seven patients with anterior cruciate ligament (ACL) reconstruction and six controls based on a previous proof-of-concept study. We identified locations and cartilage volumes susceptible to OA, based on maximum principal stresses and absolute maximum shear strains in cartilage exceeding thresholds of 7 MPa and 32%, respectively. The locations and volumes susceptible to OA were compared qualitatively and quantitatively against 2-year longitudinal changes in T₂ and T1ρ relaxation times. The degeneration volumes predicted by the FE models, based on excessive maximum principal stresses, were significantly correlated (r = 0.711, p

Published
2022

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