Biomedical subjects

Anneriet M Heemskerk

Publications and source records attributed to Anneriet M Heemskerk.

3 recordsLinked to original sources

PubMed2006

DTI-based assessment of ischemia-reperfusion in mouse skeletal muscle.

Diffusion tensor imaging (DTI) is frequently applied to characterize the microscopic geometrical properties of tissue. To establish whether and how diffusion MRI responds to transient ischemia of skeletal muscle, we studied the effects of ischemia and reperfusion using DTI and T2-weighted MRI before and during ischemia and up to 24 hr after reperfusion. Ischemia was induced by 50 min of hindlimb occlusion with or without dorsal flexor stimulation. During ischemia the apparent diffusion coefficient (ADC) tended to decrease (up to 15%), whereas the fractional anisotropy (FA) and T2 showed a varied response depending on the protocol and muscle type. During reperfusion the ADC and T2 initially increased and subsequently renormalized for the occlusion protocol. For the occlusion plus stimulation (OS) protocol, the FA was decreased by 13% and the ADC and T2 were increased by 20% and 57%, respectively, after 24 hr in the stimulated muscle complex. In the latter tissue the three DTI eigenvalues gradually increased upon reperfusion. The smallest eigenvalue (lambda3) showed the largest relative increase. Changes in DTI indices in the reperfusion phases followed a similar time course as the changes in T2. The changes in MR indices after 24 hr correlated with the tissue damage quantified with histology. The highest correlation was observed for lambda3 (R2 = 0.81). This study shows that DTI can be used to assess ischemia-induced damage to skeletal muscle.

Analysis of Variance↗

PubMed2005

Determination of mouse skeletal muscle architecture using three-dimensional diffusion tensor imaging.

Muscle architecture is the main determinant of the mechanical behavior of skeletal muscles. This study explored the feasibility of diffusion tensor imaging (DTI) and fiber tracking to noninvasively determine the in vivo three-dimensional (3D) architecture of skeletal muscle in mouse hind leg. In six mice, the hindlimb was imaged with a diffusion-weighted (DW) 3D fast spin-echo (FSE) sequence followed by the acquisition of an exercise-induced, T(2)-enhanced data set. The data showed the expected fiber organization, from which the physiological cross-sectional area (PCSA), fiber length, and pennation angle for the tibialis anterior (TA) were obtained. The values of these parameters ranged from 5.4-9.1 mm(2), 5.8-7.8 mm, and 21-24 degrees , respectively, which is in agreement with values obtained previously with the use of invasive methods. This study shows that 3D DT acquisition and fiber tracking is feasible for the skeletal muscle of mice, and thus enables the quantitative determination of muscle architecture.

Animals↗

PubMed2003

An MR-compatible device for the in situ assessment of isometric contractile performance of mouse hind-limb ankle flexors.

The goal of the present study was to develop and evaluate an isometric dynamometer for measuring mouse ankle flexor torque after electric stimulation of the nerve. The dynamometer was to be used within an magnetic resonance (MR) apparatus and should require minimal surgical intervention. To quantify the effect of the magnetic field on contractile parameters, measurements were performed both outside and inside the MR apparatus. The effect of magnetic field gradient switching that accompanies rapid MR scanning was tested also. The set-up required no surgical intervention except for chronic implantation of an electrode. The dynamometer has a high mechanical frequency response (270 Hz). Measured muscle strengths were identical outside and inside the MR scanner. However, during fast magnetic field gradient switching, the variability increased and the measured strength decreased slightly (7%). The noise level of the dynamometer (0.02-0.03 N.mm) was low compared with the strength of the dorsal flexors (2 N.mm). Fast gradient switching increased the noise level (0.07 N.mm). The dynamometer had no observable adverse effects on the quality of the MR images of the mouse hind limb. We conclude that the dynamometer enables accurate measurements of mechanical muscle performance during exercise protocols within an MR apparatus under physiological conditions.

Animals↗