The ability to measure skeletal muscle motion with phase-contrast magnetic resonance (MR) imaging was tested with a motion phantom that simulated muscle activity. Quantitative analytic data on unidimensional, bidirectional skeletal muscle motion measured in vivo was obtained in four healthy volunteers. MR images of the subjects' forearms were obtained during flexion and extension of the fingers and of the anterior and posterior muscle compartments of the lower leg with various resistances to ankle dorsiflexion and plantar flexion. It was necessary to correct the data for the effects of eddy currents. In vitro evaluation of the technique was done by studying through-plane sinusoidal motion of solid objects. The largest error was underestimation of the peak excursion of 11.5 mm by 0.09 mm (the root mean square error for the cycle was 0.04 mm) In vivo experiments demonstrated the contraction of muscles in relation to each other. Data acquisition and analysis techniques must be refined, but measuring skeletal muscle motion with phase-contrast MR imaging should enhance the understanding of bioengineering fundamentals and muscular changes in disease and adaptation.
"To do this we used cine-PC MRI. Cine-PC MRI is a dynamic imaging technique that requires numerous cycles of repeated motion to acquire multiple time frames of composite images representing one motion cycle (Drace and Pelc, 1994b; Pelc et al., 1991; Sheehan et al., 1998). The cine- PC pulse sequence encodes the three-dimensional tissue velocities in the phase of the MR signal; thus, for each of 24 frames in a cine-PC MRI movie, we obtained one anatomy image and three orthogonal direction velocity images. "
[Show abstract][Hide abstract] ABSTRACT: Rectus femoris transfer surgery is performed to convert the rectus femoris muscle from a knee extensor to a knee flexor. In this surgery, the distal tendon of the rectus femoris is detached from the patella and reattached to one of the knee flexor tendons. The outcomes of this procedure are variable, and it is not known if the surgery successfully converts the muscle to a knee flexor. We measured the motion of muscle tissue within the rectus femoris and vastus intermedius during knee extension in 10 unimpaired control subjects (10 limbs) and 6 subjects (10 limbs) after rectus femoris transfer using cine phase-contrast magnetic resonance imaging. Displacements of the vastus intermedius during knee extension were similar between control and tendon transfer subjects. In the control subjects, the rectus femoris muscle consistently moved in the direction of the knee extensors and displaced more than the vastus intermedius. The rectus femoris also moved in the direction of the knee extensors in the tendon transfer subjects; however, the transferred rectus femoris displaced less than the vastus intermedius. These results suggest that the rectus femoris is not converted to a knee flexor after its distal tendon is transferred to the posterior side of the knee, but its capacity for knee extension is diminished by the surgery. r 2002 Elsevier Science Ltd. All rights reserved.
Journal of Biomechanics 08/2002; 35(8). DOI:10.1016/S0021-9290(02)00048-9 · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Phase-contrast magnetic resonance velocity-encoding techniques were used to track two-dimensional movement of skeletal muscle tissue. Axial and longitudinal planes in the forearms of five healthy volunteers were imaged during cyclic flexion and extension of the fingers, and the resulting data were used to plot the trajectories of the motion of pieces of muscle tissue. A phantom that produced complex two-dimensional trajectories validated the accuracy of the imaging and analysis techniques; after adjustments for phase errors, two-dimensional trajectories were tracked with an root-mean-square error of 0.1 cm. Preliminary results indicate that velocity-encoded image data can characterize motion trajectories and that refinements in data acquisition and analysis techniques may make it possible to correlate the movements of different regions within a muscle, characterize muscle contraction, and quantify longitudinal strain. This ability to track velocity vectors may provide a foundation for quantitative analysis of muscle motion.
Journal of Magnetic Resonance Imaging 11/1994; 4(6):773-8. DOI:10.1002/jmri.1880040606 · 3.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The accuracy of myocardial motion measurements, computed from cine-phase contrast (cine-PC) magnetic resonance (MR) velocity data, was compared with directly visualized motion of MR signal voids caused by implanted tantalum markers in anesthetized dogs.
Magnetic resonance imaging (MRI) data were electrocardiogram-gated and divided into 16 phases per cardiac cycle. Myocardial trajectories as a function of time in the cardiac cycle were measured using both methods for four to seven markers in each of eight animals.
The peak observed in-plane excursion was 4.0 +/- 2.1 mm. The average deviation between displacements derived from velocity data versus displacements visualized directly was 1.1 +/- 0.7 mm (27.5% of the peak displacement). The difference was less if three separate MR scans were used to measure each velocity component in the cine-PC method. This improvement is probably caused by improved temporal resolution.
Cine-PC MRI offers a noninvasive method for accurate quantification of myocardial motion.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.