Accelerated 4D phase contrast MRI in skeletal muscle contraction.

Purpose: 3D time-resolved (4D) phase contrast MRI can be used to study muscle contraction. However, 3D coverage with sufficient spatiotemporal resolution can only be achieved by interleaved acquisitions during many repetitions of the motion task, resulting in long scan times. The aim of this study was to develop a compressed sensing accelerated 4D phase contrast MRI technique for quantification of velocities and strain rate of the muscles in the lower leg during active plantarflexion/dorsiflexion.

Accelerated 4D self-gated MRI of tibiofemoral kinematics.

Anatomical (static) magnetic resonance imaging (MRI) is the most useful imaging technique for the evaluation and assessment of internal derangement of the knee, but does not provide dynamic information and does not allow the study of the interaction of the different tissues during motion. As knee pain is often only experienced during dynamic tasks, the ability to obtain four-dimensional (4D) images of the knee during motion could improve the diagnosis and provide a deeper understanding of the knee joint. In this work, we present a novel approach for dynamic, high-resolution, 4D imaging of the freely moving knee without the need for external triggering.

A novel diffusion-tensor MRI approach for skeletal muscle fascicle length measurements.

Musculoskeletal (dys-)function relies for a large part on muscle architecture which can be obtained using Diffusion-Tensor MRI (DT-MRI) and fiber tractography. However, reconstructed tracts often continue along the tendon or aponeurosis when using conventional methods, thus overestimating fascicle lengths. In this study, we propose a new method for semiautomatic segmentation of tendinous tissue using tract density (TD).

Assessment of passive muscle elongation using Diffusion Tensor MRI: Correlation between fiber length and diffusion coefficients.

In this study we investigated the changes in fiber length and diffusion parameters as a consequence of passive lengthening and stretching of the calf muscles. We hypothesized that changes in radial diffusivity (RD) are caused by changes in the muscle fiber cross sectional area (CSA) as a consequence of lengthening and shortening of the muscle. Diffusion Tensor MRI (DT-MRI) measurements were made twice in five healthy volunteers, with the foot in three different positions (30° plantarflexion, neutral position and 15° dorsiflexion).

Noninvasive automated motion assessment of intestinal motility by continuously tagged MR imaging.

Purpose: To evaluate continuously tagged 3 Tesla MRI for monitoring glucagon-induced bowel motility changes in healthy volunteers.

Materials And Methods: After standardized oral bowel preparation, 10 healthy volunteers underwent a free-breathing, continuously tagged three-dimensional (3D) dynamic fast-field-echo (FFE), at a 3.36 Hz sampling frequency.

A scale space based algorithm for automated segmentation of single shot tagged MRI of shearing deformation.

Object: This study proposes a scale space based algorithm for automated segmentation of single-shot tagged images of modest SNR. Furthermore the algorithm was designed for analysis of discontinuous or shearing types of motion, i.e.

A novel MRI compatible soft tissue indentor and fibre Bragg grating force sensor.

MRI is an ideal method for non-invasive soft tissue mechanical properties investigation. This requires mechanical excitation of the body's tissues and measurement of the corresponding boundary conditions such as soft tissue deformation inside the MRI environment. However, this is technically difficult since load application and measurement of boundary conditions requires MRI compatible actuators and sensors.

Validation of continuously tagged MRI for the measurement of dynamic 3D skeletal muscle tissue deformation.

Purpose: Typically spatial modulation of the magnetization (SPAMM) tagged magnetic resonance imaging (MRI) requires many repeated motion cycles limiting the applicability to highly repeatable tissue motions only. This paper describes the validation of a novel SPAMM tagged MRI and post-processing framework for the measurement of complex and dynamic 3D soft tissue deformation following just three motion cycles. Techniques are applied to indentation induced deformation measurement of the upper arm and a silicone gel phantom.

Use of continuously MR tagged imaging for automated motion assessment in the abdomen: a feasibility study.

Purpose: To investigate the feasibility of measuring motion in the abdomen using a continuously tagged magnetic resonance imaging sequence.

Materials And Methods: To assess (nonperiodic) motion in the abdomen, a nontriggered, continuously tagged transient field echo (TFE) sequence was implemented that acquires one complete 3D dataset per prepulse after a fixed delay. In postprocessing, a frequency analysis approach was developed for compact reviewing of the data and noise suppression.

Validation of SPAMM tagged MRI based measurement of 3D soft tissue deformation.

Purpose: This study presents and validates a novel (non-ECG-triggered) MRI sequence based on spatial modulation of the magnetization (SPAMM) to noninvasively measure 3D (quasistatic) soft tissue deformations using only six acquisitions (three static and three indentations). In the current SPAMM tagged MRI approaches, data are typically constructed from many repeated motion cycles. This has so far restricted its application to the measurement of highly repeatable and periodic movements (e.