Britta Schneider

Fast phase contrast cardiac magnetic resonance imaging: improved assessment and analysis of left ventricular wall motion.

To evaluate the use of CINE phase contrast magnetic resonance imaging (MRI) to assess and characterize left ventricular wall motion by two‐ or three‐directional velocity vector fields that reflect the temporal evolution of myocardial velocities over the whole cardiac cycle.

Measurement of Left Ventricular Velocities: Phase Contrast MRI Velocity Mapping Versus Tissue-Doppler-Ultrasound in Healthy Volunteers

The aim of this study was the comparison of phase contrast magnetic resonance imaging (PCMRI) measurements of left ventricular velocities in a physiological in vivo setting with tissue-Doppler-ultrasound (tissue Doppler imaging: TDI) data in healthy volunteers. Images were acquired in short axis view using a flow compensated black blood k-space segmented gradient echo sequence. Velocity encoding was performed by adding a bipolar gradient after each rf-pulse to the otherwise identical pulse sequences. Full in-plane velocity information of the moving heart was obtained in 16 heartbeats within one breath-hold measurement. Twenty-nine healthy volunteers (mean age=25 years) were examined with both imaging modalities. Both PCMRI and TDI demonstrate a biphasic profile of radial velocities over the cardiac cycle. Intraindividual comparison of left ventricular velocity data acquired using PCMRI and TDI show a very good correspondence with r-values of 0.97. The in vivo study in 29 healthy volunteers demonstrates a high validity of time-resolved phase contrast measurements for the analysis of left ventricular myocardial velocities.

Cardiac phase contrast gradient echo MRI: measurement of myocardial wall motion in healthy volunteers and patients

A number of methods have been proposed for the noninvasive measurement of myocardial wall motion. The paper describes a strategy for assessing myocardial motion based on the sensitivity of the phase of the MR-signal to motion using a breath-hold phase contrast technique. A motion-sensitized and a motion-compensated MR-signal are measured during successive scans. The difference between the two MR-signals is used to calculate myocardial velocity in all three spatial dimensions. Postprocessing includes the transformation of the measured velocities into an internal coordinate system of the left ventricle. Also various presentation modes and further processing of the received velocity information are provided including calculation of global motion parameters. We examined 20 patients suffering from myocardial infarction. The overall left ventricular motion can be characterized by appropriate parameters describing the rotation and contraction or expansion, respectively. Regional motional disturbances are visualized using parametric images. Contrary to the highly consistent interindividual data in normal volunteers, patients showed significant localized motion deficits.

Cardiac Phase Contrast Gradient Echo Mri: Characterization of Abnormal Left Ventricular Wall Motion in Patients with Ischemic Heart Disease

Purpose In our patient study, we examined the clinical usefulness of phase contrast velocity mapping for the detection and characterization of localized abnormalities of left ventricular motion. Materials and Methods Velocity encoding is based on the fact that motion in the presence of a magnetic field gradient causes a change of the phase of the MRI signal that is proportional to the velocity of tissue motion. Left ventricular motion was characterized by parameters describing rotation and contraction/dilatation, respectively. We examined 34 patients with localized abnormalities of left ventricular motion due to ischemic heart disease. Results Three patients could not be sufficiently evaluated due to technical problems including varying positions of the heart during successive breathhold periods. In 27 of the remaining 31 patients, MRI could demonstrate abnormal radial velocities that corresponded fully or partly with perfusion deficits in single photon emission computed tomography or positron emission tomography. The abnormalities were most pronounced in early diastole. Rotational velocities did not show any regional changes. Conclusion Our study showed that our technique is suitable for the detection and characterization of localized abnormalities of left ventricular motion in patients with ischemic heart disease.

MR Physics and Imaging of Phase Contrast MRI

In recent years cardiac magnetic resonance (MR) imaging has become an important method for diagnosis of heart disease not only for morphologic evaluation but also for the characterization of myocardial function. Noninvasive measurement of myocardial wall motion with MRI is a promising method for detection of the mechanical performance of the heart in order to identify abnormal motion and potentially infarcted areas of the left ventricle. Several methods for ventricular motion mapping have already been proposed. An extensive discussion of the various approaches is found in Ref.[l].