Phase Contrast Cine Magnetic Resonance Imaging

Article (PDF Available)inMagnetic resonance quarterly 7(4):229-54 · November 1991with98 Reads
Source: PubMed
Abstract
Phase contrast cine magnetic resonance imaging (MRI) combines the flow-dependent contrast of phase contrast MRI with the ability of cardiac cine imaging to produce images throughout the cardiac cycle. Two pulse sequence types are used for sensitivity to flow in one direction, whereas four are needed for sensitivity in all directions. Several alternatives for synchronization of the data to the cardiac cycle exist. Retrospectively interpolated methods can image the entire cardiac cycle efficiently. Rapid interleaving of the various sequence types ensures immunity to motion misregistration. The technique produces images in which contrast is related to flow velocity as well as magnitude images such as those of conventional cine MRI. The data can be interpreted qualitatively to demonstrate the presence, magnitude, and direction of flow, and quantitatively to provide estimates of flow velocity, volume flow rate, and displaced volumes. Phase contrast cine MRI is helpful in the diagnosis of aortic dissections, in the study of flow distributions in large vessels such as pulmonary arteries, as well as in smaller vessels such as carotid and basilar arteries, and in the evaluation of complex anatomical variants. Future developments are expected to reduce imaging time and expand the quantitative applications.
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    • "Completely non-invasive determination of stroke volume with echocardiography and Doppler recording is versatile and readily available at the bedside, but the calculation rests on a number of assumptions such as a circular geometry of the left ventricular outflow tract [2] and a spatially flat flow profile [3]. MRI phase-contrast flow measurement has been regarded as the gold standard since it can address issues of temporally as well as spatially varying flows [4, 5]. However, MRI velocity measurements are sensitive to magnetic field inhomogeneities, concomitant gradient effects, and eddy current effects that are only partly compensated for [6]. "
    [Show abstract] [Hide abstract] ABSTRACT: Magnetic Resonance Imaging (MRI) 2D phase-contrast flow measurement has been regarded as the gold standard in blood flow measurements and can be performed with free breathing or breath held techniques. We hypothesized that the accuracy of flow measurements obtained with segmented phase-contrast during breath holding, and in particular higher number of k-space segments, would be non-inferior compared to navigator phase-contrast. Volumes obtained from anatomic segmentation of cine MRI and Doppler echocardiography were used for additional reference. Forty patients, five women and 35 men, mean age 65 years (range 53–80), were randomly selected and consented to the study. All underwent EKG-gated cardiac MRI including breath hold cine, navigator based free-breathing phase-contrast MRI and breath hold phase-contrast MRI using k-space segmentation factors 3 and 5, as well as transthoracic echocardiography within 2 days. In navigator based free-breathing phase-contrast flow, mean stroke volume and cardiac output were 79.7 ± 17.1 ml and 5071 ± 1192 ml/min, respectively. The duration of the acquisition was 50 ± 6 s. With k-space segmentation factor 3, the corresponding values were 77.7 ml ± 17.5 ml and 4979 ± 1211 ml/min (p = 0.15 vs navigator). The duration of the breath hold was 17 ± 2 s. K-space segmentation factor 5 gave mean stroke volume 77.9 ± 16.4 ml, cardiac output 5142 ± 1197 ml/min (p = 0.33 vs navigator), and breath hold time 11 ± 1 s. Anatomical segmentation of cine gave mean stroke volume and cardiac output 91.2 ± 20.8 ml and 5963 ± 1452 ml/min, respectively. Echocardiography was reliable in 20 of the 40 patients. The mean diameter of the left ventricular outflow tract was 20.7 ± 1.5 mm, stroke volume 78.3 ml ± 15.2 ml and cardiac output 5164 ± 1249 ml/min. In forty consecutive patients with coronary heart disease, breath holding and segmented k-space sampling techniques for phase-contrast flow produced stroke volumes and cardiac outputs similar to those obtained with free-breathing navigator based phase-contrast MRI, using less time. The values obtained agreed fairly well with Doppler echocardiography while there was a larger difference when compared with anatomical volume determinations using SSFP (steady state free precession) cine MRI.
    Full-text · Article · Dec 2016
    • "The ability to measure velocities by flow encoded MRI was demonstrated by Moran [1] in 1983, shortly after MR was implemented for clinical imaging. Using this strategy flow encoding was implemented for 2D and 3D acquisition by Dumoulin [2, 3] and clinical applications for vascular flow imaging were expanded by Pelc et al [4] and Wigstrom et al [5]. However, general use of the flow imaging was limited by long acquisition times, complex implementation and motion artifacts. "
    [Show abstract] [Hide abstract] ABSTRACT: Recent advances in 4DFlow MRI (Phase Contrast MRA) acquisition and reconstruction enable high resolution exams to be obtained in practical imaging times. 4DFlow MRI provides images of vascular morphology and quantitative measurements of blood velocity throughout a 3D imaging volume. Hemodynamic parameters such as flow volume, relative wall shear stress, streamlines, vorticity and pressure gradients can be derived from the velocity data. The combination of anatomic vessel wall imaging, lumen visualization and physiologic data derived from accelerated 4DFlow MRI augments the characterization of intracranial arterial stenosis, aneurysms, vascular malformations and dural sinus pathology. This review provides an update for clinicians interested in 4DFlow MRI of the brain.
    Full-text · Article · Dec 2016
    • "Based on the physical relationship between a gradient-induced phase shift and the velocity of spins in a corresponding NMR [43] or MRI experiment [65] as well as initiated by early seminal applications [66][67][68], there is nowadays extensive clinical use of velocity-encoded phase-contrast techniques for quantitative MRI studies of blood flow. For relevant reviews see [69, 70]. "
    Full-text · Thesis · May 2016 · BMC Medical Imaging
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