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Cine Images (cine + image)
Selected AbstractsHigh temporal resolution SSFP cine MRI for estimation of left ventricular diastolic parametersJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Ramkumar Krishnamurthy MS Abstract Purpose: To obtain high temporal resolution (HTR) magnetic resonance (MR) steady-state free-precession (SSFP) cine cardiac images by using multichannel radiofrequency (RF) hardware and parallel imaging techniques; to study the effect of temporal resolution; and to compare the derived left ventricular (LV) diastolic filling parameters with echocardiographic results. Materials and Methods: HTR images were acquired in 13 healthy volunteers using a 1.5 T scanner with 32 RF channels and sensitivity encoding (SENSE) and k-t broad-use linear-acquisition speedup technique (k-t BLAST) imaging techniques. LV diastolic parameters were calculated and compared to conventional echocardiographic indices such as the isovolumic relaxation time (IVRT) and E/A ratio. The need for HTR was assessed and the MR results were compared with echocardiographic results. Results: The HTR (,6-ms) images yielded higher peak filling rates, peak ejection rates, and peak atrial filling rates. A progressive decline in filling and ejection rates was observed with worsening temporal resolution. The IVRTs and E/A ratios measured with MR versus echocardiography were in broad agreement. Also, SENSE and k-t BLAST yielded similar diastolic functional parameters. Conclusion: With SENSE or k-t BLAST and modern hardware, HTR cine images can be obtained. The lower temporal resolutions (30,50 ms) used in clinical practice reduce LV filling rates by ,30% and may hinder characterization of transient phenomena such as the IVRT. J. Magn. Reson. Imaging 2010;31:872,880. ©2010 Wiley-Liss, Inc. [source] Patient motion correction for multiplanar, multi-breath-hold cardiac cine MR imagingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2007Piotr J. Slomka PhD Abstract Purpose To correct for spatial misregistration of multi-breath-hold short-axis (SA), two-chamber (2CH), and four-chamber (4CH) cine cardiac MR (CMR) images caused by respiratory and patient motion. Materials and Methods Twenty CMR studies from consecutive patients with separate breath-hold 2CH, 4CH, and SA 20-phase cine images were considered. We automatically registered the 2CH, 4CH, and SA images in three dimensions by minimizing the cost function derived from plane intersections for all cine phases. The automatic alignment was compared with manual alignment by two observers. Results The processing time for the proposed method was <20 seconds, compared to 14,24 minutes for the manual correction. The initial plane displacement identified by the observers was 2.8 ± 1.8 mm (maximum = 14 mm). A displacement of ,5 mm was identified in 15 of 20 studies. The registration accuracy (defined as the difference between the automatic parameters and those obtained by visual registration) was 1.0 ± 0.9 mm, 1.1 ± 1.0 mm, 1.1 ± 1.2 mm, and 2.0 ± 1.8 mm for 2CH-4CH alignment and SA alignment in the mid, basal, and apical regions, respectively. The algorithm variability was higher in the apex (2.0 ± 1.9 mm) than in the mid (1.4 ± 1.4 mm) or basal (1.2 ± 1.2 mm) regions (ANOVA, P < 0.05). Conclusion An automated preprocessing algorithm can reduce spatial misregistration between multiple CMR images acquired at different breath-holds and plane orientations. J. Magn. Reson. Imaging 2007;25:965,973. © 2007 Wiley-Liss, Inc. [source] High spatial and temporal resolution cardiac cine MRI from retrospective reconstruction of data acquired in real time using motion correction and resortingMAGNETIC RESONANCE IN MEDICINE, Issue 6 2009Peter Kellman Abstract Cine MRI is used for assessing cardiac function and flow and is typically based on a breath-held, segmented data acquisition. Breath holding is particularly difficult for patients with congestive heart failure or in pediatric cases. Real-time imaging may be used without breath holding or ECG triggering. However, despite the use of rapid imaging sequences and accelerated parallel imaging, real-time imaging typically has compromised spatial and temporal resolution compared with gated, segmented breath-held studies. A new method is proposed that produces a cardiac cine across the full cycle, with both high spatial and temporal resolution from a retrospective reconstruction of data acquired over multiple heartbeats during free breathing. The proposed method was compared with conventional cine images in 10 subjects. The resultant image quality for the proposed method (4.2 ± 0.4) without breath holding or gating was comparable to the conventional cine (4.4 ± 0.5) on a five-point scale (P = n.s.). Motion-corrected averaging of real-time acquired cardiac images provides a means of attaining high-quality cine images with many of the benefits of real-time imaging, such as free-breathing acquisition and tolerance to arrhythmias. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Circumferential strain in the wall of the common carotid artery: Comparing displacement-encoded and cine MRI in volunteersMAGNETIC RESONANCE IN MEDICINE, Issue 1 2008Alexander P. Lin The walls of conduit arteries undergo cyclic stretching from the periodic fluctuation of arterial pressure. Atherosclerotic lesions have been shown to localize to regions of excessive stretching of the arterial wall. We employed a displacement encoding with stimulated echoes (DENSE) sequence to image the motion of the common carotid artery wall and map the two-dimensional (2D) circumferential strain. The sequence utilizes a fully-balanced steady-state free-precession (SSFP) readout with 0.60 mm in-plane resolution. Preliminary results in volunteers at 1.5T (N = 4) and 3.0T (N = 17) are compared to measurements of the lumen circumference from cine images. The agreement between the two independent measurements at both field strengths (P , 0.001) supports the use of DENSE as a means to map the pulsatile strain in the carotid artery wall. Magn Reson Med 60:8,13, 2008. © 2008 Wiley-Liss, Inc. [source] Fully automatic, retrospective enhancement of real-time acquired cardiac cine MR images using image-based navigators and respiratory motion-corrected averagingMAGNETIC RESONANCE IN MEDICINE, Issue 4 2008Peter Kellman Abstract Real-time imaging may be clinically important in patients with congestive heart failure, arrhythmias, or in pediatric cases. However, real-time imaging typically has compromised spatial and temporal resolution compared with gated, segmented studies. To combine the best features of both types of imaging, a new method is proposed that uses parallel imaging to improve temporal resolution of real-time acquired images at the expense of signal-to-noise ratio (SNR), but then produces an SNR-enhanced cine by means of respiratory motion-corrected averaging of images acquired in real-time over multiple heartbeats while free-breathing. The retrospective processing based on image-based navigators and nonrigid image registration is fully automated. The proposed method was compared with conventional cine images in 21 subjects. The resultant image quality for the proposed method (3.9 ± 0.44) was comparable to the conventional cine (4.2 ± 0.99) on a 5-point scale (P = not significant [n.s.]). The conventional method exhibited degraded image quality in cases of arrhythmias whereas the proposed method had uniformly good quality. Motion-corrected averaging of real-time acquired cardiac images provides a means of attaining high-quality cine images with many of the benefits of real-time imaging, such as free-breathing acquisition and tolerance to arrhythmias. Magn Reson Med, 2007. © 2008 Wiley-Liss, Inc. [source] Phase-sensitive cardiac tagging,REALTAGMAGNETIC RESONANCE IN MEDICINE, Issue 1 2007J. Andrew Derbyshire Abstract Fully inverting spins, instead of merely saturating them, provides superior contrast for tagging procedures. The resulting improvement in tag contrast-to-noise ratio (CNR) yields higher-precision tag detection. Also, thinner slices and hence reduced tag separations can be employed, providing displacement and strain measurements with better spatial resolution. Alternatively, the improved tag contrast can be used to obtain cine images covering a greater portion of the cardiac cycle. The use of standard magnitude reconstruction for images of these inversion tags causes rectification of the negative-valued signals from the tags, confounding the image interpretation. Therefore, a phase-sensitive reconstruction scheme of the inverted tags must be employed. Here we demonstrate the implementation of inverted tags with phase-sensitive reconstruction in a ramped-flip-angle, steady-state free precession (SSFP) sequence. Magn Reson Med 58:206,210, 2007. © 2007 Wiley-Liss, Inc. [source] Blood velocity assessment using 3D bright-blood time-resolved magnetic resonance angiographyMAGNETIC RESONANCE IN MEDICINE, Issue 3 2006Sylvain Miraux Abstract Blood velocity is a functional parameter that is not easily assessed noninvasively, especially in small animals. A new noninvasive method that uses magnetic resonance angiography (MRA) to measure blood flows is proposed. This method is based on the time-of-flight (TOF) phenomenon. By initially suppressing the signal from the stationary spins in the area of interest, it is possible to sequentially visualize only the signal from the moving spins entering a given volume. With this method, 3D cine images of the blood flow can be generated by positive contrast, with unparalleled spatial (<200 ,m) and temporal resolutions (<10 ms/image). As a result, it is possible to measure flow in sinuous paths. The present method was applied in vivo to measure the blood velocity in mouse carotid arteries. Because of its robustness and simplicity of implementation, this method has numerous potential applications for fundamental studies in small animal models. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] | ||||||||||