Comparison of spiral and FLASH phase velocity mapping, with and without breath-holding, for the assessment of left and right coronary artery blood flow velocity

PURPOSE: To develop high temporal resolution coronary artery spiral phase velocity mapping sequences and to compare the results obtained with those from FLASH sequences. MATERIALS AND METHODS: Velocity curves were obtained in eight left and eight right coronary arteries using breath-hold interleaved spiral (BH_SP), free-breathing interleaved spiral (FB_SP), breath-hold segmented FLASH (BH_FL), and free-breathing FLASH (FB_FL) sequences. Spatial resolution, temporal resolution, and acquisition durations (cardiac cycles) were as follows-BH_SP: 0.9 mm x 0.9 mm, 30 msec, 20 cycles; FB_SP: 0.9 mm x 0.9 mm, 42 msec, 100 cycles; BH_FL: 0.9 mm x 1.8 mm, 70 msec (effective), 20 cycles; FB_FL: 0.9 mm x 1.8 mm, 30 msec, 480 cycles. Peak systolic, peak diastolic, and mean velocities were compared between sequences. RESULTS: For left and right arteries, the FB_SP velocity profiles closely followed those from the FB_FL sequence. By comparison, the BH_FL sequence failed to resolve the sharp peaks in the temporal velocity profiles of the right coronary artery, significantly underestimating the peak systolic (88 mm/second vs. 252 mm/second, P < 0.001), peak diastolic (114 mm/second vs. 153 mm/second, P < 0.01), and mean (56 mm/second vs. 93 mm/second, P < 0.001) velocities. For the less mobile left artery, the peak systolic, peak diastolic, and mean velocities were also underestimated by the BH_FL sequence, although this only reached statistical significance for the systolic peak (80 mm/second vs. 135 mm/second, P < 0.01), 142 mm/second vs. 168 mm/second, (P = ns), and 87 mm/second vs. 101 mm/second, (P = ns) respectively. CONCLUSION: We have shown that the FB_SP sequence developed agrees well with the FB_FL sequence, while the study duration is reduced by a factor of 10 for the same spatial resolution. By comparison, the BH_FL sequence underestimates flow velocities, particularly in the more mobile right coronary artery.     

Flow profiles in the left anterior descending and the right coronary artery assessed by MR velocity quantification: effects of through-plane and in-plane motion of the heart.

PURPOSE: The purpose of this work was to compare the temporal profiles of volume flow in the left anterior descending artery (LAD) and the right coronary artery (RCA) and to assess the effect of through-plane and in-plane myocardial motion. METHOD: In eight healthy volunteers, MR phase-difference velocity quantification was applied with prospective ECG triggering, pixel size of 1.16 x 0.98 mm2 (LAD) or 1.25 x 0.98 mm2 (RCA), velocity sensitivity of 40 cm/s, and data acquisition time window of 64 ms for LAD (3 ky lines per heartbeat) and 24 ms for RCA. In-plane motion was measured from the magnitude images. RESULTS: In the LAD, systolic peak and mean flow values were 0.94+/-0.28 and 0.30 +/-0.22 ml/s, respectively. Diastolic peak and mean flows were 2.42+/-0.56 and 1.38+/-0.43 ml/s. The systolic to diastolic ratio was 0.37+/-0.12 for peak flow and 0.22+/-0.15 for mean flow. Mean flow through the cardiac cycle was 59.1+/-15.0 ml/min. In the RCA, systolic peak and mean flow values were 1.96+/-0.69 and 0.74+/-0.31 ml/s, respectively. Diastolic peak and mean flows were 1.80+/-0.53 and 0.83+/-0.20 ml/s. The systolic to diastolic ratio was 0.97+/-0.58 for peak flow and 0.85+/-0.39 for mean flow. Mean flow through the cardiac cycle was 38.4+/-10.8 ml/min. The in-plane velocity of the coronary artery cross-section was 6.4+/-1.8 cm/s for the LAD and 14.9 +/-4.0 cm/s for the RCA (given by peak values in diastole). CONCLUSION: It is confirmed noninvasively with MR that the LAD shows a predominantly diastolic flow, whereas the RCA shows about equal flow values in systole and diastole. Through-plane motion correction is required for assessing the true flow patterns. The in-plane velocities of the coronary artery cross-sections imply a maximum data acquisition time window, estimated at 58 ms for the LAD and at 23 ms for the RCA.     

Assessment of flow in the right human coronary artery by magnetic resonance phase contrast velocity measurement: Effects of cardiac and respiratory motion

Flow in the human right coronary artery was determined using magnetic resonance phase contrast velocity quantification. Two methods were applied to reduce respiratory motion: imaging during breath holding, which is fast, and retrospective respiratory gating, which has a high temporal resolution (32 ms) in the cardiac cycle. Vessel cross-sectional area, through-plane velocity, and volume flow were determined in six healthy subjects. In-plane vessel displacement during the cardiac cycle, caused by cardiac contraction, was about 2–4 mm within a time frame of 32 ms in systole and early diastole. The motion resulted in blurring of images obtained during breath holding caused by the large acquisition time window (126 ms) within the cardiac cycle. Therefore, only with a high temporal resolution correct velocity images over the entire cardiac cycle could be obtained. The time- and cross-sectionally averaged velocity was 7 ± 2 cm/s, and the volume flow was 30 ± 10 ml/min.     

Heart motion adapted cine phase-contrast flow measurements through the aortic valve.

A method for magnetic resonance cine velocity mapping through heart valves with adaptation of both slice offset and angulation according to the motion of the valvular plane of the heart is presented. By means of a subtractive labeling technique, basal myocardial markers are obtained and automatically extracted for quantification of heart motion at the valvular level. The captured excursion of the basal plane is used to calculate the slice offset and angulation of each required time frame for cine velocity mapping. Through-plane velocity offsets are corrected by subtracting velocities introduced by basal plane motion from the measured velocities. For evaluation of the method, flow measurements downstream from the aortic valve were performed both with and without slice adaptation in 11 healthy volunteers and in four patients with aortic regurgitation. Maximum through-plane motion at the aortic root level as calculated from the labeled markers averaged 8.9 mm in the volunteers and 6.5 mm in the patients. The left coronary root was visible in 2-4 (mean: 2.2) time frames during early diastole when imaging with a spatially fixed slice. Time frames obtained with slice adaptation did not contain the coronary roots. Motion correction increased the apparent regurgitant volume by 5.7 +/- 0.4 ml for patients with clinical aortic regurgitation, for an increase of approximately 50%. The proposed method provides flow measurements with correction for through-plane motion perpendicular to the aortic root between the valvular annulus and the coronary ostia throughout the cardiac cycle. Magn Reson Med 42:970-978, 1999.     

MR velocity mapping of tricuspid flow: Correction for through-plane motion

We evaluated the effect of through-plane motion on tricuspid flow measurements performed with MR velocity mapping in nine normal subjects and 15 patients with possible right ventricular (RV) disease. Eight parameters of RV diastolic function were derived from the tricuspid flow measurements, both before and after a correction for through-plane motion. Measurements of E-peak, A-peak, and time-to-peak filling rate changed significantly after correction for through-plane motion (P < .05). Tricuspid flow as a marker of RV diastolic function should be corrected for the effect of throughplane motion to improve functional evaluation of the RV.     

The application of breath hold phase velocity mapping techniques to the measurement of coronary artery blood flow velocity: Phantom data and initial in vivo results

A segmented k-space breath hold phase velocity mapping technique has been developed for the study of coronary artery blood flow velocity. In vitro validation has been performed using a number of pulsatile flow phantoms and the accuracy of the technique for determining the velocity increase at the site of a stenosis demonstrated in several phantom models. Examples of both in-plane and through-plane velocity maps of the left anterior descending and right coronary arteries of normal subjects in early diastole are presented. In one subject, through-plane velocity maps were obtained in the right and left anterior descending arteries throughout the cardiac cycle in order to generate flow velocity time curves. The problems associated with coronary artery velocity mapping are discussed.     

Quantification of in-plane motion of the coronary arteries during the cardiac cycle: Implications for acquisition window duration for MR flow quantification

Motion of the coronary arteries during the heart cycle can result in image blurring and inaccurate flow quantification by MR. This condition applies particularly for longer acquisition windows that are typical of breath-hold coronary flow measurements. To determine the sensitivity of the technique to in-plane motion of different coronary arteries, the temporal variation in coronary position was measured in a plane perpendicular to the proximal portion of the vessel. The results indicated the presence of substantial displacement of the coronary arteries within the cardiac cycle, with a magnitude of motion approximately twice as large for the right as for the left coronary arteries. An estimation of the resulting vessel blurring was calculated, showing that the duration of the acquisition window for high spatial resolution coronary flow acquisitions should be less than 25 to 120 msec, depending on the specific coronary artery studied. In addition, these data specify optimal acquisition window placement for high resolution coronary angiography.     

MR-based coronary artery blood velocity measurements in patients without coronary artery disease

To evaluate the feasibility of MR-based coronary blood velocity measurements (MRvenc) in patients without coronary artery disease (CAD). Eighty-three patients with angiographically excluded CAD received MRvenc of the proximal segments of both coronary arteries (CAs). Using a retrospectively ECG-gated breath-hold phase-contrast FLASH sequence with high temporal resolution, flow data were technically acquirable in 137/166 (83%) CAs. Quantification and analysis of blood velocities in systole and diastole of both CAs were performed. Biphasic velocity profiles were found in 83/100 CAs. Median systolic and diastolic velocities differed significantly in LCA (19 cm/s, 24 cm/s; P<0.0001) and RCAs (14 cm/s, 16 cm/s; P<0.01). The diastolic/systolic velocity ratio was calculated in LCAs and RCAs with a median of 1.3 and 1.1, respectively. The velocity profiles of the remaining CAs were monophasic (17 CAs) or revealed severe alterations of the physiologic velocity profile with reduced flow undulations and steady velocities (37 CAs). Optimized clinical MRvenc is feasible to quantify blood velocities in the CAs. Potential indications are (1) non-invasive monitoring of patients after aortic valve reconstruction as well as (2) detection of asymptomatic CAD patients.     

Aortic and mitral regurgitation: quantification using moving slice velocity mapping

Comprehensive assessment of the severity of valvular insufficiency includes quantification of regurgitant volumes. Previous methods lack reliable slice positioning with respect to the valve and are prone to velocity offsets due to through-plane motion of the valvular plane of the heart. Recently, the moving slice velocity mapping technique was proposed. In this study, the technique was applied for quantification of mitral and aortic regurgitation. Time-efficient navigator-based respiratory artifact suppression was achieved by implementing a prospective k-space reordering scheme in conjunction with slice position correction. Twelve patients with aortic insufficiency and three patients with mitral insufficiency were studied. Aortic regurgitant volumes were calculated from diastolic velocities mapped with a moving slice 5 mm distal to the aortic valve annulus. Mitral regurgitant flow was indirectly assessed by measuring mitral inflow at the level of the mitral annulus and net aortic outflow. Regurgitant fractions, derived from velocity data corrected for through-plane motion, were compared to data without correction for through-plane motion. In patients with mild and moderate aortic regurgitation, regurgitant fractions differed by 60% and 15%, on average, when comparing corrected and uncorrected data, respectively. Differences in severe aortic regurgitation were less (7%). Due to the large orifice area of the mitral valve, differences were still substantial in moderate-to-severe mitral regurgitation (19%). The moving slice velocity mapping technique was successfully applied in patients with aortic and mitral regurgitation. The importance of correction for valvular through-plane motion is demonstrated.     

Three-dimensional cine imaging using variable-density spiral trajectories and SSFP with application to coronary artery angiography.

A single breath-hold 3D cardiac phase resolved steady-state free precession (SSFP) sequence was developed, allowing 3D visualization of the moving coronary arteries. A 3D stack of spirals was acquired continuously throughout the cardiac cycle, and a sliding window reconstruction was used to achieve high temporal resolution. A coil specific field of view reconstruction technique was combined with Parallel Imaging with Localized Sensitivities (PILS) to allow acquisition of a reduced field of view. A view ordering incorporating fat suppression was employed to allow use of sliding window reconstruction. The technique was evaluated on healthy volunteers (n=8), yielding images with 102 ms temporal resolution and 1.35 mm in-plane resolution, and reasonable visualization of the left and right coronary arteries was achieved.     

Rapid quantitation of high-speed flow jets.

Flow jets containing velocities up to 5-7 m/s are common in patients with congenital defects and patients with valvular disease (stenosis and regurgitation). The quantitation of peak velocity and flow volume in these jets is clinically significant but requires specialized imaging sequences. Conventional 2DFT phase contrast sequences require lengthy acquisitions on the order of several minutes. Conventional spiral phase contrast sequences are faster, but are highly corrupted by flow artifacts at these high velocities due to phase dispersion and motion during the excitation and readout. A new prospectively gated method based on spiral phase contrast is presented, which has a sufficiently short measurement interval (<4 ms) to minimize flow artifacts, while achieving high spatial resolution (2 x 2 x 4 mm(3)) to minimize partial volume effects, all within a single breathhold. A complete single-slice phase contrast movie loop with 22 ms true temporal resolution is acquired in one 10-heartbeat breathhold. Simulations indicate that this technique is capable of imaging through-plane jets with velocities up to 10 m/s, and initial studies in aortic stenosis patients show accurate in vivo measurement of peak velocities up to 4.2 m/s (using echocardiography as a reference).     

In-plane coronary arterial motion velocity: measurement with electron-beam CT

PURPOSE: To determine the speed of and changes in the speed of coronary arterial movement during the cardiac cycle with electron-beam computed tomography (CT). MATERIALS AND METHODS: With electron-beam CT, 20 consecutive cross-sectional images were acquired at the mid right coronary artery (with 50-msec acquisition time, 8-msec intersection delay, 7-mm section thickness, and intravenous administration of 40 mL of contrast agent) in 25 patients. On the basis of the displacement of the left anterior descending, left circumflex, and right coronary arterial cross sections from image to image, movement velocity in the transverse imaging plane was calculated and was correlated with the simultaneously recorded electrocardiogram. RESULTS: The velocity of in-plane coronary arterial motion varied considerably during the cardiac cycle. Peaks were caused by ventricular systole and diastole and by atrial contraction. The mean velocity was 46.6 mm/sec +/- 12. 5 (SD). The mean velocity of right coronary arterial movement (69.5 mm/sec +/- 22.5) was significantly faster than that of the left anterior descending (22.4 mm/sec +/- 4.1) or the left circumflex coronary artery (48.4 mm/sec +/- 15.0). The lowest mean velocity (27. 9 mm/sec) was at 48% of the cardiac cycle. CONCLUSION: The lowest velocity of coronary arterial movement, which displays considerable temporal variation, was at 48% of the cardiac cycle.     

Heart motion-adapted MR velocity mapping of blood velocity distribution downstream of aortic valve prostheses: initial experience

PURPOSE: To investigate blood flow velocities and shear rates at two distances downstream of an artificial aortic valve in patients. MATERIALS AND METHODS: Blood velocity was quantified downstream of the valve prosthesis (for replacement after aortic valve stenosis or combined stenosis and regurgitation) in 10 patients by using a magnetic resonance (MR) cine velocity mapping method in which the imaging section position is adapted according to the excursion of the valvular plane of the heart. Two acquisitions were performed to display the blood velocity distributions one-fourth valve diameter and one valve diameter downstream of the valve and to quantify blood volumes and shear rates. RESULTS: The velocity profiles measured during flow acceleration one-fourth valve diameter downstream were characterized by a distinct pattern of two lateral jets and one central jet of antegrade flow. High shear rates were found along the leaflet tips. The profiles obtained one valve diameter downstream were skewed, with varying velocity patterns among patients. Peak shear rates were found close to the vessel wall. With correction for through-plane motion of the valve, the mean apparent regurgitant fraction (+/- SD) was 14% +/- 6; the mean regurgitant fraction without correction was 9% +/- 5. CONCLUSION: The described noninvasive procedure for velocity mapping enables measurements close to the valve and thus evaluation of blood flow patterns with respect to valve design in humans.     

Artifact reduction in undersampled projection reconstruction MRI of the peripheral vessels using selective excitation.

The projection reconstruction (PR)-HyperTRICKS (time resolved imaging of contrast kinetics) acquisition integrates the benefits of through-plane Cartesian slice encoding and in-plane undersampled PR. It provides high spatial resolution both in-plane (about 1 mm(2)) and through-plane (1-2 mm), as well as relatively high temporal resolution (about 0.25 frames per second). However, undersampling artifacts that originate from anatomy superior or inferior to a coronal imaging FOV may severely degrade the image quality. In coronal MRA acquisitions, the slice coverage is limited in order to achieve high temporal resolution. In this report we describe an artifact reduction method that uses selective excitation in PR-HyperTRICKS. This technique significantly reduces undersampling streak artifacts while it increases the slice coverage.     

Free-breathing 3D coronary MRA: the impact of "isotropic" image resolution

During conventional x-ray coronary angiography, multiple projections of the coronary arteries are acquired to define coronary anatomy precisely. Due to time constraints, coronary magnetic resonance angiography (MRA) usually provides only one or two views of the major coronary vessels. A coronary MRA approach that allowed for reconstruction of arbitrary isotropic orientations might therefore be desirable. The purpose of the study was to develop a three-dimensional (3D) coronary MRA technique with isotropic image resolution in a relatively short scanning time that allows for reconstruction of arbitrary views of the coronary arteries without constraints given by anisotropic voxel size. Eight healthy adult subjects were examined using a real-time navigator-gated and corrected free-breathing interleaved echoplanar (TFE-EPI) 3D-MRA sequence. Two 3D datasets were acquired for the left and right coronary systems in each subject, one with anisotropic (1.0 x 1.5 x 3.0 mm, 10 slices) and one with "near" isotropic (1.0 x 1.5 x 1.0 mm, 30 slices) image resolution. All other imaging parameters were maintained. In all cases, the entire left main (LM) and extensive portions of the left anterior descending (LAD) and the right coronary artery (RCA) were visualized. Objective assessment of coronary vessel sharpness was similar (41% +/- 5% vs. 42% +/- 5%; P = NS) between in-plane and through-plane views with "isotropic" voxel size but differed (32% +/- 7% vs. 23% +/- 4%; P < 0.001) with nonisotropic voxel size. In reconstructed views oriented in the through-plane direction, the vessel border was 86% more defined (P < 0.01) for isotropic compared with anisotropic images. A smaller (30%; P < 0.001) improvement was seen for in-plane reconstructions. Vessel diameter measurements were view independent (2.81 +/- 0.45 mm vs. 2.66 +/- 0.52 mm; P = NS) for isotropic, but differed (2.71 +/- 0.51 mm vs. 3.30 +/- 0.38 mm; P < 0.001) between anisotropic views. Average scanning time was 2:31 +/- 0:57 minutes for anisotropic and 7:11 +/- 3:02 minutes for isotropic image resolution (P < 0.001). We present a new approach for "near" isotropic 3D coronary artery imaging, which allows for reconstruction of arbitrary views of the coronary arteries. The good delineation of the coronary arteries in all views suggests that isotropic 3D coronary MRA might be a preferred technique for the assessment of coronary disease, although at the expense of prolonged scan times. Comparative studies with conventional x-ray angiography are needed to investigate the clinical utility of the isotropic strategy.     

Coronary artery motion in electron beam tomography

PURPOSE: The purpose of this work was to evaluate coronary artery motion characteristics and determine optimal electron beam tomography (EBT) scan time during the cardiac cycle to image the coronary arteries. METHOD: This study evaluated the movement of coronary arteries in 20 EBT cine studies, at rest and during stress, obtained for evaluating coronary artery disease. The proximal, middle, and distal segments of each coronary artery were measured at multiple times during the cardiac cycle. The motion distance (mm) and velocity (mm/s) of each segment of the coronary arteries were then measured to establish the motion that occurs in the x and y axes during different times in the cardiac cycle. RESULTS: Coronary artery velocity ranged from 22.4 to 108.6 mm/s. The least motion (and slowest speed) occurred between 30-50 and 40-60% of the R-R interval at rest and stress, respectively. The right coronary artery moved the greatest in the x and y planes (highest speed and spatial change), followed in decreasing order by the circumflex, left main, and left anterior descending arteries. The phase of the cardiac cycle with the greatest coronary artery motion was between 0 and 20% of the R-R interval. CONCLUSION: Coronary artery motion varies greatly throughout the cardiac cycle. To minimize cardiac motion during tomographic imaging of the coronary arteries, we recommend 40-50% R-R interval as an electrocardiographic trigger time and avoiding the use of image acquisition times of >100 ms.     

Nonrigid retrospective respiratory motion correction in whole‐heart coronary MRA

A nonrigid retrospective respiratory motion correction scheme is presented for whole‐heart coronary imaging with interleaved acquisition of motion information. The quasi‐periodic nature of breathing is exploited to populate a 3D nonrigid motion model from low‐resolution 2D imaging slices acquired interleaved with a segmented 3D whole‐heart coronary scan without imposing scan time penalty. Reconstruction and motion correction are based on inversion of a generalized encoding equation. Therein, a forward model describes the transformation from the motion free image to the motion distorted k‐space data, which includes nonrigid spatial transformations. The effectiveness of the approach is demonstrated on 10 healthy volunteers using free‐breathing coronary whole‐heart scans. Although conventional respiratory‐gated acquisitions with 5‐mm gating window resulted in an average gating efficiency of 51% ± 11%, nonrigid motion correction allowed for gate‐free acquisitions, and hence scan time reduction by a factor of two without significant penalty in image quality. Image scores and quantitative image quality measures for the left coronary arteries showed no significant differences between 5‐mm gated and gate‐free acquisitions with motion correction. For the right coronary artery, slightly reduced image quality in the motion corrected gate‐free scan was observed as a result of the close vicinity of anatomical structures with different motion characteristics. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.     

Image quality of noninvasive coronary angiography using multislice spiral computed tomography and electron-beam computed tomography: intraindividual comparison in an animal model

OBJECTIVE: Comparison of coronary artery visualization by multislice spiral CT (MSCT) and electron-beam CT (EBCT). MATERIALS AND METHODS: Six minipigs underwent MSCT (collimation 4 x 1 mm, gantry rotation time 500 milliseconds, acquisition time per cardiac cycle 126 +/- 30 milliseconds) and EBCT (slice thickness 1.5 mm, acquisition time per scan 100 milliseconds). Visualized vessel length and contour sharpness was measured, contrast-to-noise ratios were calculated, and the frequency of motion artifacts were evaluated. RESULTS: MSCT depicted significantly longer segments of the coronary tree than EBCT (length: 248.8 vs. 222.8 mm; P < 0.05), delineated the vessel contours more sharply (slope of density curves: 219.2 vs. 160.2 DeltaHU/mm; P < 0.05), and had a higher contrast-to-noise ratio (13.4 vs. 7.3; P < 0.05). The frequency of motion artifacts did not differ between both modalities (94.7% vs. 95.7% of visualized vessel length; P > 0.05). CONCLUSIONS: Because its higher spatial resolution and lower image noise, MSCT seems to be superior to EBCT in the visualization of the coronary arteries. Despite different temporal resolutions motion artifacts seem to be similar with both modalities.     

Contrast-enhanced coronary artery visualization by dual-source computed tomography--initial experience

Multi-detector computed tomography (CT) scanners, by virtue of their high temporal and spatial resolution, permit imaging of the coronary arteries. However, motion artifacts, especially in patients with higher heart rates, can impair image quality. We thus evaluated the performance of a new dual-source CT (DSCT) with a heart rate independent temporal resolution of 83 ms for the visualization of the coronary arteries in 14 consecutive patients. METHODS: Fourteen patients (mean age 61 years, mean heart rate 71 min(-1)) were studied by DSCT. The system combines two arrays of an X-ray tube plus detector (64 slices) mounted on a single gantry at an angle of 90 degrees With a rotation speed of 330 ms, a temporal resolution of 83 ms (one-quarter rotation) can be achieved independent of heart rate. For data acquisition, intraveous contrast agent was injected at a rate of 5 ml/s. Images were reconstructed with 0.75 slice thickness and 0.5 mm increment. The data sets were evaluated concerning visibility of the coronary arteries and occurrence of motion artifact. RESULTS: Visualization of the coronary arteries was successful in all patients. Most frequently, image reconstruction at 70% of the cardiac cycle provided for optimal image quality (50% of patients). Of a total of 226 coronary artery segments, 222 (98%) were visualized free of motion artifact. In summary, DSCT constitutes a promising new concept for cardiac CT. High and heart rate independent temporal resolution permits imaging of the coronary arteries without motion artifacts in a substantially increased number of patients as compared to earlier scanner generations. Larger and appropriately designed studies will need to determine the method's accuracy for detection of coronary artery stenoses.     

Navigator gated high temporal resolution tissue phase mapping of myocardial motion.

Data acquisition for phase contrast velocity mapping of myocardial motion is typically based on multiple breath-held 2D measurements with limited acquisition duration and consequently relatively poor temporal resolution. In order to overcome the limitations of breath-hold acquisitions, an improved navigator-guided technique was implemented based on 2 navigator signals within each cardiac cycle in combination with paired acceptance and rejection criteria of successive navigator signals. Respiratory gated phase contrast measurements with 3-directional velocity encoding were performed in 12 healthy volunteers in basal, midventricular, and apical locations of the left ventricle during free breathing with a temporal resolution of 13.8 ms. Results were compared to standard breath-hold measurements with a temporal resolution of 69 ms. Data from the high temporal resolution study revealed details in left ventricular motion patterns that were previously not seen in phase contrast measurements and are only known from echocardiography. The proposed navigator gated technique for high temporal resolution velocity mapping is, therefore, highly promising for the detection of local and global motion abnormalities in patients with disturbed left ventricular performance, such as diastolic dysfunction.