Whole-heart Coronary Magnetic Resonance Angiography Research Articles

Assessment of Coronary Artery Disease Using Magnetic Resonance Coronary Angiography: A National Multicenter Trial

This national multicenter study determined the diagnostic performance of 1.5-T whole-heart coronary magnetic resonance angiography (MRA) in patients with suspected coronary artery disease (CAD).Whole-heart coronary MRA using steady-state free precession allows noninvasive detection of CAD without the administration of contrast medium. However, the accuracy of this approach has not been determined in a multicenter trial.Using a 1.5-T magnetic resonance imaging unit, free-breathing steady-state free precession whole-heart coronary MRA images were acquired for 138 patients with suspected CAD at 7 hospitals. The accuracy of MRA for detecting a ≥ 50% reduction in diameter was determined using X-ray coronary angiography as the reference method.Acquisition of whole-heart coronary MRA images was performed in 127 (92%) of 138 patients with an average imaging time of 9.5 ± 3.5 min. The areas under the receiver-operator characteristic curve from MRA images according to vessel- and patient-based analyses were 0.91 (95% confidence interval [CI]: 0.87 to 0.95) and 0.87 (95% CI: 0.81 to 0.93), respectively. The sensitivity, specificity, positive and negative predictive values, and accuracy of MRA according to a patient-based analysis were 88% (49 of 56, 95% CI: 75% to 94%), 72% (51 of 71, 95% CI: 60% to 82%), 71% (49 of 69, 95% CI: 59% to 81%), 88% (51 of 58, 95% CI: 76% to 95%), and 79% (100 of 127, 95% CI: 72% to 86%), respectively.Non-contrast-enhanced whole-heart coronary MRA at 1.5-T can noninvasively detect significant CAD with high sensitivity and moderate specificity. A negative predictive value of 88% indicates that whole-heart coronary MRA can rule out CAD.

Contrast-Enhanced Whole-Heart Coronary Magnetic Resonance Angiography at 3 T Using Interleaved Echo Planar Imaging

The goal of this work was to reduce the scan time of contrast-enhanced whole-heart coronary magnetic resonance angiography (MRA) by using a gradient echo interleaved echo planar imaging (GRE-EPI) sequence at 3 T field strength. A GRE-EPI sequence was optimized to acquire contrast-enhanced whole-heart coronary MRA at 3 T. First-order phase correction was used for alignment of the odd and even echoes in the GRE-EPI echo train. Single and dual reference scan techniques for estimation of the linear phase correction parameters were evaluated using both phantom and volunteer studies. The GRE-EPI readout was combined with parallel imaging for a further reduction in scan time. To avoid image distortions, calibration signals for coil sensitivity estimation were acquired in a separate low resolution GRE scan before the whole-heart GRE-EPI scan. Eight healthy volunteers were scanned with the optimized contrast-enhanced GRE-EPI sequence. GRE-EPI images were acquired during slow infusion (0.3 mL/s) of 0.1 mmol/kg body weight of Gd-BOPTA. For comparison purposes, the same 8 volunteers were scanned again in a separate scan session using a traditional GRE sequence with double the dose (0.2 mmol/kg body weight) of the same contrast agent with the same injection rate. The contrast-enhanced GRE-EPI and contrast-enhanced GRE techniques were compared in terms of relative signal-to-noise ratio (rSNR), relative contrast-to-noise ratio (rCNR), image quality scores, and visualized vessel lengths. Both, phantom and volunteer studies demonstrated that the dual reference scan phase correction technique was a key step for obtaining satisfactory image quality using GRE-EPI at 3 T. Whole-heart coronary MRA with a spatial resolution of 1.0 x 1.0 x 2.0 mm3 was acquired with the GRE-EPI sequence in an average scan time of 2.5 +/- 0.6 minutes, compared with 8.6 +/- 2.7 minutes for the GRE technique. The GRE-EPI technique had lower rCNR compared with the GRE sequence. The image quality and coronary artery visualization with the GRE-EPI technique were adequate, and there was no statistically significant difference in the image quality scores, rSNR, and visualized coronary artery lengths between the GRE-EPI and GRE techniques. Contrast-enhanced whole-heart coronary MRA using the GRE-EPI technique resulted in excellent delineation of all the major coronary arteries and compared with current GRE techniques demonstrated a factor of 2 reduction in contrast agent dose and a factor of 3 reduction in scan time.

Whole‐heart coronary magnetic resonance angiography at 3.0T using short‐TR steady‐state free precession, vastly undersampled isotropic projection reconstruction

To evaluate the feasibility of improving 3.0T steady-state free precession (SSFP) whole-heart coronary magnetic resonance angiography (MRA) using short-TR (repetition time) VIPR (vastly undersampled isotropic projection reconstruction). SSFP is highly sensitive to field inhomogeneity. VIPR imaging uses nonselective radiofrequency pulses, allowing short TR and reduced banding artifacts, while achieving isotropic 3D resolution. Coronary artery imaging was performed in nine healthy volunteers using SSFP VIPR. TR was reduced to 3.0 msec with an isotropic spatial resolution of 1.3 x 1.3 x 1.3 mm(3). Image quality, vessel sharpness, and lengths of major coronary arteries were measured. Comparison between SSFP using Cartesian trajectory and SSFP using VIPR trajectory was performed in all volunteers. Short-TR SSFP VIPR resulted in whole-heart images without any banding artifacts, leading to excellent coronary artery visualization. The average image quality score for VIPR-SSFP was 3.12 +/- 0.42 out of four while that for Cartesian SSFP was 0.92 +/- 0.61. A significant improvement (P < 0.05) in image quality was shown by Wilcoxon comparison. The visualized coronary artery lengths for VIPR-SSFP were: 10.13 +/- 0.79 cm for the left anterior descending artery (LAD), 7.90 +/- 0.91 cm for the left circumflex artery (LCX), 7.50 +/- 1.65 cm for the right coronary artery (RCA), and 1.84 +/- 0.23 cm for the left main artery (LM). The lengths statistics for Cartesian SSFP were 1.57 +/- 2.02 cm, 1.54 +/- 1.93 cm, 0.94 +/- 1.17 cm, 0.46 +/- 0.53 cm, respectively. The image sharpness was also increased from 0.61 +/- 0.13 (mm(-1)) in Cartesian-SSFP to 0.81 +/- 0.11 (mm(-1)) in VIPR-SSFP. With VIPR trajectory the TR is substantially decreased, reducing the sensitivity of SSFP to field inhomogeneity and resulting in whole-heart images without banding artifacts at 3.0T. Image quality improved significantly over Cartesian sampling.

Whole-heart magnetic resonance coronary angiography with multiple breath-holds and automatic breathing-level tracking

Whole-heart (WH) magnetic resonance coronary angiography (MRCA) studies are usually performed during free breathing while monitoring the position of the diaphragm with real-time motion correction. However, this results in a long scan time and the patient’s breathing pattern may change, causing the study to be aborted. Alternatively, WH MRCA can be performed with multiple breath-holds (mBH). However, one problem in the mBH method is that patients cannot hold their breath at the same position every time, leading to image degradation. We have developed a new WH MRCA imaging method that employs both the mBH method and automatic breathing-level tracking to permit automatic tracking of the changes in breathing or breath-hold levels. Evaluation of its effects on WH MRCA image quality showed that this method can provide high-quality images within a shorter scan time. This proposed method is expected to be very useful in clinical WH MRCA studies.

Contrast-kinetics-resolved whole-heart coronary MRA using 3DPR

Slow contrast infusion was recently proposed for contrast-enhanced whole-heart coronary MR angiography. Current protocols use Cartesian k-space sampling with empiric acquisition delays, potentially resulting in suboptimal coronary artery delineation and image artifacts if there is a timing error. This study aimed to investigate the feasibility of using time-resolved three-dimensional projection reconstruction for whole-heart coronary MR angiography. With this method, data acquisition was started simultaneously with contrast injection. Sequential time frames were reconstructed by employing a sliding window scheme with temporal tornado filtering. Additionally, a self-timing method was developed to monitor contrast enhancement during a scan and automatically determine the peak enhancement time around which optimal temporal frames were reconstructed. Our preliminary results on six healthy volunteers showed that by using time-resolved three-dimensional projection reconstruction, the contrast kinetics of the coronary artery system throughout a scan could be retrospectively resolved and assessed. In addition, the blood signal dynamics predicted using self-timing was closely correlated to the true dynamics in time-resolved reconstruction. This approach is useful for optimizing delineation of each coronary artery and minimizing image artifacts for contrast-enhanced whole-heart MRA.

Contrast-enhanced whole-heart coronary magnetic resonance angiography (MRA) in less than 5 minutes using radial EPI

Introduction Whole-heart coronary MRA is challenging due to the long data acquisition time on the order of 8-12 minutes. Interleaved EPI using Cartesian k-space sampling has been reported for reducing the scan time of whole-heart coronary MRA [1]; however, this method suffers from an increased sensitivity to motion artifacts [2]. The purpose of this work was to optimize a radial EPI [3] technique for contrast-enhanced whole-heart coronary MRA, with the goal of combining the scan efficiency of EPI with the motion insensitivity of radial sampling.

Evaluation of Cardiac Allograft Vasculopathy by Multidetector Computed Tomography and Whole-Heart Magnetic Resonance Coronary Angiography

Cardiac allograft vasculopathy (CAV) is a major complication that limits the long-term survival of recipients of heart transplants. In the present study the feasibility of 2 noninvasive approaches for detecting CAV (multidetector computed tomography (MDCT) and whole-heart magnetic resonance coronary angiography (MRCA)) was compared with conventional coronary angiography (CCAG). Of 22 heart transplant recipients who underwent CCAG screening, 13 had only MDCT, 16 had only MRCA, and 7 had both noninvasive modalities. The coronary arterial tree was divided into 9 segments. Detection of vasculopathy by coronary segments was compared between 16-/64-detector computed tomography (CT) or MRCA and CCAG. The sensitivity of both 16- and 64-detector CT for diagnosing CAV was 69.6%, and specificity was 96.8%. The sensitivity and specificity by 64-detector CT alone were 90.0% and 97.5%, respectively; its positive and negative predictive values were 81.8% and 98.7% respectively. For MRCA, sensitivity was 60%, specificity, 100%, positive predictive value, 100% and negative predictive value, 92.2%. MRCA showed no false positives. MDCT, especially 64-detector CT, is feasible for detecting CAV, whereas MRCA currently shows limited sensitivity.

Feasibility study of Global-to-Local Tandem Method for detecting the coronary stationary period in whole-heart magnetic resonance coronary angiography (WH MRCA)

Introduction WH MRCA studies are usually performed during the stationary period of coronary arteries, which is determined using cine display and therefore depends on the operator's experience. Several automatic methods have been developed. One such method uses the global heart signal for analysis [1] and is suitable for detecting motion during all cardiac phases, but this method tends to suffer from noise. Another method employs a ROI for analysis [2] and is suitable for precise detection of the stationary period, but not for all cardiac phases. We have developed the Global-to-Local Tandem Method, in which the coronary stationary period is roughly analyzed by the global method and then precisely analyzed by the local method. We have also conducted clinical feasibility studies.

Feasibility study of motion pre-analysis method for whole-heart magnetic resonance coronary angiography (WH MRCA)

Introduction WH MRCA [1] examinations are usually performed during free breathing, and the Realtime Motion Correction (RMC) coefficient is important for obtaining good image quality. However, this coefficient differs in each patient, which may result in image degradation. We have developed the Motion Pre-Analysis Method to determine the appropriate RMC coefficient before WH MRCA and have conducted feasibility studies to investigate the appropriate method for using an abdominal band.

Diagnostic performance of non-contrast whole-heart coronary magnetic resonance angiography combined with black-blood arterial wall imaging in patients with suspected coronary artery disease

Methods Thirteen patients with suspected CAD were scanned at 1.5 T (MAGNETOM Sonata, Siemens, Germany) after written informed consent was obtained. WH-CMRA was acquired using a 3D ECG-triggered, navigator-gated, fat-suppressed, T2-prepared steady-state-free-precession sequence. Cross-sectional coronary wall imaging (thinkness = 5 mm) was performed using a 2D-black-blood, navigator and ECG-gated, Turbo-Spin-Echo sequence with asymmetric-adiabatic-spectral inversion-recovery fat suppression [3]. Continous slices without gap for wall imaging were positioned from pre to post of the suspected from 13th Annual SCMR Scientific Sessions Phoenix, AZ, USA. 21-24 January 2010

3.0 T contrast-enhanced whole-heart coronary magnetic resonance angiography for the evaluation of the cardiac venous anatomy

3.0 T contrast-enhanced whole-heart coronary magnetic resonance angiography for the evaluation of the cardiac venous anatomy

2D-SENSE in isotropic slow infusion contrast-enhanced whole-heart coronary magnetic resonance angiography at 3 T

Baseline free-breathing 3D whole-heart coronary MRA with an adiabatic T2prep (TE = 50 ms)[5] was first performed. The duration of the acquisition window was adjusted to the heart-rate of the patients with a TR/TE = 3.3/1.07 ms and a flip angle(α) of 20°. 1D-SENSE (2 times accelerated) was applied in the left-right(LR) direction. The acquired isotropic voxel size was 1.3 × 1.3 × 1.3 mm3.

Contrast enhanced coronary MRA at 3.0 T using a 32 channel coil to detect coronary artery stenosis - how does it measure up against 64-slice coronary CTA and X-ray angiography?

Materials and methods 32 patients with suspected CAD who were scheduled for CAG underwent both coronary MRA and coronary CTA. 3.0 T contrast enhanced whole-heart coronary MRA was acquired by using an ECG-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence and 32 channel coils was used with GRAPPA factor of 3. Coronary CTA was performed using a 64-Slice CT scanner. For image analysis, standard 15-segment AHA classification system was used. The diagnostic accuracy of MRA and CTA in detecting significant stenoses (≥ 50% of vessel lumen) was compared on the per-segment basis using CAG as reference standard. Results MRA and CTA examinations were successfully completed in all 32 patients. The averaged imaging time of MRA was 6.1 ± 1.2 min. In a total of 419 coronary segments with a reference luminal diameter ≥ 1.5 mm on QCA, forty-nine (12%) on MRA were evaluated as non-assessable and twenty-eight on CTA were non-diagnostic. On the assessable segments basis, 3.0 T whole-heart CMRA correctly identified 45 significant stenoses, and CTA correctly identified 52 significant stenoses. The sensitivity, specificity, PPV and NPV of MRA and CTA for detecting significant stenoses were 92%, 95%, 73%, 99% and 96%, 92%, 67%, 99%, respectively, on assessable segments basis.

Coronary MRA at 3 T using 3d multi-interleaved multi-echo acquisition with varpro fat-water separation

Introduction Coronary MR Angiography is a valuable tool for non-invasive assessment of coronary arteries. Presently, contrastenhanced, fat-saturated, ECG-triggered and navigatorgated 3D spoiled gradient-echo sequence is employed for whole-heart Coronary MRA at 3 T[1]. However, large static field variations at 3 T frequently result in non-uniform fat-suppression over the field-of-view (FOV), obscuring the delineation of coronary arteries. Multi-echo Dixon approaches utilizing iterative decomposition have been shown to provide robust fat-water separation even in the presence of large field inhomogeneities. In this study, an ECG-triggered navigator-gated 3D spoiled gradientecho multi-interleaved multi-echo (GRE-MEMI) pulse sequence is introduced which utilizes VARPRO[2] fatwater separation to achieve reliable fat-suppression and provides enhanced visualization of coronary arteries.

Volume‐targeted and whole‐heart coronary magnetic resonance angiography using an intravascular contrast agent

To compare volume-targeted and whole-heart coronary magnetic resonance angiography (MRA) after the administration of an intravascular contrast agent. Six healthy adult subjects underwent a navigator-gated and -corrected (NAV) free breathing volume-targeted cardiac-triggered inversion recovery (IR) 3D steady-state free precession (SSFP) coronary MRA sequence (t-CMRA) (spatial resolution = 1 x 1 x 3 mm(3)) and high spatial resolution IR 3D SSFP whole-heart coronary MRA (WH-CMRA) (spatial resolution = 1 x 1 x 2 mm(3)) after the administration of an intravascular contrast agent B-22956. Subjective and objective image quality parameters including maximal visible vessel length, vessel sharpness, and visibility of coronary side branches were evaluated for both t-CMRA and WH-CMRA. No significant differences (P = NS) in image quality were observed between contrast-enhanced t-CMRA and WH-CMRA. However, using an intravascular contrast agent, significantly longer vessel segments were measured on WH-CMRA vs. t-CMRA (right coronary artery [RCA] 13.5 +/- 0.7 cm vs. 12.5 +/- 0.2 cm; P < 0.05; and left circumflex coronary artery [LCX] 11.9 +/- 2.2 cm vs. 6.9 +/- 2.4 cm; P < 0.05). Significantly more side branches (13.3 +/- 1.2 vs. 8.7 +/- 1.2; P < 0.05) were visible for the left anterior descending coronary artery (LAD) on WH-CMRA vs. t-CMRA. Scanning time and navigator efficiency were similar for both techniques (t-CMRA: 6.05 min; 49% vs. WH-CMRA: 5.51 min; 54%, both P = NS). Both WH-CMRA and t-CMRA using SSFP are useful techniques for coronary MRA after the injection of an intravascular blood-pool agent. However, the vessel conspicuity for high spatial resolution WH-CMRA is not inferior to t-CMRA, while visible vessel length and the number of visible smaller-diameter vessels and side-branches are improved.

Contrast-Enhanced Whole-Heart MR Coronary Angiography at 3.0 T Using the Intravascular Contrast Agent Gadofosveset

The purpose of this study was to compare contrast-enhanced (CE) whole-heart coronary magnetic resonance angiography (MRA) at 3.0 T using gadofosveset to noncontrast-enhanced steady-state free precession (SSFP) coronary MRA at 1.5 T. A prospective randomized study was conducted among 20 healthy male volunteers. The same group of subjects underwent CE whole heart MRA at 3.0 T employing a 3D FLASH sequence with IR prepulse after gadofosveset injection as well as noncontrast-enhanced coronary MRA at 1.5 T using a 3D SSFP sequence with T2-preparation. Both techniques were performed using prospective ECG-triggering and adaptive respiratory gating. Acquisition time, signal-to-noise ratio of coronary blood, contrast-to-noise ratio (CNR) between coronaries and adjacent myocardium or epicardial fat, and image quality were evaluated in each case. A significant increase of the overall CNR between coronary blood and adjacent myocardium was measured on images acquired at 3 T in comparison to 1.5 T. The mean values were 38.9 +/- 19.6 and 26.3 +/- 15.4, respectively (P[r] < 0.005). There was no significant difference in CNR between coronary blood and epicardial fat. The mean image quality for the proximal and mid coronary segments was not statistically different between 1.5 T and 3.0 T (P > 0.05), however, the distal coronary segments were rated significantly higher for the CE MRA at 3.0 T (P = 0.02). The average acquisition time (15.29 +/- 5.73 minutes at 1.5 T vs. 17.29 +/- 5.18 minutes at 3 T) and overall image quality (2.15 +/- 0.49 at 1.5 T vs. 2.35 +/- 0.39 at 3 T) were similar for both methods. CE whole-heart coronary MRA at 3.0 T demonstrated higher overall CNR between coronary blood and myocardium and an improved image quality of the distal coronary segments compared with noncontrast-enhanced SSFP coronary MRA at 1.5 T.

Contrast-Enhanced Whole-Heart Coronary Magnetic Resonance Angiography at 3.0-T: A Comparative Study With X-Ray Angiography in a Single Center

The purpose of this study was to prospectively evaluate the diagnostic performance of 3.0-T contrast-enhanced whole-heart coronary magnetic resonance angiography (CMRA) in patients with suspected coronary artery disease (CAD). A slow-infusion, contrast-enhanced whole-heart CMRA approach has recently been developed at 3.0-T. The accuracy of this technique has not yet been determined among patients with suspected CAD. The 3.0-T contrast-enhanced whole-heart CMRA was performed in 69 consecutive patients. An electrocardiography-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence was used to acquire isotropic whole-heart CMRA with slow infusion of 0.2 mmol/kg gadobenate dimeglumine. The diagnostic accuracy of whole-heart CMRA in detecting significant stenoses (≥50%) was evaluated using X-ray angiography as the reference. The CMRA examinations were successfully completed in 62 patients. Acquisition time of whole-heart CMRA procedure was 9.0 ± 1.9 min. The 3.0-T whole-heart CMRA correctly identified significant CAD in 32 patients and correctly ruled out CAD in 23 patients. The sensitivity, specificity, and accuracy of whole-heart CMRA for detecting significant stenoses were 91.6% (87 of 95), 83.1% (570 of 686), and 84.1% (657 of 781), respectively, on a per-segment basis. These values were 94.1% (32 of 34), 82.1% (23 of 28), and 88.7% (55 of 62), respectively, on a per-patient basis. Contrast-enhanced whole-heart CMRA with 3.0-T allows for the accurate detection of coronary artery stenosis with high sensitivity and moderate specificity.

Self‐tracking of contrast kinetics for automatic triggering of contrast‐enhanced whole‐heart coronary magnetic resonance angiography

To develop a method for automatically triggering centric data acquisition during contrast-enhanced whole-heart coronary magnetic resonance angiography (MRA). The hypothesis of this work is that the blood signal changes during contrast infusion can be estimated by obtaining a projection of the heart during inversion-recovery prepared data acquisition. A validation study was performed on seven healthy volunteers to test this hypothesis. The peak blood signal enhancement detected from the projection was then used to automatically trigger the start of central k-space data acquisition. Simulations were performed to compare the signal-to-noise ratio (SNR) of the proposed self-triggering method with the fixed delay method. Six healthy volunteers were scanned on a 3T MR system using the proposed self-triggered method to test its effectiveness on coronary artery visualization. Based on the validation study, the self-triggering method provides an accurate representation of the contrast enhancement. Based on the simulations, self-triggering with centric ordering is expected to give a 27% higher SNR than linear ordering with a fixed imaging delay. Self-triggering was successfully used in all volunteers and showed excellent depiction of the major coronary arteries. The self-triggering method can be used to automatically determine the optimal delay time for central k-space acquisition, for each individual subject, without the need of any extra setup or user interaction.

Acute anterior myocardial infarction superimposing double left anterior descending artery: Depiction at whole-heart coronary magnetic resonance angiography

Double left anterior descending artery arising from the left and right coronary arteries is an extremely rare congenital coronary anomaly. We describe a patient with anterior myocardial infarction, in whom whole-heart coronary magnetic resonance angiography detected double left anterior descending artery.

Feasibility of Navigator Setting on the Left Diaphragm for Whole-heart Coronary MRA: A Study in Healthy Volunteers

We prospectively compared the quality of images obtained by navigator setting on the left and right diaphragm on whole-heart coronary magnetic resonance angiography (WHCMRA). In 10 healthy volunteers, we performed free-breathing, 3-dimensional segmented true fast imaging with steady-state precession (trueFISP) WHCMRA by setting the navigator on the left and right diaphragm in random order. For the left diaphragm, we set the navigator outside the scope of the heart to avoid the influence on coronary arteries. We compared image acquisition time and visible length of coronary arteries using paired t-test and subjective image quality on a 4-point scale (1, poor; 4, excellent) using Wilcoxon signed-rank test. Mean overall subjective image quality was significantly better in the left diaphragm than the right (3.3+/-0.7 versus 2.9+/-0.9, P=0.02). Mean overall visible length of the coronary arteries was significantly better in the left diaphragm than the right (115.4+/-31.1 vs. 112.6+/-29.9 mm, P=0.02). Mean acquisition time between the left and right diaphragm was not significantly different (15.6+/-5.0 versus 16.0+/-5.7 min, P=0.79). In this small group of healthy volunteers, navigator setting for WHCMRA was superior on the left diaphragm than the right; however, feasibility of the technique requires additional consideration in a larger group of actual patients.