Cardiac function: MR evaluation in one breath hold with real-time true fast imaging with steady-state precession

High-resolution spiral real-time cardiac cine imaging with deep learning-based rapid image reconstruction and quantification

The objective of the current study was to develop and evaluate a DEep learning-based rapid Spiral Image REconstruction (DESIRE) and deep learning (DL)-based segmentation approach to quantify the left ventricular ejection fraction (LVEF) for high-resolution spiral real-time cine imaging, including 2D balanced steady-state free precession imaging at 1.5 T and gradient echo (GRE) imaging at 1.5 and 3 T. A 3D U-Net-based image reconstruction network and 2D U-Net-based image segmentation network were proposed and evaluated. Low-rank plus sparse (L+S) served as the reference for the image reconstruction network and manual contouring of the left ventricle was the reference of the segmentation network. To assess the image reconstruction quality, structural similarity index, peak signal-to-noise ratio, normalized root-mean-square error, and blind grading by two experienced cardiologists (5: excellent; 1: poor) were performed. To assess the segmentation performance, quantification of the LVEF on GRE imaging at 3 T was compared with the quantification from manual contouring. Excellent performance was demonstrated by the proposed technique. In terms of image quality, there was no difference between L+S and the proposed DESIRE technique. For quantification analysis, the proposed DL method was not different to the manual segmentation method (p > 0.05) in terms of quantification of LVEF. The reconstruction time for DESIRE was ~32 s (including nonuniform fast Fourier transform [NUFFT]) per dynamic series (40 frames), while the reconstruction time of L+S with GPU acceleration was approximately 3 min. The DL segmentation takes less than 5 s. In conclusion, the proposed DL-based image reconstruction and quantification techniques enabled 1-min image reconstruction for the whole heart and quantification with automatic reconstruction and quantification of the left ventricle function for high-resolution spiral real-time cine imaging with excellent performance.

Peak Work Rate Increases With Lower Extremity-Focused Exercise Training in Adolescents With Fontan Circulation

Background Skeletal muscle deficits are associated with worse exercise performance in the Fontan circulation and may be improved by exercise training. We aimed to assess the change in leg lean mass (a marker of skeletal muscle), exercise performance, and functional health status after a lower extremity-focused exercise intervention in adolescents with Fontan circulation. Methods and Results Densitometry for measurement of leg lean mass, cardiopulmonary exercise test, exercise cardiac magnetic resonance, peripheral vascular testing, physical activity questionnaire, and quality of life assessment were performed at baseline and after a 24-week, hybrid center- and home-based training program. Leg lean mass Z-scores were generated, and exercise parameters were expressed as percentage expected based on reference data. The effect of training was assessed by paired t-tests and simple linear regression. Twenty participants (15.6±1.7 years, 50% male) demonstrated low baseline leg lean mass Z-scores with no significant improvement with training (-1.38±1.02 pre versus -1.31±1.06 post, P=0.33). Maximum and percent predicted work increased from 121.9±29.8 (0.66±0.12) to 131.3±35.1 (0.70±0.15) watts (P=0.02). Peak respiratory exchange ratio increased (1.19±0.02 versus 1.25±0.01, P=0.02) but percent predicted oxygen consumption was unchanged, suggesting higher anaerobic activity after training. Physical activity questionnaire score positively associated with peak work at baseline (ß=18.13 [95% CI, 0.83-35.44], R²=0.21; P=0.04) but physical activity questionnaire, quality of life scores, exercise cardiac magnetic resonance performance, and peripheral vascular function were unchanged with training. Conclusions Peak work rate and anaerobic activity increased with lower extremity-focused training in adolescents with Fontan circulation. Larger studies should test the impact of these changes on functional status and quality of life.

Real-Time Spiral CMR Is Superior to Conventional Segmented Cine-Imaging for Left-Ventricular Functional Assessment in Patients with Arrhythmia

(1) Background: Segmented Cartesian Cardiovascular magnetic resonance (CMR) often fails to deliver robust assessment of cardiac function in patients with arrhythmia. We aimed to assess the performance of a tiny golden-angle spiral real-time CMR sequence at 1.5 T for left-ventricular (LV) volumetry in patients with irregular heart rhythm; (2) Methods: We validated the real-time sequence against the standard breath-hold segmented Cartesian sequence in 32 patients, of whom 11 presented with arrhythmia. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were assessed. In arrhythmic patients, real-time and standard Cartesian acquisitions were compared against a reference echocardiographic modality; (3) Results: In patients with sinus rhythm, good agreements and correlations were found between the segmented and real-time methods, with only minor, non-significant underestimation of EDV for the real-time sequence (135.95 ± 30 mL vs. 137.15 ± 31, p = 0.164). In patients with arrhythmia, spiral real-time CMR yielded superior image quality to the conventional segmented imaging, allowing for excellent agreement with the reference echocardiographic volumetry. In contrast, in this cohort, standard Cartesian CMR showed significant underestimation of LV-ESV (106.72 ± 63.51 mL vs. 125.47 ± 72.41 mL, p = 0.026) and overestimation of LVEF (42.96 ± 10.81% vs. 39.02 ± 11.72%, p = 0.039); (4) Conclusions: Real-time spiral CMR improves image quality in arrhythmic patients, allowing reliable assessment of LV volumetry.

Skeletal muscle deficits are associated with worse exercise performance in pediatric pulmonary hypertension

BACKGROUND

Skeletal muscle deficits are associated with worse exercise performance in adults with pulmonary hypertension (PH) but the impact is poorly understood in pediatric PH.

OBJECTIVE

To study muscle deficits, physical inactivity, and performance on cardiopulmonary exercise test (CPET) and exercise cardiac magnetic resonance (eCMR) in pediatric PH.

METHODS

Youth 8-18 years participated in a prospective, cross-sectional study including densitometry (DXA) for measurement of leg lean mass Z-score (LLMZ), handheld dynamometer with generation of dominant and non-dominant handgrip Z-scores, Physical Activity Questionnaire (PAQ), CPET, and optional eCMR. CPET parameters were expressed relative to published reference values. CMR protocol included ventricular volumes and indexed systemic flow at rest and just after supine ergometer exercise. Relationships between LLMZ, PAQ score, and exercise performance were assessed by Pearson correlation and multiple linear regression.

RESULTS

There were 25 participants (13.7 ± 2.8 years, 56% female, 64% PH Group 1, 60% functional class I); 12 (48%) performed both CPET and eCMR. Mean LLMZ (-0.96 ± 1.14) was associated with PAQ score (r = 50, p = 0.01) and with peak oxygen consumption (VO₂) (r = 0.74, p = < 0.001), VO₂ at anaerobic threshold (r = 0.65, p < 0.001), and peak work rate (r = 0.64, p < 0.01). Higher handgrip Z-scores were associated with better CPET and eCMR performance. On regression analysis, LLMZ and PAQ score were positively associated with peak VO₂, while handgrip Z-score and PAQ score were positively associated with peak work rate.

CONCLUSION

Muscle mass and strength are positively associated with exercise performance in pediatric PH. Future studies should determine the effect of rehabilitation programs on muscle properties and exercise performance.

Reliability of pediatric ventricular function analysis by short-axis "single-cycle-stack-advance" single-shot compressed-sensing cines in minimal breath-hold time

Objectives

Cardiovascular magnetic resonance (CMR) cine imaging by compressed sensing (CS) is promising for patients unable to tolerate long breath-holding. However, the need for a steady-state free-precession (SSFP) preparation cardiac cycle for each slice extends the breath-hold duration (e.g. for 10 slices, 20 cardiac cycles) to an impractical length. We investigated a method reducing breath-hold duration by half and assessed its reliability for biventricular volume analysis in a pediatric population.

Methods

Fifty-five consecutive pediatric patients (median age 12 years, range 7–17) referred for assessment of congenital heart disease or cardiomyopathy were included. Conventional multiple breath-hold SSFP short-axis (SAX) stack cines served as the reference. Real-time CS SSFP cines were applied without the steady-state preparation cycle preceding each SAX cine slice, accepting the limitation of omitting late diastole. The total acquisition time was 1 RR interval/slice. Volumetric analysis was performed for conventional and “single-cycle-stack-advance” (SCSA) cine stacks.

Results

Bland–Altman analyses [bias (limits of agreement)] showed good agreement in left ventricular (LV) end-diastolic volume (EDV) [3.6 mL (− 5.8, 12.9)], LV end-systolic volume (ESV) [1.3 mL (− 6.0, 8.6)], LV ejection fraction (EF) [0.1% (− 4.9, 5.1)], right ventricular (RV) EDV [3.5 mL (− 3.34, 10.0)], RV ESV [− 0.23 mL (− 7.4, 6.9)], and RV EF [1.70%, (− 3.7, 7.1)] with a trend toward underestimating LV and RV EDVs with the SCSA method. Image quality was comparable for both methods (p = 0.37).

Conclusions

LV and RV volumetric parameters agreed well between the SCSA and the conventional sequences. The SCSA method halves the breath-hold duration of the commercially available CS sequence and is a reliable alternative for volumetric analysis in a pediatric population.

Key Points

• Compressed sensing is a promising accelerated cardiovascular magnetic resonance imaging technique.

• We omitted the steady-state preparation cardiac cycle preceding each cine slice in compressed sensing and achieved an acquisition speed of 1 RR interval/slice.

• This modification called “single-cycle-stack-advance” enabled the acquisition of an entire short-axis cine stack in a single short breath hold.

• When tested in a pediatric patient group, the left and right ventricular volumetric parameters agreed well between the “single-cycle-stack-advance” and the conventional sequences.

Quantitative Analyses of the Left Ventricle Volume and Cardiac Function in Normal and Infarcted Yucatan Minipigs

(1) Background: The accuracy of the left ventricular volume (LVV) and contractility measurements with cardiac magnetic resonance imaging (CMRI) is decreased if the papillary muscles are abnormally enlarged, such as in hypertrophic cardiomyopathy in human patients or in pig models of human diseases. The purpose of this work was to establish the best method of LVV quantification with CMRI in pigs. (2) Methods: The LVV in 29 Yucatan minipig hearts was measured using two different techniques: the “standard method”, which uses smooth contouring along the endocardial surface and adds the papillary volume to the ventricular cavity volume, and the “detailed method”, which traces the papillary muscles and trabeculations and adds them to the ventricular mass. (3) Results: Papillary muscles add 21% to the LV mass in normal and infarcted hearts of Yucatan minipigs. The inclusion or exclusion of these from the CMRI analysis significantly affected the study results. In the normal pig hearts, the biggest differences were found in measurements of the LVV, ejection fraction (EF), LV mass and indices derived from the LV mass (p < 0.001). The EF measurement in the normal pig heart was 11% higher with the detailed method, and 19% higher in the infarcted pig hearts (p < 0.0001). The detailed method of endocardium tracing with CMRI closely represented the LV mass measured ex vivo. (4) Conclusions: The detailed method, which accounts for the large volume of the papillary muscles in the pig heart, provides better accuracy and interobserver consistency in the assessment of LV mass and ejection fraction, and might therefore be preferable for these analyses.

The emerging applications of cardiovascular magnetic resonance imaging in transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is an alternative to surgical aortic valve replacement in selected patients with severe symptomatic aortic stenosis (AS) and high surgical risk. The planning and follow-up of TAVI requires an array of imaging techniques, each has advantages and limitations. Echocardiography and multidetector computer tomography (MDCT) have established applications in patient selection and procedure guidance, but are limited in some patients. TAVI applications of cardiovascular magnetic resonance imaging (CMRI) are emerging. CMRI can provide the structural and functional imaging details required for TAVI procedure in away comparable or superior to that obtained by echocardiography and MDCT combined. In this review, we look at the continuously evolving role of CMRI as a complimentary or an alternative to more established imaging techniques and address the advantages and disadvantages of CMRI in this setting. We discuss the role of CMRI in selecting anatomically suitable patients for the TAVI procedure and in the post-TAVI follow-up with particular emphasis on its applications for assessing AS severity and haemodynamic impact, vascular imaging for TAVI access route, quantification of paravalvular leaks and LV remodelling in the post TAVI setting as well as providing imaging biomarkers tool for AS risk-stratification.

Imaging in patients with suspected acute heart failure: timeline approach position statement on behalf of the Heart Failure Association of the European Society of Cardiology

Acute heart failure is one of the main diagnostic and therapeutic challenges in clinical practice due to a non-specific clinical manifestation and the urgent need for timely and tailored management at the same time. In this position statement, the Heart Failure Association aims to systematize the use of various imaging methods in accordance with the timeline of acute heart failure care proposed in the recent guidelines of the European Society of Cardiology. During the first hours of admission the point-of-care focused cardiac and lung ultrasound examination is an invaluable tool for rapid differential diagnosis of acute dyspnoea, which is highly feasible and relatively easy to learn. Several portable and stationary imaging modalities are being increasingly used for the evaluation of cardiac structure and function, haemodynamic and volume status, precipitating myocardial ischaemia or valvular abnormalities, and systemic and pulmonary congestion. This paper emphasizes the central role of the full echocardiographic examination in the identification of heart failure aetiology, severity of cardiac dysfunction, indications for specific heart failure therapy, and risk stratification. Correct evaluation of cardiac filling pressures and accurate prognostication may help to prevent unscheduled short-term readmission. Alternative advanced imaging modalities should be considered to assist patient management in the pre- and post-discharge phase, including cardiac magnetic resonance, computed tomography, nuclear studies, and coronary angiography. The Heart Failure Association addresses this paper to the wide spectrum of acute care and heart failure specialists, highlighting the value of all available imaging techniques at specific stages and in common clinical scenarios of acute heart failure.

Improved Workflow for Quantification of Right Ventricular Volumes Using Free-Breathing Motion Corrected Cine Imaging

Cardiac MR traditionally requires breath-holding for cine imaging. Younger or less stable patients benefit from free-breathing during cardiac MR but current free-breathing cine images can be spatially blurred. Motion corrected re-binning (MOC) is a novel approach that acquires and then reformats real-time images over multiple cardiac cycles with high spatial resolution. The technique was previously limited by reconstruction time but distributed computing has reduced these times. Using this technique, left ventricular volumetry has compared favorably to breath-held balanced steady-state free precession cine imaging (BH), the current gold-standard, however, right ventricular volumetry validation remains incomplete, limiting the applicability of MOC in clinical practice. Fifty subjects underwent cardiac MR for evaluation of right ventricular size and function by end-diastolic (EDV) and end-systolic (ESV) volumetry. Measurements using MOC were compared to those using BH. Pearson correlation coefficients and Bland-Altman plots tested agreement across techniques. Total scan plus reconstruction times were tested for significant differences using paired t-test. Volumes obtained by MOC compared favorably to BH (R = 0.9911 for EDV, 0.9690 for ESV). Combined acquisition and reconstruction time (previously reported) were reduced 37% for MOC, requiring a mean of 5.2 min compared to 8.2 min for BH (p < 0.0001). Right ventricular volumetry compares favorably to BH using MOC image reconstruction, but is obtained in a fraction of the time. Combined with previous validation of its use for the left ventricle, this novel method now offers an alternative imaging approach in appropriate clinical settings.

Segmented radial cardiac MRI during arrhythmia using retrospective electrocardiogram and respiratory gating

PURPOSE

To improve segmented cardiac MRI image quality during arrhythmia.

METHODS

Electrocardiogram (ECG) and respiratory waveforms were recorded during imaging. Imaging readouts were retrospectively classified into heartbeat-types based on the RR interval of the current and preceding beats, QRS morphology, and respiratory phase. Image data were sorted by these classifiers to generate separate cine images of different heartbeat-types during sinus rhythm and arrhythmia. A simulation study evaluated the efficiency of K-space sampling over a range of heart rhythms, heart rates, and respiratory rates. In vivo imaging was performed in volunteers with sinus rhythm, swine with arrhythmia simulated by pacing, and a human subject with spontaneous premature beats.

RESULTS

K-space sampling uniformity and image quality incrementally improve with additional occurrences of the desired normal sinus or arrhythmia heartbeat-type. To approach the image quality of breath-hold imaging, sufficiently restrictive gating parameters are required. Compared with real-time imaging, retrospective gated images had reduced noise and improved sharpness while maintaining desired cine temporal resolution. Variations of cardiac function between arrhythmia heartbeats could be observed in arrhythmia imaging cases that are not captured by conventional segmented imaging.

CONCLUSION

Retrospective ECG and respiratory gating permits imaging of various heartbeats during arrhythmia with fewer resolution restrictions compared to real-time imaging. For a fixed imaging time, imaging quality depends on frequency of the imaged heartbeat-type. Imaging additional heartbeats permits incremental improvement in image quality.

Leg lean mass correlates with exercise systemic output in young Fontan patients

OBJECTIVE

We previously described lower leg lean mass Z-scores (LLMZ) in Fontan patients associated with worse peak oxygen consumption on metabolic exercise testing. We hypothesised that LLMZ correlates with indexed systemic flow (Qsi) and cardiac index (CI) on exercise cardiac magnetic resonance (eCMR).

METHODS

Thirteen patients had LLM measured by dual-energy X-ray absorptiometry within mean 40 (range 0-258) days of eCMR. LLM was converted to sex and race-specific Z-scores based on healthy reference data. Ventricular volumes and flow measurements of the ascending and descending (DAO) aorta and superior vena cava (SVC) were obtained by CMR at rest and just after supine ergometer exercise to a heart rate associated with anaerobic threshold on prior exercise test. Baseline and peak exercise measures of Qsi (SVC+DAO/BSA) and CI, as well as change in Qsi and CI with exercise, were compared with LLMZ by linear regression.

RESULTS

LLMZ was not correlated with resting flows, stroke volume or CI. There was a strong linear correlation between LLMZ and change in both CI (r=0.77, p=0.002) and Qsi (r=0.73, p=0.005) from rest to exercise. There was also a significant correlation between LLMZ and Qsi at exercise (r=0.70, p=0.008). The correlation between LLMZ and CI at exercise did not reach significance (r=0.3, p=0.07).

CONCLUSIONS

In our cohort, there was a strong linear correlation between LLMZ and change in both CI and Qsi from rest to exercise, suggesting that Fontan patients with higher LLMZ may be better able to augment systemic output during exercise, improving performance.

Magnetic resonance imaging planning in children with complex congenital heart disease - A new approach

OBJECTIVES

To compare a standard sequential 2D Planning Method (2D-PM) with a 3D offline Planning Method (3D-PM) based on 3D contrast-enhanced magnetic resonance angiography (CE-MRA) in children with congenital heart disease (CHD).

DESIGN

In 14 children with complex CHD (mean: 2.6 years, range: 3 months to 7.6 years), axial and coronal cuts were obtained with single slice spin echo sequences to get the final double oblique longitudinal cut of the targeted anatomical structure (2D-PM, n = 31). On a separate workstation, similar maximal intensity projection (MIP) images were generated offline from a 3D CE-MRA. MIP images were localizers for repeated targeted imaging using the previous spin echo sequence (3D-PM). Finally, image coverage, spatial orientation and acquisition time were compared for 2D-PM and 3D-PM.

MAIN OUTCOME MEASURES

2D-PM and 3D-PM images were similar: both perfectly covered the selected anatomic regions and no spatial differences were found (p>0.05). The mean time for creation of the final imaging plane was 241 ± 31 s (2D-PM) compared to 71 ± 18 s (3D-PM) (p<0.05).

CONCLUSIONS

3D-PM shows similar results compared to 2D-PM, but allows faster and offline planning thereby reducing the scan time significantly. As newly developed high-resolution 3D datasets can also be used further improvement of this technology is expected.

Improved workflow for quantification of left ventricular volumes and mass using free-breathing motion corrected cine imaging

BACKGROUND

Traditional cine imaging for cardiac functional assessment requires breath-holding, which can be problematic in some situations. Free-breathing techniques have relied on multiple averages or real-time imaging, producing images that can be spatially and/or temporally blurred. To overcome this, methods have been developed to acquire real-time images over multiple cardiac cycles, which are subsequently motion corrected and reformatted to yield a single image series displaying one cardiac cycle with high temporal and spatial resolution. Application of these algorithms has required significant additional reconstruction time. The use of distributed computing was recently proposed as a way to improve clinical workflow with such algorithms. In this study, we have deployed a distributed computing version of motion corrected re-binning reconstruction for free-breathing evaluation of cardiac function.

METHODS

Twenty five patients and 25 volunteers underwent cardiovascular magnetic resonance (CMR) for evaluation of left ventricular end-systolic volume (ESV), end-diastolic volume (EDV), and end-diastolic mass. Measurements using motion corrected re-binning were compared to those using breath-held SSFP and to free-breathing SSFP with multiple averages, and were performed by two independent observers. Pearson correlation coefficients and Bland-Altman plots tested agreement across techniques. Concordance correlation coefficient and Bland-Altman analysis tested inter-observer variability. Total scan plus reconstruction times were tested for significant differences using paired t-test.

RESULTS

Measured volumes and mass obtained by motion corrected re-binning and by averaged free-breathing SSFP compared favorably to those obtained by breath-held SSFP (r = 0.9863/0.9813 for EDV, 0.9550/0.9685 for ESV, 0.9952/0.9771 for mass). Inter-observer variability was good with concordance correlation coefficients between observers across all acquisition types suggesting substantial agreement. Both motion corrected re-binning and averaged free-breathing SSFP acquisition and reconstruction times were shorter than breath-held SSFP techniques (p < 0.0001). On average, motion corrected re-binning required 3 min less than breath-held SSFP imaging, a 37% reduction in acquisition and reconstruction time.

CONCLUSIONS

The motion corrected re-binning image reconstruction technique provides robust cardiac imaging that can be used for quantification that compares favorably to breath-held SSFP as well as multiple average free-breathing SSFP, but can be obtained in a fraction of the time when using cloud-based distributed computing reconstruction.

Noise behavior of MR brain reconstructions using compressed sensing

Compressed sensing (CS) has demonstrated great potential to reconstruct high quality MR images from undersampled k-space data. However, successful application of CS in clinic is still limited by many factors. One of the key factors is that the noise behavior in CS reconstructions remains largely unexplored. The main objective of this work is to analyze the noise behavior of MR reconstructions using CS method with different reduction factors. Our work focuses on brain CS-MRI reconstructions using non-linear conjugate gradient (NLCG) solvers. After reconstruction, the noise behavior is characterized using the MP-Law method. The results show that the spatial noise distributed non-uniformly, and the noise variance from CS reconstruction increases with reduction factors. A kind of fitting model is given, which can be used to predict the noise behavior parameter for different reduction factors, and the noise amplification factor maps are shown to prove the denoising capability of CS reconstruction. The results provide a qualitative and quantitative understanding of the noise behavior in CS-MRI with different reduction factors.

Fast in vivo quantification of T1 and T2 MRI relaxation times in the myocardium based on inversion recovery SSFP with in vitro validation post Gd-based contrast administration

PURPOSE

A fast clinical imaging technique for quantifying myocardial T1 and T2 relaxation times after Gadolinium (Gd)-based contrast administration within a single breathhold is presented with in vitro validation.

MATERIALS AND METHODS

From signal intensity curves in ECG-gated segmented inversion recovery balanced steady state free precession (IR-bSSFP) images, T1 and T2 values were determined for 24 agarose samples made from solutions of Omniscan (0.25-2 mg/mL) and copper-sulfate (0.52-22.17 mg/mL). T1 and T2 were also measured using turbo spin-echo (TSE) acquisitions and compared with IR-bSSFP results. In vivo T1 and T2 values from post-contrast IR-bSSFP images of five healthy volunteers were determined for (I) the left ventricular wall, (II) the interventricular septum (IVS) and (III) the lateral wall of the left ventricle (LV). Spin system simulations were performed for selected T1 and T2 values.

RESULTS

Good agreement between TSE and IR-bSSFP for T1 for realistic in vivo post-contrast values (below 1,250 ms, R=0.88) and for T2 (entire range, R=0.97) was found. Spin system simulations were in good agreement with measurements. In vivo average T1 was 546±32 ms and average T2 was 59±9 ms.

CONCLUSIONS

A fast imaging protocol for absolute quantification of myocardial T1 and T2 post-contrast is presented, validated in vitro and consecutively applied in vivo in humans.

Free-breathing steady-state free precession cine cardiac magnetic resonance with respiratory navigator gating

PURPOSE

To develop and validate a respiratory motion compensation method for free-breathing cardiac cine imaging.

METHODS

A free-breathing navigator-gated cine steady-state free precession acquisition (Cine-Nav) was developed which preserves the equilibrium state of the net magnetization vector, maintains the high spatial and temporal resolutions of standard breath-hold (BH) acquisition, and images entire cardiac cycle. Cine image data is accepted only from cardiac cycles occurring entirely during end-expiration. Prospective validation was performed in 10 patients by obtaining in each three complete ventricular image stacks with different respiratory motion compensation approaches: (1) BH, (2) free-breathing with 3 signal averages (3AVG), and (3) free-breathing with Cine-Nav.

RESULTS

The subjective image quality score (1 = worst, 4 = best) for Cine-Nav (3.8 ± 0.4) was significantly better than for 3AVG (2.2 ± 0.5, P = 0.002), and similar to BH (4.0 ± 0.0, P = 0.13). The blood-to-myocardium contrast ratio for Cine-Nav (6.3 ± 1.5) was similar to BH (5.9 ± 1.6, P = 0.52) and to 3AVG (5.6 ± 2.5, P = 0.43). There were no significant differences between Cine-Nav and BH for the ventricular volumes and mass. In contrast, there were significant differences between 3AVG and BH in all of these measurements but right ventricular mass.

CONCLUSION

Free-breathing cine imaging with Cine-Nav yielded comparable image quality and ventricular measurements to BH, and was superior to 3AVG.

Advances in cardiac magnetic resonance imaging and computed tomography

Imaging evaluation of the heart encompasses structural evaluation of the chambers, valves and coronary arteries, and functional evaluation, including assessment of perfusion, wall motion and myocardial viability. Magnetic resonance imaging is well established for the structural and functional evaluation of the heart, and benefits from direct multiplanar image acquisition and a lack of ionizing radiation. Magnetic resonance imaging assessment of myocardial viability after myocardial infarction appears to be helpful in predicting benefit from revascularization procedures. Magnetic resonance imaging continues to hold promise as the least invasive method of coronary artery evaluation, and continuing developments are improving image quality and decreasing examination time. The development of cardiac-gating techniques for multidetector computed tomography has the potential to provide widespread availability of cardiac computed tomography. Short examination times and straightforward scanning procedures promise a convenient method for the examination of cardiac structure and function. However, this convenience must be balanced against radiation dose and contrast-media requirements when determining the appropriate use of cardiac computed tomography. Computed tomography coronary-calcium scoring can aid in the prediction of significant coronary events in all but the lowest-risk patients. The high negative-predictive value of computed tomography coronary angiography may allow some patients to avoid cardiac catheterization, but its role in the assessment of patients with moderate coronary atherosclerosis remains unclear. New software tools can assist in the complex and tedious analysis of the large volumes of data produced by these examinations.

High spatial and temporal resolution retrospective cine cardiovascular magnetic resonance from shortened free breathing real-time acquisitions

BACKGROUND

Cine cardiovascular magnetic resonance (CMR) is challenging in patients who cannot perform repeated breath holds. Real-time, free-breathing acquisition is an alternative, but image quality is typically inferior. There is a clinical need for techniques that achieve similar image quality to the segmented cine using a free breathing acquisition. Previously, high quality retrospectively gated cine images have been reconstructed from real-time acquisitions using parallel imaging and motion correction. These methods had limited clinical applicability due to lengthy acquisitions and volumetric measurements obtained with such methods have not previously been evaluated systematically.

METHODS

This study introduces a new retrospective reconstruction scheme for real-time cine imaging which aims to shorten the required acquisition. A real-time acquisition of 16-20s per acquired slice was inputted into a retrospective cine reconstruction algorithm, which employed non-rigid registration to remove respiratory motion and SPIRiT non-linear reconstruction with temporal regularization to fill in missing data. The algorithm was used to reconstruct cine loops with high spatial (1.3-1.8 × 1.8-2.1 mm²) and temporal resolution (retrospectively gated, 30 cardiac phases, temporal resolution 34.3 ± 9.1 ms). Validation was performed in 15 healthy volunteers using two different acquisition resolutions (256 × 144/192 × 128 matrix sizes). For each subject, 9 to 12 short axis and 3 long axis slices were imaged with both segmented and real-time acquisitions. The retrospectively reconstructed real-time cine images were compared to a traditional segmented breath-held acquisition in terms of image quality scores. Image quality scoring was performed by two experts using a scale between 1 and 5 (poor to good). For every subject, LAX and three SAX slices were selected and reviewed in the random order. The reviewers were blinded to the reconstruction approach and acquisition protocols and scores were given to segmented and retrospective cine series. Volumetric measurements of cardiac function were also compared by manually tracing the myocardium for segmented and retrospective cines.

RESULTS

Mean image quality scores were similar for short axis and long axis views for both tested resolutions. Short axis scores were 4.52/4.31 (high/low matrix sizes) for breath-hold vs. 4.54/4.56 for real-time (paired t-test, P = 0.756/0.011). Long axis scores were 4.09/4.37 vs. 3.99/4.29 (P = 0.475/0.463). Mean ejection fraction was 60.8/61.4 for breath-held acquisitions vs. 60.3/60.3 for real-time acquisitions (P = 0.439/0.093). No significant differences were seen in end-diastolic volume (P = 0.460/0.268) but there was a trend towards a small overestimation of end-systolic volume of 2.0/2.5 ml, which did not reach statistical significance (P = 0.052/0.083).

CONCLUSIONS

Real-time free breathing CMR can be used to obtain high quality retrospectively gated cine images in 16-20s per slice. Volumetric measurements and image quality scores were similar in images from breath-held segmented and free breathing, real-time acquisitions. Further speedup of image reconstruction is still needed.

Monitoring and compensating phase imperfections in cine balanced steady-state free precession

PURPOSE

To analyze and correct for eddy current-induced phase imperfections in cardiac cine balanced steady-state free precession (bSSFP) imaging.

METHODS

Eddy current-induced phase offsets were measured for different phase-encoding schemes using a higher order dynamic field camera. Based on these measurements, offset phases were corrected for in postprocessing and by run-time phase compensation applying radiofrequency phase increments and additional compensatory gradient areas. The findings were validated using numerical simulations, phantom experiments, and in vivo cardiac scans.

RESULTS

Depending on the phase-encoding scheme, significant eddy current-induced phase offsets were detected. Time-varying phase offsets were observed at subsequent excitations leading to steady-state distortions and hence to profile-dependent amplitude modulations in k-space. Taking into account measured k-space trajectories algebraic image reconstruction allowed compensating imperfect spatial encoding. Correction of amplitude modulations was successfully accomplished by run-time phase compensation.

CONCLUSION

Using magnetic field monitoring, artifacts in cine balanced steady-state free precession caused by uncompensated eddy current fields can be significantly reduced.

Real-time phase-contrast MRI of cardiovascular blood flow using undersampled radial fast low-angle shot and nonlinear inverse reconstruction

Velocity-encoded phase-contrast MRI of cardiovascular blood flow commonly relies on electrocardiogram-synchronized cine acquisitions of multiple heartbeats to quantitatively determine the flow of an averaged cardiac cycle. Here, we present a new method for real-time phase-contrast MRI that combines flow-encoding gradients with highly undersampled radial fast low-angle shot acquisitions and phase-sensitive image reconstructions by regularized nonlinear inversion. Apart from calibration studies using steady and pulsatile flow, preliminary in vivo applications focused on through-plane flow in the ascending aorta of healthy subjects. With bipolar velocity-encoding gradients of alternating polarity that overlap the slice-refocusing gradient, the method yields flow-encoded images with an in-plane resolution of 1.8 mm, section thickness of 6 mm and measuring time at 3 T of 24 ms (TR/TE = 3.44/2.76 ms; flip angle, 10º; seven radial spokes per image). Accordingly, phase-contrast maps and corresponding velocity profiles achieve a temporal resolution of 48 ms. The evaluated peak velocities, stroke volumes, flow rates and respective variances over at least 20 consecutive heartbeats are in general agreement with literature data.

Cardiovascular magnetic resonance physics for clinicians: part I

There are many excellent specialised texts and articles that describe the physical principles of cardiovascular magnetic resonance (CMR) techniques. There are also many texts written with the clinician in mind that provide an understandable, more general introduction to the basic physical principles of magnetic resonance (MR) techniques and applications. There are however very few texts or articles that attempt to provide a basic MR physics introduction that is tailored for clinicians using CMR in their daily practice. This is the first of two reviews that are intended to cover the essential aspects of CMR physics in a way that is understandable and relevant to this group. It begins by explaining the basic physical principles of MR, including a description of the main components of an MR imaging system and the three types of magnetic field that they generate. The origin and method of production of the MR signal in biological systems are explained, focusing in particular on the two tissue magnetisation relaxation properties (T1 and T2) that give rise to signal differences from tissues, showing how they can be exploited to generate image contrast for tissue characterisation. The method most commonly used to localise and encode MR signal echoes to form a cross sectional image is described, introducing the concept of k-space and showing how the MR signal data stored within it relates to properties within the reconstructed image. Before describing the CMR acquisition methods in detail, the basic spin echo and gradient pulse sequences are introduced, identifying the key parameters that influence image contrast, including appearances in the presence of flowing blood, resolution and image acquisition time. The main derivatives of these two pulse sequences used for cardiac imaging are then described in more detail. Two of the key requirements for CMR are the need for data acquisition first to be to be synchronised with the subject's ECG and to be fast enough for the subject to be able to hold their breath. Methods of ECG synchronisation using both triggering and retrospective gating approaches, and accelerated data acquisition using turbo or fast spin echo and gradient echo pulse sequences are therefore outlined in some detail. It is shown how double inversion black blood preparation combined with turbo or fast spin echo pulse sequences acquisition is used to achieve high quality anatomical imaging. For functional cardiac imaging using cine gradient echo pulse sequences two derivatives of the gradient echo pulse sequence; spoiled gradient echo and balanced steady state free precession (bSSFP) are compared. In each case key relevant imaging parameters and vendor-specific terms are defined and explained.

A method to assess spatially variant noise in dynamic MR image series

Accurate measurement of spatially variant noise in MR images acquired using parallel imaging techniques is challenging. Image-based noise measurement methods such as the subtraction method proposed by the National Electrical Manufacturers Association or the multiple acquisition method often cannot be applied in vivo due to motion and/or dynamic contrast changes. Based on the Karhunen-Loeve transform and random matrix theory, we propose a novel method to accurately assess the noise variance in image series bearing temporal redundancy. The method fits the probability density function of eigenvalues from the temporal covariance matrix of the image series to the Marcenko-Pastur distribution. The accuracy of our method was validated using numerical simulation and an MR noise measurement experiment. The ability of this method to derive the g-factor map of a static phantom was validated against the multiple acquisition method. The method was applied to in vivo cardiac and brain image series and the results agreed with subtraction and multiple acquisition methods, respectively. This new image-based noise measurement method provides a practical means of retrospectively evaluating the noise level and/or g-factor map from multiframe image series.

Morpho-functional patterns of physiologic oropharyngeal swallowing evaluated with dynamic fast MRI

With the advent of dynamic fast MRI sequences the act of deglutition can be dynamically visualized in cine-mode. Twenty-three healthy volunteers were enrolled in this study to define the morpho-functional patterns of oral and pharyngeal deglutition using new dynamic MRI techniques. All subjects were previously submitted to video endoscopic assessment, to exclude swallowing abnormalities. As contrast material a combination of yogurt mixed with gadolinium-diethylene diamine pentaacetic acid was used. The protocol was divided into three parts: (a) preliminary assessment of the oral cavity, pharynx and laryngeal structures; (b) morphologic assessment of tongue, soft palate, pharynx, epiglottis and larynx-hyoid bone; (c) dynamic assessment of swallowing without administrating any contrast media and, in subsequent phase, by injecting 5 ml of yogurt-based contrast medium in the patient's mouth. The time resolution was 3-4 images/s. The MR protocol revealed to be effective in the evaluation of normal motility patterns of the structures involved in swallowing. Moreover, the evaluation of the bolus progression, slowdown or stagnation, was possible. On the contrary problems were encountered in calculating precisely the bolus progression time, because of the insufficient temporal resolution. However, more energy should be invested to optimize the spatial and temporal resolution of turbo-FLASH sequences, to obtain a better dynamic representation of a complex function such as deglutition.

Accelerated two- and three-dimensional cine MR imaging of the heart by using a 32-channel coil

PURPOSE

To compare accelerated real-time two-dimensional (2D) and segmented three-dimensional (3D) cine steady-state free precession magnetic resonance (MR) imaging techniques by using a 32-channel coil with a conventional 2D cine imaging approach for imaging the heart and to evaluate any difference caused by free breathing and breath holding for real-time imaging.

MATERIALS AND METHODS

In this institutional review board-approved HIPAA-compliant study, 10 healthy volunteers and 22 consecutive patients who were suspected of having or were known to have heart disease underwent cardiac MR imaging by using a 32-channel coil. A conventional multisection 2D real-time cine sequence was used as the reference standard, and three additional accelerated cine sequences were implemented. Volumetric parameters, including ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume(SV), and myocardial mass, were derived. Wall motion and image quality were assessed by two radiologists. In addition, image time was registered. An additional set of images was acquired by using real-time sequences with free breathing, and quantitative measurements were compared with measurements on images obtained with breath holding. For quantitative analysis, repeated-measures analysis of variance, paired t test, and Bland-Altman analysis were used; for qualitative analysis, nonparametric Wilcoxon signed-rank test was used.

RESULTS

All volumetric measurements were significantly correlated with those of the standard sequence (r > 0.80, P < .01). No significant difference among protocols was observed in terms of mean levels for EF or ESV (P > .05). However, a significant difference was indicated for EDV and SV (P < .01).The accelerated protocols had significantly shorter image times (P < .001). Wall motion scores were concordant with the standard sequence in 43-44 (93%-96%) segments for the accelerated protocols, with a strong interreader agreement (intraclass correlation coefficient, > or =0.93). No significant difference was identified between real-time protocols with free breathing and those with breath holding for measurement of volumetric parameters.

CONCLUSION

Accelerated real-time 2D and segmented 3D cine techniques are comparable to the standard clinical protocol in assessment of left ventricular global and regional parameters in substantially shorter image times.

Advances in Cardiovascular MRI for Diagnostics: Applications in Coronary Artery Disease and Cardiomyopathies

BACKGROUND: Cardiac magnetic resonance (CMR) imaging has emerged as an important cardiac imaging technique for the evaluation of multiple cardiac pathologies. OBJECTIVE/METHOD: The goal of this review is to describe recent advances in techniques which have extended the potential applications of CMR. The focus will be on the clinical applications of CMR for the evaluation of coronary artery disease and heart failure/cardiomyopathies which are major causes of morbidity and mortality worldwide. CONCLUSION: CMR provides unique tissue characterization which is not available from other imaging modalities and has demonstrated important diagnostic and prognostic information in many forms of heart disease.

Real-time fetal magnetic resonance imaging for the dynamic visualization of the pouch in esophageal atresia

Esophageal atresia is the principal cause of congenital esophageal obstruction. Prenatal suspicion of esophageal atresia is usually based on the presence of polyhydramnios together with an absent stomach bubble. More recently, visualization of the dilatation of the blind-ending esophagus (esophageal pouch) during fetal swallowing has been reported and proposed as the most reliable sign for predicting esophageal atresia. Improvement of radiofrequency and computer technology as well as parallel data acquisition has greatly reduced magnetic resonance (MR) scanning time, allowing visualization of the fetus in cine-mode using fast imaging employing steady-state acquisition (FIESTA). We describe the application of FIESTA sequences in fetuses with suspected esophageal atresia for visualization of the esophageal pouch using MR imaging.

Application of the Karhunen-Loeve transform temporal image filter to reduce noise in real-time cardiac cine MRI

Real-time dynamic magnetic resonance imaging (MRI) typically sacrifices the signal-to-noise ratio (SNR) to achieve higher spatial and temporal resolution. Spatial and/or temporal filtering (e.g., low-pass filtering or averaging) of dynamic images improves the SNR at the expense of edge sharpness. We describe the application of a temporal filter for dynamic MR image series based on the Karhunen-Loeve transform (KLT) to remove random noise without blurring stationary or moving edges and requiring no training data. In this paper, we present several properties of this filter and their effects on filter performance, and propose an automatic way to find the filter cutoff based on the autocorrelation of the eigenimages. Numerical simulation and in vivo real-time cardiac cine MR image series spanning multiple cardiac cycles acquired using multi-channel sensitivity-encoded MRI, i.e., parallel imaging, are used to validate and demonstrate these properties. We found that in this application, the noise standard deviation was reduced to 42% of the original with no apparent image blurring by using the proposed filter cutoff. Greater noise reduction can be achieved by increasing the length of the image series. This advantage of KLT filtering provides flexibility in the form of another scan parameter to trade for SNR.

Assessment of left ventricular volumes and function by cine-MR imaging depending on the investigator's experience

AIMS

To analyze the reproducibility of LV volumes calculated by cardiac magnetic resonance imaging (CMRI) and to compare them to those obtained by conventional ventriculography.

METHODS

A total of 30 patients with stable ischemic heart disease were prospectively included. Each underwent CMRI twice and ventriculography. Left ventricular end diastolic volume (EDV), end systolic volume (ESV) and LV ejection fraction (EF) were calculated by two radiologists at different level of experience. Intraobserver, interobserver and interstudy variabilities were assessed.

RESULTS

The cut off values were: intraobserver variability (EDV, ESV, EF): 9.4 ml, 5.3 ml, 3.3% for well-trained radiologist; 13.1 ml, 7.5 ml, 4.1% for less-trained radiologist. interobserver variability: EDV: 11.7 and 10.4 ml; ESV: 7.0 and 6.6 ml; EF: 3.9 and 4.2%. interstudy variability (EDV, ESV, EF): 11.6 and 12.6 ml, 7.1 and 7.4 ml, 3.9 and 3.5%, for experienced and less-trained observers. Statistical differences were found between CMRI and ventriculography: CMRI underestimation of EDV and EF, overestimation of ESV.

CONCLUSIONS

CMRI volumetric quantification of LV volumes and function is highly reproducible at different levels of experience, but not interchangeable with those obtained by ventriculography.

Feasibility of single breath-hold left ventricular function with 3 Tesla TSENSE acquisition and 3D modeling analysis

BACKGROUND

A single breath-hold evaluation of ventricular function would allow assessment in cases where scan time or patient tolerance is limited. Spatiotemporal acceleration techniques such as TSENSE decrease cardiovascular MR acquisition time, but standard slice summation analysis requires enough short axis slices to cover the left ventricle (LV). By reducing the number of short axis slices, incorporating long axis slices, and applying a 3D model based analysis, it may be possible to obtain accurate LV mass and volumes. We evaluated LV volume, mass and ejection fraction at 3.0 T using a 3D modeling analysis in 9 patients with a history of myocardial infarction and one healthy volunteer. Acquisition consisted of a standard short axis SSFP stack and a 15 heart-beat single breath-hold six slice multi-planar (4 short and 2 long axis) TSENSE SSFP protocol with an acceleration factor of R = 4.

RESULTS

Differences (standard minus accelerated protocol mean +/- s.d.) and coefficients of variation (s.d. of differences as a percentage of the average estimate) were 7.5 +/- 9.6 mL and 6% for end-diastolic volume (p = 0.035), 0.4 +/- 5.1 mL and 7% for end-systolic volume (p = NS), 7.1 +/- 8.1 mL and 9% for stroke volume (p = 0.022), 2.2 +/- 2.8% and 5% for ejection fraction (p = 0.035), and -7.1 +/- 6.2 g and 4% for LV mass (p = 0.005), respectively. Intra- and inter-observer errors were similar for both protocols (p = NS for all measures).

CONCLUSION

These results suggest that clinically useful estimates of LV function can be obtained in a TSENSE accelerated single breath-hold reduced slice acquisition at 3T using 3D modeling analysis techniques.

ACR appropriateness criteria on suspected congenital heart disease in adults

The number of adults with congenital heart disease is increasing in North America. This is attributable to a variety of factors, including improvements in surgical techniques and increases in immigration. Cardiac imaging is critical for the initial assessment of adults with newly suspected congenital heart disease as well as for the serial assessment of adults with known congenital heart disease. Chest radiography and echocardiography continue to be the initial tools used to evaluate adult congenital heart disease. However, cardiac computed tomography and magnetic resonance imaging have significantly improved over the years and have become integral to the evaluation of adult congenital heart disease, often precluding the necessity for invasive cardiac catheterization. Noninvasive imaging is particularly useful for the surveillance of patients with surgically corrected congenital heart disease, who often require 2 or more additional operations.

[Quantification of ventricular mass and function using real-time free-breathing SSFP sequences]

OBJECTIVES

To compare real-time free-breathing steady-state free precession (SSFP) sequences with conventional breath-hold segmented SSFP sequences on the quantification of ventricular mass and function.

MATERIAL AND METHODS

Cardiac function and mass were assessed in 15 consecutive patients with cardiopathies who underwent MRI for diverse indications. Sequences were planned in the short axis to include the area from the base to the apex of the ventricle. Two sequences were used: 1) a conventional breath-hold segmented SSFP sequence with 7-mm-thick slices and 3-mm gap between slices and 2) a real-time free-breathing SSFP sequence with 10-mm-thick slices. The systolic and diastolic volumes (VTD, VTS) and ejection fraction (EF) of both ventricles were evaluated and the mass of the left ventricle (LVM) was measured. The correlation between the different sequences was studied for each variable.

RESULTS

An excellent correlation was observed between the two sequences on the quantification of cardiac parameters in both ventricles (0.9; p < 0.01). The mean differences for EF, VTD, VTS, and stroke volume (VTD-VTS) were 2.5% (2.1), 5.6 ml (14.2), -0.8 ml (6.4), 6.4 ml (9.4), respectively, for the left ventricle and 1.7% (3.1), 1.8 ml (18.7), -1.9 ml (9.8), 3.7 ml (10.8), respectively, for the right ventricle. The mean difference between the LVM was 4.8 g (6.3).

CONCLUSIONS

The real-time free-breathing SSFP sequence is useful for the quantification of ventricular mass and function. The correlation with conventional SSFP is excellent. Both sequences allow the cardiac parameters to be precisely quantified and the results are reproducible.

Balanced steady-state free precession vs. segmented fast low-angle shot for the evaluation of ventricular volumes, mass, and function at 3 Tesla

PURPOSE

To compare balanced steady-state free precession (SSFP) and segmented fast low angle shot (FLASH) for quantification of left and right ventricular volumes and function and for left ventricular mass at high field (3 Tesla).

MATERIALS AND METHODS

A total of 33 patients (19 male, mean age 54 years) with various forms of heart disease underwent ventricular function studies using cine SSFP and FLASH sequences with identical slice orientations.

RESULTS

Using SSFP, left ventricular end-diastolic (+10 mL [4.7%], P < 0.001) and end-systolic volumes (+9 mL [6.1%], P < 0.001) measured larger whereas mass was considerably smaller (-23 g [-12.9%], P < 0.001) and ejection fraction (-1% [-3.2%], P < 0.01) marginally smaller. Right ventricular end-diastolic (+4 mL [2.6%], P = 0.001) and end-systolic volumes (+4 mL [5.1%], P < 0.01) were also larger, but no significant difference for right ventricular ejection fraction (P = 0.05) was found.

CONCLUSION

Similar to previous results at 1.5 Tesla, at high magnetic field the cine SSFP technique led to discrete but significantly higher ventricular volume measurements and to a significantly smaller measurement of left ventricular mass in patients. The effect on left and right ventricular ejection fraction was minor, although the difference remained significant for the left ventricle.

Assessment of ventricular function with cardiovascular magnetic resonance

The high spatial and temporal resolution of cardiovascular magnetic resonance (CMR) images makes it well-suited for use in the assessment of right ventricular and left ventricular function in patients who have cardiovascular disorders. This article reviews CMR methods used to assess regional and global ventricular function.

Assessment of global left ventricular functional parameters: analysis of every second short-axis Magnetic Resonance Imaging slices is as accurate as analysis of consecutive slices

The purpose of this study was to assess whether accurate global left-ventricular (LV) functional parameters can be obtained by analyzing every second short-axis magnetic resonance imaging cine series instead of consecutive slices, in order to reduce post-processing time. Forty patients, were scanned on a 1.5 T MRI-system (Magnetom Sonata, Siemens Medical Systems, Erlangen, Germany) using a steady-state free precession (SSFP) sequence. A stack of short-axis cine series from above the mitral valve through the apex was acquired. Post-processing was started at the most basal slice of the left ventricle, in which at least 50% of the circumference was myocardium. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and LV mass (LVM), were calculated. Data analysis was repeated, but now only every second slice was analyzed. Bland-Altman analysis showed slightly lower values for all LV parameters when only every second slice was analyzed, ranging from 1.7% difference for EF (limits of agreement -3.5 to 5.0) to 4.6% for SV (limits of agreement -7.2 to 15.0). Analysis of every second slice for quantification of global LV function is time-saving and as accurate as analysis of consecutive slices.

Accuracy of contrast-enhanced cine-MR sequences in the assessment of left ventricular function: comparison with precontrast cine-MR sequences. Results of a bicentric study

The accuracy of contrast-enhanced cine magnetic resonance (cine-MR) imaging to determine left ventricular function was assessed by comparison with the established noncontrast cine-MR sequences. Contrast-enhanced balanced steady-state free precession (cine-SSFP) sequences were compared with precontrast cine-SSFP sequences in the assessment of left ventricular contractile function in 30 consecutive patients with various cardiac diseases. Five to eight short-axis image sections were obtained in each patient. Quantitative data were analyzed using a paired t-test and linear regression analysis. Qualitative assessment of images was made following a 16-segment analysis. There was no significant difference between the two sequences in regional wall motion, end-diastolic volumes (EDV) and end-systolic volumes (ESV), stroke volume, left ventricular mass, as well as left ventricular ejection fraction (LVEF), despite slight delayed subendocardial enhancement in ten patients with myocardial infarction. All the values studied above were closely correlated between both cine-SSFP sequences (Spearman r=0.85-0.97, P<0.0001 for all comparisons). Contrast-enhanced cine-SSFP sequences can be used as a similar diagnostic tool as precontrast cine-MR sequences in the assessment of left ventricular contractile function.