3D Late Gadolinium Enhancement Research Articles

T1-refBlochi: high resolution 3D post-contrast T1 myocardial mapping based on a single 3D late gadolinium enhancement volume, Bloch equations, and a reference T1

BackgroundHigh resolution 3D T1 mapping is important for assessment of diffuse myocardial fibrosis in left atrium or other thin-walled structures. In this work, we investigated a fast single-TI 3D high resolution T1 mapping method that directly transforms a 3D late gadolinium enhancement (LGE) volume to a 3D T1 map.MethodsThe proposed method, T1-refBlochi, is based on Bloch equation modeling of the LGE signal, a single-point calibration, and assumptions that proton density and T2* are relatively uniform in the heart. Several sources of error of this method were analyzed mathematically and with simulations. Imaging was performed in phantoms, eight swine and five patients, comparing T1-refBlochi to a standard spin-echo T1 mapping, 3D multi-TI T1 mapping, and 2D ShMOLLI, respectively.ResultsThe method has a good accuracy and adequate precision, even considering various sources of error. In phantoms, over a range of protocols, heart-rates and T1 s, the bias ±1SD was -3 ms ± 9 ms. The porcine studies showed excellent agreement between T1-refBlochi and the multi-TI method (bias ±1SD = −6 ± 22 ms). The proton density and T2* weightings yielded ratios for scar/blood of 0.94 ± 0.01 and for myocardium/blood of 1.03 ± 0.02 in the eight swine, confirming that sufficient uniformity of proton density and T2* weightings exists among heterogeneous tissues of the heart. In the patients, the mean T1 bias ±1SD in myocardium and blood between T1-refBlochi and ShMOLLI was -9 ms ± 21 ms.ConclusionT1-refBlochi provides a fast single-TI high resolution 3D T1 map of the heart with good accuracy and adequate precision.

Quantitative comparison of 2D and 3D late gadolinium enhancement MR imaging in patients with Fabry disease and hypertrophic cardiomyopathy

BackgroundThis study aims to determine whether the quantification of myocardial fibrosis in patients with Fabry disease (FD) and hypertrophic cardiomyopathy (HCM) using a late gadolinium enhancement (LGE) singlebreath-hold three-dimensional (3D) inversion recovery magnetic resonance (MR) imaging sequence is comparable with a clinically established two-dimensional (2D) multi-breath-hold sequence. MethodsIn this retrospective, IRB-approved study, 40 consecutive patients (18 male; mean age 50±17years) with Fabry disease (n=18) and HCM (n=22) underwent MR imaging at 1.5T. Spatial resolution was the same for 3D and 2D images (field-of-view, 350×350mm2; in-plane-resolution, 1.2×1.2mm2; section-thickness, 8mm). Datasets were analyzed for subjective image quality; myocardial and fibrotic mass, and total fibrotic tissue percentage were quantified. ResultsThere was no significant difference in subjective image quality between 3D and 2D acquisitions (P=0.1 and P=0.3) for either disease. In patients with Fabry disease there were no significant differences between 3D and 2D acquisitions for myocardial mass (P=0.55), fibrous tissue mass (P=0.89), and total fibrous percentage (P=0.67), with good agreement between acquisitions according to Bland–Altman analyses. In patients with HCM there were also no significant differences between acquisitions for myocardial mass (P=0.48), fibrous tissue mass (P=0.56), and total fibrous percentage (P=0.67), with good agreement according to Bland–Altman analyses. Acquisition time was significantly shorter for 3D (25±5s) as compared to the 2D sequence (349±62s, P<0.001). ConclusionsIn patients with Fabry disease and HCM, 3D LGE imaging provides equivalent diagnostic information in regard to quantification of myocardial fibrosis as compared with a standard 2D sequence, but at superior acquisition speed.

Compressed sensing for rapid late gadolinium enhanced imaging of the left atrium: A preliminary study

Current late gadolinium enhancement (LGE) imaging of left atrial (LA) scar or fibrosis is relatively slow and requires 5–15min to acquire an undersampled (R=1.7) 3D navigated dataset. The GeneRalized Autocalibrating Partially Parallel Acquisitions (GRAPPA) based parallel imaging method is the current clinical standard for accelerating 3D LGE imaging of the LA and permits an acceleration factor ~R=1.7. Two compressed sensing (CS) methods have been developed to achieve higher acceleration factors: a patch based collaborative filtering technique tested with acceleration factor R~3, and a technique that uses a 3D radial stack-of-stars acquisition pattern (R~1.8) with a 3D total variation constraint. The long reconstruction time of these CS methods makes them unwieldy to use, especially the patch based collaborative filtering technique. In addition, the effect of CS techniques on the quantification of percentage of scar/fibrosis is not known.We sought to develop a practical compressed sensing method for imaging the LA at high acceleration factors. In order to develop a clinically viable method with short reconstruction time, a Split Bregman (SB) reconstruction method with 3D total variation (TV) constraints was developed and implemented. The method was tested on 8 atrial fibrillation patients (4 pre-ablation and 4 post-ablation datasets). Blur metric, normalized mean squared error and peak signal to noise ratio were used as metrics to analyze the quality of the reconstructed images, Quantification of the extent of LGE was performed on the undersampled images and compared with the fully sampled images. Quantification of scar from post-ablation datasets and quantification of fibrosis from pre-ablation datasets showed that acceleration factors up to R~3.5 gave good 3D LGE images of the LA wall, using a 3D TV constraint and constrained SB methods. This corresponds to reducing the scan time by half, compared to currently used GRAPPA methods. Reconstruction of 3D LGE images using the SB method was over 20 times faster than standard gradient descent methods.

A clinical combined gadobutrol bolus and slow infusion protocol enabling angiography, inversion recovery whole heart, and late gadolinium enhancement imaging in a single study.

BackgroundThe use of gadolinium contrast agents in cardiovascular magnetic resonance is well-established and serves to improve both vascular imaging as well as enable late gadolinium enhancement (LGE) imaging for tissue characterization. Currently, gadofosveset trisodium, an intravascular contrast agent, combined with a three-dimensional inversion recovery balanced steady state free precession (3D IR bSSFP) sequence, is commonly used in pediatric cardiac imaging and yields excellent vascular imaging, but cannot be used for late gadolinium enhancement. Gadofosveset use remains limited in clinical practice, and manufacture was recently halted, thus an alternative is needed to allow 3D IR bSSFP and LGE in the same study.MethodsHere we propose a protocol to give a bolus of 0.1 mL/kg = 0.1 mmol/kg gadobutrol (GADAVIST/GADOVIST) for time-resolved magnetic resonance angiography (MRA). Subsequently, 0.1 mmol/kg is diluted up to 5 or 7.5 mL with saline and then loaded into intravenous tubing connected to the patient. A 0.5 mL short bolus is infused, then a slow infusion is given at 0.02 or 0.03 mL/s. Image navigated (iNAV) 3D IR bSSFP imaging is initiated 45–60 s after the initiation of the infusion, with a total image acquisition time of ~5 min. If necessary, LGE imaging using phase sensitive inversion recovery reconstruction (PSIR) is performed at 10 min after the infusion is initiated.ResultsWe have successfully performed the above protocol with good image quality on 10 patients with both time-resolved MRA and 3D IR bSSFP iNAV imaging. Our initial attempts to use pencil beam respiratory navigation failed due to signal labeling in the liver by the navigator. We have also performed 2D PSIR LGE successfully, with both LGE positive and LGE negative results.ConclusionA bolus of gadobutrol, followed later by a slow infusion, allows time-resolved MRA, 3D IR bSSFP using the iNAV navigation technique, and LGE imaging, all in a single study with a single contrast agent.

Abstract 14014: Early Detection of Myocardial Involvement in Idiopathic Inflammatory Myopathies Assessed by Cardiac Magnetic Resonance Imaging

Background: Idiopathic inflammatory myopathies are heterogeneous autoimmune systemic diseases characterized by chronic progressive muscle weakness and inflammatory infiltrates in skeletal muscle. The frequency of cardiac involvement varies between 9% and 72%, mainly dependent on patient selection, definition and diagnostic tools applied. Heart failure is the most frequent finding. Cardiac magnetic resonance imaging (CMR) has been shown to provide reliable and valuable information about cardiac function and inflammatory process in one examination. Hypothesis: Aim of our prospective study was to characterize cardiac involvement using a comprehensive CMR protocol. Methods: Fifty-three consecutive patients with histologically proven idiopathic inflammatory myopathy were enrolled into the study. Blood levels of Creatine kinase (CK) and myocardial CK (CK-MB) were analyzed from each patient. All patients underwent CMR examination in a 1.5-T whole body scanner. 3D short-axis functional steady-state free precession and late gadolinium enhancement (LGE) sequences were acquired in all patients covering the entire left and right ventricle. CMR images were analyzed by two experienced and blinded readers in consensus. Besides functional analysis LGE images were analyzed for hyperenhancement and quantified as LGE percentage of myocardial mass. Results: Reduced left ventricular function (ejection fraction &lt; 60%) was present in 9 (17%) patients. These patients exhibited significantly higher blood levels of CK-MB (283±193 vs. 175±221 U/l, p=0.02) than patients with preserved LVEF. Early myocardial enhancement (&gt;45% signal intensity increase) was more often present (6 out of 9 [66.7%] vs. 25 out of 44 [56.8%], p=.014) as well as LGE patterns consistent with myocardial inflammation (9 out of 9 [100%] vs. 24 out of 44 [54.5%], p=.001). LGE was most often observed in the inferior and lateral segments. Conclusion: The results of this study show that CMR is able to detect cardiac involvement in idiopathic inflammatory myopathies. Early diagnosis using CMR could result in early therapy of heart failure, leading to beneficial ventricular remodeling and thus improving living quality and survival in these patients.

Modified wideband three-dimensional late gadolinium enhancement MRI for patients with implantable cardiac devices.

To study the effects of cardiac devices on three-dimensional (3D) late gadolinium enhancement (LGE) MRI and to develop a 3D LGE protocol for implantable cardioverter defibrillator (ICD) patients with reduced image artifacts. The 3D LGE sequence was modified by implementing a wideband inversion pulse, which reduces hyperintensity artifacts, and by increasing bandwidth of the excitation pulse. The modified wideband 3D LGE sequence was tested in phantoms and evaluated in six volunteers and five patients with ICDs. Phantom and in vivo studies results demonstrated extended signal void and ripple artifacts in 3D LGE that were associated with ICDs. The reason for these artifacts was slab profile distortion and the subsequent aliasing in the slice-encoding direction. The modified wideband 3D LGE provided significantly reduced ripple artifacts than 3D LGE with wideband inversion only. Comparison of 3D and 2D LGE images demonstrated improved spatial resolution of the heart using 3D LGE. Increased bandwidth of the inversion and excitation pulses can significantly reduce image artifacts associated with ICDs. Our modified wideband 3D LGE protocol can be readily used for imaging patients with ICDs given appropriate safety guidelines are followed.

Single breath-hold 3D LGE using stack of spiral trajectory

Background Late gadolinium enhancement (LGE) imaging is the gold standard for noninvasive evaluation of myocardial scar. In the clinical setting, the standard imaging protocol involves a breath-held segmented inversion-prepared 2D Cartesian acquisition at a single location. This breathhold scan is repeated 10 -14 times to cover the entire left ventricle. Although multislice 2D LGE has shown great diagnostic accuracy, the multiple breath-holds increase the scan time to approximately 10min and patient fatigue which can result in poor breath-holding and ghosting artifact. In this study, we propose to perform the 3D LGE imaging in a single breath-hold using a stack of spiral trajectory. Methods Single breath-hold 3D stack of spiral LGE images covering the entire LV were acquired in 27 subjects undergoing clinical scans following the conventional multisilce 2D LGE on a Siemens 1.5T Avanto scanner. The 3D spiral LGE sequence consisted of 12 partitions of a dual density spiral trajectory. Each spiral readout was 4ms long with 24 interleaves to support 1.5x Nyquist in the center and 0.7x Nyquist in the edge of kspace. At each cardiac cycle, 2 out of 24 interleaves were acquired for each partition resulting in an acquisition window of approximately 160ms. All of the spirals were acquired in a single 12 heart beat breath-hold. Other sequence parameters included: TR 7ms, TE 1ms, TI 300~400ms, FA 20, FOV 340mm, in-plane resolution 1.5mm, 12 slices, and thickness 8mm. The images

Modified wideband 3D late gadolinium enhancement (LGE) MRI for patients with implantable cardiac devices

Background Late gadolinium enhancement (LGE) cardiac MRI is the clinical gold standard for non-invasive assessment of myocardial viability and plays an important role in guiding catheter ablation of ventricular tachycardia (VT). The majority of VT patients have implanted cardiac devices such as implantable cardioverter defibrillators (ICDs). The presence of ICDs gives rise to strong off-resonance within the myocardium. This produces hyper-intensity (HI) artifacts in LGE, which can mask scar tissue, compromising the diagnostic value of LGE. Recent studies show that HI artifacts can be eliminated by using a wideband inversion recovery (IR) pulse in the LGE sequence. However, the current wideband LGE is a 2D sequence, which limits spatial resolution, especially slice thickness (8 mm). This is problematic for using LGE to guide catheter ablation of VT. High resolution LGE is feasible using a 3D LGE sequence. However, no prior studies have explored 3D LGE under the influence of strong off-resonance imposed by ICDs.

Imaging surrogate of the ventricular arrhythmia substrate in a swine model of ventricular tachycardia: high resolution LGE vs. high resolution electro-anatomical mapping

Background Assessment of risk of sudden cardiac death (SCD) due to ventricular tachycardia and fibrillation (VT/VF) remains one of the most challenging areas in management of patients with chronic myocardial infarction. VT substrate consists of reentry circuits near or within a chronic scar. Invasive catheter mapping using electroanatomical system (EAM) is the clinical standard for identification of reentry circuits. However, current EAM systems have low spatial resolution which may contribute to the high recurrence rate of VT after ablation (50% at 2 years). Better identification of reentry circuits can potentially improve SCD risk assessment and outcome of VT ablation procedures. Late gadolinium enhancement (LGE) CMR has the potential for noninvasive identification of reentry circuits, but LGE sequences suffer from low spatial resolution and partial voluming (1). In this study, we sought to utilize a highresolution 3D LGE with 1 mm isotropic spatial resolution to image the VT surrogate in swine model of VT.

Free-breathing 3D late gadolinium enhancement imaging of the left ventricle using a stack of spirals at 3T.

PurposeTo develop navigator-gated free-breathing 3D spiral late gadolinium enhancement (LGE) imaging of the left ventricle at 3T and compare it with conventional breath-hold 2D Cartesian imaging.Materials and MethodsEquivalent slices from 3D spiral and multislice 2D Cartesian acquisitions were compared in 15 subjects in terms of image quality (1, nondiagnostic to 5, excellent), sharpness (1–3), and presence of artifacts (0–2). Blood signal-to-noise ratio (SNR), blood/myocardium contrast-to-noise ratio (CNR), and quantitative sharpness were also compared.ResultsAll 3D spiral scans were completed faster than an equivalent 2D Cartesian short-axis stack (85 vs. 230 sec, P < 0.001). Image quality was significantly higher for 2D Cartesian images than 3D spiral images (3.7 ± 0.87 vs. 3.4 ± 1.05, P = 0.03) but not for mid or apical slices specifically. There were no significant differences in qualitative and quantitative sharpness (95% confidence interval [CI]: 1.91 ± 0.67 vs. 1.93 ± 0.69, P = 0.83 and 95% CI: 0.41 ± 0.07 vs. 0.40 ± 0.09, P = 0.25, respectively), artifact scores (95% CI: 0.16 ± 0.37 vs. 0.40 ± 0.58, P = 0.16), SNR (95% CI: 121.5 ± 55.3 vs. 136.4 ± 77.9, P = 0.13), and CNR (95% CI: 101.6 ± 48.4 vs. 102.7 ± 61.8, P = 0.98). Similar enhancement ratios (0.65 vs. 0.62) and volumes (13.8 vs. 14.1cm3) were measured from scar regions of three patients.ConclusioNavigator-gated 3D spiral LGE imaging can be performed in significantly and substantially shorter acquisition durations, although with some reduced image quality, than multiple breath-hold 2D Cartesian imaging while providing higher resolution and contiguous coverage..

Dynamic inversion time for improved 3D late gadolinium enhancement imaging in patients with atrial fibrillation

High resolution three-dimensional (3D) late gadolinium enhancement (LGE) imaging is performed with single R-wave gating to minimize lengthy acquisition durations. In patients with atrial fibrillation (AF), heart rate variability results in variable magnetization recovery between sequence repeats, and image quality is often poor. In this study, we implemented and tested a dynamic inversion time (dynamic-TI) scheme designed to reduce sequence sensitivity to heart rate variations. An inversion-prepared 3D segmented gradient echo sequence was modified so that the TI varied automatically from beat-to-beat (dynamic-TI) based on the time since the last sequence repeat. 3D LGE acquisitions were performed in 17 patients prior to radio frequency ablation of persistent AF both with and without dynamic-TI. Qualitative image quality scores, blood signal-to-ghosting ratios (SGRs). and blood-myocardium contrast-to-ghosting ratios (CGRs) were compared. Image quality scores were higher with dynamic-TI than without dynamic-TI (2.2 ± 0.9 vs. 1.8 ± 1.1, P = 0.008), as were blood-myocardium CGRs (13.8 ± 7.6 vs. 8.3 ± 6.1, P = 0.003) and blood SGRs (19.6 ± 8.5 vs. 13.1 ± 8.0, P = 0.003). The dynamic-TI algorithm improves image quality of 3D LGE imaging in this difficult patient population by reducing the sequence sensitivity to RR interval variations

Highly accelerated 3D myocardial late fadolinium enhancement MRI using ESPIRiT compressed sensing: initial feasibility

Background Myocardial late gadolinium enhancement (LGE) MRI has become a standard clinical exam for characterizing myocardial viability after infarction and for assessing many nonischemic myocardial diseaseses. Typically, a 3D slab covering the myocardium is scanned within a single breath-hold. However, 3D LGE with sufficient resolution and slice coverage requires a long scan time and is challenging in cardiac patients with limited breath-hold capability. Recently, compressed sensing (CS) [1] has demonstrated the ability to further accelerate MRI on top of parallel imaging (PI) and has demonstrated promising results for 3D LGE [2]. This work intended to evaluate the feasibility of a CS-PI method based on ESPIRiT [3-5] and optimize its data acquisition for improving the robustness of 3D LGE with high acceleration.

3D LGE imaging of the LV short axis stack using spiral readouts at 3T

Background Clinical assessment of the viability of myocardium is commonly performed using 2D breath-hold late gadolinium enhancement (LGE) imaging with Cartesian k-space coverage and data acquisition windows (AWs) ranging from 140-200 ms. More efficient k-space coverage using spiral trajectories could allow improved spatial resolution and reduced AWs without greatly extending acquisition durations. To this end, we have developed a navigator-gated spiral 3D LGE sequence and present the results in 10 patients attending for clinical 2D LGE imaging on a 3T Siemens Skyra scanner. Methods The navigator-gated 3D sequence consisted of a stack of spirals (acquired: 8 kz at 1.4 × 1.4 × 10 mm, reconstructed: 16 slices at 0.7 × 0.7 × 5 mm). Each spiral readout was 10 ms long with 16 interleaves required to fill kx-ky space. All 8 kz for a given spiral interleaf were acquired in a single cardiac cycle (AW = 88 ms). Acquisition duration was 34 cardiac cycles assuming 100% respiratory efficiency (alternate R-wave gating). 3D imaging was performed after the acquisition of a stack of conventional clinical breathhold 2D LGE images in 10 patients (acquired resolution: 1.4 × 1.8 mm reconstructed to 0.7 × 0.7 mm). The 2D

Improved 3D late gadolinium enhancement (LGE) imaging with dynamic-TI in patients with persistent atrial fibrillation

Background High resolution 3D late gadolinium enhancement (LGE) imaging prior to RF ablation of atrial fibrillation (AF) is performed with single R-wave gating to reduce lengthy acquisition times [1]. However, this increases the sequence sensitivity to RR interval variations and missed cardiac triggers which cause variable magnetization recovery between sequence repeats, leading to ghosting of blood pool and unsuppressed fat, together with poor myocardial nulling. 3D LGE image quality in AF is consequently often poor. We have developed a dynamic inversion recovery (dynamic-TI) 3D LGE sequence which minimises variations in the longitudinal magnetisation (Mz) of myocardium throughout the acquisition [2] and have performed a study to assess its efficacy in 17 patients in persistent AF.

Detection of left atrial scar and changes of cardiac function in relation to AF ablation, by 3D late gadolinium enhancement

Background Atrial Fibrillation (AF) is the most common arrhythmia in clinical practice; cathete ra blation (AFCA) is aw idespread treatment. Determinants of AFCA success and post-AFCA left atrial remodeling are poorly understood. Delayed Enhancement Cardiac Magnetic Resonance (DE-CMR) has been used to image LA scar post-AFCA and its relation to ablation outcome. Here we explored the role of postablation LA scar in subsequent cardiac remodeling. Methods We correlated post AFCA scar with cardiac volumes and function including LA volume, LV ejection fraction (LVEF), and LV cardiac output (LVCO). In a retrospective analysis, we identified 46 patients who underwent AFCA -pulmonary vein antral isolation in whom DE-CMR was obtained before and after AFCA (174 ± 160 days postablation). In 20 patients, a repeat AFCA procedure was performed due to recurrent AF. DE-CMR procedure was performed utilizing a navigated 3D inversion recovery gradient echo sequence (Siemens 1.5T Avanto or 3.0T Verio) approximately 15 minutes after administration of 0.2 mmol/kg Gadolinium (Magnevist). Scans were ECG-gated and acquired during a 150 ms window in mid-diastole with navigator-gating and fat suppression. We have developed an image analysis method and graphical user interface (GUI) to semi-automatically quantify hyperenhanced regions (scar) in the entire LA wall. Scar was quantified semi-automatically as fraction of LA contour in every slice from base to roof. STATA/IC 13.0 was used for statistical analysis. Two-way Interclass Correlation (ICC) for rater agreement was tested for LA perimeter and LA scar detection between two independent readers for 40 MRI slices. Variable normality was assessed with the Shapiro-Wilk test. The Wilcoxon signed-rank test was used to determine statistical significance between non-parametric variables in pre and post AFCA. Results ICC indicates similarity between observers in both LA Perimeter (ICC: 0.785, CI: 0.59-0.886, p < 0.05) and LA Scar (ICC: 0.609, CI: -0.14-0.844, p < 0.05). The extent of LA Scar was higher in postablation (Median: 8.62, IQR: 5.43-16.4) DE-CMR compared to baseline

3D free-breathing late gadolinium enhancement 3T MRI: comparison with standard 2D Imaging

Background Clinical cardiovascular magnetic resonance imaging (CMR) is routinely performed during multiple breathholds in predefined 2D image orientations. 3D CMR is desirable, since it allows post-acquisition reformatting in any desired imaging plane. However, 3D CMR is hampered by long breath-hold duration, introducing patient discomfort and technical limitations. These limitations can be overcome by application of respiratory navigator techniques, for example to perform late gadolinium enhanced (LGE) CMR. The presently proposed 3D approach allows to: (1) perform 3D CMR during free-breathing; (2) increase image resolution; (3) average out heart rate variability by using a phase sensitive inversion recovery sequence (PSIR); (4) improve myocardial nulling, especially relevant at higher MR field strength such as 3T. Therefore, the purpose of the present study was to develop and clinically test 3D free-breathing PSIR LGE CMR using a respiratory navigator approach at 3T in comparison to a standard 2D breath-hold sequence.

Quantitative comparison of 2D and 3D late gadolinium enhancement MR imaging for cardiomyopathies

Background LGE is widely used as a means to quantify scar or fibrotic tissue in patients suffering from cardiomyopathies. In clinical routine 2D data acquisition is most commonly practiced, albeit having the drawback of multiple breath-holds and long acquisition times. 3D acquisition can significantly reduce acquisition time. This leads to shortened scan time and a more efficient use of available MRI resources. So our purpose was to determine whether the quantification of myocardial fibrosis in patients with Fabry disease and hypertrophic cardiomyopathy (HCM) using a late gadolinium enhancement (LGE) single-breath-hold threedimensional (3D) inversion recovery magnetic resonance (MR) imaging sequence is comparable with a clinically established two-dimensional (2D) multi-breath-hold sequence.

Rapid single‐breath‐hold 3D late gadolinium enhancement cardiac MRI using a stack‐of‐spirals acquisition

To develop a rapid single-breath-hold 3D late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) method, and demonstrate its feasibility in cardiac patients. An inversion recovery dual-density 3D stack-of-spirals imaging sequence was developed. The spiral acquisition was 2-fold accelerated by self-consistent parallel imaging reconstruction (SPIRiT), which resulted in a total scan time of 12 heartbeats. Field map-based linear off-resonance correction was incorporated to the SPIRiT reconstruction. The 3D spiral LGE scans were performed in 15 patients who were referred for clinically ordered cardiac MR examinations that included the standard 2D multislice LGE imaging. Image sharpness and overall quality were qualitatively assessed based on 5-point scales. Scar-induced hyper-LGE was identified in 4 out of the 15 patients by both 3D spiral and 2D multislice LGE tests. On average over all datasets (n = 15), the image sharpness scores were 3.9 (3D spiral) and 4.0 (2D multislice), and the image quality scores were 4.1 (3D spiral) and 4.0 (2D multislice) with no significant difference in both metrics (paired t-test; P > 0.1). The average scar contrast enhancement ratios were 0.72 and 0.75 in 3D and 2D images, respectively (n = 4). The average difference of fractional scar volumes measured in 3D and 2D images was 4.3% (n = 3). Stack-of-spiral acquisition combined with non-Cartesian SPIRiT parallel imaging enables rapid 3D LGE MRI in a 12 heartbeat-long breath-hold.J.

Optimal Techniques for Late Gadolinium-Enhanced MRI: Comparison of Delay Time, Slice Thickness, and Multiplanar Reconstruction vs Maximum Intensity Projection for Assessment of Fibrosis in Atrial Fibrillation

Background Left atrial (LA) late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) has varying protocols, which may limit interstudy comparisons. This study evaluates whether changes in image acquisition and reconstruction parameters affect quantification of LA LGE MRI. Methods A total of 200 LGE MRI scans were prepared using various techniques from 5 subjects. 3D respiratory and ECG-gated LGE images were acquired at 15, 20, 25, and 30 minutes after contrast. Multiplanar reconstructions (MPR) and maximum intensity projections (MIP) were created from 3D data at various slice thicknesses. LA LGE was quantified with image intensity ratio (IIR, atrial wall signal intensity divided by blood pool). Mean IIR was calculated for the entire LA as a metric of LGE burden. Additionally, in 42 consecutive preablation patients, local IIR values from 3.5-mm MPR and MIP reconstructions were separately registered to LA electroanatomic voltage maps (EAM) obtained prior to ablation procedure. Results Multitime point LGE-MRI showed a rise in baseline mean IIR of 0.5% ± 0.1% per minute ( P P P P Conclusions Variations in timing of acquisition, image reconstruction methods, and slice thickness result in changes in LA LGE quantity.

Navigator artifact reduction in three‐dimensional late gadolinium enhancement imaging of the atria

Navigator-gated three-dimensional (3D) late gadolinium enhancement (LGE) imaging demonstrates scarring following ablation of atrial fibrillation. An artifact originating from the slice-selective navigator-restore pulse is frequently present in the right pulmonary veins (PVs), obscuring the walls and making quantification of enhancement difficult. We describe a simple sequence modification to greatly reduce or remove this artifact. A navigator-gated inversion-prepared gradient echo sequence was modified so that the slice-selective navigator-restore pulse was delayed in time from the nonselective preparation (NAV-restore-delayed). Both NAV-restore-delayed and conventional 3D LGE acquisitions were performed in 11 patients and the results compared. One patient was excluded due to severe respiratory motion artifact in both NAV-restore-delayed and conventional acquisitions. Moderate to severe artifact was present in 9 of the remaining 10 patients using the conventional sequence and was considerably reduced when using the NAV-restore-delayed sequence (ostial PV to blood pool ratio, 1.7 ± 0.5 versus 1.1 ± 0.2, respectively [P < 0.0001]; qualitative artifact scores, 2.8 ± 1.1 versus 1.2 ± 0.4, respectively [P < 0.001]). While navigator signal-to-noise ratio was reduced with the NAV-restore-delayed sequence, respiratory motion compensation was unaffected. Shifting the navigator-restore pulse significantly reduces or eliminates navigator artifact. This simple modification improves the quality of 3D LGE imaging and potentially aids late enhancement quantification in the atria.