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Purpose: Our aim is to assess the potential of an MR system with ultrahigh performance gradients (200 mT/m maximum gradient strength) to address two interrelated challenges in cardiac DTI: low SNR and sensitivity to bulk motion. Methods: Imaging was performed in 20 healthy volunteers, two patients, and one swine post‐myocardial infarction. The impact of maximum gradient strength was assessed with spin echo cardiac DTI featuring second‐order motion compensation and varying maximum system gradient strengths (40, 80, 200 mT/m). Motion compensation requirements at 200 mT/m were assessed with sequences featuring zeroth‐, first‐, and second‐order motion compensation. SNR, mean diffusivity, fractional anisotropy, helix angle transmurality, and secondary eigenvector angle in the left ventricle were compared. Results: Increasing maximum system gradient strength from 40 and 80 mT/m to 200 mT/m increased SNR of b = 500 s/mm2 images by 150% and 40% due to reductions in TE. Observed improvements in DTI metrics included reduction in variance in mean diffusivity and helix angle transmurality across healthy volunteers, improved visualization of myocardial borders and delineation of suspected scar. Whereas second‐order motion compensation acquisitions were robust to motion‐induced signal dropout, zeroth‐ and first‐order motion compensation acquisitions suffered from severe signal loss and localized signal voids, respectively. Conclusion: Ultrahigh performance gradients (200 mT/m) enable high SNR DWIs of the heart and resultant improvements in diffusion tensor metrics. Despite reduced diffusion‐encoding duration, second‐order motion compensation is required to overcome sensitivity to cardiac motion. [ABSTRACT FROM AUTHOR]

Purpose: To develop and evaluate a phase unwrapping method for cine phase contrast MRI based on graph cuts. Methods: A proposed Iterative Graph Cuts method was evaluated in 10 cardiac patients with two‐dimensional flow quantification which was repeated at low venc settings to provoke wrapping. The images were also unwrapped by a path‐following method (ROMEO), and a Laplacian‐based method (LP). Net flow was quantified using semi‐automatic vessel segmentation. High venc images were also wrapped retrospectively to asses the residual amount of wrapped voxels. Results: The absolute net flow error after unwrapping at venc = 100 cm/s was 1.8 mL, which was 0.83 mL smaller than for LP. The repeatability error at high venc without unwrapping was 2.5 mL. The error at venc = 50 cm/s was 7.5 mL, which was 8.2 mL smaller than for ROMEO and 5.7 mL smaller than for LP. For retrospectively wrapped images with synthetic venc of 100/50/25 cm/s, the residual amount of wrapped voxels was 0.00/0.12/0.79%, which was 0.09/0.26/8.0 percentage points smaller than for LP. With synthetic venc of 25 cm/s, omitting magnitude information resulted in 3.2 percentage points more wrapped voxels, and only spatial/temporal unwrapping resulted in 4.6/21 percentage points more wrapped voxels compared to spatiotemporal unwrapping. Conclusion: Iterative Graph Cuts enables unwrapping of cine phase contrast MRI with very small errors, except for at extreme blood velocities, with equal or better performance compared to ROMEO and LP. The use of magnitude information and spatiotemporal unwrapping is recommended. [ABSTRACT FROM AUTHOR]

Background: The impact of left ventricular mechanical dyssynchrony (LVMD) on the long‐term prognosis of ST‐segment elevation myocardial infarction (STEMI) is unclear. Hypothesis: MR uniformity ratio estimates (URE) can detect LVMD and assess STEMI prognosis. Study Type: Retrospective analysis of a prospective multicenter registry (EARLY‐MYO trial, NCT 03768453). Population: Overall, 450 patients (50 females) with first‐time STEMI were analyzed, as well as 40 participants without cardiovascular disease as controls. Field Strength/Sequence: 3.0‐T, balanced steady‐state free precession cine and late gadolinium enhancement imaging. Assessment: MRI data were acquired within 1 week of symptom onset. Major adverse cardiovascular events (MACEs), including cardiovascular death, nonfatal re‐infarction, hospitalization for heart failure, and stroke, were the primary clinical outcomes. LVMD was represented by circumferential URE (CURE) and radial URE (RURE) calculated using strain measurements. The patients were grouped according to clinical outcomes or URE values. Patients' clinical characteristics and MR indicators were compared. Statistical Tests: The Student's t‐test, Mann–Whitney U test, chi‐square test, Fisher's exact test, receiver operating characteristic curve analysis with area under the curve, Kaplan–Meier analysis, Cox regression, logistic regression, intraclass correlation coefficient, c‐index, and integrated discrimination improvement were used. P < 0.05 was considered statistically significant. Results: CURE and RURE were significantly lower in patients with STEMI than in controls. The median follow‐up was 60.5 months. Patients with both lower CURE and RURE values experienced a significantly higher incidence of MACEs by 3.525‐fold. Both CURE and RURE were independent risk factors for MACEs. The addition of UREs improved diagnostic efficacy and risk stratification based on infarct size and left ventricular ejection fraction (LVEF). The indicators associated with LVMD included male sex, serum biomarkers (peak creatine phosphokinase and cardiac troponin I), infarct size, and LVEF. Data Conclusion: CURE and RURE may be useful to evaluate long‐term prognosis after STEMI. Evidence Level: 4 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

The aim of the current study was to develop a novel approach for 2D breath‐hold cardiac cine imaging from a single heartbeat, by combining cardiac motion‐corrected reconstructions and nonrigidly aligned patch‐based regularization. Conventional cardiac cine imaging is obtained via motion‐resolved reconstructions of data acquired over multiple heartbeats. Here, we achieve single‐heartbeat cine imaging by incorporating nonrigid cardiac motion correction into the reconstruction of each cardiac phase, in conjunction with a motion‐aligned patch‐based regularization. The proposed Motion‐Corrected CINE (MC‐CINE) incorporates all acquired data into the reconstruction of each (motion‐corrected) cardiac phase, resulting in a better posed problem than motion‐resolved approaches. MC‐CINE was compared with iterative sensitivity encoding (itSENSE) and Extra‐Dimensional Golden Angle Radial Sparse Parallel (XD‐GRASP) in 14 healthy subjects in terms of image sharpness, reader scoring (range: 1–5) and reader ranking (range: 1–9) of image quality, and single‐slice left ventricular assessment. MC‐CINE was significantly superior to both itSENSE and XD‐GRASP using 20 heartbeats, two heartbeats, and one heartbeat. Iterative SENSE, XD‐GRASP, and MC‐CINE achieved a sharpness of 74%, 74%, and 82% using 20 heartbeats, and 53%, 66%, and 82% with one heartbeat, respectively. The corresponding results for reader scoring were 4.0, 4.7, and 4.9 with 20 heartbeats, and 1.1, 3.0, and 3.9 with one heartbeat. The corresponding results for reader ranking were 5.3, 7.3, and 8.6 with 20 heartbeats, and 1.0, 3.2, and 5.4 with one heartbeat. MC‐CINE using a single heartbeat presented nonsignificant differences in image quality to itSENSE with 20 heartbeats. MC‐CINE and XD‐GRASP at one heartbeat both presented a nonsignificant negative bias of less than 2% in ejection fraction relative to the reference itSENSE. It was concluded that the proposed MC‐CINE significantly improves image quality relative to itSENSE and XD‐GRASP, enabling 2D cine from a single heartbeat. [ABSTRACT FROM AUTHOR]

Purpose: Develop a novel approach for accelerated 2D free‐breathing myocardial perfusion via low‐rank motion‐corrected (LRMC) reconstructions. Methods: Myocardial perfusion imaging requires high spatial and temporal resolution, despite scan time constraints. Here, we incorporate LRMC models into the reconstruction‐encoding operator, together with high‐dimensionality patch‐based regularization, to produce high quality, motion‐corrected myocardial perfusion series from free‐breathing acquisitions. The proposed framework estimates beat‐to‐beat nonrigid respiratory (and any other incidental) motion and the dynamic contrast subspace from the actual acquired data, which are then incorporated into the proposed LRMC reconstruction. LRMC was compared with iterative SENSitivity Encoding (SENSE) (itSENSE) and low‐rank plus sparse (LpS) reconstruction in 10 patients based on image‐quality scoring and ranking by two clinical expert readers. Results: LRMC achieved significantly improved results relative to itSENSE and LpS in terms of image sharpness, temporal coefficient of variation, and expert reader evaluation. Left ventricle image sharpness was approximately 75%, 79%, and 86% for itSENSE, LpS and LRMC, respectively, indicating improved image sharpness for the proposed approach. Corresponding temporal coefficient of variation results were 23%, 11% and 7%, demonstrating improved temporal fidelity of the perfusion signal with the proposed LRMC. Corresponding clinical expert reader scores (1–5, from poor to excellent image quality) were 3.3, 3.9 and 4.9, demonstrating improved image quality with the proposed LRMC, in agreement with the automated metrics. Conclusion: LRMC produces motion‐corrected myocardial perfusion in free‐breathing acquisitions with substantially improved image quality when compared with iterative SENSE and LpS reconstructions. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) is a versatile modality that can generate high‐resolution images with a variety of tissue contrasts. However, MRI is a slow technique and requires long acquisition times, which increase with higher temporal and spatial resolution and/or when multiple contrasts and large volumetric coverage is required. In order to speedup MR data acquisition, several approaches have been introduced in the literature. Most of these techniques acquire less data than required and exploit intrinsic redundancies in the MR images to recover the information that was not sampled. This article presents a review of MR acquisition and reconstruction methods that have exploited redundancies in the temporal, spatial, and contrast/parametric dimensions to accelerate image data acquisition, focusing on cardiac and abdominal MR imaging applications. The review describes how each of these dimensions has been separately exploited for speeding up MR acquisition to then discuss more advanced techniques where multiple dimensions are exploited together for further reducing scan times. Finally, future directions for multidimensional image acceleration and remaining technical challenges are discussed. Evidence Level: 5 Technical Efficacy: 1 [ABSTRACT FROM AUTHOR]

Purpose: To develop a compact MR‐compatible ergometer for exercise stress and to initially evaluate the reproducibility of myocardial native T1 and myocardial blood flow (MBF) measurements during exercise stress performed on this ergometer. Methods: The compact ergometer consists of exercise, workload, and data processing components. The exercise stress can be achieved by pedaling on a pair of cylinders at a predefined frequency with adjustable resistances. Ten healthy subjects were recruited to perform cardiac MRI scans twice in a 3.0T MR scanner, at different days to assess reproducibility. Myocardial native T1 and MBF were acquired at rest and during a moderate exercise. The reproducibility of the two tests was determined by the intra‐group correlation coefficient (ICC) and coefficient of variation (CoV). Results: The mean exercise intensity in this pilot study was 45 Watts (W), with an exercise duration of 5 min. Stress induced a significant increase in systolic blood pressure (from 113 ± 11 mmHg to 141 ± 12, P < 0.05) and maximal increase in heart rate by 74 ± 19%. The rate pressure product increased two‐fold (P < 0.001). Excellent reproducibility was demonstrated in native T1 during the exercise (CoV = 3.0%), whereas the reproducibility of MBF and myocardial perfusion reserve during the exercise was also good (CoV = 10.7% and 8.8%, respectively). Conclusion: This pilot study demonstrated that it is possible to acquire reproducible measurements of myocardial native T1 and MBF during the exercise stress in healthy volunteers using our new compact ergometer. [ABSTRACT FROM AUTHOR]

Aims: Sepsis‐induced cardiomyopathy is a major complication of septic shock and contributes to its high mortality. This pilot study investigated myocardial tissue differentiation in critically ill, sedated, and ventilated patients with septic shock using cardiovascular magnetic resonance (MR). Methods and results: Fifteen patients with septic shock were prospectively recruited from the intensive care unit. Individuals received a cardiac MR scan (1.5 T) within 48 h after initial catecholamine peak and a transthoracic echocardiography at 48 and 96 h after cardiac MR. Left ventricular ejection fraction was assessed using both imaging modalities. During cardiac MR imaging, balanced steady‐state free precession imaging was performed for evaluation of cardiac anatomy and function in long‐axis and short‐axis views. Native T1 maps (modified Look–Locker inversion recovery 5 s(3 s)3 s), T2 maps, and extracellular volume maps were acquired in mid‐ventricular short axis and assessed for average plane values. Patients were given 0.2 mmol/kg of gadoteridol for extracellular volume quantification and late gadolinium enhancement imaging. Critical care physicians monitored sedated and ventilated patients during the scan with continuous invasive monitoring and realized breathholds through manual ventilation breaks. Laboratory analysis included high‐sensitive troponine T and N terminal pro brain natriuretic peptide levels. Twelve individuals with complete datasets were available for analysis (age 59.5 ± 16.9 years; 6 female). Nine patients had impaired systolic function with left ventricular ejection fraction (LVEF) < 50% (39.8 ± 5.7%), and three individuals had preserved LVEF (66.9 ± 6.7%). Global longitudinal strain was impaired in both subgroups (LVEF impaired: 11.0 ± 1.8%; LVEF preserved: 16.0 ± 5.8%; P = 0.1). All patients with initially preserved LVEF died during hospital stay; in‐hospital mortality with initially impaired LVEF was 11%. Upon echocardiographic follow‐up, LVEF improved in all previously impaired patients at 48 (52.3 ± 9.0%, P = 0.06) and 96 h (54.9 ± 7.0%, P = 0.02). Patients with impaired systolic function had increased T2 times as compared with patients with preserved LVEF (60.8 ± 5.6 ms vs. 52.2 ± 2.8 ms; P = 0.02). Left ventricular GLS was decreased in all study individuals with impaired LVEF (11.0 ± 1.8%) and less impaired with preserved LVEF (16.0 ± 5.8%; P = 0.01). T1 mapping showed increased T1 times in patients with LVEF impairment as compared with patients with preserved LVEF (1093.9 ± 86.6 ms vs. 987.7 ± 69.3 ms; P = 0.03). Extracellular volume values were elevated in patients with LVEF impairment (27.9 ± 2.1%) as compared with patients with preserved LVEF (22.7 ± 1.9%; P < 0.01). Conclusions: Septic cardiomyopathy with impaired LVEF reflects inflammatory cardiomyopathy. Takotsubo‐like contractility patterns occur in some cases. Cardiac MR is safely feasible in critically ill, sedated, and ventilated patients using extensive monitoring and experienced staff. Trial Registration: retrospectively registered (ISRCTN85297773) [ABSTRACT FROM AUTHOR]

Purpose: Develop a novel 2D cardiac MR fingerprinting (MRF) approach to enable simultaneous T1, T2, T2*, and fat fraction (FF) myocardial tissue characterization in a single breath‐hold scan. Methods: Simultaneous, co‐registered, multi‐parametric mapping of T1, T2, and FF has been recently achieved with cardiac MRF. Here, we further incorporate T2* quantification within this approach, enabling simultaneous T1, T2, T2*, and FF myocardial tissue characterization in a single breath‐hold scan. T2* quantification is achieved with an eight‐echo readout that requires a long cardiac acquisition window. A novel low‐rank motion‐corrected (LRMC) reconstruction is exploited to correct for cardiac motion within the long acquisition window. The proposed T1/T2/T2*/FF cardiac MRF was evaluated in phantom and in 10 healthy subjects in comparison to conventional mapping techniques. Results: The proposed approach achieved high quality parametric mapping of T1, T2, T2*, and FF with corresponding normalized RMS error (RMSE) T1 = 5.9%, T2 = 9.6% (T2 values <100 ms), T2* = 3.3% (T2* values <100 ms), and FF = 0.8% observed in phantom scans. In vivo, the proposed approach produced higher left‐ventricular myocardial T1 values than MOLLI (1148 vs 1056 ms), lower T2 values than T2‐GraSE (42.8 vs 50.6 ms), lower T2* values than eight‐echo gradient echo (GRE) (35.0 vs 39.4 ms), and higher FF values than six‐echo GRE (0.8 vs 0.3 %) reference techniques. The proposed approach achieved considerable reduction in motion artifacts compared to cardiac MRF without motion correction, improved spatial uniformity, and statistically higher apparent precision relative to conventional mapping for all parameters. Conclusion: The proposed cardiac MRF approach enables simultaneous, co‐registered mapping of T1, T2, T2*, and FF in a single breath‐hold for comprehensive myocardial tissue characterization, achieving higher apparent precision than conventional methods. [ABSTRACT FROM AUTHOR]

Purpose: To develop and validate a three‐parameter model for improved precision multiparametric SAturation‐recovery single‐SHot Acquisition (mSASHA) cardiac T1 and T2 mapping with high accuracy in a single breath‐hold. Methods: The mSASHA acquisition consists of nine images of variable saturation recovery and T2 preparation in 11 heartbeats with T1 and T2 values calculated using a three‐parameter model. It was validated in simulations and phantoms at 3 T with comparison to a four‐parameter joint T1‐T2 technique. The mSASHA acquisition was compared with MOLLI, SASHA, and T2‐prepared balanced SSFP in 10 volunteers. Results: The mSASHA technique had high accuracy in phantoms compared to spin echo, with −0.2 ± 0.3% T1 error and −2.4 ± 1.3% T2 error. The mSASHA coefficient of variation in phantoms for T1 was similar to MOLLI (0.7 ± 0.2% for both) and T2‐prepared balanced SSFP for T2 (1.3 ± 0.7% vs 1.4 ± 0.3%, adjusted p >.05 for both). In simulations, three‐parameter mSASHA had higher precision than four‐parameter joint T1‐T2 for both T1 and T2 (46% and 11% reductions in T1 and T2 interquartile range for native myocardium). In vivo myocardial mSASHA T1 was similar to SASHA (1523 ± 18 ms vs 1520 ± 18 ms) with similar coefficient of variation to both MOLLI and SASHA (3.3 ± 0.6% vs 3.1 ± 0.6% and 3.3 ± 0.5% respectively, adjusted p >.05 for all). Myocardial mSASHA T2 was 37.1 ± 1.1 ms with similar precision to T2‐prepared balanced SSFP (6.7 ± 1.7% vs 6.0 ± 1.6%, adjusted p >.05). Conclusion: Three‐parameter mSASHA provides high‐accuracy cardiac T1 and T2 quantification in a single breath‐hold with similar precision to MOLLI and T2‐prepared balanced SSFP. Further study is required to both establish normative values and demonstrate clinical utility in patient populations. [ABSTRACT FROM AUTHOR]

Background: Cardiac magnetic resonance (MR) images are often collected with different imaging parameters, which may impact the calculated values of myocardial radiomic features. Purpose: To investigate the sensitivity of myocardial radiomic features to changes in imaging parameters in cardiac MR images. Study Type: Prospective. Population: A total of 11 healthy participants/five patients. Field Strength/ Sequence: A 3 T/cine balanced steady‐state free‐precession, T1‐weighted spoiled gradient‐echo, T2‐weighted turbo spin‐echo, and quantitative T1 and T2 mapping. For each sequence, the flip angle, in‐plane resolution, slice thickness, and parallel imaging technique were varied to study the sensitivity of radiomic features to alterations in imaging parameters. Assessment: Myocardial contours were manually delineated by experienced readers, and a total of 1023 radiomic features were extracted using PyRadiomics with 11 image filters and six feature families. Statistical Tests: Sensitivity was defined as the standardized mean difference (D effect size), and the robust features were defined at sensitivity < 0.2. Sensitivity analysis was performed on predefined sets of reproducible features. The analysis was performed using the entire cohort of 16 subejcts. Results: 64% of radiomic features were robust (sensitivity < 0.2) to changes in any imaging parameter. In qualitative sequences, radiomic features were most sensitive to changes in in‐plane spatial resolution (spatial resolution: 0.6 vs. flip angle: 0.19, parallel imaging: 0.18, slice thickness: 0.07; P < 0.01 for all); in quantitative sequences, radiomic features were least sensitive to changes in spatial resolution (spatial resolution: 0.07 vs. slice thickness: 0.16, flip angle: 0.24; P < 0.01 for all). In an individual feature level, no singular feature family/image filter was identified as robust (sensitivity < 0.2) across sequences; however, highly sensitive features were predominantly associated with high‐frequency wavelet filters across all sequences (32/50 features). Data Conclusion: In cardiac MR, a considerable number of radiomic features are sensitive to changes in sequence parameters. Evidence Level: 1 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

Background: Coronavirus 2019 (COVID‐19) causes morbidity and mortality in an increasing number of people worldwide. Although it mainly affects the respiratory system, it influences all organs, including the heart. It is associated with a broad spectrum of widespread cardiovascular problems ranging from mild myocardial injury to fulminant myocarditis. We aimed to evaluate the presence and prevalence of cardiac involvement in asymptomatic or symptomatic patients after they recovered from COVID 19 infection. Methods: A total of 100 consecutive patients with COVID‐19 proven by reverse transcription polymerase chain reaction (RT‐PCR), under 40 years of age and without any known additional chronic diseases were analyzed retrospectively for cardiac magnetic resonance (CMR) results and symptoms. Results: Cardiac involvement was detected in 49 out of 100 patients on CMR imaging. In the cardiac involvement group, the number of patients with chest pain and/or dyspnea was 41 (84%), which was statistically significant (p = 0.001). Twenty‐four patients (47%) in the without cardiac involvement group were asymptomatic and this was also statistically significant (p = 0.001). LV ejection fraction was statistically significantly lower in the group with cardiac involvement (61% vs 66%, p = 0.001). LV stroke volume and tricuspid annular plane systolic excursion (TAPSE) were statistically significantly lower in patients with cardiac involvement (p = 0.028 and p = 0.019, respectively). Conclusion: Based on single center experience, myocardial involvement is common in symptomatic patients after COVID‐19. More studies are needed for long‐term side effects and clinical results in these patients. [ABSTRACT FROM AUTHOR]

Abstract: Aims: This study aims to assess subclinical changes in functional and morphological myocardial magnetic resonance parameters very early into an anthracycline treatment, which may predict subsequent development of anthracycline‐induced cardiomyopathy (aCMP). Methods and results: Thirty sarcoma patients with planned anthracycline‐based chemotherapy (360–400 mg/m2 doxorubicin‐equivalent) were recruited. Median treatment time was 19.1 ± 2.1 weeks. Enrolled individuals received three cardiovascular magnetic resonance studies (before treatment, 48 h after first anthracycline treatment, and upon completion of treatment). Native T1 mapping (modified Look–Locker inversion recovery 5s(3s)3s), T2 mapping, and extracellular volume maps were acquired in addition to a conventional cardiovascular magnetic resonance with steady‐state free precession cine imaging at 1.5 T. Patients were given 0.2 mmol/kg gadoteridol for extracellular volume quantification and late gadolinium enhancement imaging. Development of relevant aCMP was defined as drop of left ventricular ejection fraction (LVEF) by >10%. For analysis, 23 complete data sets were available. Nine patients developed aCMP with LVEF reduction >10% until end of chemotherapy. Baseline LVEF was not different between patients with and without subsequent aCMP. When assessed 48 h after first dose of antracyclines, patients with subsequent aCMP had significantly lower native myocardial T1 times compared with before therapy (1002.0 ± 37.9 vs. 956.5 ± 29.2 ms, P < 0.01) than patients who did not develop aCMP (990.9 ± 56.4 vs. 978.4 ± 57.4 ms, P > 0.05). Patients with aCMP had decreased left ventricular mass upon completion of therapy (86.9 ± 24.5 vs. 81.1 ± 22.3 g; P = 0.02), while patients without aCMP did not show a change in left ventricular mass (81.8 ± 21.0 vs. 79.2 ± 18.1 g; P > 0.05). No patient developed new myocardial scars or compact myocardial fibrosis under chemotherapy. Conclusions: Early decrease of T1 times 48 h after first treatment with anthracyclines can predict the development of subsequent aCMP after completion of chemotherapy. [ABSTRACT FROM AUTHOR]

Purpose: A combined breathing maneuver of hyperventilation, followed by a long voluntary breathhold leads to coronary vasodilation. We investigated the impact of breathing maneuvers on MR first-pass cardiac perfusion imaging and its potential clinical utility.Materials and Methods: We studied 24 healthy volunteers (37 ± 12 years; 62.5% men) on a clinical 3 Tesla MRI system and performed first-pass perfusion MR at rest, during a short breathhold (S-HVBH) following 60 s of hyperventilation, and at the end of a long breathhold (L-HVBH) following the hyperventilation, performed in random order. A blinded reader analyzed signal intensity upslope, upslope index, and time between 20 and 80% of maximal signal.Results: All volunteers tolerated the breathing maneuvers well and completed the study protocol. The upslope of the signal-intensity-over-time curve was increased during S-HVBH (1.86 ± 0.70 units/s, P < 0.05) and at the end of L-LVBH (1.77 ± 0.82 units/s), when compared with baseline results (1.34 ± 0.58 units/s). Corrected for the arterial input, the upslope was higher at the end of the L-HVBH (0.095 ± 0.019 units/s versus 0.077 ± 0.016 units/s at rest, P < 0.01) as was the myocardial perfusion reserve index (1.25 ± 0.22 versus 1.09 ± 0.17; P < 0.001). In a multiple regression model, only gender, rate-pressure product, and breathhold time were independently and significantly related to the upslope (R = 0.771; P < 0.001).Conclusion: In conclusion, a voluntary long breathhold after hyperventilation leads to an increase of the myocardial perfusion reserve index. This may impact findings from current practice of first-pass perfusion imaging. The clinical utility of breathing maneuvers as a vasodilatory stimulus for first-pass perfusion imaging may warrant further research. J. MAGN. RESON. IMAGING 2016;44:947-955. [ABSTRACT FROM AUTHOR]

Background Patients with acute ST-elevation myocardial infarction (STEMI) benefit substantially from emergent coronary reperfusion. The principal mechanism is to open the occluded coronary artery to minimize myocardial injury. Thus the size of the area at risk is a critical determinant of the patient outcome, although other factors, such as reperfusion injury, have major impact on the final infarct size. Acute coronary occlusion almost immediately induces metabolic changes within the myocardium, which can be assessed with both the electrocardiogram (ECG) and cardiac magnetic resonance (CMR) imaging. Methods The 12-lead ECG is the principal diagnostic method to detect and risk-stratify acute STEMI. However, to achieve a correct diagnosis, it is paramount to compare different ECG parameters with golden standards in imaging, such as CMR. In this review, we discuss aspects of ECG and CMR in the assessment of acute regional ischemic changes in the myocardium using the 17 segment model of the left ventricle presented by American Heart Association (AHA), and their relation to coronary artery anatomy. Results Using the 17 segment model of AHA, the segments 12 and 16 remain controversial. There is an important overlap in myocardial blood supply at the antero-lateral region between LAD and LCx territories concerning these two segments. Conclusion No all-encompassing correlation can be found between ECG and CMR findings in acute ischemia with respect to coronary anatomy. [ABSTRACT FROM AUTHOR]

Purpose To investigate the efficacy of a novel respiratory motion scheme, where only the center of k-space is gated using respiratory navigators, versus a fully respiratory-gated acquisition for three-dimensional flow imaging. Methods Three-dimensional flow images were acquired axially using a gradient echo sequence in a volume, covering the ascending and descending aorta, and the pulmonary artery bifurcation in 12 healthy subjects (33.2 ± 15.8 years; five men). For respiratory motion compensation, two gating and tracking strategies were used with a 7-mm gating window: (1) All of k-space acquired within the gating window (fully gated) and (2) central k-space acquired within the gating window, and the remainder of k-space acquired without any gating (center gated). Each scan was repeated twice. Stroke volume, mean flow, peak velocity, and signal-to-noise-ratio measurements were performed both on the ascending and on the descending aorta for all acquisitions, which were compared using a linear mixed-effects model and Bland-Altman analysis. Results There were no statistical differences between the fully gated and the center-gated strategies for the quantification of stroke volume, peak velocity, and mean flow, as well as the signal-to-noise-ratio measurements. Furthermore, the proposed center-gated strategy had significantly shorter acquisition time compared to the fully gated strategy (13:19 ± 3:02 vs. 19:35 ± 5:02, P < 0.001). Conclusions The proposed novel center-gated strategy for three-dimensional flow MRI allows for markedly shorter acquisition time without any systematic variation in quantitative flow measurements in this small group of healthy volunteers. Magn Reson Med 71:2172-2179, 2014. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Purpose To evaluate the accuracy of a three-dimensional dual phase (3D DP) whole-heart technique for cardiac volumetric assessment in pediatric patients with cardiac abnormalities. Materials and Methods The institutional approved this study, and informed consent was obtained from patients or their guardians. This prospective study involved 31 pediatric patients (mean age, 7.9 years; range, 15 days to 15 years) for the assessment of cardiac abnormalities using cardiovascular MR. A standard protocol was performed for assessing cardiac anatomy and function. For evaluating the 3D DP technique, statistical comparison with a 2D cine multi-slice technique (2D steady-state free-precession [SSFP]) was performed using linear regression, intraclass correlation coefficient, and Bland Altman plots. Results Left (LV) and right (RV) ventricular cardiac volumes obtained with the 3D DP technique were in strong agreement with those obtained with the 2D SSFP technique for small and large ventricular volumes. The intraclass correlation coefficients (ICC) between both techniques were 0.992 for the LV end-diastolic volume (EDV), 0.983 for the LV end-systolic volume (ESV), 0.952 for the LV-systolic volume (SV), 0.992 for the RV-EDV, 0.992 for the RV-ESV, 0.928 for the RV-SV. Interobserver analysis indicated good reproducibility for both the 2D SSFP and the 3D DP techniques. Conclusion The 3D DP technique provides as accurate cardiac volumes as the 2D SSFP technique in the pediatric population, but with the added benefits of easier data acquisition and detailed anatomical information of the whole heart and great vessels in a single free-breathing scan. J. Magn. Reson. Imaging 2014;39:708-716. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Purpose To improve compressed sensing (CS) reconstruction of accelerated breath-hold (BH) radial cine magnetic resonance imaging (MRI) by exploiting auxiliary data acquired between different BHs. Materials and Methods Cardiac function is usually assessed using segmented cine acquisitions over multiple BHs to cover the entire left ventricle (LV). Subjects are given a resting period between adjacent BHs, when conventionally no data are acquired and subjects rest in the scanner. In this study the resting periods between BHs were used to acquire additional free-breathing (FB) data, which are subsequently used to generate a sparsity constraint for each cardiac phase. Images reconstructed using the proposed sparsity constraint were compared with conventional CS using a composite image generated by averaging different cardiac phases. The efficacy of the proposed reconstruction was compared using indices of LV function and blood-myocardium sharpness. Results The proposed method provided accurate LV ejection fraction measurements for 33% and 20% sampled datasets compared with fully sampled reference images, and showed 14% and 11% higher blood-myocardium border sharpness scores compared to the conventional CS. Conclusion The FB data acquired during resting periods can be efficiently used to improve the image quality of the undersampled BH data without increasing the total scan time. J. Magn. Reson. Imaging 2014;39:179-188. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Phase contrast (PC) cardiac MR is widely used for the clinical assessment of blood flow in cardiovascular disease. One of the challenges of PC cardiac MR is the long scan time which limits both spatial and temporal resolution. Compressed sensing reconstruction with accelerated PC acquisitions is a promising technique to increase the scan efficiency. In this study, we sought to use the sparsity of the complex difference of the two flow-encoded images as an additional constraint term to improve the compressed sensing reconstruction of the corresponding accelerated PC data acquisition. Using retrospectively under-sampled data, the proposed reconstruction technique was optimized and validated in vivo on 15 healthy subjects. Then, prospectively under-sampled data was acquired on 11 healthy subjects and reconstructed with the proposed technique. The results show that there is good agreement between the cardiac output measurements from the fully sampled data and the proposed compressed sensing reconstruction method using complex difference sparsity up to acceleration rate 5. In conclusion, we have developed and evaluated an improved reconstruction technique for accelerated PC cardiac MR that uses the sparsity of the complex difference of the two flow-encoded images. Magn Reson Med 70:851-858, 2013. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Purpose: To develop and evaluate an algorithm that automatically identifies high-susceptibility areas and excludes them from T(2) * measurements in the left ventricle (LV) for myocardial iron measurements.Materials and Methods: An autoregressive moving average (ARMA) model was implemented on multigradient echo scans of 24 patients (age range 3-45 years, 10 male/14 female). Voxels with relatively high susceptibility (>3 Hz/mm) were flagged and deselected from the T(2) * calculations for iron quantification. The mean, standard deviation, and coefficient of variation (CoV) of the ARMA-defined region were compared to the CoV of four distinct regions of the LV and the entire LV using a Student's t-test (α = 0.05).Results: The CoV of T(2) * values obtained by the ARMA method are comparable with that in the interventricular septum (IS), where susceptibility was the lowest (CoV = 0.31). The ARMA method provides a greater area (51.9 ± 13.7% of the LV) to measure T(2) * than that using the IS alone (21.1 ± 3.4%, P < 0.0001). Areas where low susceptibility are measured corroborate with areas reported in previous studies that investigated T(2) * variations throughout the LV.Conclusion: An automated method to measure T(2) * relaxation in the LV with minimal effects from susceptibility has been developed. Variability is reduced while covering more regions for cardiac T2 * calculation. [ABSTRACT FROM AUTHOR]

Purpose To develop and evaluate an algorithm that automatically identifies high-susceptibility areas and excludes them from T2* measurements in the left ventricle (LV) for myocardial iron measurements. Materials and Methods An autoregressive moving average (ARMA) model was implemented on multigradient echo scans of 24 patients (age range 3-45 years, 10 male/14 female). Voxels with relatively high susceptibility (>3 Hz/mm) were flagged and deselected from the T2* calculations for iron quantification. The mean, standard deviation, and coefficient of variation (CoV) of the ARMA-defined region were compared to the CoV of four distinct regions of the LV and the entire LV using a Student's t-test (α = 0.05). Results The CoV of T2* values obtained by the ARMA method are comparable with that in the interventricular septum (IS), where susceptibility was the lowest (CoV = 0.31). The ARMA method provides a greater area (51.9 ± 13.7% of the LV) to measure T2* than that using the IS alone (21.1 ± 3.4%, P < 0.0001). Areas where low susceptibility are measured corroborate with areas reported in previous studies that investigated T2* variations throughout the LV. Conclusion An automated method to measure T2* relaxation in the LV with minimal effects from susceptibility has been developed. Variability is reduced while covering more regions for cardiac T2* calculation. J. Magn. Reson. Imaging 2013;38:441-447. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A disadvantage of three-dimensional (3D) isotropic acquisition in whole-heart coronary MRI is the prolonged data acquisition time. Isotropic 3D radial trajectories allow undersampling of k-space data in all three spatial dimensions, enabling accelerated acquisition of the volumetric data. Compressed sensing (CS) reconstruction can provide further acceleration in the acquisition by removing the incoherent artifacts due to undersampling and improving the image quality. However, the heavy computational overhead of the CS reconstruction has been a limiting factor for its application. In this article, a parallelized implementation of an iterative CS reconstruction method for 3D radial acquisitions using a commercial graphics processing unit is presented. The execution time of the graphics processing unit-implemented CS reconstruction was compared with that of the C++ implementation, and the efficacy of the undersampled 3D radial acquisition with CS reconstruction was investigated in both phantom and whole-heart coronary data sets. Subsequently, the efficacy of CS in suppressing streaking artifacts in 3D whole-heart coronary MRI with 3D radial imaging and its convergence properties were studied. The CS reconstruction provides improved image quality (in terms of vessel sharpness and suppression of noise-like artifacts) compared with the conventional 3D gridding algorithm, and the graphics processing unit implementation greatly reduces the execution time of CS reconstruction yielding 34-54 times speed-up compared with C++ implementation. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Background: Pulmonary vein isolation (PVI) as a treatment for atrial fibrillation (AF) is commonly performed. This procedure can damage the esophagus. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) offers noninvasive assessment of scar. We sought to examine the prevalence of esophageal hyperenhancement on LGE-CMR prior to and following PVI. Methods: Seventy-four patients underwent LGE-CMR prior to and 1.7 ± 1.9 months post PVI for AF. Transmural esophageal hyperenhancement was visually assessed. The pre- and post PVI esophageal position was measured, relative to the vertebral body. Results: Prior to PVI, 3% (2/74) of patients had esophageal LGE on CMR. At post-PVI follow-up, 30% (23/74) of the studies demonstrated new esophageal hyperenhancement adjacent to an ablation site. Most (74%, 17/27) positive esophageal LGE studies were performed >30 days after PVI, while no (0/9) studies performed >2 months post PVI were positive for esophageal hyperenhancement. The presence of post-procedural esophageal hyperenhancement was not associated with longer ablation time (P = 0.42), use of an irrigated catheter (74% with LGE vs 47% without, P = 0.16), right-sided esophageal location (56% with LGE vs 39% without, P = 0.17), size of left atrium cavity (58 ± 8 mm with LGE vs 61 ± 10 mm without, P = 0.15), or the timing of the LGE-CMR study after PVI (36 ± 10 days with LGE vs 60 ± 66 days without, P = 0.09). Conclusion: Though rare before PVI, new esophageal LGE is seen in almost one-third of patients after PVI. The clinical implications to remain to be explored, but clinicians should be aware of this frequent imaging finding. (PACE 2010; 33:661–666) [ABSTRACT FROM AUTHOR]