High-resolution Cardiovascular Magnetic Resonance Research Articles

2D high resolution vs. 3D whole heart myocardial perfusion cardiovascular magnetic resonance.

AimsDevelopments in myocardial perfusion cardiovascular magnetic resonance (CMR) allow improvements in spatial resolution and/or myocardial coverage. Whole heart coverage may provide the most accurate assessment of myocardial ischaemic burden, while high spatial resolution is expected to improve detection of subendocardial ischaemia. The objective of this study was to compare myocardial ischaemic burden as depicted by 2D high resolution and 3D whole heart stress myocardial perfusion in patients with coronary artery disease.Methods and resultsThirty-eight patients [age 61 ± 8 (21% female)] underwent 2D high resolution (spatial resolution 1.2 mm2) and 3D whole heart (in-plane spatial resolution 2.3 mm2) stress CMR at 3-T in randomized order. Myocardial ischaemic burden (%) was visually quantified as perfusion defect at peak stress perfusion subtracted from subendocardial myocardial scar and expressed as a percentage of the myocardium. Median myocardial ischaemic burden was significantly higher with 2D high resolution compared with 3D whole heart [16.1 (2.0–30.6) vs. 13.4 (5.2–23.2), P = 0.004]. There was excellent agreement between myocardial ischaemic burden (intraclass correlation coefficient 0.81; P < 0.0001), with mean ratio difference between 2D high resolution vs. 3D whole heart 1.28 ± 0.67 (95% limits of agreement −0.03 to 2.59). When using a 10% threshold for a dichotomous result for presence or absence of significant ischaemia, there was moderate agreement between the methods (κ = 0.58, P < 0.0001).Conclusion2D high resolution and 3D whole heart myocardial perfusion stress CMR are comparable for detection of ischaemia. 2D high resolution gives higher values for myocardial ischaemic burden compared with 3D whole heart, suggesting that 2D high resolution is more sensitive for detection of ischaemia.

Identification of high risk clinical and imaging features for intracranial artery dissection using high-resolution cardiovascular magnetic resonance

BackgroundIntracranial artery dissection (IAD) often causes headache and cerebral vascular ischemic events. The imaging characteristics of IAD remain unclear. This study aims to characterize the appearance of culprit and non-culprit IAD using high-resolution cardiovascular magnetic resonance imaging (hrCMR) and quantify the incremental value of hrCMR in identifying higher risk lesions.MethodsImaging data from patients who underwent intervention examination or treatment using digital subtraction angiography (DSA) and hrCMR using a 3 T CMR system within 30 days after the onset of neurological symptoms were collected. The CMR protocol included diffusion-weighted imaging (DWI), black blood T1-, T2- and contrast-enhanced T1-weighted sequences. Lesions were classified as culprit and non-culprit according to imaging findings and patient clinical presentations. Univariate and multivariate analyses were performed to assess the difference between culprit and non-culprit lesions and complementary value of hrCMR in identifying higher risk lesions.ResultsIn total, 75 patients were included in this study. According to the morphology, lesions could be classified into five types: Type I, classical dissection (n = 50); Type II, fusiform aneurysm (n = 1); Type III, long dissected aneurysm (n = 3); Type IV, dolichoectatic dissecting aneurysm (n = 9) and Type V, saccular aneurysm (n = 12). Regression analyses showed that age and hypertension were both associated with culprit lesions (age: OR, 0.83; 95% CI 0.75–0.92; p < 0.001 and hypertension: OR, 66.62; 95% CI 5.91–751.11; p = 0.001). Hematoma identified by hrCMR was significantly associated with culprit lesions (OR, 16.80; 95% CI 1.01–280.81; p = 0.037). Moreover, 17 cases (16 lesions were judged to be culprit) were diagnosed as IAD but not visible in DSA and 15 were Type I lesion.ConclusionhrCMR is helpful in visualizing and characterizing IAD. It provides a significant complementary value over DSA for the diagnosis of IAD.

Diffuse right ventricular fibrosis in heart failure with preserved ejection fraction and pulmonary hypertension

AimsWhile right ventricular (RV) dysfunction is associated with worse prognosis in co‐morbid pulmonary hypertension and heart failure with preserved ejection fraction (PH‐HFpEF), the mechanisms driving RV dysfunction are unclear. We evaluated the extent and clinical correlates of diffuse RV myocardial fibrosis in PH‐HFpEF, as measured by cardiovascular magnetic resonance‐derived extracellular volume (ECV).Methods and resultsWe prospectively enrolled participants with PH‐HFpEF (n = 14), pulmonary arterial hypertension (PAH; n = 13), and controls (n = 8). All participants underwent high‐resolution cardiovascular magnetic resonance, and case subjects (PH‐HFpEF and PAH) additionally underwent right heart catheterization. T1 mapping was performed using high‐resolution modified look‐locker inversion recovery with a 1 × 1 mm2 in‐plane resolution. RV free wall T1 values were quantified, and ECV was calculated. Participants with PH‐HFpEF were older and carried higher rates of hypertension and obstructive sleep apnoea than those with PAH. While RV ECV was similar between PH‐HFpEF and PAH (33.1 ± 8.0 vs. 34.0 ± 4.5%; P = 0.57), total pulmonary resistance was lower in PH‐HFpEF compared with PAH [PH‐HFpEF: 5.68 WU (4.70, 7.66 WU) vs. PAH: 8.59 WU (8.14, 12.57 WU); P = 0.01]. RV ECV in PH‐HFpEF was associated with worse indices of RV structure (RV end‐diastolic volume: r = 0.67, P = 0.01) and RV function (RV free wall strain: r = 0.59, P = 0.03) but was not associated with RV afterload (total pulmonary resistance: r = 0.08, P = 0.79). Conversely, there was a strong correlation between RV ECV and RV afterload in PAH (r = 0.57, P = 0.04).ConclusionsDiffuse RV fibrosis, as measured by ECV, is present in PH‐HFpEF and is associated with adverse RV structural and functional remodelling but not degree of pulmonary vasculopathy. In PH‐HFpEF, diffuse RV fibrosis may occur out of proportion to the degree of RV afterload.

Cardiovascular Magnetic Resonance-Based Three-Dimensional Structural Modeling and Heterogeneous Tissue Channel Detection in Ventricular Arrhythmia

Geometrical structure of the myocardium plays an important role in understanding the generation of arrhythmias. In particular, a heterogeneous tissue (HT) channel defined in cardiovascular magnetic resonance (CMR) has been suggested to correlate with conduction channels defined in electroanatomic mapping in ventricular tachycardia (VT). Despite the potential of CMR for characterization of the arrhythmogenic substrate, there is currently no standard approach to identify potential conduction channels. Therefore, we sought to develop a workflow to identify HT channel based on the structural 3D modeling of the viable myocardium within areas of dense scar. We focus on macro-level HT channel detection in this work. The proposed technique was tested in high-resolution ex-vivo CMR images in 20 post-infarct swine models who underwent an electrophysiology study for VT inducibility. HT channel was detected in 15 animals with inducible VT, whereas it was only detected in 1 out of 5 animal with non-inducible VT (P < 0.01, Fisher’s exact test). The HT channel detected in the non-inducible animal was shorter than those detected in animals with inducible VTs (inducible-VT animals: 35 ± 14 mm vs. non-inducible VT animal: 9.94 mm). Electrophysiology study and histopathological analyses validated the detected HT channels. The proposed technique may provide new insights for understanding the macro-level VT mechanism.

Shearlet-based compressed sensing for fast 3D cardiac MR imaging using iterative reweighting

High-resolution three-dimensional (3D) cardiovascular magnetic resonance (CMR) is a valuable medical imaging technique, but its widespread application in clinical practice is hampered by long acquisition times. Here we present a novel compressed sensing (CS) reconstruction approach using shearlets as a sparsifying transform allowing for fast 3D CMR (3DShearCS) using 3D radial phase encoding (RPE). An iterative reweighting scheme was applied during image reconstruction to ensure fast convergence and high image quality. Shearlets are mathematically optimal for a simplified model of natural images and have been proven to be more efficient than classical systems such as wavelets. 3DShearCS was compared to three other commonly used reconstruction approaches. Image quality was assessed quantitatively using general image quality metrics and using clinical diagnostic scores from expert reviewers. The proposed technique had lower relative errors, higher structural similarity and higher diagnostic scores compared to the other reconstruction techniques especially for high undersampling factors, i.e. short scan times. 3DShearCS provided ensured accurate depiction of cardiac anatomy for fast imaging and could help to promote 3D high-resolution CMR in clinical practice.

Quantitative assessment of symptomatic intracranial atherosclerosis and lenticulostriate arteries in recent stroke patients using whole-brain high-resolution cardiovascular magnetic resonance imaging

BackgroundIt has been shown that intracranial atherosclerotic stenosis (ICAS) has heterogeneous features in terms of plaque instability and vascular remodeling. Therefore, quantitative information on the changes of intracranial atherosclerosis and lenticulostriate arteries (LSAs) may potentially improve understanding of the pathophysiological mechanisms underlying stroke and may guide the treatment and work-up strategies. Our present study aimed to use a novel whole-brain high-resolution cardiovascular magnetic resonance imaging (WB-HRCMR) to assess both ICAS plaques and LSAs in recent stroke patients.MethodsTwenty-nine symptomatic and 23 asymptomatic ICAS patients were enrolled in this study from Jan 2015 through Sep 2017 and all patients underwent WB-HRCMR. Intracranial atherosclerotic plaque burden, plaque enhancement volume, plaque enhancement index, as well as the number and length of LSAs were evaluated in two groups. Enhancement index was calculated as follows: ([Signal intensity (SI)plaque/SInormal wall on post-contrast imaging] − [SIplaque/SInormal wall on matched pre-contrast imaging])/(SIplaque / SInormal wall on matched pre-contrast imaging). Logistic regression analysis was used to investigate the independent high risk plaque and LSAs features associated with stroke.ResultsSymptomatic ICAS patients exhibited larger enhancement plaque volume (20.70 ± 3.07 mm3 vs. 6.71 ± 1.87 mm3P = 0.001) and higher enhancement index (0.44 ± 0.08 vs. 0.09 ± 0.06 P = 0.001) compared with the asymptomatic ICAS. The average length of LSAs in symptomatic ICAS (20.95 ± 0.87 mm) was shorter than in asymptomatic ICAS (24.04 ± 0.95 mm) (P = 0.02). Regression analysis showed that the enhancement index (100.43, 95% CI − 4.02-2510.96; P = 0.005) and the average length of LSAs (0.80, 95% CI − 0.65-0.99; P = 0.036) were independent factors for predicting of stroke.ConclusionWB-HRCMR enabled the comprehensive quantitative evaluation of intracranial atherosclerotic lesions and perforating arteries. Symptomatic ICAS had distinct plaque characteristics and shorter LSA length compared with asymptomatic ICAS.

Reduced myocardial perfusion in post renal transplant population is not associated with aortic stiffness

Background Objective: The purpose of this study was to assess central (aortic) vascular dysfunction in post renal transplant patients by high-resolution cardiovascular magnetic resonance imaging (CMR). Background: Renal transplant recipients are at increased risk of cardiovascular (CV) disease. The cardiac phenotype in post-transplant recipients is not well defined. A recent study suggested myocardial perfusion is impaired in renal transplant patients irrespective of the degree of left ventricular hypertrophy [1].We hypothesized that post transplant patients have persistently increased aortic stiffness, and that it could be correlated with reduced myocardial perfusion.

Fractional flow reserve and the correlation with ischaemic burden measured by cardiovascular magnetic resonance perfusion imaging

Objectives To investigate the relationship between the Fractional Flow Reserve (FFR) value in a coronary territory and the extent of myocardial ischaemia measured by high resolution Cardiovascular Magnetic Resonance Imaging (CMR) scanning Methods: 49 patients with angina and known or suspected coronary artery disease (CAD) referred for coronary angiography also underwent CMR perfusion imaging. FFR was measured in all vessels with a stenosis of >50%. The extent of ischaemia (both global and individual arterial territories) was measured as a percentage of the LV myocardium on CMR imaging. Interstudy reproducibility of the measurements of ischaemia was also assessed. Results: The correlation between the extent of ischaemia on a per vessel basis measured by CMR and the FFR value was good (r= -0.854, p<0.0005) An FFR value of 0.75 or above in a coronary artery was associated with no myocardial ischaemia. The maximum amount of ischaemia (mean value 23.0% (±1.5) was demonstrated at FFR values between 0.4 and 0.5. The mean value for global ischaemic burden was 12.69% (±12%). In patients with one vessel disease (49%) the mean value for percentage ischaemia was 15.3% (±8.3%). In patients with 2 vessel disease (18%) the mean value was 26% (±12%). Reproducibility for measurement of ischaemic burden was very good with a Kappa coefficient (k=0.826, p=0.048). ![Figure][1] FFR values and % ischaemia per vessel Conclusions: There is good correlation between the FFR value within a coronary artery and the amount of myocardial ischaemia caused. Relating the amount of ischaemia to the FFR value could lead to more targeted revascularisation to reduce ischaemic burden, potentially resulting in improved patient outcome. [1]: pending:yes

Abstract 19806: Left Atrial Remodeling in Hypertrophic Cardiomyopathy and Markers for Atrial Fibrillation: Assessment by Cardiovascular Magnetic Resonance Imaging

Introduction. Atrial fibrillation (AF) is the most common sustained arrhythmia in hypertrophic cardiomyopathy (HCM), and an important determinant of clinical deterioration due primarily to heart failure and embolic stroke Hypothesis. Left atrial (LA) structural and functional parameters were assessed with high resolution cardiovascular magnetic resonance imaging (CMR) to provide imaging markers associated with the risk for developing AF in HCM patients. Methods. We studied 438 consecutive HCM patients (age 47 17 years) with CMR, including 57 with a history of paroxysmal AF, 13 in persistent AF, 368 without AF history, as well as 244 normal controls. The LA chamber was assessed for absolute and indexed end-diastolic volume (LAEDV) and end-systolic volume (LAESV), and % ejection fraction (LAEF). Results. Absolute LAEDV was significantly greater in HCM patients with AF (157 ± 73 ml) than in patients without AF (109 ± 39 ml), or normal controls (80 ± 24 ml; p &lt; 0.001). LAEF was lower in HCM with AF (34 ± 17%) than in HCM without AF (46 ± 12%) or controls (55 ± 9%; p &lt; 0.001), and decreased progressively from control values to HCM without AF to HCM with paroxysmal AF (37 ±16 ml), and to those patients with persistent/chronic AF (18 ±13%; p &lt; 0.001). A multivariate model showed LAEF (&lt; 40%) and LAEDV (&gt; 125 ml), as well as age (&gt; 46 years) each to be independently associated with occurrence of AF. Combining these 3 CMR variables most accurately discriminated the susceptibility to AF with the area under ROC curve = 0.805, and the accuracy = 82%. Conclusions. In HCM, % LAEF, as assessed by CMR, is a novel marker associated with AF, and in conjunction with increased LAEDV and older age.

086 Assessment of ischaemic burden in patients with three-vessel coronary artery disease using high-resolution myocardial perfusion cardiovascular MRI

IntroductionPatients with three-vessel disease (3VD) have a worse prognosis than those with less extensive disease; but detecting a 3VD pattern of ischaemia can be very challenging due to balanced hypoperfusion....

087 Incremental value of high-resolution cardiovascular magnetic resonance myocardial perfusion imaging in suspected coronary artery disease

IntroductionAlthough accelerated high-spatial-resolution cardiovascular magnetic resonance (CMR) perfusion imaging has recently been shown to be clinically feasible, there has not yet been a direct comparison with standard-resolution methods. We hypothesised...

Atherosclerosis and arterial stiffness in obstructive sleep apnea—A cardiovascular magnetic resonance study

ObjectiveObstructive sleep apnoea (OSA) has been linked to cardiovascular risk factors, such as hypertension, and clinical cardiovascular endpoints. Our aim was to assess whether OSA is independently associated with atherosclerosis and vascular dysfunction as assessed by cardiovascular magnetic resonance (CMR). Methods58 patients with OSA and 39 matched control subjects without OSA underwent CMR of the aorta and carotid arteries. Carotid and aortic wall thickness and aortic distensibility were measured. Multi-weighted, high resolution CMR imaging was used for carotid atheroma characterization according to the American Heart Association (AHA) atheroma classification, modified for CMR. ResultsCarotid [1.47±0.03mm vs. 1.26±0.05mm, (P<0.01)] and aortic wall thickness [2.95±0.09mm vs. 2.05±0.07mm, (P<0.001)] were increased in patients with OSA compared to controls. Aortic distensibility was decreased in patients with OSA [3.62±0.3 vs. 4.75±0.2mmHg−1×10−3, (P<0.05)]. Prevalence of carotid plaque, average carotid atheroma class, and prevalence of high risk features of carotid atheroma were increased in patients with OSA (P<0.005 for all). On multivariate analysis, Oxygen desaturation index (ODI) emerged as an independent predictor of carotid and aortic wall thickness, but not of aortic stiffness. ConclusionsOSA is associated with increased carotid and aortic atheroma burden and with advanced, high risk carotid atherosclerotic plaques, but not with aortic stiffening.

High-resolution versus standard-resolution cardiovascular magnetic resonance perfusion imaging for the detection of coronary artery disease

Summary This study compared the diagnostic accuracy of highresolution and standard-resolution cardiovascular magnetic resonance (CMR) perfusion imaging in patients with suspected coronary artery disease (CAD). Background Although accelerated high-spatial-resolution CMR perfusion imaging has recently been shown to be clinically feasible, there has not yet been a direct comparison with standard-resolution methods. We hypothesised that higher spatial resolution detects more subendocardial ischemia and leads to greater diagnostic accuracy for the detection of angiographically defined CAD. Methods A total of 111 patients with suspected CAD were prospectively recruited. All patients underwent two separate perfusion CMR studies on a 1.5 Tesla CMR scanner (Intera CV, Philips Healthcare, Best, the Netherlands), one with standard-resolution (2.5 x 2.5mm in-plane resolution) and one with high-resolution (1.6 x 1.6mm in-plane resolution) acquisition. High-resolution acquisition was facilitated by eight-fold k-t broad linear speed up technique (BLAST) acceleration. Two observers visually graded perfusion in each myocardial segment on a 4-point scale. Segmental scores were summed to produce a perfusion score for each patient. All patients underwent invasive coronary angiography. Significant CAD was defined as a coronary artery stenosis of ≥ 50% diameter on quantitative coronary angiography. Results CMR data were successfully obtained in 100 patients. A typical example is shown in Figure 1. In patients with CAD (n=70), more segments were determined to have subendocardial ischemia with high-resolution acquisition than with standard-resolution acquisition (279 vs.108; p<0.001). High-resolution acquisition had a greater diagnostic accuracy than standard-resolution acquisition for identifying single-vessel disease (area under the curve [AUC]: 0.88 vs. 0.73; p<0.001) or multi-vessel disease (AUC: 0.98 vs. 0.91; p=0.002) and overall (AUC: 0.93 vs. 0.83; p<0.001) (Figure 2). Conclusions Our study shows that high-resolution CMR perfusion imaging has greater diagnostic accuracy than standardresolution acquisition for the detection of CAD in both single and multi-vessel disease and detects more subendocardial ischemia. Funding

Does heart rate influence CMR image quality of the coronary vessel wall?

Does heart rate influence CMR image quality of the coronary vessel wall?

Aortic stiffness in type-1 diabetes mellitus; beware of hypertension

Over the past years considerable progress has been made in the field of cardiovascular magnetic resonance (CMR), providing accurate evaluation of left ventricular mass, volumes and function [1–9]. CMR has shown unique abilities in characterizing myocardial tissue composition. In particular, high-resolution contrast-enhanced CMR has been used to visualize myocardial fibrosis with a high accuracy [10–16]. For instance, in patients with acute myocardial infarction, the injured myocardium shows increased CMR contrast compared to normal myocardium when imaged by delayed gadolinium enhancement. The transmural extent of delayed gadolinium enhancement predicts functional outcome after interventional procedures performed in patients with acute myocardial infarction and chronic ischemic heart disease [16–21]. Not only in the setting of an acute myocardial infarction, but also in patients with various manifestations of cardiomyopathy, evidence of delayed gadolinium enhancement may have important clinical and prognostic implications [22–30]. Magnetic resonance angiography (MRA) has been introduced as a method that can provide visualization of all three major coronary arteries, coronary bypasses and the aorta within a single three-dimensional acquisition [31–40]. CMR has become the first choice imaging modality in complex congenital heart disease and imaging great vessels [41–46]. In particular, CMR has proven to be of indispensable value in identifying aortic stiffness in Marfan patients using pulse wave velocity measurements [47, 48]. In these patients pulse wave velocity is the propagation speed of the pressure or flow wave front traveling along the aorta. For instance, it has been shown that aortic stiffness in Marfan syndrome, together with mean blood pressure, is reduced by beta-blocker therapy, and CMR is well suited to detect these changes by measuring aortic distensibility and pulse wave velocity. In the present issue of the International Journal of Cardiovascular Imaging, Brandts et al. [49] investigated in type-1 diabetes mellitus patients the role of hypertension and of diabetes mellitus itself on aortic stiffness by using CMR. The hypothesis of the study was that hypertension has a predominant effect on aortic stiffness in type-1 diabetes mellitus patients. In addition, it was established to what extent type-1 diabetes mellitus itself independently adds to aortic stiffness. Subjects were divided into 4 groups: 32 healthy volunteers, 20 diabetes mellitus patients, 31 hypertensive patients, and 28 patients with both diabetes mellitus and hypertension. Aortic stiffness was measured by means of pulse wave velocity using velocity-encoded CMR (Medis, Leiden). Mean aortic pulse wave velocity was 5.7 ± 1.2 m/s in healthy volunteers, 5.9 ± 1.2 m/s in diabetes mellitus patients without hypertension, 7.3 ± 1.2 m/s in hypertensive patients, and 7.3 ± 1.3 m/s in patients with both diabetes mellitus and hypertension. Compared to healthy control subjects, aortic pulse wave velocity was significantly higher in patients with hypertension and in patients with both diabetes mellitus and hypertension. However, aortic pulse wave velocity was not increased in patients having diabetes mellitus alone. The authors concluded that hypertension has a predominant contributive effect on aortic stiffness in diabetes mellitus patients whereas the direct diabetic effect on aortic stiffness was insignificant. The main finding of the study was that the independent effect of type-1 diabetes mellitus on aortic pulse wave velocity was minor; aortic pulse wave velocity was not significantly different between healthy volunteers and type-1 diabetes mellitus patients. Secondly, the independent effect of hypertension on aortic pulse wave velocity was most important; aortic pulse wave velocity was significantly higher in hypertensive patients than in healthy volunteers. In addition, the combination of type-1 diabetes mellitus and hypertension resulted in increased aortic stiffness, and was significantly higher than in patients having type-1 diabetes mellitus alone. Interestingly, the authors showed that aortic stiffness in type-1 diabetes patients mainly depends on having additional hypertension, and not on diabetes alone. Therefore, identification of hypertension in patients with type-1 diabetes is of importance for risk stratification and can be used for guiding therapy in order to improve cardiovascular outcome. Investigating the hypertensive contribution on aortic stiffness in patients with type-1 diabetes mellitus is utmost relevant for cardiovascular risk assessment as type-1 diabetes mellitus is often associated with hypertension. The current study is unique in the sense that it used CMR-assessed pulse wave velocity measurements. More recent studies from the same group showed that stiffness of the aorta was independently associated with systolic left ventricular function [50]. In addition, aortic stiffness independently predicted white matter brain atrophy in patients with type-1 diabetes mellitus [51]. In summary, the study by Brandts et al. [49], using CMR-determined pulse wave velocity measurements, convincingly demonstrates that hypertension has a predominant contributive effect on aortic stiffness in diabetes mellitus type-1 patients, whereas the direct diabetic effect on aortic stiffness was very small. Since aortic stiffness and diabetes mellitus are highly associated with adverse cardiovascular events, identifying hypertension in diabetes mellitus type-1 patients seems utmost relevant for further risk stratification.

Longitudinally and circumferentially directed movements of the left ventricle studied by cardiovascular magnetic resonance phase contrast velocity mapping.

ObjectiveUsing high resolution cardiovascular magnetic resonance (CMR), we aimed to detect new details of left ventricular (LV) systolic and diastolic function, to explain the twisting and longitudinal movements of the left ventricle.MethodsUsing CMR phase contrast velocity mapping (also called Tissue Phase Mapping) regional wall motion patterns and longitudinally and circumferentially directed movements of the left ventricle were studied using a high temporal resolution technique in healthy male subjects (n = 14, age 23 ± 3 years).ResultsPreviously undescribed systolic and diastolic motion patterns were obtained for left ventricular segments (based on the AHA segmental) and for basal, mid and apical segments. The summation of segmental motion results in a complex pattern of ventricular twisting and longitudinal motion in the normal human heart which underlies systolic and diastolic function. As viewed from the apex, the entire LV initially rotates in a counter-clockwise direction at the beginning of ventricular systole, followed by opposing clockwise rotation of the base and counter-clockwise rotation at the apex, resulting in ventricular torsion. Simultaneously, as the entire LV moves in an apical direction during systole, the base and apex move towards each other, with little net apical displacement. The reverse of these motion patterns occur in diastole.ConclusionLeft ventricular function may be a consequence of the relative orientations and moments of torque of the sub-epicardial relative to the sub-endocardial myocyte layers, with influence from tethering of the heart to adjacent structures and the directional forces associated with blood flow. Understanding the complex mechanics of the left ventricle is vital to enable these techniques to be used for the evaluation of cardiac pathology.

Dual stack black blood carotid artery CMR at 3T: application to wall thickness visualization.

BackgroundThe increasing understanding of atherosclerosis as an important risk factor for the development of acute ischemic events like ischemic stroke has stimulated increasing interest in non-invasive assessment of the structure, composition and burden of plaque depositions in the carotid artery wall. Vessel wall imaging by means of cardiovascular magnetic resonance (CMR) is conventionally done by 2D dual inversion recovery (DIR) techniques, which often fail in covering large volumes of interest as required in plaque burden assessment. Although the technique has been extended to 2D multislice imaging, its straight extension to 3D protocols is still limited by the prolonged acquisition times and incomplete blood suppression. A novel approach for rapid overview imaging of large sections of the carotid artery wall at isotropic spatial resolutions is presented, which omits excitation of the epiglottis. By the interleaved acquisition of two 3D stacks with the proposed motion sensitized segmented steady-state black-blood gradient echo technique (MSDS) the coverage of the carotid artery trees on both sides in reasonable scan times is enabled.Results10 patients were investigated with the proposed technique and compared to conventional transversal DIR turbo spin and gradient echo approaches centered at the height of the carotid bifurcation. In all MSDS experiments sufficient black-blood contrast could be obtained over the entire covered volumes. The contrast to noise ratio between vessel and suppressed blood was improved by 73% applying the motion sensitizing technique. In all patients the suspicious areas of vessel wall thickening could be clearly identified and validated by the conventional local imaging approach. The average assessable vessel wall segment length was evaluated to be 18 cm. While in 50% of the cases motion artifacts could be appreciated in the conventional images, none were detected for the MSDS technique.ConclusionThe proposed technique enables the time efficient coverage of large areas of the carotid arteries without compromising wall-lumen CNR to get an overview about detrimental alterations of the vessel wall. Thickening of the vessel wall can be identified and the suspicious segments can be targeted for subsequent high-resolution CMR. The exclusion of the epiglottis may further facilitate reduction of swallowing induced motion artifacts.

Functional Assessment of Isolated Right Heart Failure by High Resolution In-Vivo Cardiovascular Magnetic Resonance in Mice

Precise and noninvasive characterization of the development of the cardiac phenotype in murine models of heart failure has been widely demanded in modern cardiovascular research. High-resolution cardiovascular magnetic resonance (CMR) has been proven to be a powerful tool for the accurate and reproducible assessment of LV and RV parameters in healthy mice. Whereas changes in LV parameters in models of heart failure have been thoroughly evaluated, RV dysfunction has not. Purpose of this study was to characterize a model of isolated RV failure induced by pulmonal banding by in vivo CMR at 7T. RV parameters differed significantly from those of normal mice in terms of RV end-diastolic volume (EDV: 85 +/- 14 microL vs. control 36 +/- 3 microL, p < 0.0001), RV end-systolic volume (ESV: 121 +/- 10 microL vs. control 84 +/- 4 microL, p < 0.005) and RV ejection fraction (EF: 31 +/- 6 % vs. control 57 +/- 2 %, p < 0.001). With regard to EDV, ESV, SV and EF LV parameters, there were no significant differences between pulmonary banded and control mice indicating overt isolated RV failure.