Cardiovascular Magnetic Resonance Tagging Research Articles

Role of Noninvasive Imaging in the Diagnosis of Cardiac Allograft Vasculopathy

Cardiac allograft vasculopathy (CAV) is common, with a prevalence of 52% at 10 years after transplantation, and represents a leading cause of death beyond the first year, responsible for approximately 15% of deaths annually.1 It is characterized by diffuse and concentric intimal proliferation, typically involving the intramural as well as epicardial coronary arteries. Its diagnosis is difficult to establish clinically because of denervation of the transplanted heart. Consequently, it presents late with silent myocardial infarction, progressive heart failure, or arrhythmic sudden death.2 Screening is therefore required for its early detection. Although coronary intravascular ultrasound (IVUS) is considered the gold-standard technique for detecting the anatomic features of CAV (Table 1), its broad clinical use in this context is limited by cost and lack of widespread expertise, and its evaluation is limited to epicardial vessels.3 Coronary angiography, performed annually or biannually, remains the most common clinical screening method.4 However, because of the diffuse nature of CAV with a lack of normal reference segments and the relatively late occurring luminal narrowing, the sensitivity of angiography is as low as 30% when compared with IVUS (Figure 1).5 As a result, complications frequently occur before disease is evident angiographically.6 Furthermore, angiography is associated with significant albeit uncommon complications (overall complication rate, 7.4/1000 procedures, including rates of 0.65/1000, 1.6/1000, and 0.72/1000 for cerebrovascular accidents, vascular complications, and death, respectively), is disliked by transplant recipients, is costly, and repeated studies are associated with an important cumulative radiation dose.7 View this table: Table 1. Stanford Classification of CAV Severity on IVUS Figure 1. Invasive assessment of cardiac allograft vasculopathy (CAV) in a patient with severe disease, highlighting the limited sensitivity of conventional coronary angiography. Although no left anterior descending (LAD) flow-limiting stenoses are seen on angiography ( A ), intravascular ultrasound ( B ) shows significant intimal thickening, measuring up to …

166 Cardiovascular magnetic resonance (CMR) tagging identifies differential ventricular remodelling in patients with bicuspid vs tricuspid aortic valve disease

<h3>Background</h3> Bicuspid aortic valves (BAV) are a common inherited abnormality with a very high rate of adverse cardiac events at an earlier age than tricuspid aortic valves (TAV). Risk stratification for moderate to severe aortic stenosis, in both bicuspid and tricuspid disease, remains a significant clinical challenge. It is unknown whether pathological left ventricular (LV) remodelling, a strong predictor of adverse cardiac events, differs between patients with bicuspid and tricuspid valvular disease with comparable transvalvular gradients. Cardiovascular magnetic resonance (CMR) tagging provides detailed characterisation of global and regional contractility, and is a powerful investigative tool in the assessment of myocardial disease. We therefore assessed left ventricular strain (using CMR tagging), valve morphology and LV hypertrophy in patients with bicuspid and tricuspid aortic valve disease matched for transvalvular gradient. <h3>Methods</h3> 42 subjects were recruited in total: 24 patients with moderate to severe BAV (age 55 ±15 yrs, female 21%, peak trans-aortic velocity 3.1±0.6/ms, LV mass 172±48 g; SBP 127 ±14 mm Hg DBP 76 ±10 mm Hg) and 18 patients with velocity-matched TAV (age 74 ±6 years, female 28%, velocity 3.1±0.6/ ms, LV mass 147±27 g; SBP 136±17 mm Hg; DBP 79±7 mm Hg; Abstract 166 table 1). Patients were scanned using a 1.5 T Avanto scanner (Siemens Healthcare, Erlangen, Germany) and basal, mid-ventricular and apical short axis tagging images were acquired. Peak systolic global circumferential strain was calculated at each ventricular level using CimTag2D software v.7 (Auckland MRI Research Group, New Zealand). <h3>Results</h3> Patients with BAV had significantly greater left ventricular hypertrophy (BAV 172 ±48 g vs TAV 147±27 g; p=0.04) despite similar degrees of valve stenosis. Peak systolic circumferential strain was lower (ie, reduced contractility) in patients with BAV than TAV (Basal BAV 20±3% vs TAV 22±3% P=0.04; Mid BAV 19 ± 2% vs TAV 21 ± 2% p=0.07; apical BAV 17±4% vs TAV 19±3%; p&lt;0.04), despite the younger age and lower blood pressure. <h3>Conclusion</h3> Ventricular remodelling differs between BAV and TAV patients with equivalent transvalvular gradients. BAV patients, despite being younger and having lower systolic blood pressure, have more severe hypertrophy and lower myocardial contractility. This finding may have implications for monitoring disease progression or more timely medical or surgical intervention in patients with BAV.

130 Comparison of harmonic phase imaging with local sine wave modelling for the assessment of circumferential myocardial strain using tagged cardiovascular magnetic resonance images

IntroductionAssessment of myocardial strain promises to become an important quantitative tool in early diagnosis of cardiac disease and treatment monitoring. Advances in image processing software have facilitated rapid and clinically...

Assessment of left ventricular apical rotation in obese by Cardiovascular MR tagging

Background Obesity is associated with cardiac remodelling with increased left ventricular mass and end-diastolic volume. CMR is a unique technique to evaluate cardiac morphology and function in obese individuals. Among CMR techniques, myocardial tagging allows to quantify myocardial strain and left ventricular rotation along the RR cycle (1). The aim of this preliminary study was to explore the feasibility of left ventricular apical rotation quantification by CMR tagging in obese individuals and exploring possible alteration of myocardial motion pattern. Methods 8 healthy controls (18 30) without other cardiovascular risk factors and with normal left ventricular ejection fraction were imaged using a 1.5T Espree system (wider bore, well adapted to obese subjects). We used an ECG gated, single breath hold balanced SSFP line tagging sequence with LISA, with CSPAMM acquisition scheme (2). The field of view was 340 x340 mm, matrix 256 with 32% phase resolution, bandwidth 850 Hz, slice thickness 7 mm, tag spacing 7 mm, TE 1.28 (TE 1.54 @ 3T) and Flip angle 20° (15° @ 3T). Images were analyzed and apical rotations were computed using Extrema Temporal Chaining (ETC) (3). Results The left ventricular apical systolic rotation measured by CMR tagging was increased and delayed in obese patients while the diastolic apical untwisting was prolonged, when compared to control subjects (Fig.1). Conclusions Our preliminary results confirm the presence of an abnormal pattern of left ventricular rotation in obese individuals that can be identified with CMR tagging. This abnormal pattern may reflect the remodeling secondary to increased hemodynamic requirements (volume-overload and sympathetic system activation) in obese subjects, while the delayed diastolic untwisting may precede a diastolic dysfunction. These preliminary data confirm that CMR with myocardial tagging may allow identifying early abnormalities of left ventricular function in obese individuals with normal left ventricular ejection fraction.

CMR tagging in the polar coordinate system

Strain of the myocardium is conventionally presented in the polar coordinate system since it adapts best to the morphology of the heart. Strain calculation would be facilitated considerably if the CMR tagging patterns were in the radial or circumferential direction. However, the CMR tagging is implemented mostly in the Cartesian coordinate system as it is prescribed by SPAMM technique in which the gradient fields create only parallel taglines. Radial tagging is not used widely due to SAR problem for tight radial pattern. Implementation of circular tagging, to the best of our knowledge, has not been reported yet. Here we introduce an approach that makes both patterns possible for tagging based on off-resonance excitation. Its theoretical basis and practical details as well as initial results in phantoms and human hearts are presented.

Magnetic resonance imaging of post-systolic shortening in a closed-chest rat model of coronary occlusion using myocardial tagging

The aim of the study was to evaluate the reliability and sensitivity of tagged cardiac magnetic resonance imaging (cMRI) in assessment of regional cardiac dysfunction induced by short ischemia. For clinical low dose dobutamine tests, quantitative strain analyses derived from tagged cMRI have been shown to be able to detect viable myocardium. However these preliminary data were obtained in patients with high grade coronary stenosis, likely to have a large ischemic territory. So it is not known whether MRI tagging could detect coronary occlusion i) of short duration and ii) in small ischemic areas. A model of closed-chest coronary artery occlusion was developed in Sprague-Dawley rats. 10 rats underwent a 3 minutes coronary occlusion followed by 30 minutes of reperfusion, directly in a 1.5 Tesla clinical MRI scanner. Efficiency and reversibility of the coronary occlusion was assessed by modifications of the ECG recording. Tagged images were acquired every 2.5 minutes using C-SPAMM with segmented cine fast field echo sequence. Strain analysis was performed with the Extrema Temporal Chaining algorithm in six sectors of the short axis slice, classified in 2 groups: anterolateral and inferolateral sectors were considered as ischemic whereas inferior, inferoseptal and anteroseptal sectors were remote. Contraction (maximum strain) and contractility (strain rate) derived from the myocardial strain curves were analysed using a linear model. Eight rats underwent hemodynamic measurements by intraventricular catheterism to evaluate global cardiac function along a similar protocol of ischemia-reperfusion. During the occlusion, contraction was reduced and delayed in the ischemic sectors compared to remote group (p<0.001). The contraction remained delayed during the first minutes of reperfusion (p<0.005) in the ischemic group, demonstrating post-systolic shortening. Contractility was decreased both during the occlusion and the first minutes of reperfusion. Hemodynamic measurements dit not show any abnormality of the systolic or diastolic function after the first minutes of reperfusion. We showed for the first time in a rat model that MRI tagging of a short coronary occlusion is feasible, on a 1.5 Tesla clinical scanner. We demonstrated in the ischemic sectors a transient contractile dysfunction which was not demonstrated by hemodynamic measurements. Besides the interest of such a method for non-invasive study of cardiac function in rodent, our data also suggest that tagged MRI could bring an important improvement in evaluation of the human cardiac function during stress imaging.

Myocardial tagging by cardiovascular magnetic resonance: evolution of techniques--pulse sequences, analysis algorithms, and applications.

Cardiovascular magnetic resonance (CMR) tagging has been established as an essential technique for measuring regional myocardial function. It allows quantification of local intramyocardial motion measures, e.g. strain and strain rate. The invention of CMR tagging came in the late eighties, where the technique allowed for the first time for visualizing transmural myocardial movement without having to implant physical markers. This new idea opened the door for a series of developments and improvements that continue up to the present time. Different tagging techniques are currently available that are more extensive, improved, and sophisticated than they were twenty years ago. Each of these techniques has different versions for improved resolution, signal-to-noise ratio (SNR), scan time, anatomical coverage, three-dimensional capability, and image quality. The tagging techniques covered in this article can be broadly divided into two main categories: 1) Basic techniques, which include magnetization saturation, spatial modulation of magnetization (SPAMM), delay alternating with nutations for tailored excitation (DANTE), and complementary SPAMM (CSPAMM); and 2) Advanced techniques, which include harmonic phase (HARP), displacement encoding with stimulated echoes (DENSE), and strain encoding (SENC). Although most of these techniques were developed by separate groups and evolved from different backgrounds, they are in fact closely related to each other, and they can be interpreted from more than one perspective. Some of these techniques even followed parallel paths of developments, as illustrated in the article. As each technique has its own advantages, some efforts have been made to combine different techniques together for improved image quality or composite information acquisition. In this review, different developments in pulse sequences and related image processing techniques are described along with the necessities that led to their invention, which makes this article easy to read and the covered techniques easy to follow. Major studies that applied CMR tagging for studying myocardial mechanics are also summarized. Finally, the current article includes a plethora of ideas and techniques with over 300 references that motivate the reader to think about the future of CMR tagging.

Iron overload in polytransfused patients without heart failure is associated with subclinical alterations of systolic left ventricular function using cardiovascular magnetic resonance tagging.

BackgroundIt remains incompletely understood whether patients with transfusion related cardiac iron overload without signs of heart failure exhibit already subclinical alterations of systolic left ventricular (LV) dysfunction. Therefore we performed a comprehensive evaluation of systolic and diastolic cardiac function in such patients using tagged and phase-contrast CMR.Methods19 patients requiring regular blood transfusions for chronic anemia and 8 healthy volunteers were investigated using cine, tagged, and phase-contrast and T2* CMR. LV ejection fraction, peak filling rate, end-systolic global midventricular systolic Eulerian radial thickening and shortening strains as well as left ventricular rotation and twist, mitral E and A wave velocity, and tissue e' wave and E/e' wave velocity ratio, as well as isovolumic relaxation time and E wave deceleration time were computed and compared to cardiac T2*.ResultsPatients without significant iron overload (T2* > 20 ms, n = 9) had similar parameters of systolic and diastolic function as normal controls, whereas patients with severe iron overload (T2* < 10 ms, n = 5), had significant reduction of LV ejection fraction (54 ± 2% vs. 62 ± 6% and 65 ± 6% respectively p < 0.05), of end-systolic radial thickening (+6 ± 4% vs. +11 ± 2 and +11 ± 4% respectively p < 0.05) and of rotational twist (1.6 ± 0.2 degrees vs. 3.0 ± 1.2 and 3.5 ± 0.7 degrees respectively, p < 0.05) than patients without iron overload (T2* > 20 ms) or normal controls. Patients with moderate iron overload (T2* 10-20 ms, n = 5), had preserved ejection fraction (59 ± 6%, p = NS vs. pts. with T2* > 20 ms and controls), but showed reduced maximal LV rotational twist (1.8 ± 0.4 degrees). The magnitude of reduction of LV twist (r = 0.64, p < 0.001), of LV ejection fraction (r = 0.44, p < 0.001), of peak radial thickening (r = 0.58, p < 0.001) and of systolic (r = 0.50, p < 0.05) and diastolic twist and untwist rate (r = -0.53, p < 0.001) in patients were directly correlated to the logarithm of cardiac T2*.ConclusionMultiple transfused patients with normal ejection fraction and without heart failure have subclinical alterations of systolic and diastolic LV function in direct relation to the severity of cardiac iron overload. Among all parameters, left ventricular twist is affected earliest, and has the highest correlation to log (T2*), suggesting that this parameter might be used to follow systolic left ventricular function in patients with iron overload.

Cardiovascular magnetic resonance tagging of the right ventricular free wall for the assessment of long axis myocardial function in congenital heart disease.

BackgroundRight ventricular ejection fraction (RV-EF) has traditionally been used to measure and compare RV function serially over time, but may be a relatively insensitive marker of change in RV myocardial contractile function. We developed a cardiovascular magnetic resonance (CMR) tagging-based technique with a view to rapid and reproducible measurement of RV long axis function and applied it in patients with congenital heart disease.MethodsWe studied 84 patients: 56 with repaired Tetralogy of Fallot (rTOF); 28 with atrial septal defect (ASD): 13 with and 15 without pulmonary hypertension (RV pressure > 40 mmHG by echocardiography). For comparison, 20 healthy controls were studied. CMR acquisitions included an anatomically defined four chamber cine followed by a cine gradient echo-planar sequence in the same plane with a labelling pre-pulse giving a tag line across the basal myocardium. RV tag displacement was measured with automated registration and tracking of the tag line together with standard measurement of RV-EF.ResultsMean RV displacement was higher in the control (26 ± 3 mm) than in rTOF (16 ± 4 mm) and ASD with pulmonary hypertension (18 ± 3 mm) groups, but lower than in the ASD group without (30 ± 4 mm), P < 0.001. The technique was reproducible with inter-study bias ± 95% limits of agreement of 0.7 ± 2.7 mm. While RV-EF was lower in rTOF than in controls (49 ± 9% versus 57 ± 6%, P < 0.001), it did not differ between either ASD group and controls.ConclusionsMeasurements of RV long axis displacement by CMR tagging showed more differences between the groups studied than did RV-EF, and was reproducible, quick and easy to apply. Further work is needed to assess its potential use for the detection of longitudinal changes in RV myocardial function.

Motion estimation of tagged cardiac magnetic resonance images using variational techniques

This work presents a new method for motion estimation of tagged cardiac magnetic resonance sequences based on variational techniques. The variational method has been improved by adding a new term in the optical flow equation that incorporates tracking points with high stability of phase. Results were obtained through simulated and real data, and were validated by manual tracking and with respect to a reference state-of-the-art method: harmonic phase imaging (HARP). The error, measured in pixels per frame, obtained with the proposed variational method is one order of magnitude smaller than the one achieved by the reference method, and it requires a lower computational cost.

Left ventricular T2 distribution in Duchenne muscular dystrophy.

BackgroundAlthough previous studies have helped define the natural history of Duchenne Muscular Dystrophy (DMD)-associated cardiomyopathy, the myocardial pathobiology associated with functional impairment in DMD is not yet known.The objective of this study was to assess the distribution of transverse relaxation time (T2) in the left ventricle (LV) of DMD patients, and to determine the association of myocardial T2 heterogeneity to the severity of cardiac dysfunction. DMD patients (n = 26) and normal control subjects (n = 13) were studied by Cardiovascular Magnetic Resonance (CMR). DMD subject data was stratified based on subject age and LV Ejection Fraction (EF) into the following groups: A (<12 years old, n = 12); B (≥12 years old, EF ≤ 55%, n = 8) and C (≥12 years old, EF = 55%, n = 6). Controls were also stratified by age into Groups N1 (<12 years, n = 6) and N2 (>12 years, n = 5). LV mid-slice circumferential myocardial strain (εcc) was calculated using tagged CMR imaging. T2 maps of the LV were generated for all subjects using a black blood dual spin echo method at two echo times. The Full Width at Half Maximum (FWHM) was calculated from a histogram of LV T2 distribution constructed for each subject.ResultsIn DMD subject groups, FWHM of the T2 histogram rose progressively with age and decreasing EF (Group A FWHM= 25.3 ± 3.8 ms; Group B FWHM= 30.9 ± 5.3 ms; Group C FWHM= 33.0 ± 6.4 ms). Further, FWHM was significantly higher in those with reduced circumferential strain (|εcc| ≤ 12%) (Group B, and C) than those with |εcc| > 12% (Group A). Group A FWHM was not different from the two normal groups (N1 FWHM = 25.3 ± 3.5 ms; N2 FWHM= 24.0 ± 7.3 ms).ConclusionReduced EF and εcc correlates well with increased T2 heterogeneity quantified by FWHM, indicating that subclinical functional impairments could be associated with pre-existing abnormalities in tissue structure in young DMD patients.

Calculation of left ventricular volume based on GVF model and optical flow field

Concerning the problems of difficult segmentation and large computation in calculating the Left Ventricular (LV) volume using tagged cardiac magnetic resonance image,a new method of calculating the LV volume was proposed. First an advanced snake model based on the gradient vector field (GVF-snake) was used to segment the contour of the left ventricular and an initial snake line of the contour was got,then optical flow method was used to track the contour of the LV in the successive images. Finally,the Simpson method was applied to calculate the volume of the LV. The comparison of the result by this method with the result got manually shows that the combination of the GVF-snake model and optical flow method is feasible to calculate the volume of the LV.

Circumferential myocardial strain in cardiomyopathy with and without left bundle branch block.

BackgroundCardiac resynchronization therapy (CRT) has been shown to decrease mortality in 60-70% of advanced heart failure patients with left bundle branch block (LBBB) and QRS duration > 120 ms. There have been intense efforts to find reproducible non-invasive parameters to predict CRT response. We hypothesized that different left ventricular contraction patterns may exist in LBBB patients with depressed systolic function and applied tagged cardiovascular magnetic resonance (CMR) to assess circumferential strain in this population.MethodsWe determined myocardial circumferential strain at the basal, mid, and apical ventricular level in 35 subjects (10 with ischemic cardiomyopathy, 15 with non-ischemic cardiomyopathy, and 10 healthy controls). Patterns of circumferential strain were analyzed. Time to peak systolic circumferential strain in each of the 6 segments in all three ventricular slices and the standard deviation of time to peak strain in the basal and mid ventricular slices were determined.ResultsDyskinesis of the anterior septum and the inferior septum in at least two ventricular levels was seen in 50% (5 out of 10) of LBBB patients while 30% had isolated dyskinesis of the anteroseptum, and 20% had no dyskinesis in any segments, similar to all of the non-LBBB patients and healthy controls. Peak circumferential strain shortening was significantly reduced in all cardiomyopathy patients at the mid-ventricular level (LBBB 9 ± 6%, non-LBBB 10 ± 4% vs. healthy 19 ± 4%; both p < 0.0001 compared to healthy), but was similar among the LBBB and non-LBBB groups (p = 0.20). The LBBB group had significantly greater dyssynchrony compared to the non-LBBB group and healthy controls assessed by opposing wall delays and 12-segment standard deviation (LBBB 164 ± 30 ms vs. non-LBBB 70 ± 17 ms (p < 0.0001), non-LBBB vs. healthy 65 ± 17 ms (p = 0.47)).ConclusionsSeptal dyskinesis exists in some patients with LBBB. Myocardial circumferential strain analysis enables detailed characterization of contraction patterns, strengths, and timing in cardiomyopathy patients with and without LBBB.

Multimodality Noninvasive Imaging for Assessment of Congenital Heart Disease

Major advances in the field of pediatric cardiology and cardiac surgery over the last several decades have led to a dramatic improvement in survival rates for most forms of congenital heart disease (CHD). For example, hypoplastic left heart syndrome, a previously lethal defect, now has early survival rates up to 90% at major centers.1 These improved outcomes have produced a growing population of survivors with complex CHD who are now reaching adulthood (Figure 1). During this period, improvements in surgical and medical treatments have been accompanied by developments in diagnostic modalities. Echocardiography has replaced catheterization as the primary diagnostic modality, and it is now uncommon for newborn infants to undergo catheterization for purely diagnostic purposes. Although echocardiography remains the bedrock of noninvasive cardiac imaging, the array of diagnostic modalities and techniques available continue to grow and this has spawned the specialty of “noninvasive cardiac imaging” and the need for the “cardiac imager” to be adept in all the different modalities. Figure 1. Percentage of patients under the age of 1 year (grey bars) and over the age of 18 years (black bars) undergoing echocardiography at Children’s Hospital Boston from 1983 through 2006. Note the reverse trends of these age groups reflecting the steady increase in the proportion of adult patients with congenital heart disease. Although the absolute number of infants undergoing echocardiography during this time period has increased, their proportion has steadily declined. Echocardiography, cardiac magnetic resonance (CMR), and cardiac computed tomography (CCT) are the primary modalities used for noninvasive cardiac imaging in patients with CHD. Nuclear scintigraphy is used in selected circumstances. The Table summarizes the strengths and weaknesses of each modality. Figure 2 shows temporal trends in utilization for the various noninvasive cardiac imaging techniques at our center. It is clear that echocardiography is the most frequently …

HIV infection and abnormal regional ventricular function

To examine the effect of HIV infection on regional left ventricular dysfunction in cardiovascularly asymptomatic individuals. Nineteen HIV-negative and 27 HIV-positive cardiovascularly asymptomatic study participants in Baltimore, Maryland were selected and underwent tagged cardiac magnetic resonance imaging. Regional left ventricular myocardial mid-wall peak systolic circumferential strain (Ecc) and early diastolic strain rate (SRE) of the left ventricle were assessed with the use of the harmonic phase analysis. The average Ecc and SRE measurements were compared between HIV-negative and HIV-positive individuals. Compared with the HIV-negatives, the HIV-positives had lower average Ecc and SRE measurements in 90% of the 16 standard left ventricular segments. Of the 14 segments with decreased Ecc strain, 3 were statistically significant and of 14 with decreased strain rate (SRE), 6 were statistically significant. HIV infection may be associated with subclinical regional left ventricular systolic and diastolic dysfunction in individuals free of overt cardiovascular disease.

Noninvasive Evaluation of Cardiac Allograft Rejection by Cellular and Functional Cardiac Magnetic Resonance

We sought to use cardiac magnetic resonance (CMR) to establish sensitive and reliable indexes for noninvasive detection of acute cardiac allograft rejection. Appropriate surveillance for acute allograft rejection is vitally important for graft survival. The current gold standard for diagnosing and staging rejection after organ transplantation is endomyocardial biopsy, which is not only invasive but also prone to sampling errors. The motivation of this study is to establish a CMR-based alternative that is noninvasive and sensitive for early detection of allograft rejection before irreversible damage occurs. We employed a noninvasive 2-pronged approach to detect acute cardiac allograft rejection using a rodent working heart and lung transplantation model. We used CMR to detect immune-cell infiltration at sites of rejection by monitoring the accumulation of dextran-coated ultra-small superparamagnetic-iron-oxide-labeled immune cells (in particular macrophages) in vivo. Simultaneously, we used CMR tagging and strain analysis to detect regional myocardial function loss resulting from acute rejection. Immune cells infiltration, mainly macrophages and monocytes, could be identified with CMR by in vivo labeling with ultra-small superparamagnetic-iron-oxide. Our data show that immune-cell infiltration in cardiac allograft rejection was highly heterogeneous. Thus, it is not surprising to find inconsistencies between rejection and endomyocardial biopsy results because of the limited number and small samples available. Tagged CMR and strain analysis showed that, as with immune-cell infiltration, ventricular functional loss was also heterogeneous. Although changes in global systolic function were generally not observed until the later stages of rejection, our data revealed that a functional index derived from local strain analysis correlated well with rejection grades, which may be a more sensitive parameter for detecting early rejection. CMR is noninvasive and provides a 3-dimensional, whole-heart perspective of the rejection status, potentially allowing more reliable detection of acute allograft rejection.

Assessment of subendocardial vs. subepicardial left ventricular rotation and twist using two-dimensional speckle tracking echocardiography: comparison with tagged cardiac magnetic resonance

The aim of this article is to evaluate the accuracy and reproducibility of two-dimensional speckle tracking echocardiography (2D-STE) for the estimation of left ventricular (LV) twist, using tagged cardiac magnetic resonance (cMR) as the reference standard, and to assess how much 2D-STE rotational parameters are affected by the level at which measurements are made within the LV. Forty-three patients with various heart diseases and 10 healthy volunteers underwent cMR and 2D-STE on the same day. With both methods, basal and apical time-rotation curves were generated at endocardial, midwall, and epicardial levels. By using the most apical cMR short-axis cross-section as a comparator, apical rotation was significantly underestimated by 2D-STE. When 2D-STE and cMR short-axis cross-sections were matched for their internal dimensions, measurements of endocardial, midwall, and epicardial twists no longer differ between cMR and 2D-STE (12.6 +/- 5.9 vs. 12.5 +/- 5.7 degrees , 10.5 +/- 4.6 vs. 9.7 +/- 4.1 degrees , and 8.9 +/- 4.0 vs. 8.4 +/- 3.7 degrees , respectively, all P = ns). Compared with tagged cMR, 2D-STE underestimates apical rotation and LV twist. This is related to the inability of 2D-STE to image the real LV apex in most of the patients. However, when 2D-STE and cMR data are compared at similar acquisition levels, both techniques provide similar values.

Early manifestation of alteration in cardiac function in dystrophin deficient mdx mouse using 3D CMR tagging.

BackgroundDuchenne muscular dystrophy (DMD) is caused by the absence of the cytoskeletal protein, dystrophin. In DMD patients, dilated cardiomyopathy leading to heart failure may occur during adolescence. However, early cardiac dysfunction is frequently undetected due to physical inactivity and generalized debilitation. The objective of this study is to determine the time course of cardiac functional alterations in mdx mouse, a mouse model of DMD, by evaluating regional ventricular function with CMR tagging.MethodsIn vivo myocardial function was evaluated by 3D CMR tagging in mdx mice at early (2 months), middle (7 months) and late (10 months) stages of disease development. Global cardiac function, regional myocardial wall strains, and ventricular torsion were quantified. Myocardial lesions were assessed with Masson's trichrome staining.ResultsGlobal contractile indexes were similar between mdx and C57BL/6 mice in each age group. Histology analysis showed that young mdx mice were free of myocardial lesions. Interstitial fibrosis was present in 7 month mdx mice, with further development into patches or transmural lesions at 10 months of age. As a result, 10 month mdx mice showed significantly reduced regional strain and torsion. However, young mdx mice showed an unexpected increase in regional strain and torsion, while 7 month mdx mice displayed similar regional ventricular function as the controls.ConclusionDespite normal global ventricular function, CMR tagging detected a biphasic change in myocardial wall strain and torsion, with an initial increase at young age followed by progressive decrease at older ages. These results suggest that CMR tagging can provide more sensitive measures of functional alterations than global functional indexes in dystrophin-related cardiomyopathies.

CMR tagging for measurement of the long axis function and deformation rate of the systemic right ventricular free wall

CMR tagging for measurement of the long axis function and deformation rate of the systemic right ventricular free wall

Abstract 6115:Assessment of Circumferential and Longitudinal Strain using Speckle Tracking Echocardiography. Comparison With Tagged Cardiac Magnetic Resonance

Background. Speckle tracking echocardiography (STE) is a new method that allows to quantitalively measure myocardial deformation in an angle-independent manner. The aim of this study was to evaluate the accuracy of STE-derived estimates of circumferential and longitudinal strains, in patients with variable degrees of LV dysfunction, using tagged cardiac magnetic resonance (cMR) as the reference standard. Methods. A total of 80 patients (66 men, mean age 54 ± 16 years) with a variety of cardiac diseases underwent STE and cMR on the same day. For circumferential strain, data were analyzed on matched short-axis cross-sections (at basal and apical levels) using either the QLab software (for STE) or HARP (for tagged cMR). For longitudinal strain, data were analyzed on similar 4-, 3- and 2-chamber views using either QLab (for STE) or a custom-made program that allows for tracking of cMR tags in long-axis projections (for tagged cMR). Results. 87% of myocardial segments could be analyzed. Correlation and limits of agreement between STE and cMR were good for both global (r = 0.95, p&lt;0.001 and 1.2 ± 5.1%, respectively) and segmental circumferential strain (r=0.84, p&lt;0.001 and 1.1 ± 9.9%, respectively, figure1 ). Correlation and limits of agreement between STE and cMR were similarly good for global (r =0.96, p&lt;0.001 and −0.1 ± 3.0%, respectively) and segmental longitudinal strain (r = 0.77, p&lt;0.001 and 0.2 ± 9.6%, respectively, figure1 ). Conclusions. STE provides accurate measurements of segmental circumferential and longitudinal strains and thus offers the opportunity to routinely assess these parameters in daily clinical practice.