Rebekka Kammerer

Age- and gender-related normal left ventricular deformation assessed by cardiovascular magnetic resonance feature tracking.

BackgroundAssessment of left (LV) ventricular function is one of the most important tasks of cardiovascular magnetic resonance (CMR). Impairment of LV deformation is a strong predictor of cardiovascular outcome in various cardiac diseases like ischemic heart disease or cardiomyopathies. The aim of the study was to provide reference values for myocardial deformation derived from the CMR feature tracking imaging (FTI) algorithm in a reference population of healthy volunteers.MethodsFTI was applied to standard short axis and 2-, 3- and 4-chamber views of vector-ECG gated CMR cine SSFP sequences of 150 strictly selected healthy volunteers (75 male/female) of three age tertiles (mean age 45.8yrs). Global peak and mean radial, circumferential and longitudinal endo- and myocardial systolic strain values as well as early diastolic strain rates were measured using FTI within a standard protocol on a 1.5T whole body MR scanner.ResultsGlobal peak systolic values were 36.3 ± 8.7% for radial, −27.2 ± 4.0% for endocardial circumferential, −21.3 ± 3.3% for myocardial circumferential, −23.4 ± 3.4% for endocardial longitudinal and −21.6 ± 3.2% for myocardial longitudinal strain. Global peak values were -2.1 ± 0.5s−1 for radial, 2.1 ± 0.6s−1 for circumferential endocardial, 1.7 ± 0.5s−1 for circumferential myocardial, 1.8 (1.5-2.2)s−1 for longitudinal endocardial, 1.6 (1.4-2.0)s−1 for longitudinal myocardial early diastolic strain rates. Men showed a higher radial strain than women whereas the circumferential and longitudinal strains were lower resulting in less negative values. Circumferential and longitudinal strain rates were significantly higher in female subjects. Radial strain increased significantly with age whereas the diastolic function measured by the radial, circumferential and longitudinal strain rates showed a decrease.The coefficients of variation determined in ten further subjects, who underwent two CMR examinations within 12 days, were −4.8% for circumferential and −4.5% for longitudinal endocardial mean strains.ConclusionsMyocardial deformation analysis using FTI is a novel technique and robust when applied to standard cine CMR images providing the possibility of a reliable, objective quantification of global LV deformation. Since strain values and strain rates differed partly between genders as well as between age groups, the application of specific reference values as provided by this study is recommendable.

Feature tracking cardiac magnetic resonance imaging for the evaluation of myocardial strain in patients with dilated cardiomyopathy and in healthy controls.

Background In clinical routine, quantification of myocardial strain using CMR tagging is currently the gold standard. Additional pulse sequences for the generation of tagged images and specialized software for the quantification of myocardial strain is necessary, so that alternative ways using conventional steady-state-free-precession (SSFP) sequence images would be preferable. This advantage may be ensured by feature tracking imaging algorithm, a novel method of two-dimensional deformation analysis. To quantify myocardial deformation with two-dimensional feature tracking cardiac magnetic resonance (CMR) in patients with heart failure due to nonischemic cardiomyopathy and in healthy controls. Methods Eighty-eight patients with dilated cardiomyopathy and thirty healthy subjects were examined in a 1.5T CMRscanner. SSFP cine sequences of the four chamber view and mid-ventricular short axis view were analyzed using feature tracking imaging software (2D CPA MR©, TomTec Imaging Systems GmbH). Generated parameters of the myocardial quantification were circumferential and longitudinal strain, respectively. Furthermore, patients were divided in subgroups classified by left-ventricular ejection-fraction LV-EF≤35% and EF>35% and in patients with the presence or absence of late-gadolinium enhancement (LGE), respectively. Results In patients with dilated cardiomyopathy, close correlation were observed for the LV-EF with circumferential strain (r^2=0.8, p 35% and with LV-EF ≤35% (p<0.0001). In addition, patients with LGE yielded significant lower circumferential and longitudinal strain values, compared to those without LGE (p<0.0001 and p=0.02, respectively). Conclusions Feature tracking imaging determines global myocardial function in patients with dilated cardiomyopathy and provides further insight into the underlying remodeling processes. Further investigation is necessary to analyze the impact of this new method on clinical outcome. Funding none

Cardiac magnetic resonance strain imaging in systemic light chain amyloidosis

Background Systemic light chain amyloidosis (AL) is associated with a high cardiovascular morbidity and mortality. Cardiovascular involvement and determination of prognosis is underestimated by standard imaging parameters. Recently, cardiac deformation analysis of global circumferential and longitudinal strain has been shown to have great clinical impact on the assessment of prognosis and survival in this rare disease. For further analysis we applied the novel non-invasive post-processing feature tracking imaging (FTI) algorithm on pre-acquired regular CMR SSFP images in healthy volunteers and in patients with AL and sought to investigate different strain patterns. Methods 87 patients (mean age 60 ± 11 years) with biopsy proven systemic AL were scanned on a clinical 1.5 T CMR scanner (Philips Achieva). Short axis slices covering entirely both ventricles as well as 2-, 3- and 4-chamber views were acquired using standard SSFP-sequences before initiation of any specific pharmaceutical AL therapies. The control group consisted of 47 healthy subjects (mean age 59 ± 5 years). Besides the standard CMR parameters for volumes, ejection fraction, myocardial mass and wall thickness we measured the circumferential and the longitudinal strain on cine SSFP images by the application of the post-processing FTI algorithm. Results In patients with AL mean longitudinal strain from the four chamber view (-15.9 ± 5.6% vs -21.3 ± 4%, p < 0.05) as well as midventricular mean circumferential strain (-22.8 ± 6.7% vs -25.1 ± 4.5%, p < 0.05) were significantly reduced compared to healthy subjects. Global circumferential strain and global longitudinal strain correlated with left ventricular ejection fraction (r = -0.61, p < 0.05; r = -0.62, p < 0.05). In the subgroup analysis of AL patients with a mean wall thickness less than 12 mm global longitudinal strain showed significantly reduced values in comparison to healthy control subjects (-18.3 ± 5.3% vs -21.3 ± 4%, p < 0.05), whereas global circumferential strain did not show a significant difference. Patients with an ejection fraction ≥55% already had reduced global longitudinal strains (-18 ± 4.7% vs -21.3 ± 4%, p < 0.05), again global circumferential strain did not show a significant difference. Conclusions FTI strain analysis derived from regular cine SSFP sequences offers the possibility for a fast quantitative assessment of myocardial strain imaging patterns without additional and time-consuming strain imaging sequences. FTI strain analysis provides important insight into the disturbed contraction in AL. Further investigations are necessary to analyze the impact of this new method on the prediction of clinical outcome in AL patients. Funding None.

Feature tracking in cardiac magnetic resonance imaging to evaluate normal myocardial function

Background Assessment of left ventricular function (LV) is one of the most important tasks of clinical cardiac magnetic resonance imaging (CMR). Regional and global LV function has been recognized to differentiate various myocardial disorders. The aim of the study was to provide normal values for myocardial deformation parameters derived from the feature tracking imaging (FTI) algorithm applied to standard CMR cine SSFP sequences in a large group of healthy subjects. The feature tracking algorithm (2D CPA MR©, TomTec Imaging Systems GmbH), is a two dimensional deformation analysis of the myocardium that was originally designed for echocardiographic image analysis, which has now been transferred to CMR SSFP sequences without the need for additional scans. This novel approach may have potential advantages over existing methods, such as broad availability, vendor independency and lack of timeconsuming post processing.

Non-invasive risk stratification of patients with TTR amyloidosis

Methods 30 patients (21 male, 9 female; median age 69.5 years) with diagnosis of TTR amyloidosis (wild-type n=13, hereditary n=17) were evaluated by cardiac MRI (CMR; Achieva Intera Philips Medical Systems, Best, The Netherlands), and Technetium-DPD scintigraphy. EDV, ESV, EF and myocardial mass were analyzed on a standard workstation (Philips Viewforum). Longitudinal function was assessed by mitral (MAPSE) and tricuspid (TAPSE) annular plane systolic excursion. Atrial septum thickness was measured on SSFP-4 chamber views. Gadolinium contrast-enhanced CMR (CE-CMR) was assessed semi-quantitatively (absent=0, weak=1, moderate=2, severe=3) in an AHA modified 16 segment model of the left ventricle as well as for the right/left atrium and right ventricle. Nuclear DPDretention was assessed semi-quantitatively using a region of interest technique by comparison of counts in the heart at 3 hours after injection with whole body counts at 5 min after injection.

Early assessment of infarct size by feature tracking cardiac MRI in patients with myocardial infarction

Background The degree and quantification of contractile dysfunction and myocardial scar in patients after acute myocardial infarction (AMI) has important prognostic implications. Myocardial deformation parameters like strain and strain rate have been shown to be more sensitive markers for contractile dysfunction than standard 2-D parameters. We sought to investigate whether strain and strain rate imaging, assessed by a novel non-invasive post-processing feature tracking algorithm (FTI) on pre-acquired regular CMR SSFP images, would allow quantification of regional left ventricular (LV) function and its relation to degrees of infarct trans-murality in patients after AMI. Methods

Feature tracking cardiac magnetic resonance in systemic light chain amyloidosis

Background Systemic light chain amyloidosis (AL) is associated with a high cardiovascular morbidity and mortality. Cardiovascular involvement and determination of prognosis is underestimated by standard imaging parameters. Recently, cardiac deformation analysis of global circumferential and longitudinal strain has been shown to have great clinical impact on the assessment of prognosis and survival in this rare disease. For quantification of cardiac deformation analysis we applied a novel non-invasive post-processing feature tracking algorithm (FTI) on pre-acquired regular CMR SSFP images in healthy volunteers and in patients with AL and sought to investigate wall motion differences between both groups. Methods 65 patients (mean age 58 ± 11 years; 41 male, 24 female patients) with biopsy proven systemic AL were scanned on a clinical 1.5 T CMR scanner (Philips Achieva). Short axis slices covering entirely both ventricles as well as 2-, 3- and 4-chamber were acquired using standard SSFP-sequences before initiation of specific pharmaceutical AL therapies. The control group consisted of 50 healthy subjects (mean age 58 ± 5 years; 23 male, 27 female). Besides the standard CMR parameters for volumes, ejection fraction (EF) and myocardial mass and wall thickness we measured global circumferential and longitudinal strain on SSFP images by the application of the post-processing feature tracking algorithm. Results Global circumferential strain and global longitudinal strain correlated well with left ventricular ejection fraction (r^2=0.64, p<0.05; r^2=0.47, p<0.05). In patients with AL global longitudinal strain was significantly reduced compared to healthy subjects (-16.9±5.1% vs -23±3.3%, p<0.05), whereas global circumferential strain was not (-25.1±7.0% vs -27.1±5.0%, n.s.). In the subgroup analysis of AL patients without cardiac involvement (mean wall thickness ≤ 12mm) global longitudinal strain showed significantly reduced values in comparison to healthy control subjects (-20.3±4.7% vs -23±3.3%, p<0.05), whereas global circumferential strain did not show a significant difference. Patients with an ejection fraction ≥50% already had reduced global longitudinal strains (-18.5±4.5% vs -23±3.3%, p<0.05), again global circumferential strain did not show a significant difference. Conclusions

NON-INVASIVE RISK STRATIFICATION OF PATIENTS WITH TTR AMYLOIDOSIS

We evaluated the impact of different imaging tools for risk assessment in transthyretin (TTR) amyloidosis patients. 30 patients (21 male, 9 female; median age 69.5 years) with ATTR (wild-type n=13, hereditary n=17) were evaluated by cardiac MRI (CMR), and 99mTc-DPD scintigraphy. EDV, ESV, EF and

Thickness of the midventricular left ventricular wall is predictive of survival in different forms of cardiac amyloidosis

Background Systemic amyloidosis is a disorder characterized by extracellular deposition of different insoluble protein fibrils in various organs leading to organ dysfunction. Cardiac involvement is associated with limited survival. We aimed to use cardiac magnetic resonance imaging (CMR) to identify structural and functional alterations related to the different forms of amyloidosis, e. g. hereditary and wild-type transthyretin (TTR) amyloidosis as well as light-chain (AL) amyloidosis. Methods In total, 130 patients (82 male, 38 female; mean age 60.7 ±1.1 years) with different forms of amyloidosis (AL n= 72, TTR n=58) were evaluated by two blinded experienced observers employing a Vector-ECG gated 1.5T wholebody CMR (Achieva Intera ® Philips Medical Systems, Best, The Netherlands). The study included SSFP and gadolinium contrast delayed enhancement (CE-CMR) 2,3-,4-chamber and short-axis planes. EDV, ESV, EF and myocardial mass were analyzed on a standard workstation (Philips Viewform). Regional wall thickness was analyzed in modified 16 segment AHA-model of the left ventricle as well as the interatrial wall and compared between the different forms of amyloidosis. Univariate and multivariate analysis were performed to define predictors of survival. Results Patients with TTR amyloidosis were significantly older as compared to patients with AL. They had higher left ventricular mass (171.9±8.1g vs. 146.1±6.9g, p<0.01) and thickness of interatrial septum (7.3±0.3mm vs. 5.7±0.2mm; p<0.001) with highest LV mass and thickness of interatrial septum in patients with wild-type amyloidosis (n=26). Distribution of regional wall thickness is shown in figure 1. In AL patients univariate analysis revealed median of maximal wall thickness of the basal (14 mm), midventricular (10 mm) and apical (7 mm) segments as predictors of survival. In multivariate analysis midventricular maximal wall thickness was the only independent predictor of survival. In TTR patients univariate analysis revealed median of maximal wall thickness of the midventricular (13.5 mm) and apical (8 mm), but not basal (16.0 mm) segments as predictors of survival. There was no independent predictor of survival in multivariate analysis of these patients.

Comparison of late gadolinium enhancement patterns in different forms of cardiac amyloidosis

Background Cardiac involvement is common in different forms of amyloidosis and associated with limited survival. We aimed to use gadolinium (GAD) contrast-enhanced cardiac magnetic resonance imaging (CE-CMR) to characterize CE-CMR patterns that are related to the different forms of amyloidosis. Methods In total, 115 patients (70 male, 45 female; mean age 60.7 ±1.2 years) with different forms of amyloidosis (AL n= 63, TTR n=52) were evaluated by evaluated by VectorECG gated 1.5T whole-body CMR (Achieva Intera ® Philips Medical Systems, Best, the Netherlands) and included SSFP and CE-CMR 2-,3-,4-chamber and shortaxis planes. EDV, ESV, EF and myocardial mass were analyzed on a standard workstation. Longitudinal function was assessed by mitral (MAPSE) and tricuspid (TAPSE) annular plane systolic excursion. CE-CMR patterns were analyzed qualitatively (subepicardial, subendocardial, patchy) and semi-quantitatively (absent = 0, weak = 1, moderate = 2, severe = 3) in a modified 16 segment AHA model (maximal sum 48) of the left ventricle. Univariate and multivariate analysis were performed to define predictors of survival. Results Patients with TTR amyloidosis were significantly older and had lower TAPSE (14.6±0.9 mm vs. 17.3±0.9 mm; p<0.05) as compared to patients with AL. Both cohorts did not differ in LV mass, LV ejection fraction, and MAPSE. CE-CMR was observed in 107 (93%) of the patients (AL n=59, 93.7%; TTR n=48, 92.3%). There was no difference between both forms of amyloidosis concerning sum of CE-CMR in the 16 segments by semiquantitative analysis (AL 25.8±2.2; TTR 28.6±2.2). In each of the 16 LV segments more severe CE-CMR was associated with an increase of LV mass as well as a decrease of LV ejection fraction, MAPSE and TAPSE, respectively (p<0.001). In TTR patients a more intensive CE-CMR was found in the subepicardial layer of the basal anterolateral (p<0.001), inferolateral (p<0.001) and of the midventricular inferolateral segment (p<0.001) as compared to AL patients. During mean survival of 34.2±2.4 months there were 49 fatal events (death n=33; heart transplant n=16). Survival of AL patients was significantly worse as compared to TTR patients (p<0.05; logrank 6.225). In AL patients presence of subepicardial, subendocardial and patchy CE-CMR, LV mass, MAPSE, and TAPSE, but not LV ejection fraction, CE-CMR of LA, RA, RV or interatrial septum were predictors of survival by univariate analysis. By multivariate analysis subendocardial and patchy CE-CMR as well as LV mass were independent predictors of survival. Conclusions Prevalence of CE-CMR is high and appears to be associated with the severity of cardiac dysfunction in different forms of cardiac amyloidosis. Survival of patients with AL amyloidosis was worse as compared to TTR amyloidosis. Besides LV mass subendocardial and patchy CE-CMR were independent predictors of survival in patients with AL amyloidosis.