Christian Galuschky

Quantitative Assessment of Left Ventricular Size and Function Side-by-Side Comparison of Real-Time Three-Dimensional Echocardiography and Computed Tomography With Magnetic Resonance Reference

Background— Cardiac CT (CCT) and real-time 3D echocardiography (RT3DE) are being used increasingly in clinical cardiology. CCT offers superb spatial and contrast resolution, resulting in excellent endocardial definition. RT3DE has the advantages of low cost, portability, and live 3D imaging without offline reconstruction. We sought to compare both CCT and RT3DE measurements of left ventricular size and function with the standard reference technique, cardiac MR (CMR). Methods and Results— In 31 patients, RT3DE data sets (Philips 7500) and long-axis CMR (Siemens, 1.5 T) and CCT (Toshiba, 16-slice MDCT) images were obtained on the same day without β-blockers. All images were analyzed to obtain end-systolic and end-diastolic volumes and ejection fractions using the same rotational analysis to eliminate possible analysis-related differences. Intertechnique agreement was tested through linear regression and Bland-Altman analyses. Repeated measurements were performed to determine intraobserver and interobserver variability. Both CCT and RT3DE measurements resulted in high correlation (r2>0.85) compared with CMR. However, CCT significantly overestimated end-diastolic and end-systolic volumes (26 and 19 mL; P<0.05), resulting in a small but significant bias in ejection fraction (−2.8%). RT3DE underestimated end-diastolic and end-systolic volumes only slightly (5 and 6 mL), with no significant bias in EF (0.3%; P=0.68). The limits of agreement with CMR were comparable for the 2 techniques. The variability in the CCT measurements was roughly half of that in either RT3DE or CMR values. Conclusions— CCT provides highly reproducible measurements of left ventricular volumes, which are significantly larger than CMR values. RT3DE measurements compared more favorably with the CMR reference, albeit with higher variability.

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.

Prediction of functional recovery by cardiac magnetic resonance feature tracking imaging in first time ST-elevation myocardial infarction. Comparison to infarct size and transmurality by late gadolinium enhancement

PURPOSE To investigate whether myocardial deformation imaging, assessed by feature tracking cardiac magnetic resonance (FTI-CMR), would allow objective quantification of myocardial strain and estimation of functional recovery in patients with first time ST-elevation myocardial infarction (STEMI). METHODS Cardiac magnetic resonance (CMR) imaging was performed in 74 consecutive patients 2-4 days after successfully reperfused STEMI, using a 1.5T CMR scanner (Philips Achieva). Peak systolic circumferential and longitudinal strains were measured using the FTI applied to SSFP cine sequences and were compared to infarct size, determined by late gadolinium enhancement (LGE). Follow-up CMR at 6 months was performed in order to assess residual ejection fraction, which deemed as the reference standard for the estimation of functional recovery. RESULTS During the follow-up period 53 of 74 (72%) patients exhibited preserved residual ejection fraction ≥50%. A cut-off value of -19.3% for global circumferential strain identified patients with preserved ejection fraction ≥50% at follow-up with sensitivity of 76% and specificity of 85% (AUC=0.86, 95% CI=0.75-0.93, p<0.001), which was superior to that provided by longitudinal strain (ΔAUC=0.13, SE=0.05, z-statistic=2.5, p=0.01), and non-inferior to that provided by LGE (ΔAUC=0.07, p=NS). Multivariate analysis showed that global circumferential strain and LGE exhibited independent value for the prediction of preserved LV-function, surpassing that provided by age, diabetes and baseline ejection fraction (HR=1.4, 95% CI=1.0-1.9 and HR=1.4, 95% CI=1.1-1.7, respectively, p<0.05 for both). CONCLUSIONS Estimation of circumferential strain by FTI provides objective assessment of infarct size without the need for contrast agent administration and estimation of functional recovery with non-inferior accuracy compared to that provided by LGE.

Quantitative analysis of left ventricular strain using cardiac computed tomography

OBJECTIVES To investigate whether cardiac computed tomography (CCT) can determine left ventricular (LV) radial, circumferential and longitudinal myocardial deformation in comparison to two-dimensional echocardiography in patients with congestive heart failure. BACKGROUND Echocardiography allows for accurate assessment of strain with high temporal resolution. A reduced strain is associated with a poor prognosis in cardiomyopathies. However, strain imaging is limited in patients with poor echogenic windows, so that, in selected cases, tomographic imaging techniques may be preferable for the evaluation of myocardial deformation. METHODS Consecutive patients (n=27) with congestive heart failure who underwent a clinically indicated ECG-gated contrast-enhanced 64-slice dual-source CCT for the evaluation of the cardiac veins prior to cardiac resynchronization therapy (CRT) were included. All patients underwent additional echocardiography. LV radial, circumferential and longitudinal strain and strain rates were analyzed in identical midventricular short axis, 4-, 2- and 3-chamber views for both modalities using the same prototype software algorithm (feature tracking). Time for analysis was assessed for both modalities. RESULTS Close correlations were observed for both techniques regarding global strain (r=0.93, r=0.87 and r=0.84 for radial, circumferential and longitudinal strain, respectively, p<0.001 for all). Similar trends were observed for regional radial, longitudinal and circumferential strain (r=0.88, r=0.84 and r=0.94, respectively, p<0.001 for all). The number of non-diagnostic myocardial segments was significantly higher with echocardiography than with CCT (9.6% versus 1.9%, p<0.001). In addition, the required time for complete quantitative strain analysis was significantly shorter for CCT compared to echocardiography (877±119 s per patient versus 1105±258 s per patient, p<0.001). CONCLUSION Quantitative assessment of LV strain is feasible using CCT. This technique may represent a valuable alternative for the assessment of myocardial deformation in selected patients with poor echogenic windows and general contraindications for magnetic resonance imaging.

Standardized assessment of global longitudinal and circumferential strain - a modality independent software approach

Mean GLS values were -16.2±5.3% and -17.3±5.3% for echocardiography and CMR, respectively. GLS did not differ significantly between the two imaging modalities, which showed strong correlation (r=0.86), a small bias (-1.1%) and narrow 95% limits of agreement (LOA, ±5.4%). Mean GCS values were -17.9±6.3% and -24.4 ±7.8% for echocardiography and CMR, respectively. GCS was significantly underestimated by echocardiography (p<0.001). A weaker correlation (r=0.73), a higher bias (-6.5%) and wider LOA (±10.5%) were observed for GCS. GLS showed a strong correlation (r=0.92) when image quality was good, while correlation dropped to r=0.82 with poor acoustic windows in echocardiography. GCS assessment revealed only a strong correlation (r=0.87) when echocardiographic image quality was good. No significant differences for GLS between two different echocardiographic vendors could be detected. Conclusions Quantitative assessment of GLS using a standardized software algorithm allows the direct comparison of values acquired irrespective of the imaging modality. GLS may therefore serve as a reliable parameter for the assessment of global left ventricular function in clinical routine besides standard evaluation of the ejection fraction.

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

LV rotational mechanics in patients with dilated cardiomyopathy compared to healthy individuals: Experience from the European CMR Registry

Background Left ventricular rotation is an important part of myocardial mechanics during the cardiac cycle. Understanding the mechanisms of LV rotation in different cardiac diseases could play an important role for diagnosis, risk stratification and prediction of heart failure. We sought to analyze LV rotation using the feature tracking technique in patients with dilated cardiomyopathy (DCM) included in the European CMR Registry.

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.

Prognostic value of myocardial strain analysis with cardiac magnetic resonance in patients with dilated cardiomyopathy

Background Myocardial deformation analysis is an important task in the evaluation of heart failure. We and other previously showed that myocardial strain is a more sensitive marker for the prediction of cardiac events compared with leftventricular ejection-fraction (LV-EF). The current gold standard technique to quantify myocardial deformation is CMR tagging. However, additional pulse sequences and specialized software are necessary with tagging, so that alternative ways for the estimation of strain in CMR using conventional steady-state-free-precession (SSFP) cine images would be preferable. In this regards, feature tracking is a novel tool, which can be run on conventional cine images and can help estimating myocardial strain and strain rate without the need of specialized tagging sequences. The aim was to investigate the prognostic impact of myocardial strain using feature tracking cardiac magnetic resonance in patients with dilated cardiomyopathy. Methods Patients with dilated cardiomyopathy (n = 210) were examined in a 1.5T CMR-scanner. SSFP cine sequences of the three short and the three long axis views were analyzed using a prototype feature tracking software algorithm (2D CPA MR