Mirja Neizel

Evaluation of aortic root for definition of prosthesis size by magnetic resonance imaging and cardiac computed tomography: Implications for transcatheter aortic valve implantation

BACKGROUND This study sought to compare cardiac magnetic resonance imaging (CMR) with dual source computed tomography (DSCT) for analysis of aortic root dimensions prior to transcatheter aortic valve implantation (TAVI). In addition, the potential impact of CMR and DSCT measurements on TAVI strategy defined by 2D-transesophageal echocardiography (TEE) was evaluated. METHODS Aortic root dimensions were measured using CMR and DSCT in 58 patients referred for evaluation of TAVI. The TAVI strategy (choice of prosthesis size and decision to implant) was based on 2D-TEE annulus measurements. RESULTS CMR and DSCT aortic root measurements showed an overall good correlation (r=0.86, p<0.001 for coronal aortic annulus diameters). There was also a good correlation between TEE and CMR as well as between TEE and DSCT for measurement of sagittal aortic annulus diameters (r=0.69, p<0.001). However, annulus diameters assessed by TEE (22.1±2.3mm) were significantly smaller than coronal aortic annulus diameters assessed by CMR (23.4±1.8mm, p<0.001) or DSCT (23.6±1.8, p<0.001). Regarding TAVI strategy, the agreement between TEE and sagittal CMR (kappa=0.89) as well as sagittal DSCT measurements (kappa=0.87) was statistically perfect. However, decision based on coronal CMR- or MSCT measurements would have modified TAVI strategy as compared to a TEE based choice in a significant number of patients (22% to 24%). CONCLUSION In patients referred for TAVI, CMR measurements of aortic root dimensions show a good correlation with DSCT measurements and thus CMR may be an alternative 3D-imaging modality. Aortic annulus measurements using TEE, CMR and DSCT were close but not identical and the method used has important potential implications on TAVI strategy.

Strain-Encoded Magnetic Resonance Imaging for Evaluation of Left Ventricular Function and Transmurality in Acute Myocardial Infarction

Background—Strain-encoded imaging (SENC) is a new technique for myocardial deformation analysis in cardiac MRI. The aim of the study was, therefore, to evaluate whether myocardial deformation imaging performed by SENC allows for quantification of regional left ventricular function and is related to transmurality states of infarcted tissue in patients with acute myocardial infarction. Methods and Results—Cardiac MRI was performed in 38 patients with acute myocardial infarction 3±1 days after successful reperfusion using a clinical 1.5-T MRI scanner. Ten healthy volunteers served as controls. SENC is a technique that directly measures peak circumferential strain from long-axis views and peak longitudinal strain from short-axis views. Measurements were obtained for each segment in a modified 17-segment model. Wall motion and infarcted tissue were evaluated semiquantitatively from steady-state free-precession cine sequences and contrast-enhanced MR images and were then related to myocardial strain. Comparison of peak circumferential strain assessed by SENC and MR tagging was performed. In total, 456 segments were analyzed. Peak circumferential and longitudinal strain calculated from SENC images was significantly different in regions defined as normokinetic, hypokinetic, or akinetic (P<0.001). A cutoff peak systolic circumferential strain value of −10% differentiated nontransmural from transmural infarcted myocardium, with a sensitivity of 97% and a specificity of 94%. Strain analysis of SENC and MR tagging correlated well (r=0.76) with narrow limits of agreement (−9.9% to 8.5%). Conclusions—SENC provides rapid and objective quantification of regional myocardial function and allows discrimination between different transmurality states in patients with acute myocardial infarction.

Layer-specific analysis of myocardial deformation for assessment of infarct transmurality: comparison of strain-encoded cardiovascular magnetic resonance with 2D speckle tracking echocardiography

AIMS Separate analysis of endocardial and epicardial myocardial layer deformation has become possible using strain-encoded cardiovascular magnetic resonance (SENC) and 2D-dimensional speckle tracking echocardiography (Echo). This study evaluated and compared both modalities for the assessment of infarct transmurality as defined by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR). METHODS AND RESULTS In 29 patients (age 62.4 ± 11.7 years, 23 male) with ischaemic cardiomyopathy, SENC using 1.5 T CMR and Echo were performed. Peak circumferential systolic strain of the endocardial and the epicardial layer of 304 myocardial segments was assessed by SENC and by Echo. The segmental transmurality of myocardial infarction was determined as relative amount of LGE (0%: no infarction; 1-50%: non-transmural infarction; 51-100%: transmural infarction). Endocardial and epicardial strain defined by SENC and by Echo differed significantly between segments of different infarct transmurality determined by CMR. Endocardial layer circumferential strain analysis by Echo and by SENC allowed distinction of segments with non-transmural infarction from non-infarcted segments with similar accuracy [area under the curve (AUC) 0.699 vs. 0.649, respectively, P = 0.239]. Epicardial layer circumferential strain analysis by Echo and by SENC allowed distinction of transmural from non-transmural myocardial infarction defined by LGE CMR with similar accuracy (AUC 0.721 vs. 0.664, respectively, P = 0.401). Endocardial strain by SENC correlated moderately with endocardial strain by Echo (r = 0.50; standard error of estimate = 5.2%). CONCLUSION Layer-specific analysis of myocardial deformation by Echo and by SENC allows discrimination between different transmurality categories of myocardial infarction with similar accuracy. However, accuracy of both methods is non-optimal, indicating that further tools for improvement should be evaluated in the future.

T2 mapping in different cardiomyopathies: first clinical experience

Background Structural myocardial changes accompany myocardial pathologies such as myocardial ischemia, myocarditis, hypertrophy (HCM) and myocardial remodeling. These changes affect T2 relaxation times which can noninvasively be detected by cardiovascular magnetic resonance imaging (CMR). Since the interpretation of T2 weighted images remains a “risky business” due to subjectivity, the purpose of our study was to evaluate direct T2 value quantification by T2 mapping in different types of cardiomyopathies. Methods T2 maps were calculated from images recorded with a gated multislice GRASE sequence (9 echos, separated by TE = 7 ms, TR = 750 ms, TA = 5 min, Voxel Size: 2x2x10mm, fat saturation). For creation of T2 maps an exponential decay curve was fitted to the intensity progression of each pixel within the images obtained from the multi echo sequence using a dedicated software based on the graphical programming language LabVIEW (National Instruments, Austin, TX). T2 value distribution in 3 short axis slices (apical, mid-ventricular and basal) were evaluated. Mean, median and standard deviation of values were calculated automatically after manual identification of left ventricular myocardium. T2 maps were analysed in patients with low grade (1450ng/l) high sensitive troponin T (hsTnT) elevation (n=10), myocarditis (n=10), HCM (n=10) and in a young (mean age: 25 years; n=5) as well as elderly

Magnetic resonance imaging of the cardiac venous system and magnetic resonance-guided intubation of the coronary sinus in swine: a feasibility study.

Objectives:To visualize the coronary sinus using magnetic resonance (MR), and to demonstrate the feasibility of MR-guided intubation of the cardiac venous system (CVS) in swine. Materials and Methods:A total of 6 pigs were investigated. All experiments were performed using an interventional 1.5-Tesla MRI system. The CVS was visualized using an inversion-recovery navigator-gated whole-heart steady-state free-precession sequence after administration of gadobenate dimeglumine contrast agent. The coronary sinus was then intubated under MR-guidance with a passive MR-compatible guidewire modified by incorporation of iron oxide markers for improved visualization and a nonbraided Cobra-catheter. MR-guided interventions were monitored using a steady-state free-precession real-time imaging sequence. Time needed was measured for MR-guided intubation of the CVS and compared with the time needed for fluoroscopy guided intubation of the CVS. Results:Visualization and intubation of the coronary sinus and its site branches was feasible in all cases. Time spent for MR-guided intubation of the CVS was comparable to time spent for fluoroscopy-guided intubation (8.2 ± 2 minutes vs. 8.3 ± 1.3 minutes; P = 0.85). Conclusions:MR-visualization and MR-guided intubation of the coronary sinus and its side branches is feasible. The feasibility of MR-guided intubation of the CVS might have relevance for procedures like cardiac resynchronization therapy and percutaneous transcatheter mitral annuloplasty, requiring improved 3-dimensional knowledge about cardiac vein anatomy in the near future.

Layer-specific strain-encoded MRI for the evaluation of left ventricular function and infarct transmurality in patients with chronic coronary artery disease

BACKGROUND The study aimed to evaluate whether layer-specific myocardial deformation imaging performed by strain-encoded imaging (SENC) allows quantification of regional left ventricular function and is related to scar transmurality defined by contrast-enhanced magnetic resonance imaging (ceMRI) in patients with chronic coronary artery disease (CAD). METHODS 50 patients (mean age 62 ± 10 years) with CAD underwent ceMRI. Regional myocardial function was evaluated semi-quantitatively from steady-state free-precession cine sequences. Layer-specific peak circumferential strain was measured from long-axis views and peak longitudinal strain was evaluated from short-axis views in a 16-segment model. The extent of myocardial infarction was determined semiautomatically for each segment as relative amount of hyperenhancement by ceMRI. Wall motion and the degree of hyperenhancement were related to layer-specific myocardial strain. RESULTS A total of 589 of 600 segments (98%) were analysed. Endocardial and epicardial circumferential as well as longitudinal strain showed significant differences between visually defined segmental function states and differed also significantly between the degree of infarct transmurality (all p<0.001). A cutoff peak circumferential endocardial strain value of -15% differentiated nontransmural from transmural infarcted myocardium with a sensitivity of 100% and a specificity of 86% (area under the curve (AUC) 0.94). Distinction of nontransmural infarcted myocardium from transmural infarcted myocardium was done more accurately using circumferential endocardial strain compared to longitudinal endocardial strain (AUC 0.94 vs. AUC 0.76, p=0.003). CONCLUSIONS Quantitative analysis of segmental deformation by layer-specific SENC allows accurate discrimination between different transmurality states of myocardial infarction in patients with chronic CAD. Circumferential endocardial strain showed the best distinction between the different degrees of infarct transmurality.

A giant pericardial cyst as unusual cause for atrial flutter.

![Figure][1] [![Graphic][3] ][3] A 59-year-old woman was referred to our institution with atrial flutter and pre-syncope. A chest roentgenogram and an echocardiogram were obtained and showed a large intrathoracic mass (A and B, arrow) . Cardiac magnetic resonance with steady-state

A fully automatic cardiac model with integrated scar tissue information for improved assessment of viability

Summary This study evaluates whether integration of scar tissue into a patient specific heart model derived from Magnetic Resonance images is feasible. Background Treatment of coronary artery disease can only be effective if myocardial tissue can be identified, that is still viable. To localize scar tissue in relation to the coronary vessels would therefore be desirable for interventional guidance. The aim of this study was to evaluate 1) whether integration of scar tissue into a patient specific heart model derived from Magnetic Resonance (MR) images is feasible and 2) whether this patient specific heart model allows for accurate assessment of the amount of myocardial scar compared to conventional manual infarct sizing. Methods 20 patients with clinical indication for viability testing (EF 47±13%) were investigated on a 1.5 Tesla MRI (Achieva, Philips, The Netherlands). Images using a free-breathing 3D-wholeheart balanced TFE sequence triggered to end-diastole were acquired. 10 minutes after injection of a contrast agent (0.2 ml/kg/body weight Magnevist ® , Bayer, Germany) delayed enhancement (DE) images were acquired using a 3D inversion recovery sequence. Fully automatic segmentation of the heart and great vessels was performed using a comprehensive surface model (Philips Research Laboratories, Aachen, Germany). In addition, information of scar tissue was merged fully automatically from 3D-DE sequence into the segmented whole heart model. Finally, an automatic signal intensity threshold for scar identification was determined. Infarct size and end diastolic left ventricular (ED-LV) volume derived from this model were compared to conventional manual assessment of infarct size and LV volume. Results

Evaluation of aortic root for definition of prosthesis size by magnetic resonance imaging and cardiac computed tomography: implications for transcatheter aortic valve implantation

Prior to transcatheter aortic valve implantation (TAVI), dual-source computed tomography (DSCT) is currently the preferred imaging modality for correct prothesis selection by accurate analysis of aortic annulus and ascending aorta. However, DSCT is associated with the need for contrast administration and radiation exposure.

Strain-Encoded Cardiac Magnetic Resonance Imaging as an Adjunct for Dobutamine Stress Testing. Incremental Value to Conventional Wall Motion Analysis

Background—High-dose dobutamine stress MRI is safe and feasible for the diagnosis of coronary artery disease (CAD) in humans. However, the assessment of cine scans relies on the visual interpretation of regional wall motion, which is subjective. Recently, strain-encoded MRI (SENC) has been proposed for the direct color-coded visualization of myocardial strain. The purpose of our study was to compare the diagnostic value of SENC with that provided by conventional wall motion analysis for the detection of inducible ischemia during dobutamine stress MRI. Methods and Results—Stress-induced ischemia was assessed by wall motion analysis and by SENC in 101 patients with suspected or known CAD and in 17 healthy volunteers who underwent dobutamine stress MRI in a clinical 1.5-T scanner. Quantitative coronary angiography deemed as the standard reference for the presence or absence of significant CAD (≥50% diameter stenosis). On a coronary vessel level, SENC detected inducible ischemia in 86 of 101 versus 71 of 101 diseased coronary vessels (P<0.01 versus cine) and showed normal strain response in 189 of 202 versus 194 of 202 vessels with <50% stenosis (P=NS versus cine). On a patient level, SENC detected inducible ischemia in 63 of 64 versus 55 of 64 patients with CAD (P<0.05 versus cine) and showed normal strain response in 32 of 37 versus 34 of 37 patients without CAD (P=NS versus cine). Quantification analysis demonstrated a significant correlation between strain rate reserve and coronary artery stenosis severity (r2=0.56, P<0.001), and a cutoff value of strain rate reserve of 1.64 was deemed as a highly accurate marker for the detection of ≥50% stenosis (area under the curve, 0.96; SE, 0.01; 95% CI, 0.94 to 0.98; P<0.001). Conclusions—The direct color-coded visualization of strain on MR images is a useful adjunct for dobutamine stress MRI, which provides incremental value for the detection of CAD compared with conventional wall motion readings on cine images.Background— High-dose dobutamine stress MRI is safe and feasible for the diagnosis of coronary artery disease (CAD) in humans. However, the assessment of cine scans relies on the visual interpretation of regional wall motion, which is subjective. Recently, strain-encoded MRI (SENC) has been proposed for the direct color-coded visualization of myocardial strain. The purpose of our study was to compare the diagnostic value of SENC with that provided by conventional wall motion analysis for the detection of inducible ischemia during dobutamine stress MRI. Methods and Results— Stress-induced ischemia was assessed by wall motion analysis and by SENC in 101 patients with suspected or known CAD and in 17 healthy volunteers who underwent dobutamine stress MRI in a clinical 1.5-T scanner. Quantitative coronary angiography deemed as the standard reference for the presence or absence of significant CAD (≥50% diameter stenosis). On a coronary vessel level, SENC detected inducible ischemia in 86 of 101 versus 71 of 101 diseased coronary vessels ( P <0.01 versus cine) and showed normal strain response in 189 of 202 versus 194 of 202 vessels with <50% stenosis ( P =NS versus cine). On a patient level, SENC detected inducible ischemia in 63 of 64 versus 55 of 64 patients with CAD ( P <0.05 versus cine) and showed normal strain response in 32 of 37 versus 34 of 37 patients without CAD ( P =NS versus cine). Quantification analysis demonstrated a significant correlation between strain rate reserve and coronary artery stenosis severity ( r 2=0.56, P <0.001), and a cutoff value of strain rate reserve of 1.64 was deemed as a highly accurate marker for the detection of ≥50% stenosis (area under the curve, 0.96; SE, 0.01; 95% CI, 0.94 to 0.98; P <0.001). Conclusions— The direct color-coded visualization of strain on MR images is a useful adjunct for dobutamine stress MRI, which provides incremental value for the detection of CAD compared with conventional wall motion readings on cine images. Received May 3, 2008; accepted December 10, 2008. # CLINICAL PERSPECTIVE {#article-title-2}