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.

Rapid right ventricular pacing with MR-compatible pacemaker lead for MR-guided aortic balloon valvuloplasty in swine.

PURPOSE: To assess the feasibility and effectiveness of rapid right ventricular pacing with a magnetic resonance (MR)-compatible pacemaker lead during MR-guided aortic valvuloplasty. MATERIALS AND METHODS: This study was approved by the institutional animal research committee. Seven pigs were investigated. All experiments were performed with an interventional 1.5-T MR system. Interventions were monitored with a steady-state free precession real-time imaging sequence. An MR-compatible pacemaker lead was placed in the right ventricular apex with MR guidance before valvuloplasty. After positioning the balloon in valve position, valvuloplasty was performed with rapid right ventricular rapid pacing at a heart rate of 180 beats per minute to minimize cardiac output. RESULTS: Positioning of the pacemaker lead with MR guidance was feasible in all swine (sensing, 6 mV +/- 1; threshold, 1 V +/- 0.5). The lead could be seen on steady-state free precession images without inducing any artifacts. Rapid right ventricular pacing was feasible in all swine, and balloon stability at the time of inflation was achieved with no balloon movement. Aortic valvuloplasty was successfully accomplished in all experiments. CONCLUSION: Rapid right ventricular pacing with an MR-compatible pacemaker lead is feasible and effective.

Quantitation of the thickness of the non-enhanced myocardial rim predicts recovery of territorial myocardial function in chronic ischemic heart disease: a cardiac magnetic resonance imaging study.

OBJECTIVES: We sought to determine whether the thickness of the non-contrast-enhanced myocardial rim (RIM) predicts recovery of territorial myocardial function after revascularization in chronic ischemic cardiomyopathy (ICM). BACKGROUND: Non-contrast-enhanced dysfunctional myocardium at late gadolinium-enhanced CMR depicts the presence of viable myocardium. METHODS: In 29 patients (65 +/- 8 years) with ICM (EF 33 +/- 10), ceCMR and cine images were acquired 5 +/- 10 days before revascularization. Cine images were repeated after 6 months. Regional wall thickness, wall thickening and RIM were determined in each of 12 segments per short-axis slice (4-8/patient), which were assigned to the respective supplying coronary artery (LAD, LCX and RCA). A threshold for normal wall-thickening was derived from a control group (n = 14; 52 +/- 17 years). Functional improvement at follow-up was defined as wall thickening >2 mm. RESULTS: Of the 1,896 analyzed segments, 655 segments showed severe dysfunction. At follow-up, 307 segments demonstrated functional improvement. The RIM differed between segments with and without improvement (6.6 +/- 2.4 mm vs. 2.8 +/- 2.0 mm; p < 0.0001). The area under the receiver operator characteristic (ROC) for predicting overall functional recovery was 0.91 (95%, CI 0.88-0.93, p < 0.001). A RIM of 4.0 mm predicted functional recovery after revascularization of the supplying coronary artery with a sensitivity and a specificity of 88 and 82% for the LAD, 96 and 86% for the RCA and 88 and 83% for the LCX, respectively. CONCLUSION: RIM may be a useful marker for predicting territorial functional recovery after revascularization in patients with chronic ICM.

Unusual malignant coronary artery anomaly: results of coronary angiography, MR imaging, and multislice CT.

We report the case of a man with an uncommon anomaly of the origin and course of the left coronary artery. Clinical, coronary angiography, magnetic resonance imaging, and multislice computed tomography findings of this intermittently symptomatic 49 year-old patient with the rare anomaly of his left coronary artery stemming from the right sinus of Valsalva and taking an interarterial and intraseptal course are presented. The diagnostic value of the different imaging modalities is discussed.

Feasibility, safety, and efficacy of real-time three-dimensional transoesophageal echocardiography for guiding device closure of interatrial communications: initial clinical experience and impact on radiation exposure.

AIMS: Our aim was to assess the feasibility and safety of real-time (RT) three-dimensional (3D) transoesophageal echocardiography (TEE) for guiding transcatheter closure of interatrial communications and to evaluate its additional benefit over conventional 2D TEE in reducing radiation exposure for the patient. METHODS AND RESULTS: Twenty-five patients undergoing device closure of their interatrial defect had the procedure guided by fluoroscopy, 2D TEE, and RT 3D TEE. We retrospectively compared this group with a historical control group in which interventional guidance was performed using fluoroscopy and 2D TEE alone. The application of RT 3D TEE allowed safe device deployment in all patients without any complications, resulting in a reduction of mean fluoroscopy time (10 +/- 6 to 6 +/- 4 min, P < 0.01), mean dose area product (DAP) (964 +/- 628 to 535 +/- 464 cGy cm(2), P < 0.01), and mean DAP per individual body surface area (494 +/- 317 to 273 +/- 221 cGy cm(2)/m(2), P < 0.01). CONCLUSION: RT 3D TEE as an adjunct to 2D TEE is a feasible and safe tool to guide transcatheter device closure of interatrial communications, resulting in a reduction of radiation exposure. These data indicate that RT 3D TEE can be used to safely monitor interatrial defect closure in clinical routine.

Rapid and accurate determination of relative infarct size in humans using contrast-enhanced magnetic resonance imaging.

BACKGROUND: In clinical routine, rapid infarct sizing techniques are warranted, as objective and precise infarct sizing is important for clinical decision-making. Accurate and objective measures of relative infarct size (rIS) using contrast-enhanced cardiac magnetic resonance (ceCMR) have been extensively demonstrated in experimental animals, but less in humans. The aim of this study was therefore to quantify rIS assessed by ceCMR in patients with chronic myocardial infarction using semi-automatic quantitation techniques. METHODS: A total of 62 patients (mean age 66 +/- 9 years) with ischemic cardiomyopathy (EF 24 +/- 8%) underwent ceCMR for viability testing. rIS was obtained by two time-saving semi-automatic thresholding methods based on: (1) visual definition of a single signal intensity cutoff value (VISUAL) and (2) the full-width-at-half-maximum technique (FWHM). Results were compared to manual tracing (MANUAL) as the reference standard. RESULTS: VISUAL showed better agreement [r = 0.99; intraclass correlation coefficient (ICC) = 0.98, limits of agreement +/-3.2%] to MANUAL than the FWHM technique (r = 0.77, ICC = 0.76, limits of agreement +/-12%). Infarct sizing using MANUAL was twice as time-consuming (3.1 +/- 0.2 min) compared to VISUAL (1.6 +/- 0.1 min) or FWHM (1.6 +/- 0.2 min). CONCLUSIONS: Visual estimation of signal intensity cutoff values allows rapid and accurate determination of rIS in patients with chronic myocardial infarction using ceCMR and is superior to the FWHM technique.

Real-time three-dimensional transoesophageal echocardiography for guidance of non-coronary interventions in the catheter laboratory.

The growing need for less invasive therapies of cardiac disease creates the necessity for improved imaging guidance. Although two-dimensional transthoracic and transoesophageal echocardiography (TEE) have been shown to be essential tools for planning and execution of cardiac interventions, the benefit of three-dimensional TEE for the guidance of interventional procedures still needs to be evaluated. This review aims to describe our first experiences with real-time (RT) three-dimensional TEE for the guidance of percutaneous non-coronary interventions in the catheter laboratory. We used a matrix array TEE probe capable of generating three-dimensional images of cardiac structures in RT. We applied this innovative technique to monitor atrial septal defects or patent foramen ovale closures, valve procedures such as mitral and aortic valve interventions, and electrophysiological procedures. Our first experience using RT three-dimensional TEE for the guidance of percutaneous cardiac interventions in the catheter laboratory demonstrates that this technique is feasible to guide interventions, providing fast and complete information about the underlying pathomorphology, improving spatial orientation, and additionally allowing the online monitoring of the procedure. These benefits may accelerate the learning curve and improve confidence of the interventional cardiologist in order to increase safety, accuracy, and efficacy of interventional cardiac procedures.

Quantification of left ventricular volumes and ejection fraction from gated 99mTc-MIBI SPECT: MRI validation of the EXINI heart software package.

UNLABELLED: The aim of the study was to validate the accuracy of the EXINI heart software (EXINI) package in assessing left ventricular end-diastolic/systolic volumes (EDV, ESV) and ejection fraction (LVEF) from gated (99m)Tc-MIBI single-photon emission tomography (SPECT). Cardiac magnetic resonance imaging (cMRI) was used as reference. Furthermore, effects of perfusion defects and image quality in SPECT on correlation between gated SPECT and magnetic resonance imaging were investigated. METHODS: Seventy patients were examined using gated SPECT (rest study, eight gates per cardiac cycle). EDV, ESV and LVEF were calculated from gated SPECT using EXINI. Directly before or after SPECT, cMRI (20 gates cardiac per cycle) was performed. EDV, ESV and LVEF were calculated using Simpson's rule. Perfusion defects were quantified using the summed-rest-score (SRS). Total number of myocardial counts were used to rate image quality. RESULTS: Correlation between results of gated SPECT and cMRI was high for EDV (R = 0.89) and ESV (R = 0.94) and good for LVEF (R = 0.78). ESV (EXINI 54 +/- 31 ml versus cMRI 57 +/- 34 ml) and LVEF (EXINI 62.9 +/- 11.7% versus cMRI 60.6 +/- 13.9%) did not differ significantly whereas EXINI overestimated EDV significantly compared with cMRI (EXINI 144 +/- 41 ml versus cMRI 137 +/- 36 ml; P<0.005). No correlation was found between absolute differences of the results given by gated SPECT and cMRI and SRS or total myocardial counts (R < 0.18). CONCLUSION: End-diastolic volume, ESV and LVEF calculated from gated SPECT using EXINI agree with cMRI over a wide range of values. Correlation between both the methods was good for EDV and ESV, and acceptable for LVEF. No relevant influence of image quality or SRS on the accuracy of EXINI results was found.

Feasibility and initial experience of assessment of mechanical dyssynchrony using cardiovascular magnetic resonance and semi-automatic border detection.

BACKGROUND: The systolic dyssynchrony index (SDI) has been introduced as a measure of mechanical dyssynchrony using three-dimensional echocardiography to select patients who may benefit from cardiac resynchronization therapy (CRT). However, three-dimensional echocardiography may be inadequate in a number of patients with suboptimal acoustic window and no single echocardiographic measure of dyssynchrony has proven to be of value in selecting patients for CRT. Thus, the aim of this study was to determine the value of cardiovascular magnetic resonance (CMR) for the assessment of the SDI in patients with reduced LV function as well as in healthy controls using semi-automatic border tracking. METHODS: We investigated a total of 45 patients including 35 patients (65 +/- 8 years) with reduced LV function (EF 30 +/- 11%) and a wide QRS complex as well as 10 control subjects (42 +/- 21 years, EF 70 +/- 11%). For cine imaging a standard SSFP imaging sequence was used with a temporal resolution of 40 frames per RR-interval. Quantitative analysis was performed off-line using a software prototype for semi-automatic border detection. Global volumes, ejection fraction and the SDI were calculated in each subject. SDI was compared with standard echocardiographic parameters of dyssynchrony. RESULTS: The mean SDI differed significantly between patients (14 +/- 5%) and controls (5 +/- 2%, p < 0.001). An exponential correlation between the EF and the SDI was observed (r = -0.84; p < 0.001). In addition, a significant association between the SDI and the standard deviation of time to peak systolic motion of 12 LV segments (Ts-SD) determined by echocardiography was observed (r = 0.66, p = 0.002). CONCLUSION: The results of this preliminary study suggest that CMR with semi-automatic border detection may be useful for the assessment of mechanical dyssynchrony in patients with reduced LV function.

Real-time 3-dimensional echocardiographic quantification of left ventricular volumes: multicenter study for validation with magnetic resonance imaging and investigation of sources of error.

OBJECTIVES: We sought to study: 1) the accuracy and reproducibility of real-time 3-dimensional echocardiographic (RT3DE) analysis of left ventricular (LV) volumes in a multicenter setting, 2) interinstitutional differences in relationship with the investigators' specific experience, and 3) potential sources of volume underestimation. BACKGROUND: Reproducibility and accuracy of RT3DE evaluation of LV volumes has not been validated in multicenter studies, and LV volumes have been reported to be underestimated compared to cardiac magnetic resonance (CMR) standard. METHODS: A total of 92 patients with a wide range of ejection fractions underwent CMR and RT3DE imaging at 4 different institutions. Images were analyzed to obtain LV end-systolic volume (ESV) and end-diastolic volume (EDV). Reproducibility was assessed using repeated analyses. The investigation of potential sources of error included: phantom imaging, intermodality analysis-related differences, and differences in LV boundary identification, such as inclusion of endocardial trabeculae and mitral valve plane in the LV volume. RESULTS: The RT3DE-derived LV volumes correlated highly with CMR values (EDV: r = 0.91; ESV: r = 0.93), but were 26% and 29% lower consistently across institutions, with the magnitude of the bias being inversely related to the level of experience. The RT3DE measurements were less reproducible (4% to 13%) than CMR measurements (4% to 7%). Minimal changes in endocardial surface position (1 mm) resulted in significant differences in measured volumes (11%). Exclusion of trabeculae and mitral valve plane from the CMR reference eliminated the intermodality bias. CONCLUSIONS: The RT3DE-derived LV volumes are underestimated in most patients because RT3DE imaging cannot differentiate between the myocardium and trabeculae. To minimize this difference, tracing the endocardium to include trabeculae in the LV cavity is recommended. With the understanding of these intermodality differences, RT3DE quantification of LV volume is a reliable tool that provides clinically useful information.

Cardiac amyloidosis: MR imaging findings and T1 quantification, comparison with control subjects.

In cardiac amyloidosis an interstitial deposition of amyloid fibrils causes concentric thickening of the atrial and ventricular walls. We describe the results of tissue characterization of the myocardium by T1 quantification and MRI findings in a patient with cardiac amyloidosis. The T1 time of the myocardium was elevated compared to that in individuals without amyloidosis. The T1 time of the myocardium was 1387 +/- 63 msec (mean value obtained from four measurements +/- standard deviation [SD]) in the patient with cardiac amyloidosis, while the reference value obtained from the myocardium of 10 individuals without known myocardial disease was 1083 +/- 33 msec (mean value +/- SD). In combination with other MR findings suggestive of amyloidosis, such as homogeneous thickening of the ventricular and atrial walls, thickening of the valve leaflets, restrictive filling pattern, and reduction of systolic function, T1 quantification may increase diagnostic confidence.

Volumetric assessment of epicardial adipose tissue with cardiovascular magnetic resonance imaging.

OBJECTIVE: Previous studies determined the amount of epicardial fat by measuring the right ventricular epicardial fat thickness. However, it is not proven whether this one-dimensional method correlates well with the absolute amount of epicardial fat. In this prospective study, a new cardiovascular magnetic resonance imaging (CMR) method using the three-dimensional summation of slices method was introduced to assess the total amount of epicardial fat. RESEARCH METHODS AND PROCEDURES: CMR was performed in 43 patients with congestive heart failure and in 28 healthy controls. The absolute amount of epicardial fat was assessed volumetrically in consecutive short-axis views by means of the modified Simpson's rule. Additionally, the right ventricular epicardial fat thickness was measured in two different imaging planes: long-axis view (EFT-4CV) and consecutive short-axis views (EFT-SAX). RESULTS: Using the volumetric approach, patients with congestive heart failure had less epicardial fat mass than controls (51 g vs. 65 g, p=0.01). This finding was supported by EFT-SAX (2.9 mm vs. 4.3 mm, p<0.0001) but not by EFT-4CV (3.5 mm vs. 3.8 mm, p=not significant). Epicardial fat mass correlated moderately with EFT-SAX in both groups (r=0.466, p=0.012 in controls and r=0.590, p<0.0001 in patients) and with EFT-4CV in controls (r=0.387, p=0.042). There were no significant differences between EFT-4CV and EFT-SAX in controls (4.3 mm vs. 3.8 mm, p=0.240). However, in the heart failure group, EFT-4CV was significantly higher compared with EFT-SAX (3.5 mm vs. 2.9 mm, p=0.003). Interobserver variability and reproducibility were superior for the volumetric approach compared with thickness measurements. DISCUSSION: Quantitative assessment of epicardial fat mass using the CMR-based volumetric approach is feasible and yields superior reproducibility compared with conventional methods.

Comparison of magnetic resonance perfusion imaging versus invasive fractional flow reserve for assessment of the hemodynamic significance of epicardial coronary artery stenosis.

This study evaluated whether first-pass perfusion cardiovascular magnetic resonance (FP-CMR) could predict the hemodynamic significance of epicardial coronary artery stenosis as defined by invasively determined fractional flow reserve at coronary angiography. In 19 patients with known coronary artery disease (CAD), the hemodynamic relevance of 22 stenoses (mean angiographic severity 73 +/- 9%) was determined using fractional flow reserve measurements (cutoff 0.75). Results were compared with a territorial index of myocardial perfusion reserve (MPR) derived from FP-CMR. In addition, 9 age-matched patients with low prevalence of risk factors and without CAD at angiography served as a control group. A cutoff of 1.5 for MPR separated hemodynamically relevant from nonrelevant stenoses with a sensitivity and specificity of 92% and 92%, respectively. The area under the receiver-operator characteristic curve was 0.97. In the patient group, territories supplied by arteries without significant stenosis (

MDCT detection of mitral valve calcification: prevalence and clinical relevance compared with echocardiography.

OBJECTIVE: The purpose of this study was to analyze the prevalence and clinical significance of mitral valve calcification incidentally detected on chest CT scans in comparison with echocardiography. MATERIALS AND METHODS: The data of 390 patients (227 men and 163 women; mean age, 62.4 +/- 12.2 years) who underwent MDCT of the chest and echocardiography were retrospectively evaluated. On MDCT, mitral valve leaflet and annulus calcification were visually graded on a scale of 0-3, with grade 0 denoting no calcification and grade 3 indicating severe calcification. CT findings were correlated with hemodynamic data obtained at echocardiography. Unpaired Student's t tests, chi-square analysis, and a weighted-kappa test were used to compare results. RESULTS: In 32 (8.2%) of 390 patients, chest MDCT revealed mitral valve leaflet calcification. Fifteen of these patients (15/390, 3.8%) presented with mitral valve stenosis. Excellent agreement (kappa = 0.882) was seen between the presence of mitral valve calcification on MDCT and echocardiographically proven mitral valve sclerosis. Mitral valve leaflet calcification on MDCT and the severity of mitral valve disease on echocardiography showed a substantial agreement (kappa = 0.730). A significant relationship was seen between the degree of mitral valve calcification on MDCT and the echocardiographically determined severity of mitral valve disease (no sclerosis vs mitral sclerosis vs mitral stenosis; p < 0.0001). CONCLUSION: Mitral valve leaflet calcification on MDCT indicates mitral valve sclerosis or stenosis. Thus, patients presenting with incidentally detected mitral valve leaflet calcification on chest CT may benefit from a functional assessment with echocardiography.

Evaluation of aortocoronary bypass stents with cardiac MDCT compared with conventional catheter angiography.

OBJECTIVE: The objective of our study was to determine the accuracy of 16-MDCT for evaluation of stent patency and in-stent stenosis in venous coronary bypass grafts. SUBJECTS AND METHODS: Fourteen patients who had previous stent placements in stenosed venous coronary bypass grafts underwent contrast-enhanced MDCT of the heart (collimation, 16 x 0.75 mm; 120 kV; 550 mAs(eff)) and invasive coronary angiography. A total of 20 stents were evaluated: Vessel and stent diameters proximal to, distal to, and at various sites inside the stent were measured on both techniques, and Bland-Altman plots and correlations were calculated. Image noise and image quality were also assessed applying a Student's t test for data comparison of image noise. RESULTS: All 20 bypass stents were correctly classified as patent. Vessel diameters outside the stent showed an excellent correlation (r = 0.90) and in-stent diameters showed a good correlation (r = 0.72), with lower values for MDCT due to blooming artifacts. All significant in-stent stenoses were correctly classified. CONCLUSION: In patients suspected of bypass in-stent stenosis, 16-MDCT may be considered as a valuable alternative to conventional angiography for evaluating bypass patency and in-stent stenosis.

Reliable 5-min real-time MR technique for left-ventricular-wall motion analysis.

The aim of this study was to investigate the value of a real-time magnetic resonance imaging (MRI) approach for the assessment of left-ventricular-wall motion in patients with insufficient transthoracic echocardiography in terms of accuracy and temporal expenditure. Twenty-five consecutive patients were examined on a 1.5-Tesla whole-body MR system (ACS-NT, Philips Medical Systems, Best, NL) using a real-time and ECG-gated (the current gold standard) steady-state free-precession (SSFP) sequence. Wall motion was analyzed by three observers by consensus interpretation. In addition, the preparation, scanning, and overall examination times were measured. The assessment of the wall motion demonstrated a close agreement between the two modalities resulting in a mean kappa coefficient of 0.8. At the same time, each stage of the examination was significantly shortened using the real-time MR approach. Real-time imaging allows for accurate assessment of left-ventricular-wall motion with the added benefit of decreased examination time. Therefore, it may serve as a cost-efficient alternative in patients with insufficient echocardiography.

The value of non-contrast harmonic transthoracic echocardiography for the detection of left ventricular thrombi in patients with cardiomyopathy: comparison with contrast-enhanced magnetic resonance imaging.

We sought to assess the value of non-contrast enhanced transthoracic harmonic echocardiography (TEE) for the visualization of left ventricular thrombi in 34 patients with cardiomyopathy. Results were compared to contrast-enhanced magnetic resonance imaging as reference standard. Maximal thrombus size was quantified with both modalities. Magnetic resonance imaging demonstrated thrombi in 15 patients. In these subjects echocardiography was negative in seven patients. Thrombi were excluded in 19 patients with magnetic resonance while echocardiography was deemed positive in 5 subjects. Thrombus size by ce-CMR was not different for clots visualized or not visualized by echocardiography (P = 0.71). Moreover, observer agreement was superior for ce-CMR (kappa = 0.94) as compared to TTE (kappa= 0.71). Non-contrast-enhanced harmonic TTE has limited value for the visualization of thrombi in patients with cardiomyopathy.

[Diagnosis and assessment of severity of aortic valve stenosis]. / Diagnose und Schweregradbeurteilung bei Aortenklappenstenose.

Calcific aortic valve stenosis is the most common valvular heart disease in the elderly. Although the diagnosis can often be assumed at clinical presentation, determination of the disease severity is usually not accurately possible based on patient history and physical examination alone. In the past, invasive cardiac catheterization has been the most important strategy for assessing the hemodynamic severity of aortic stenosis. Nowadays, Doppler echocardiography has largely replaced invasive catheterization in many centers, since this modality allows for a comprehensive evaluation of the morphological and functional characteristics of the stenotic valve and for assessment of the prognosis of the disease. This article summarizes the current knowledge on the evaluation of aortic stenosis severity using Doppler echocardiography.