Regional left ventricular wall thickening by magnetic resonance imaging: evaluation in normal persons and patients with global and regional dysfunction

Role of Cardiovascular Magnetic Resonance in Ischemic Cardiomyopathy

Ischemic heart disease is the most common cause of cardiovascular morbidity and mortality. Cardiac magnetic resonance (CMR) improves on other noninvasive modalities in detection, assessment, and prognostication of ischemic heart disease. The incorporation of CMR in clinical trials allows for smaller patient samples without the sacrifice of power needed to demonstrate clinical efficacy. CMR can accurately quantify infarct acuity, size, and complications; guide therapy; and prognosticate recovery. Timing of revascularization remains the holy grail of ischemic heart disease, and viability assessment using CMR may be the missing link needed to help reduce morbidity and mortality associated with the disease.

Sensitivity analysis of a strongly-coupled human-based electromechanical cardiac model: Effect of mechanical parameters on physiologically relevant biomarkers

The human heart beats as a result of multiscale nonlinear dynamics coupling subcellular to whole organ processes, achieving electrophysiologically-driven mechanical contraction. Computational cardiac modelling and simulation have achieved a great degree of maturity, both in terms of mathematical models of underlying biophysical processes and the development of simulation software. In this study, we present the detailed description of a human-based physiologically-based, and fully-coupled ventricular electromechanical modelling and simulation framework, and a sensitivity analysis focused on its mechanical properties. The biophysical detail of the model, from ionic to whole-organ, is crucial to enable future simulations of disease and drug action. Key novelties include the coupling of state-of-the-art human-based electrophysiology membrane kinetics, excitation-contraction and active contraction models, and the incorporation of a pre-stress model to allow for pre-stressing and pre-loading the ventricles in a dynamical regime. Through high performance computing simulations, we demonstrate that 50% to 200% - 1000% variations in key parameters result in changes in clinically-relevant mechanical biomarkers ranging from diseased to healthy values in clinical studies. Furthermore mechanical biomarkers are primarily affected by only one or two parameters. Specifically, ejection fraction is dominated by the scaling parameter of the active tension model and its scaling parameter in the normal direction ( k ort 2 ); the end systolic pressure is dominated by the pressure at which the ejection phase is triggered ( P ej ) and the compliance of the Windkessel fluid model ( C ); and the longitudinal fractional shortening is dominated by the fibre angle ( ϕ ) and k ort 2 . The wall thickening does not seem to be clearly dominated by any of the considered input parameters. In summary, this study presents in detail the description and implementation of a human-based coupled electromechanical modelling and simulation framework, and a high performance computing study on the sensitivity of mechanical biomarkers to key model parameters. The tools and knowledge generated enable future investigations into disease and drug action on human ventricles.

Disparate Impact of Ischemic Injury on Regional Wall Dysfunction in Acute Anterior vs Inferior Myocardial Infarction

BACKGROUND

Acute transmural ischemia should induce similar magnitude of wall motion abnormality (WMA) in both anterior myocardial infarction (AMI) and inferior (IMI). However, patients with AMI generally suffer more severe hemodynamic compromise.

METHODS

This retrospective study compared WMA's in ST segment elevation MI patients undergoing primary reperfusion and subsequent cardiac MRI. Regional systolic wall motion and thickening were assessed in all segments throughout the left ventricle (LV).

RESULTS

We analyzed 37 patients (AMI = 24 vs IMI = 13). Reperfusion success was achieved in all and there were no differences between groups in door-to-balloon time (AMI median 77 vs IMI 119 min, p = 0.085). Compared to IMI, in AMI LV ejection fraction was more depressed (37 ± 7.6% vs 51 ± 10.3%, P = 0.0006) and regional WMA more severe (total regional WMA score = 2.63 ± 0.53 vs IMI = 2.1 ± 0.52, P = 0.007). Regional dyskinesis was commonly observed in AMI patients but was rare in IMI (79% vs 7% of cases). Similarly, AMI manifested systolic thinning, whereas thickening was depressed but still present in IMI patients. Strikingly, WMA severity differed downstream relative to the origin of the infarct artery: In all AMI cases, WMA worsened from proximal anterior toward the distal apical zone; in IMI the pattern was reverse, with WMA consistently most severe in the basal segment of the inferior-posterior wall with preservation toward the apical distribution of the infarct vessel.

CONCLUSION

These results demonstrate a disparate impact of ischemic injury on mechanical performance of the anterior vs inferior-posterior walls. These findings may be attributable to differences between the walls in architecture, mechanics and coronary blood flow. These observations may have implications for myocardial salvage, remodeling and prognosis.

“Chess-Board Pattern” Spatial Modulation of Magnetization

Heart motion is a complex combination of translation, rotation, and concentric contraction. Evaluation of these complex motions has been difficult using conventional slice-selective methods. Non-Invasive tagging of the heart has been obtained by the use of slice-selective radiofrequency pulses. Through spatial modulation of the magnetization the entire image can be labeled in different patterns. Two new pulse sequences are presented, giving a chess-board like spatial modulation. These pulse sequences have several advantages compared with the previously published methods, as the modulation time is half that required to obtain a 2-dimensional grid, the area in the image with high signal intensity was significantly larger, and the radiofrequency power deposition was substantially decreased. By labeling the heart at diastole the chess-board pattern tagging of the heart wall could be followed through systole. Using this method the complex motions of the heart can be mapped.

[Myocardial regional thickness in patients with and without cardiomyopathy assessed by cardiac magnetic resonance]

OBJECTIVE

To explore regional differences in myocardial wall thickness (WT) among the most prevalent cardiomyopathies and in individuals without structural heart disease using cardiac magnetic resonance.

METHODS

Patients older than 18 years referred to cardiac magnetic resonance during the period between January 2014 and September 2014, with a diagnosis of hypertrophic cardiomyopathy, idiopathic dilated cardiomyopathy, ischemic cardiomyopathy, and myocarditis were retrospectively selected from our database.

RESULTS

One hundred twenty patients patients were included. The control group had an average WT of 5.9±1.1mm, with a WT index of 2.9±0.8. Significantly lower mean WT in the apical segments were identified in both the control group (basal 6.7±1.3 vs. mid 6.0±1.3 vs. apical 4.6±1.0mm, P<.0001) and in all evaluated cardiomyopathies (hypertrophic cardiomyopathy: basal 10.5±2.4 vs. mid 10.8±2.7 vs. apical 7.3±3.3mm, P<.0001; idiopathic dilated cardiomyopathy: basal 7.7±1.7 vs. mid 7.6±1.3 vs. apical 5.4±1.3mm, P<.0001; ischemic cardiomyopathy: basal 7.4±1.7 vs. mid 7.5±1.9 vs. apical 5.5±1.8mm, P<.0001; myocarditis: basal 7.1±1.5 vs. mid 6.4±1.1 vs. apical 5.1±0.8, P<.0001). Significant gender differences were also evident regarding the mean WT both in the control group (male 6.5±2.1 vs. female 5.2±1.7mm, P<.0001), as in hypertrophic cardiomyopathy (10.5±5.3 vs. 8.5±5.7mm, P<.0001) and myocarditis (6.6±2.0 vs. 5.2±1.6mm, P<.0001).

CONCLUSION

We found a relatively high prevalence of segments commonly deemed thinned among patients without structural heart disease. We also observed a marked asymmetry and longitudinal gradient in wall thickness both in controls and in the various cardiomyopathies evaluated.

Normal left ventricular myocardial thickness for middle-aged and older subjects with steady-state free precession cardiac magnetic resonance: the multi-ethnic study of atherosclerosis

BACKGROUND

Increased left ventricular myocardial thickness (LVMT) is a feature of several cardiac diseases. The purpose of this study was to establish standard reference values of normal LVMT with cardiac magnetic resonance and to assess variation with image acquisition plane, demographics, and left ventricular function.

METHODS AND RESULTS

End-diastolic LVMT was measured on cardiac magnetic resonance steady-state free precession cine long and short axis images in 300 consecutive participants free of cardiac disease (169 women; 65.6 ± 8.5 years) of the Multi-Ethnic Study of Atherosclerosis cohort. Mean LVMT on short axis images at the mid-cavity level was 5.3 ± 0.9 mm and 6.3 ± 1.1 mm for women and men, respectively. The average of the maximum LVMT at the mid-cavity for women/men was 7/9 mm (long axis) and 7/8 mm (short axis). Mean LVMT was positively associated with weight (0.02 mm/kg; P=0.01) and body surface area (1.1 mm/m(2); P<0.001). No relationship was found between mean LVMT and age or height. Greater mean LVMT was associated with lower left ventricular end-diastolic volume (0.01 mm/mL; P<0.01), a lower left ventricular end-systolic volume (-0.01 mm/mL; P=0.01), and lower left ventricular stroke volume (-0.01 mm/mL; P<0.05). LVMT measured on long axis images at the basal and mid-cavity level were slightly greater (by 6% and 10%, respectively) than measurements obtained on short axis images; apical LVMT values on long axis images were 20% less than those on short axis images.

CONCLUSIONS

Normal values for wall thickness are provided for middle-aged and older subjects. Normal LVMT is lower for women than men. Observed values vary depending on the imaging plane for measurement.

Pharmacological stress cardiovascular magnetic resonance

Over the past decade, cardiovascular magnetic resonance (CMR) has evolved into a cardiac stress testing modality that can be used to diagnose myocardial ischemia using intravenous dobutamine or vasodilator perfusion agents such as adenosine or dipyridamole. Because CMR produces high-resolution tomographic images of the human heart in multiple imaging planes, it has become a highly attractive noninvasive testing modality for those suspected of having myocardial ischemia. The purpose of this article is to review the clinical, diagnostic, and prognostic utility of stress CMR testing for patients with (or suspected of having) coronary artery disease.

[Evaluation of diastolic function in patients with constrictive pericarditis before and after pericardectomy]

PURPOSE

The aim of the study was to evaluate diastolic function in patients with constrictive pericarditis using velocity-encoded flow measurements before and after pericardectomy.

MATERIALS AND METHODS

Velocity-encoded flow measurements were performed at the atrioventricular valves in nine patients with constrictive pericarditis. The resulting flow curves were evaluated. For assessment of diastolic function the amplitudes of the E and A waves were measured and the E to A wave ratios calculated. Appearance of mid-diastolic flow, indicating diastolic dysfunction, was registered.

RESULTS

The measurements at the mitral valves prior to pericardectomy revealed diastolic dysfunction grade I in two patients, grade II in three patients, and grade III in three patients. Mid-diastolic flow was detected in two patients. At the tricuspid valves diastolic dysfunction grade I was present in two patients, grade II in four patients, and grade III in three patients. Improvement of diastolic function after pericardectomy was documented in five patients at the mitral valve and in two patients at the tricuspid valve.

CONCLUSION

Velocity-encoded flow measurements are feasible and a valuable tool for assessment of diastolic function in patients with constrictive pericarditis prior to and after pericardectomy.

CT of Cardiac Function

Multidetector computed tomography (MDCT) can play a role in diagnosis of coronary artery disease and in the assessment of left ventricle (LV) and right ventricle global function, with initial good correlation results with standard modalities. With the latest scanners, regional LV contractility with both qualitative and quantitative assessment has become possible. MDCT function evaluation by specific postprocessing software can be performed considering simultaneously different parameters plus the subjective visual perception of anomalies on 2-dimensional and 3-dimensional cine-loop models. MDCT's ability to make high-resolution 3-dimensional reconstructions throughout the cardiac cycle allows this imaging modality to evaluate both coronary and LV anatomy and morphology, and also LV functional parameters. The ability to provide functional information of the right ventricle represents another important application of MDCT both in patients with acute pulmonary embolism and with congenital cardiovascular disease. Initial results on accuracy are promising and the clinical applicability of MDCT should rapidly increase.

Dobutamine cardiovascular magnetic resonance: A review

Dobutamine cardiovascular magnetic resonance (DCMR) is useful for identifying myocardial ischemia and viability in patients with known or suspected coronary artery disease (CAD). This article reviews the performance and utility of DCMR, its association with dobutamine stress echocardiography (DSE), and areas of active investigative research.

Resting myocardial blood flow is impaired in hibernating myocardium: a magnetic resonance study of quantitative perfusion assessment

BACKGROUND

Although impairment in perfusion reserve is well recognized in hibernating myocardium, there is substantial controversy as to whether resting myocardial blood flow (MBF) is reduced in such circumstances. Quantitative first-pass cardiovascular magnetic resonance (CMR) perfusion imaging allows absolute quantification of MBF. We hypothesized that MBF assessed at rest by quantitative CMR perfusion imaging is reduced in hibernating myocardium.

METHODS AND RESULTS

Twenty-seven patients with 1 or 2-vessel coronary disease and at least 1 dysfunctional myocardial segment undergoing PCI were studied with preprocedure, early (24 hours), and late (9 months) postprocedure CMR imaging. First-pass perfusion images at rest were acquired in 3 short-axis planes by use of a T1-weighted turboFLASH sequence. In each slice, MBF was determined for 8 myocardial segments in mL . min(-1) . g(-1) by deconvolution of signal intensity curves with an arterial input function measured in the left ventricular blood pool. Cine MRI for assessment of global and segmental function and delayed enhancement MRI for detection of viability were also obtained. All coronary lesions were 80% to 95% stenosis in severity. Over all segments, mean MBF normalized by rate-pressure product ("corrected MBF") was 1.2+/-0.3 mL . min(-1) . g(-1) . (mm Hg . bpm/10(4))(-1) in segments without significant coronary stenosis and 0.7+/-0.2 mL . min(-1) . g(-1) . (mm Hg . bpm/10(4))(-1) in segments with coronary stenosis before PCI (mixed model controlling for slice and segment z=-23.9, P<0.001). Early after the procedure, the MBF was 1.2+/-0.2 mL . min(-1) . g(-1) . (mm Hg . bpm/10(4))(-1) in revascularized segments and 1.3+/-0.2 mL . min(-1) . g(-1) . (mm Hg . bpm/10(4))(-1) in nondiseased segments (z=-6.1, P<0.001). Late after PCI, the systolic wall thickening and end-diastolic wall thickness both increased significantly more (both P<0.001) in the myocardial segments subtended by severe coronary stenosis (8+/-17% to 40+/-19% and 6.5+/-1.1 to 9.3+/-2 mm, respectively) than in the myocardial segments supplied by nondiseased vessels. Mean MBF in dysfunctional segments with significantly improved contraction after revascularization was 0.8+/-0.2 mL . min(-1) . g(-1) . (mm Hg . bpm/10(4))(-1) before PCI and 1.2+/-0.2 mL . min(-1) . g(-1) . (mm Hg . bpm/10(4))(-1) after PCI (z=2.0, P=0.04).

CONCLUSIONS

CMR perfusion imaging detects impaired resting MBF in hibernating myocardial segments.

Quantification of synchronous contraction of left ventricle in normal subjects using ECG-gated-SPECT images

Intact heart muscles are believed to contract synchronously to produce maximum effective work at a minimum energy cost. Temporal correlation coefficients between the left ventricular volume and muscle contraction were introduced to assess the synchronicity of left ventricular contraction (synchronous contraction index, SCI), and applied to eight normal volunteers. Area-contraction and length-shortening parallel to and perpendicular to the long axis were computed from electrocardiogram (ECG)-gated single-photon emission computed tomographies (SPECT) using a homemade computer programme. The cardiac wall was divided into nine segments, and the average values of accumulation of perfusion agents, amplitude of contraction and SCI were obtained in each segment. The area-SCI was 91.4% +/- 4.3% and relatively uniform over the whole cardiac wall (p = 0.014, analysis of variance (ANOVA)), whereas the accumulation and amplitude of contraction varied significantly in different segments (p < 0.0001, ANOVA). This study suggested that in normal subjects the myocardial contraction was synchronous, and that the amplitude of contraction was not spatially uniform.

MR imaging in ischemic heart disease

This article reviews the current MR imaging literature with respect to ischemic heart disease and focuses on the clinical practicalities of cardiac MR imaging today.

Quantifying myocardial deformation throughout the cardiac cycle: a comparison of ultrasound strain rate, grey-scale M-mode and magnetic resonance imaging

Strain rate imaging (SRI) is a new ultrasound (US) approach to the quantification of regional myocardial deformation. It previously has been validated in vitro and in vivo against other imaging techniques. However, in all such studies, only peak strain values were compared, and the temporal evolution of the strain curve was not studied. Yet, it is the temporal evolution of the strain curves that contains the more important clinical information (e.g., asynchrony, viability, etc). Thus, the aim of this study was to compare the evolution of strain during the complete cardiac cycle as measured by US SRI, US grey-scale M-mode and magnetic resonance imaging (MRI). In 10 healthy volunteers and 20 patients with chronic ischaemic heart disease, radial deformation of the inferolateral segment of the left ventricle was measured by US SRI, US M-mode and MRI. The correspondence of the temporal characteristics of these strain curves were compared by defining an intraclass correlation coefficient (ICC). In healthy volunteers, an overall good agreement (mean ICC: 0.75 and 0.63 for systole and diastole) was found between the different methods. However, in patients with abnormal segmental deformation and low peak strain values, the agreement was less (mean ICC: 0.42 and 0.32), but remained within acceptable limits for clinical decision making. Myocardial deformation measurements using SRI correlated well with MRI and US M-mode measurements throughout the complete cardiac cycle.

Regional and global right ventricular dysfunction in asymptomatic or minimally symptomatic patients with congenitally corrected transposition

Patients with congenitally corrected transposition are at risk of right ventricular dysfunction and failure. With this in mind, we examined 13 patients with congenitally corrected transposition, 7 not having undergone surgery, and 6 after physiological repair, comparing them with 6 healthy subjects matched for age and sex, using cardiac magnetic resonance imaging, at rest and during dobutamine stress, in order to determine regional and global right ventricular response to stress. At rest, the patients had significantly decreased overall wall motion compared to their healthy peers (7.2 +/- 0.5, versus 9.8 +/- 0.4 mm). During infusion of dobutamine, overall wall motion increased to 12.8 +/- 0.4 mm in the healthy subjects, versus 8.8 +/- 1.0 mm in patients. At the regional level, significant differences in mural motion were found between patients and controls in the anterior (9.5 +/- 1.1, versus 13.2 +/- 0.6 mm), posterior (10.2 +/- 1.6, versus 13.2 +/- 0.8 mm), and septal segments (5.0 +/- 0.8, versus 11.2 +/- 0.6 mm). At rest, overall mural thickening in patients was similar to that of controls, but significantly less in patients during stress. During dobutamine stress, patients showed significantly less regional wall thickening than controls, particularly in the septal (2.7 +/- 0.6, versus 6.0 +/- 0.4 mm, respectively) and in the anterior segments (4.2 +/- 0.6, versus 7.8 +/- 0.6 mm, respectively). Right ventricular ejection fraction strongly correlated with mural motion and thickening, both at rest and during stress. Abnormal regional function in the systemic morphologically right ventricle may occur in patients with congenitally corrected transposition, which strongly correlates with right ventricular ejection fraction. Our findings support the hypothesis that, in patients with congenitally corrected transposition, ischemia of the right ventricular myocardium contributes to the development of right ventricular dysfunction.

Magnetic resonance imaging for the assessment of myocardial viability

The identification of myocardial viability in the setting of left ventricular (LV) dysfunction is crucial for the prediction of functional recovery following revascularization. Although echocardiography, positron emission tomography (PET), and nuclear imaging have validated roles, recent advances in cardiac magnetic resonance (CMR) technology and availability have led to increased experience in CMR for identification of myocardial viability. CMR has unique advantages in the ability of magnetic resonance spectroscopy (MRS) to measure subcellular components of myocardium, and in the image resolution of magnetic resonance proton imaging. As a result of excellent image resolution and advances in pulse sequences and coil technology, magnetic resonance imaging (MRI) can be used to identify the transmural extent of myocardial infarction (MI) in vivo for the first time. This review of the role of CMR in myocardial viability imaging describes the acute and chronic settings of ventricular dysfunction and concepts regarding the underlying pathophysiology. Recent advances in MRS and MRI are discussed, including the potential for dobutamine MRI to identify viable myocardium and a detailed review of the technique of delayed gadolinium (Gd) contrast hyperenhancement for visualization of viable and nonviable myocardium.

MR imaging assessment of cardiac function

Magnetic resonance (MR) imaging is an accurate and reproducible technique for assessment of ventricular function. Although echocardiography is the mainstay for evaluation of cardiac function, dobutamine stress MR imaging has been shown to be as safe as echocardiography for patients with coronary artery disease and more accurate in patients with suboptimal echocardiographic image quality. This article reviews MR imaging techniques, methods of pharmacologic stress, and clinical applications for assessment of cardiac function, primarily left ventricular function.

Apical tissue tracking echocardiography for characterization of regional left ventricular function: comparison with magnetic resonance imaging in patients after myocardial infarction

OBJECTIVE

The purpose of this study was to characterize the normal pattern of apical tracking and to investigate whether tissue tracking imaging is more useful for evaluation of regional left-ventricular function than noncontrast harmonic echocardiography in patients after myocardial infarction.

BACKGROUND

Left ventricular longitudinal shortening plays an important role in cardiac contraction, and can be evaluated online by a new Doppler tissue imaging method.

METHODS

We included 40 healthy participants and 40 patients after myocardial infarction. They underwent tissue tracking imaging and noncontrast harmonic imaging by an experienced and an inexperienced observer. Diagnostic accuracy of semiquantitative evaluation of left ventricular function was compared using magnetic resonance imaging as reference method.

RESULTS

Velocity-time integrals decreased from basal to apical segments in healthy participants. Tissue tracking imaging has a higher diagnostic sensitivity than noncontrast imaging for the diagnosis of regional wall-motion abnormalities (expert, 78% vs 97%, P <.01; beginner, 63% vs 91%, P <.001), whereas specificity remained unchanged (expert, 99% vs 97%, not significant; beginner, 91% vs 92%, not significant).

CONCLUSIONS

Tissue tracking imaging is feasible and evaluates regional systolic myocardial function quantitatively with high diagnostic accuracy compared with magnetic resonance imaging in patients after myocardial infarction, and is more accurate than noncontrast harmonic echocardiography.

MR imaging of myocardial perfusion and viability

CMR is a rapidly developing new modality with applications in clinical cardiology for detection and assessment of myocardial ischemia and viability. CMR perfusion results for the detection of ischemia in comparison with stress echocardiography and scintigraphic techniques are reasonable, but all the studies reported to date have been conduced in selected patients. Larger studies in patient populations reflecting a broader spectrum of disease are necessary before perfusion CMR can be envisaged as a clinically reliable and robust diagnostic tool. Other CMR techniques provide a variety of novel methods of obtaining information on postischemic viability. Signs of viability that can be observed by CMR are the absence of late gadolinium-based contrast enhancement in a myocardial region involved in a recent infarct, any sign of wall thickening at rest (which is detectable with high accuracy by CMR), wall thickening after stimulation by low-dose dobutamine, and preserved wall thickness. Conversely, myocardial necrosis is characterized by signal enhancement of the infarct area after injection of Gd-DTPA, reduced wall thickness in chronic infarcts, and absence of a contractile reserve during dobutamine stimulation. Dobutamine CMR and late enhancement contrast-enhanced CMR predict contractile improvement after revascularization.

Clinical validation of an automated boundary tracking algorithm on cardiac MR images

The goal of this research was to develop an automated algorithm for tracking the borders of the left ventricle (LV) in a cine-MRI gradient-echo temporal data set. The algorithm was validated on four patient populations: healthy volunteers and patients with dilated cardiomyopathy (DCM), left ventricular hypertrophy (LVH), or left ventricular aneurysm (LVA). A full tomographic set (approximately 11 slices/case) of short-axis images through systole was obtained for each patient. Initial endocardial and epicardial contours for the end-diastolic (ED) and end-systolic (ES) frames were manually traced on the computer by an experienced radiologist. The ED tracings were used as the starting point for the algorithm. The borders were tracked through each phase of the temporal data set, until the ES frame was reached (approximately 7 phases/slice). Peak gradients along equally spaced chords calculated perpendicular to a centerline determined midway between the endocardial and epicardial borders were used for border detection. This approach was tested by comparing the LV epicardial and endocardial volumes calculated at ES to those based on the manual tracings. The results of the algorithm compared favorably with both the endocardial (r2 = 0.72 - 0.98) and epicardial (r2 = 0.96 - 0.99) volumes of the tracer.

Qualitative and quantitative analysis of regional left ventricular wall dynamics using real-time magnetic resonance imaging: comparison with conventional breath-hold gradient echo acquisition in volunteers and patients

A real-time magnetic resonance imaging (MRI) acquisition sequence was evaluated for the assessment of left ventricular wall motion (WM) and wall thickening (WT). Ten normal volunteers and 21 patients were studied. Short-axis cine images of the left ventricle (LV) were acquired with a fast gradient echo and an ultrafast segmented echo-planar imaging (EPI) sequence. Qualitative and quantitative analysis of WM and WT was performed on a segmental basis. Qualitative scores agreed between the two methods in 691 of 724 segments (95.4%) with good reproducibility. Quantitative measurements of WM and WT were significantly lower (P < 0.001) with the real-time method (WM: mean bias, 0.49 mm; WT: mean bias, 0.61 mm). The largest differences were observed in the anterior and lateral segments and in patients with dilated ventricles. The lower resolution of the real-time sequence and artifacts was probably responsible for these differences. In conclusion, real-time cardiac MRI can be used for qualitative assessment of wall dynamics but is presently insufficient for quantitative analysis.

Assessment of regional myocardial wall motion and thickening by gated 99Tcm-tetrofosmin SPECT: a comparison with magnetic resonance imaging

Gated single photon emission computed tomography (SPECT) imaging allows the simultaneous assessment of both perfusion and function by using one single study. The assessment of regional wall motion and thickening pattern with gated SPECT allows viability studies to be performed. Magnetic resonance imaging (MRI) is well validated for the assessment of myocardial wall motion and thickening in patients with normal and impaired ventricular function. The aim of the study was to analyse the concordance between wall motion and thickening scores derived by gated SPECT and MRI imaging. Furthermore, the agreement for myocardial wall motion and thickening according to myocardial perfusion was analysed with both techniques. We studied a group of 21 patients, including 13 with a previous myocardial infarction (all more than 4 months before the study), using both gated SPECT 99Tcm-tetrofosmin myocardial perfusion imaging and MRI. A 13-segment model was used for both gated SPECT and MRI and each segment was visually scored using a scale of 1-3 for wall motion and thickening. There was a high agreement between gated SPECT and MRI for both wall motion (229/273, 84%; k = 0.72, P<0.001) and wall thickening (236/273, 86%; k = 0.77, P<0.001). The agreement for wall motion and thickening was 80% (k = 0.66) and 83% (k = 0.70), respectively, for patients with myocardial infarction; and 90% (k = 0.81) and 92% (k = 0.86), respectively (P = NS), for patients without myocardial infarction. Agreement in segmental wall motion and thickening scores between gated SPECT and MRI was 90% (k = 0.80) and 91% (k = 0.84), respectively, for segments with normal or mild to moderate hypoperfusion; and 71% (k = 0.45) and 77% (k = 0.57), respectively, for segments with severe hypoperfusion or no perfusion. Of the 70 (41%) segments that had severely diminished or no perfusion in post-myocardial infarction patients, 22 (31%) showed preserved wall motion and 17 (24%) showed preserved wall thickening both by gated SPECT and MRI, suggesting residual myocardial viability in malperfused segments. Our results suggest that gated SPECT imaging is a reliable tool for the assessment of regional wall motion and thickening in patients with known or suspected coronary artery disease. In patients with a previous myocardial infarction gated SPECT imaging has the potential to detect preserved wall motion and thickening in regions with fixed perfusion defects indicating the potential presence of residual myocardial viability.

Magnetic resonance imaging in coronary heart disease

Modern level of cardiac magnetic resonance imaging (MRI) development already allows its routine use (with proper indications) in coronary heart disease patients for studies of heart morphology and functions, performance of stress tests for evaluation of myocardial perfusion and contractile function. Coronary MRA and some other new MR techniques are close to its wide-scale clinical application. It has been shown that cardiac MRI is a valuable tool for detection of postinfarction scars, aneurysms, pseudoaneurysms, septal defects, mural thrombi and valvular regurgitations. Due to intrinsic advantages of the method it is of special value when these pathological conditions cannot be fully confirmed or excluded with echocardiography. MRI is recognized as the best imaging method for quantification of myocardial thickness, myocardial mass, systolic myocardial thickening, chamber volumes, ejection fraction and other parameters of global and regional systolic and diastolic function. MRI is used in studies of cardiac remodeling in postinfarction patients. The most attractive areas for cardiovascular applications of MRI are assessment of myocardial perfusion and non-invasive coronary angiography. Substantial progress has been achieved in these directions. There are some other new developments in studies of coronary artery disease with MRI. High-resolution MR is used for imaging and quantification of atherosclerotic plaque composition in vivo. Intravascular MR devices suitable for performing imaging-guided balloon angioplasty are created. But before MRI will be widely accepted by the medical community as a important cardiovascular imaging modality several important problems have to be solved. Further technical advances are necessary for clinical implementation of all major diagnostic capabilities of cardiac MRI. The subjective obstacles for growth of clinical applications of cardiac MRI are lack of understanding of its possibilities and benefits both by clinicians and radiologists themselves. So proper training of specialists and promotion of this promising modality among the medical community are necessary.

Quantification of regional contractile function after infarction: strain analysis superior to wall thickening analysis in discriminating infarct from remote myocardium

OBJECTIVES

Using two-dimensional wall thickening (WT) (expressed as percentage) and strain analysis, regional contractile myocardial function was quantified and compared in 13 control subjects and 13 patients with a first myocardial infarction (MI). The findings in the patient group were related to global ventricular function and infarct size.

BACKGROUND

In patients with coronary artery disease, regions with dysfunctional myocardium cannot be differentiated easily from regions with normal function by planar WT analysis. Physiologic factors, in combination with limitations of conventional imaging techniques, affect the calculation of WT. Quantitative assessment of contractile function by magnetic resonance (MR) tissue tagging and strain analysis may be less affected by these factors.

METHODS

Two-dimensional regional WT and strain were calculated in three short-axis MR cine and tagged images, respectively. Left ventricular volumes and ejection fraction (EF) were obtained from a series of contiguous short-axis cine images.

RESULTS

In patients with infarct-related ventricles, WT and strain analysis both revealed reduced myocardial function, as compared with control subjects (p < 0.005 and p < 0.001, respectively). However, WT analysis yielded no significant regional differences in function between infarct-related and remote myocardium (p = 0.064), whereas strain analysis did (p < 0.005). For detecting dysfunctional myocardium of electrocardiographically and angiographically defined infarct areas, WT analysis had a sensitivity of 69% and a specificity of 92%, whereas strain analysis demonstrated a sensitivity of 92% and a specificity of 99%. The EF correlated with WT (r = 0.76, p < 0.005) and strain (r = 0.89, p < 0.001).

CONCLUSIONS

Two-dimensional strain analysis is more accurate than planar WT analysis in discriminating dysfunctional from functional myocardium, and it provides a strong correlation between regional myocardial and global ventricular function.

Quantitative analysis of regional wall motion and thickening by quantitative gated SPECT: comparison with visual analysis

PURPOSE

Electrocardiograph-gated myocardial SPECT permits a quantitative assessment of global and regional functions by quantitative gated SPECT software. To validate quantitative indexes of wall motion and wall thickening, the authors compared these indexes with visual scores.

MATERIALS AND METHODS

Gated myocardial SPECT was performed 60 minutes after the administration of Tc-99m sestamibi at rest in 42 patients with coronary artery disease. Regional wall motion (measured in millimeters and wall thickening (expressed as a percentage) were calculated by quantitative gated SPECT software in nine left ventricular myocardial segments and the results were compared with the five-point visual score interpretations of cinematic display.

RESULTS

A high correlation of wall motion was observed between the quantitative and visual analyses (r = 0.810; P < 0.001). In addition, a high but somewhat less significant correlation of wall thickening was observed between the quantitative and visual analyses (r = 0.606; P < 0.001).

CONCLUSIONS

In conclusion, regional wall motion and wall thickening can be evaluated quantitatively by electrocardiograph-gated myocardial SPECT and quantitative gated SPECT software. This will be useful for functional assessments made with various interventions.

The role of cardiovascular magnetic resonance in heart failure

Cardiovascular Magnetic Resonance (CMR) is an accepted gold standard for non-invasive, accurate, and reproducible assessment of cardiac mass and function. The interest in its use for viability, myocardial perfusion and coronary artery imaging is also widespread and growing rapidly as the hardware and expertise becomes available in more centres, and the scans themselves become more cost effective. In patients with heart failure, accurate and reproducible serial assessment of remodelling is of prognostic importance and the lack of exposure to ionizing radiation is helpful. The concept of an integrated approach to heart failure and its complications using CMR is fast becoming a reality, and this will be tested widely in the coming few years, with the new generation of dedicated CMR scanners.

Dobutamine magnetic resonance imaging as a predictor of myocardial functional recovery after revascularisation

OBJECTIVE

To assess the use of dobutamine magnetic resonance imaging (MRI) as a preoperative predictor of myocardial functional recovery after revascularisation, comparing wall motion and radial wall thickening analyses by observer and semi-automated edge detection.

PATIENTS

25 men with multivessel coronary disease and resting wall motion abnormalities were studied with preoperative rest and stress MRI.

MAIN OUTCOME MEASURES

Observer analysis for radial wall thickening was compared with a normal range, while wall motion analysis used a standard four point scale. Semi-automated analysis was performed using an edge detection algorithm. Segments displaying either improved or worsened thickening or motion with dobutamine were considered viable. Postoperative rest images were performed 3-6 months after coronary artery bypass grafting (CABG) for comparison.

RESULTS

For observer analysis the values for sensitivity and specificity were 50% and 72% for wall motion, with respective values of 50% and 68% for thickening. With semi-automated edge detection the figures for motion were 60% and 73%, with corresponding values of 79% and 58% for thickening. Combining thickening and motion for the semi-automated method to describe any change in segmental function yielded a sensitivity of 71% and specificity of 70%.

CONCLUSIONS

Dobutamine MRI is a reasonably good predictor of myocardial functional recovery after CABG. The use of semi-automated edge detection analysis improved results.

The effect of diastolic stiffness on ventricular function after partial ventriculectomy: a finite element simulation

Partial ventriculectomy (PV) has been proposed by Batista and colleagues to improve cardiac function in patients with dilated cardiomyopathy (DCM); however, results have been mixed. We tested the hypothesis that preoperative diastolic function affects the stroke volume/end-diastolic pressure (Starling) relationship after PV. A previously described finite element simulation of DCM and PV was used. Diastole and end systole were represented by separate elastic finite element models with different unloaded shapes and nonlinear material properties. Left ventricular (LV) end-systolic elastance (E(ES)), diastolic compliance (DC), and Starling relationships were calculated. DC was varied by changing Ogden material property alpha(i) from 12 (compliant) to 20 (stiff). PV was simulated at 20% LV mass reduction. The slope of the Starling relationship increased from 1.82 to 1.21 as alpha(i) increased from 12 to 20. Partial ventriculectomy increased the Starling relationship in each case from 1.34 to 1.01 respectively. However, the net result in each case is a decrement in the Starling relationship with resection, and the smallest decrement was associated with the highest diastolic stiffness (alpha(i) = 20). Partial ventriculectomy depressed the Starling relationship for all values of diastolic compliance. It is expected that patients with a higher diastolic stiffness should do better.

Multislice MR perfusion imaging and regional myocardial function analysis: complimentary findings in chronic myocardial ischemia

PURPOSE

The purpose of this study is to assess the reliability of multislice MR perfusion imaging in comparison to regional wall function and nuclear medicine and to test different qualitative and quantitative parameters for perfusion assessment.

MATERIAL AND METHODS

15 patients with chronic myocardial ischemia underwent CINE and first-pass perfusion MR imaging. Functional myocardial imaging was performed using a segmented CINE FLASH sequence and systolic myocardial wall thickening was assessed after semiautomated segmentation. MR first-pass perfusion studies were performed using a multislice saturation recovery TurboFLASH sequence. Different parameters were calculated for assessment of hypoperfused segments and results of MR imaging compared to 99mTc-SestaMIBI SPECT.

RESULTS

MR perfusion imaging showed a sensitivity of 72% and a specificity of 98%. In combination with MR CINE imaging and wall thickening analysis we calculated a sensitivity of 100% and a specificity of 93%. Qualitative and quantitative perfusion parameter analysis showed significant differences between normal and hypoperfused segments for the signal intensity increase (p < 0.001), the signal intensity upslope (p < 0.001) as well as for the myocardial mean transit time (p < 0.001).

CONCLUSION

The combination of systolic wall thickening analysis and myocardial perfusion can markedly improve the sensitivity of MRI in depiction of LV myocardial perfusion abnormalities. For assessment of hypoperfusion, different quantitative and qualitative parameters can be calculated showing significant differences between normal state and hypoperfusion.

MR imaging of the heart in patients after myocardial infarction: effect of increasing intersection gap on measurements of left ventricular volume, ejection fraction, and wall thickness

PURPOSE

To determine the extent to which the number of planes imaged at magnetic resonance (MR) imaging could be reduced without modifying the calculated volume and thickness of the left ventricle.

MATERIALS AND METHODS

Sixty-one patients were examined after a myocardial infarction. The whole left ventricle was imaged by using 5-mm contiguous breath-hold cine MR short-axis sections with no gap (SAng) (two-dimensional fast low-angle shot sequence, 9/4.8 [repetition time msec/echo time msec]). The effect of omitting one section in two (short-axis sections with 5-mm gap [SA5 mm]) or two sections in three (short-axis sections with 10-mm gap [SA10 mm]) was studied.

RESULTS

In the comparison of SA5 mm or SA10 mm with respect to the reference SAng, the standard error of the estimate (SEE) for the diastolic volume did not exceed the 6.1% interobserver SEE, and the SEE for the ejection fraction remained lower than the 3% interobserver SEE. The measured wall thickness was not affected. In addition, six simple geometric models were compared with SAng and yielded an SEE of 9.5%-28.1% for the diastolic volume and 3.8%-13.3% for the ejection fraction.

CONCLUSION

In the study of left ventricles with heterogeneous contractility, short-axis imaging is more accurate than geometric modeling and permits wall thickness measurements when an intersection gap of 5 or 10 mm is used.

Assessment of myocardial perfusion using multisection first-pass MRI and color-coded parameter maps: a comparison to 99mTc Sesta MIBI SPECT and systolic myocardial wall thickening analysis

The most recently reported magnetic resonance first-pass myocardial perfusion studies were restricted to single slice imaging or a data analysis based on interactively placed regions of interest. This study was designed to investigate a new saturation recovery TurboFLASH sequence for multisection myocardial perfusion imaging and to develop a pixel-based software tool to calculate qualitative perfusion parameters. The findings of perfusion imaging were compared to percent systolic myocardial wall thickening analysis and 99mTc Sesta MIBI SPECT. Six healthy volunteers and twelve patients with proven coronary artery disease (CAD) or chronic myocardial infarction were examined. Diagnostic images were acquired for all volunteers and patients with the multisection saturation recovery TurboFLASH sequence. Perfusion defects could be visualized on parameter maps for signal intensity increase over baseline and signal intensity upslope. Sensitivity and specificity were 76.9% and 97.1% for first-pass perfusion MRI, and respectively 84.6% and 94.3% for CINE imaging. All perfusion defects determined with 99mTc Sesta MIBI SPECT were identified by the combined analysis of myocardial perfusion and wall thickening. The presented software demonstrated a pixel-based analysis of first-pass perfusion studies and simplified image interpretation in a clinical setting. The combination of perfusion and wall motion imaging provided complementary information for the treatment of patients suffering from CAD.

Determination of normal regional left ventricular function from cine-MR images using a semi-automated edge detection method

A semi-automated edge detection method for the delineation of the endo- and epicardial borders of the left ventricle from cine MR images has been developed. The feasibility of this was demonstrated by processing end diastolic and end systolic ECG-gated images of four short axis images in 10 healthy subjects. The first derivative method combined with a 2D weighted polynomial fitting procedure was used to determine the endo- and epicardial borders, which then allowed determination of the wall motion, wall thickening, and ejection fraction, of the left ventricle. The results show that the end-systolic radial wall motion varies from (32+/-8)% to (76+/-12)%, and wall thickening from (0.60+/-0.46) cm to (1.26+/-0.50) cm. An average ejection fraction of (69+/-6)% was found which agrees well with literature values. The method described, for the delineation of the borders, reduces considerably the long and tedious operator time inherent in manual measurement and greatly increases the reproducibility of the measurements.

The effect of ventricular volume reduction surgery in the dilated, poorly contractile left ventricle: a simple finite element analysis

OBJECTIVES

Ventricular volume reduction surgery has been proposed by Batista to improve cardiac function in patients with dilated cardiomyopathy. However, limited clinical data exist to determine the efficacy of this operation. A finite element simulation is therefore used to determine the effect of volume reduction surgery on left ventricular end-systolic elastance, diastolic compliance, stroke work/end-diastolic volume (preload recruitable stroke work), and stroke work/end-diastolic pressure (Starling) relationships.

METHODS

End-diastole and end-systole were represented by elastic finite element models with different unloaded shapes and nonlinear material properties. End-systolic elastance, diastolic compliance, preload recruitable stroke work, and Starling relationships, as well as energy expenditure per gram of unresected myocardium, were calculated. Two different types of volume reduction surgery (apical and lateral) were simulated at 10% and 20% left ventricular mass reduction.

RESULTS

Ventricular volume reduction surgery causes diastolic compliance to shift further to the left on the pressure-volume diagram than end-systolic elastance. Volume reduction surgery increases the slope of the preload recruitable stroke work relationship (dilated cardiomyopathy 0.006 J/mL; 20% lateral volume reduction surgery 0.009 J/mL) but decreases the slope of the Starling relationship (dilated cardiomyopathy 0.028 J/mm Hg; 20% lateral volume reduction 0.023 J/mm Hg). For a given amount of resection, lateral volume reduction has a greater effect than apical volume reduction. Ten-percent and 20% lateral volume reduction reduces energy expenditure by 7% and 17%, respectively.

CONCLUSION

Ventricular volume reduction surgery shifts end-systolic elastance and diastolic compliance to the left on the pressure-volume diagram. The net effect on ventricular function is mixed. Volume reduction surgery increases the slope of preload recruitable stroke work, but increased diastolic compliance causes a small decrease in the Starling relationship (3 mm Hg difference between dilated cardiomyopathy and volume reduction surgery at stroke work = 0.5 J).

Delayed reduction of tissue water diffusion after myocardial ischemia

The apparent diffusion coefficient (ADC) of water after regional myocardial ischemia was measured in isolated, perfused rabbit hearts by using magnetic resonance imaging (MRI) techniques. After ligation of the left anterior descending coronary artery, the ADC of the nonperfused region showed a gradual but significant decreasing trend over time, whereas that of the normally perfused myocardium remained constant. Morphological analysis revealed that the ADC decrease reflected the expansion of a subregion of reduced ADC within the nonperfused myocardium. The dynamics of the diffusion change and the morphological progression of the affected tissue suggest that the ADC decrease may be linked to the onset of myocardial infarction, which is known to involve myocyte swelling. The ADC reduction provides a potentially valuable MRI tissue-contrast mechanism for noninvasively determining the viability of the ischemic myocardium and assessing the dynamics of acute myocardial infarction.

Automatic quantitation of regional myocardial wall motion and thickening from gated technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography

OBJECTIVES

We developed an automatic quantitative algorithm for the measurement of regional myocardial wall motion and wall thickening from three-dimensional gated technetium-99m sestamibi myocardial perfusion single-photon emission computed tomographic images.

BACKGROUND

The algorithm measures the motion of the three-dimensional endocardial surface using a modification of the centerline method, as well as wall thickening using both geometry (gaussian fit) and partial volume (counts).

METHODS

The algorithm was tested using a "variable thickness" heart phantom, and the quantitative results were compared with visual segmental assessment of myocardial motion and thickening in 79 clinical patients with a wide range of ejection fractions (6% to 87%).

RESULTS

Phantom measurements of simulated motion and thickening were accurate regardless of the camera used (dual or triple detector), the angular span of reconstructed data (180 degrees or 360 degrees), the amount of motion (3 or 6 mm) or the amount of thickening (33%, 50% or 100%). Quantitative measurements of segmental motion and thickening in the patients were correlated with visual scores (r = 0.668, exact agreement 72.6%, kappa 0.433 and r = 0.550, exact agreement 74.7%, kappa 0.408, respectively). Significant inverse linear relations exist between the global (summed) visual motion score and the average quantitative motion, and between the global (summed) visual thickening score and the average quantitative thickening. Automatic quantitative ejection fraction measurements correlated extremely well with average quantitative motion (r = 0.929) and thickening (r = 0.959).

CONCLUSIONS

Our algorithm is accurate and may be the first automatic technique for the quantitative three-dimensional assessment of regional ventricular function in cardiology.

Comparison between qualitative and quantitative wall motion analyses using dipyridamole stress breath-hold cine magnetic resonance imaging in patients with severe coronary artery stenosis

Breath-hold cine magnetic resonance imaging (MRI) at rest and during dipyridamole infusion was used to study wall motion abnormalities in patients with severe coronary artery stenosis proven by coronary angiography. Sixteen patients without myocardial infarction but at least one major coronary artery with > or = 70% diameter narrowing were included. Qualitative "visual" assessment of wall motion, as well as quantitative measurement "wall thickening changes (%)" were compared using receiver operating characteristic curve analysis. 201Tl-single-photon emission computed tomography (SPECT) was also studied for comparison. Using qualitative analysis, coronary artery disease detection rate was comparable when assessing wall motion abnormalities with dipyridamole-MRI (79%) and with dipyridamole-induced perfusion defects with 201-thallium-SPECT (75%). Furthermore, sensitivity and specificity for identification of all diseased coronary territories were comparable for both imaging modalities (sensitivity of dipyridamole-MRI and 201thallium-SPECT, 80% vs. 69%; specificity, 75% vs. 80%). The quantitative method has a substantially higher sensitivity than the qualitative method in identifying all diseased territories (Az = 0.81, p < 0.01 vs. Az = 0.55 and 0.59). In addition, we demonstrated that the quantitative method had higher performance than the qualitative one in identifying the diseased vessels territories related to 1-vessel, 2-vessel, and each of individual coronary artery stenoses.

Usefulness of magnetic resonance imaging early after acute myocardial infarction

In patients, early after acute myocardial infarction (AMI), rapid magnetic resonance imaging (MRI) techniques have been used to assess left ventricular (LV) structure, global and regional function, infarct artery patency, or contrast uptake individually. We hypothesized that MRI could be used as a comprehensive evaluation of the post-AMI patient, studying all of these parameters in < 1 hour. Twenty-seven patients were studied after first AMI. Complete examinations were performed in 23 patients, 16 with anterior and 7 with inferior wall myocardial infarction, on day 5 +/- 2 after the event. For measurement of LV structure and regional function, a breath-hold segmented k-space gradient echo tagging sequence was used. A fat-suppressed segmented k-space breath-hold sequence was used for coronary artery imaging. MRI contrast-enhanced images during bolus gadoteridol transit through the myocardium were obtained to assess first-pass contrast uptake. No adverse events were noted during the MRI scanning, which was completed in 46 +/- 5 minutes. The LV mass index, end-diastolic and end-systolic volume indexes, and ejection fraction were (mean +/- SD) 107 +/- 13 g/m2, 87 +/- 23 ml/m2, 54 +/- 20 ml/m2, and 39 +/- 12%, respectively. Intramyocardial percent circumferential shortening was 11 +/- 6% at the apex, 14 +/- 4% in the midventricle, and 15 +/- 4% at the base. Flow within all infarct arteries was visualized. Seventeen of 23 patients had regions of reduced contrast uptake on first-pass imaging with mean signal intensity of 47 +/- 24% that of remote regions. In patients with recent AMI, comprehensive assessment of LV structure and function, infarct artery patency, and regional myocardial contrast uptake was safe and feasible with MRI of < 1 hour.

Changes of the left ventricle after myocardial infarction--estimation with cine magnetic resonance imaging during the first six months

BACKGROUND

In recent years, the interest of cardiologists has focused increasingly on the morphologic and functional changes of the left ventricle after myocardial infarction (MI), due to their great prognostic significance for the patient.

HYPOTHESIS

The aim of this study was to evaluate changes in left ventricular morphology and function during the first 6 months following MI.

METHODS

In all, 61 patients (17 women, 44 men, age 36-83 years) were examined with cine magnetic resonance imaging (CMRI) 1, 4, and 26 weeks after myocardial infarction. Thirty-two patients had anterior MI and 29 patients had posterior MI. According to enzyme-derived infarct weight, 15 patients had small infarcts (< 20 g), 19 had intermediate-sized infarcts (20-40 g), and 27 patients had large infarcts (> 40 g). CMRI was performed in the true short axis of the left ventricle. In each examination, left ventricular end-diastolic and end-systolic volume indices (LVEDVI, LVESVI), stroke volume index (LVSVI), ejection fraction (LVEF), and regional thickness, mass, and motility of the myocardial wall-diastolic thickness (IDdia), infarct mass (IM) and motility (IMOT) of the infarct area and diastolic and systolic thickness (VDdia, VDsys), muscular mass (VM), and motility (VMOT)-were determined. In addition, patients were divided into subgroups according to New York Heart Association (NYHA) functional status at baseline.

RESULTS

In the total group, LVEDVI increased from 73.9 +/- 23.5 ml/m2 to 85.4 +/- 28.1 ml/m2 (p < 0.001) and LVESVI from 40.5 +/- 19.4 ml/m2 to 51.2 +/- 29.0 ml/m2 (p < 0.001). In the subgroups the development depended on infarct size and location. LVSVI and LVEF remained more or less constant except for large anterior infarctions. All changes of the myocardial wall depended on infarct size and location: In all patients IDdia decreased from 10.4 +/- 1.6 mm to 8.9 +/- 1.7 mm (p < 0.001), IMOT from 2.0 +/- 1.6 mm to 0.5 +/- 2.9 mm (p < 0.001). IM increased from 41 +/- 21 g to 45 +/- 25 g (p < 0.001). In the total group, VDdia increased from 11.9 +/- 1.6 mm to 12.4 +/- 1.8 mm (p < 0.05), VDsys from 16.6 +/- 2.5 mm to 17.2 +/- 3.1 mm (p < 0.05). In the subgroups changes varied: VDdia and VDsys decreased markedly in large anterior wall infarctions. VM increased in the total cohort from a mean of 246 +/- 66 g to 276 +/- 80 g (p < 0.001). VMOT decreased from 7.1 +/- 2.4 mm to 6.3 +/- 2.7 mm (p < 0.05). Loss of motility was most pronounced in anterior infarctions. The volume-mass ratio, a measure of the success of compensation of volume increase by myocardial hypertrophy, decreased in small infarcts, remained unchanged in intermediate infarcts, and increased in large infarcts. There was a trend toward improvement of the NYHA functional status during the observation period.

CONCLUSIONS

Changes of the left ventricular chamber during the first 6 months following MI are dependent on its size and location, with large anterior infarctions having the worst course. Myocardial wall remodeling is also dependent on infarct size and location, and the volume-mass ratio increases in the presence of large areas of necrosis, indicating the non-compensatory effect of myocardial hypertrophy. However, these changes have no clinical effect during the first half year after MI.

Detection and quantification of dysfunctional myocardium by magnetic resonance imaging. A new three-dimensional method for quantitative wall-thickening analysis

BACKGROUND

Regional left ventricular dysfunction is a major consequence of myocardial ischemia, and its extent determines long-term prognosis. Accurate and reproducible analysis of left ventricular dysfunction is therefore useful for risk stratification and patient management.

METHODS AND RESULTS

Short-axis cardiac cine magnetic resonance (MR) imaging was performed in 25 patients after anterior myocardial infarction at 21 +/- 2.1 days after the acute onset. The MR images were analyzed with the use of a dedicated analytical software package (MASS version 1.0), which includes a modified centerline method and a new three-dimensional analysis approach. A database of 48 healthy volunteers was constructed to objectively depict myocardial dysfunction in the patients; this database was compared with enzymatically determined infarct size. The mean (+/-SEM) quantity of dysfunctional myocardium and enzymatically calculated infarct size equaled 24.0 +/- 3.0 and 22.3 +/- 2.9 g, respectively (P = .69). Enzymatically determined infarct size correlated strongly with left ventricular dysfunction determined by cine MR imaging (y = 0.90x + .92. P < .0001). Segments related to the distribution of the left anterior descending coronary artery showed a significantly lower percentage wall thickening in patients than did corresponding segments of 48 normal subjects (46.0 +/- 8.22% versus 87.1 +/- mean SEM, respectively; P < .001). The mean (+/-SEM) end diastolic wall thickness of the infarcted segment did not differ from that of corresponding normal segments (7.4 +/- 0.33 versus 7.5 +/- 0.15 mm; P = .75).

CONCLUSIONS

We conclude that the use of three-dimensional quantitative analysis of cine MR images accurately quantities the extent of regional left ventricular dysfunction in the infarcted heart. This method of analysis may be useful in assessing the effect of interventional therapies.

Regional three-dimensional geometry of the normal human left ventricle using cine computed tomography

The aim of this study is to provide accurate three-dimensional measurements of left ventricular geometrical indices in relation to regional myocardial function. The analysis of the three-dimensional regional geometry and function of left ventricles of ten normal human volunteers is based on three-dimensional reconstructions of the left ventricle from cine computed tomography images, at end diastole and end systole, demonstrating normal left ventricular spatial, geometrical, and functional variability. Regional wall thickness, curvature and surface normals, as well as wall thickening and endocardial wall motion, are calculated and mapped for the entire left ventricle. The circumferential asymmetry of the left ventricle is reflected by the smaller circumferential and meridional curvatures at the septum. Thickening is highest at the anterior and lateral walls. Longitudinally, circumferential curvature increases toward the apex, whereas both wall thickness and wall thickening at end systole are largest at the midventricular level, decreasing toward the apex and base. This study describes the circumferential and apex-to-base variations in regional left ventricular geometric parameters of the normal human left ventricle, using three-dimensional imaging and analysis.