Late Enhancement Magnetic Resonance Imaging Research Articles

Liver function quantification of patients with portal vein embolization using dynamic contrast-enhanced MRI for assessment of hepatocyte uptake and elimination

PurposeWe evaluated pharmacokinetic models which quantify liver function including biliary elimination based on a dynamic Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) technique with sparse data collection feasible in clinical routine. MethodsTwelve patients with embolized liver segments following interventional treatment of primary liver cancer or hepatic metastasis underwent MRI. During Gd-EOB-DTPA bolus administration, a 3D dynamic gradient-echo (GRE) MRI examination was performed over approx. 28 min. Interrupted data sampling was started approx. 5 min after contrast agent administration. Different implementations of dual-inlet models were tested, namely the Euler method (DE) and convolution with residue functions (C). A simple uptake model (U) and an uptake- elimination model (UE) extended by incorporating the biliary contrast agent elimination rate (Ke) were evaluated. ResultsThe uptake-elimination model, calculated via the simple Euler method (UE- DE) and by convolution (UE-C), yielded similar overall estimates in terms of fitting quality and agreement with published values. The Euler method was approx. 50 times faster and yielded a mean elimination rate of Ke=1.8±1.2mL/(min·100 mL) in nonembolized liver tissue, which was significantly higher (p=8.8·10-4) than in embolized tissue Ke=0.4±0.4 mL/(min·100 mL). Fractional hepatocyte volume vh was not significantly higher in nonembolized tissue (52.4 ± 13.4 mL/100 mL) compared to embolized tissue (44.4 ± 26.1 mL/100 mL). ConclusionsInterrupted late enhancement MRI data sampling in conjunction with the uptake-elimination model, deconvolved by integration of the differential rate equation and combined with the simple uptake model implemented with the Euler method (U-DE), turned out to be a stable and practical method for reliable noninvasive assessment of liver function.

Relationship between microvascular changes, autonomic denervation, and myocardial fibrosis in Chagas cardiomyopathy: Evaluation by MRI and SPECT imaging

BackgroundThe relationship between microvasculopathy, autonomic denervation, and myocardial fibrosis, in Chagas cardiomyopathy is incompletely understood. The aim of this study was to explore the relative extent and anatomic distribution of myocardial hypoperfusion, autonomic denervation, and myocardial scarring using Single-Photon Emission Computerized Tomography (SPECT) imaging and Magnetic Resonance Imaging (MRI). MethodsThirteen patients with Chagas disease all had Iodine-123-metaiodobenzylguanidine (MIBG) SPECT, 99mTc-Sestamibi (MIBI) rest-stress SPECT, and gadolinium late enhancement MRI imaging within a 2-month interval. The anatomic location and extent of denervation, of stress-induced hypoperfusion and fibrosis, were assessed through image co-registration and quantification of abnormal tissue areas as a percent of total myocardium. ResultsThe results showed a strong general anatomic concordance between areas of hypoperfusion, denervation, and fibrosis, suggesting that the three abnormal features may be correlated. Myocardial denervation was anatomically and quantitatively closely associated areas of stress hypoperfusion. ConclusionCombined myocardial analysis of the extent and location of autonomic denervation, hypoperfusion, and scarring may allow for better understanding of the pathophysiology of Chagas cardiomyopathy. Autonomic myocardial denervation may be a more sensitive marker of cardiac involvement in Chagas Disease than finding by other imaging modalities.

P784Identification of border-zone corridors in the left ventricle with late-enhancement magnetic resonance images

P784Identification of border-zone corridors in the left ventricle with late-enhancement magnetic resonance images

First Case of Multiple Primary Cardiac Leiomyosarcoma on a 17 Years Old Boy, Evaluated by Cardiac MR Imaging

In this case report we present the history of a patient with Cardiac mass detected at echocardiography. By further evaluation, the patient has undergone cardiac magnetic resonance (MR) imaging prior to cardiac surgery. This study can therefore contribute to the diagnosis of multiple cardiac masses and its relationship to other cardiac structures. These assessments are important to plan strategy of surgical intervention. MR Imaging technique offers the ability to enable discrimination of different tissue characteristics. The use of contrast material MR imaging, has additional properties such as examination of vascularity degree of tissue. This information can be showed by first-pass perfusion technique and the late-enhancement MR imaging study. The purpose of this paper is to describe MR Imaging findings of this extremely un frequent presentation of multiple primary cardiac liomyosarcoma in a young boy.

Analysis of Clinical Parameters and Cardiac Magnetic Resonance Imaging as Predictors of Outcome in Pediatric Myocarditis

Myocarditis causes significant morbidity and mortality in pediatric patients, with potential adverse outcomes including heart failure, transplantation requirement, and/or death. The objective of this study was to determine predictors of early and late poor outcomes, defined as requirement for extracorporeal membrane oxygenation, ventricular assist device, transplantation, or death in pediatric myocarditis patients. A retrospective cohort study was conducted to evaluate pediatric myocarditis presenting over a 5-year period at a pediatric institution. Patients were identified using an institutional heart failure database and International Classification of Diseases, Ninth Revision, discharge diagnosis codes for myocarditis and confirmed by review of medical records. Data extraction included epidemiologic factors, the presenting ejection fraction (EF), initial and peak troponin levels, brain natriuretic peptide (BNP) level, pathogen identification, cardiac magnetic resonance imaging (MRI), and outcomes. Univariate and multivariate regression was performed to identify variables predictive of outcomes. Because published pediatric cardiac MRI data are sparse, whether late enhancement was associated with specific clinical variables or predictive of outcomes was also evaluated. Fifty-eight patients were identified. The mean age was 10.5 years, 64% were male, 62% were Caucasian, 15% were African-American, and 23% were Hispanic or Asian. Eighty-one percent presented at the institution <1 week after symptom onset. Presenting EFs were normal (>50%) or mildly decreased (40% to 50%) in 48%, moderately decreased (30% to 40%) in 9%, and severely decreased (<30%) in 42%. Thirty patients (52%) underwent viral studies; 17 of these (56%) had acute viral origins of myocarditis identified, including 8 with parvovirus (2 with influenza coinfection), 7 with enterovirus, 1 with Epstein-Barr virus, and 1 with cytomegalovirus. Twenty-eight percent had poor outcomes. Univariate analysis identified Hispanic or Asian race (odds ratio [OR] 4.5, p = 0.05), a severely decreased EF (OR 13, p = 0.002), initial BNP >10,000 pg/ml (OR 5.6, p = 0.01), and peak BNP >10,000 pg/ml (OR 13.65, p = 0.001) as risk factors for poor outcomes; initial and peak troponin >1 ng/ml were correlated significantly with good outcomes (OR 0.22, p = 0.04, and OR 0.26, p = 0.05, respectively). Multivariate analysis adjusting for severe EF, troponin, BNP, and cardiac MRI revealed peak BNP >10,000 ng/L (OR 27.71, p = 0.04), a severely decreased EF (OR 12.8, p = 0.03), and late enhancement on cardiac MRI (OR 24.51, p = 0.04) as risk factors for poor outcomes. Thirty-four patients underwent cardiac MRI (50% with abnormal and 50% with normal results). No significant differences were found between these groups with respect to gender, race, symptom duration, the EF, BNP, troponin, inflammation on cardiac biopsy, or pathogen identification. In conclusion, this study provides data from a large cohort of pediatric myocarditis patients. A presenting EF <30%, peak BNP >10,000 ng/L, and cardiac MRI late enhancement were identified as predictors of poor outcomes.

Automatic cardiac LV segmentation in MRI using modified graph cuts with smoothness and interslice constraints

Magnetic resonance imaging (MRI), specifically late-enhanced MRI, is the standard clinical imaging protocol to assess cardiac viability. Segmentation of myocardial walls is a prerequisite for this assessment. Automatic and robust multisequence segmentation is required to support processing massive quantities of data. A generic rule-based framework to automatically segment the left ventricle myocardium is presented here. We use intensity information, and include shape and interslice smoothness constraints, providing robustness to subject- and study-specific changes. Our automatic initialization considers the geometrical and appearance properties of the left ventricle, as well as interslice information. The segmentation algorithm uses a decoupled, modified graph cut approach with control points, providing a good balance between flexibility and robustness. The method was evaluated on late-enhanced MRI images from a 20-patient in-house database, and on cine-MRI images from a 15-patient open access database, both using as reference manually delineated contours. Segmentation agreement, measured using the Dice coefficient, was 0.81±0.05 and 0.92±0.04 for late-enhanced MRI and cine-MRI, respectively. The method was also compared favorably to a three-dimensional Active Shape Model approach. The experimental validation with two magnetic resonance sequences demonstrates increased accuracy and versatility.

Identification of left atrial fibrosis with a late-enhancement MR sequence (LE-MR): preliminary results

This study was done to identify left atrial fibrosis in a group of consecutive patients with atrial fibrillation (AF) candidate for percutaneous radiofrequency catheter ablation (RFCA) by using a late-enhancement magnetic resonance (LE-MR) sequence, and to validate the technique by comparison with electroanatomical mapping (EAM). We enrolled 37 patients (29 males; mean age, 61 years) candidate for percutaneous RFCA of AF, who were studied with LE-MR and EAM. To identify left AF we used a three-dimensional LE sequence with cardiac gating and respiratory navigator. The EAM study involved the acquisition of 200 points in the left atrium (LA). The LA was divided into seven segments (pulmonary vein antra, floor, anterior wall, posterior wall-roof). Two blinded radiologists assessed the presence of fibrosis (area of hyperintense signal), reaching a consensus in discordant cases. Inter-observer variability was also evaluated to estimate the reproducibility of the method. We analysed the anatomical agreement between the results obtained with LE-MR imaging and EAM. Five patients were excluded because of to poor image quality. As for the other 32 patients, inter-observer agreement was good [Cohen's kappa κ = 0.72 with 95 % confidence interval (CI) of 0.55, 0.89]. In the classification of LA segments affected by fibrosis, LE-MR had a sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of 66 % (95 % CI 53.7 %, 77.2 %); 87 % (95 % CI 80.9 %, 91.9 %); 69 % (95 % CI 56.5 %, 80.1 %); 85.5 % (95 % CI 79.1 %, 90.6 %) and 81 % (95 % CU 75.1 %, 85.7 %). Despite the small size of the sample studied, the LE-MR sequence proved more useful for excluding the presence of AF than for confirming its existence. Identification of AF prior to RFCA is paramount to select those patients who are truly amenable to the ablation procedure, which is expensive and not entirely free of risks.

Interactive Hierarchical-Flow Segmentation of Scar Tissue From Late-Enhancement Cardiac MR Images

We propose a novel multi-region image segmentation approach to extract myocardial scar tissue from 3-D whole-heart cardiac late-enhancement magnetic resonance images in an interactive manner. For this purpose, we developed a graphical user interface to initialize a fast max-flow-based segmentation algorithm and segment scar accurately with progressive interaction. We propose a partially-ordered Potts (POP) model to multi-region segmentation to properly encode the known spatial consistency of cardiac regions. Its generalization introduces a custom label/region order constraint to Potts model to multi-region segmentation. The combinatorial optimization problem associated with the proposed POP model is solved by means of convex relaxation, for which a novel multi-level continuous max-flow formulation, i.e., the hierarchical continuous max-flow (HMF) model, is proposed and studied. We demonstrate that the proposed HMF model is dual or equivalent to the convex relaxed POP model and introduces a new and efficient hierarchical continuous max-flow based algorithm by modern convex optimization theory. In practice, the introduced hierarchical continuous max-flow based algorithm can be implemented on the parallel GPU to achieve significant acceleration in numerics. Experiments are performed in 50 whole heart 3-D LE datasets, 35 with left-ventricular and 15 with right-ventricular scar. The experimental results are compared to full-width-at-half-maximum and Signal-threshold to reference-mean methods using manual expert myocardial segmentations and operator variabilities and the effect of user interaction are assessed. The results indicate a substantial reduction in image processing time with robust accuracy for detection of myocardial scar. This is achieved without the need for additional region constraints and using a single optimization procedure, substantially reducing the potential for error.

Postinfarction Ventricular Tachycardia Substrate Characterization: A Comparison Between Late Enhancement Magnetic Resonance Imaging and Voltage Mapping Using an MR-Guided Electrophysiology System

Catheter ablation of ventricular tachycardia (VT) is preceded by characterization of the myocardial substrate via electroanatomical voltage mapping (EAVM). The purpose of this study was to characterize the relationship between chronic myocardial fibrotic scar detected by multicontrast late enhancement (MCLE) MRI and by EAVM obtained using an MR-guided electrophysiology system, with a final aim to better understand how these measures may improve identification of potentially arrhythmogenic substrates. Real-time MR-guided EAVM was performed in six chronically infarcted animals in a 1.5T MR system. The MCLE images were analyzed to identify the location and extent of the fibrotic infarct. Voltage maps of the left ventricle (LV) were created with an average of 231 ± 35 points per LV. Correlation analysis was conducted between bipolar voltage and three MR parameters (infarct transmurality, tissue categorization into healthy and scar classes, and normalized relaxation rate R1). In general, tissue regions classified as scar by normalized R1 values were well correlated with locations with low bipolar voltage values. Moreover, our results demonstrate that MRI information (transmurality, tissue classification, and relaxation rate) can accurately predict areas of myocardial fibrosis identified with bipolar voltage mapping, as demonstrated by ROC analysis. MCLE can help overcome limitations of bipolar voltage mapping including long durations and lower spatial discrimination and may help identify the sites within scars, which are commonly believed to trigger arrhythmic events in postinfarction patients.

Esophageal Tissue Injury Following Pulmonary Vein Isolation Using the PVAC: Assessment by Endoscopy and Magnetic Resonance Imaging

We investigate the frequency of esophageal tissue injury (ETI) following ablation of atrial fibrillation (AF) using the pulmonary vein ablation catheter (PVAC) ascertained by esophageal endoscopy (ESE) and corresponding magnetic resonance imaging (MRI). A total of 41 patients with symptomatic AF presenting for pulmonary vein isolation (PVI) were included consecutively in two observational groups. Group A received MRI the day before and ESE plus MRI within 3-4 weeks following the ablation procedure using the PVAC. Group B received MRI the day before and ESE plus MRI within 2 days after PVI. MRI included T2-weighted and T1-weighted postcontrast with fat suppression (fs) and late-enhancement scans to demonstrate postprocedural edema and contrast enhancement of the esophageal wall. A total of 13 (32%) patients were enrolled in Group A (26 ± 11 days post-PVI), and 28 (68%) patients in Group B (2 ± 0.6 days post-PVI). ETI was found by ESE in one (2%) patient (Group B) and resolved under conservative therapy. Corresponding MRI showed a false negative result with no alterations of esophageal structures using T1-weighted, T2-weighted, and late enhancement scans. In addition, false positive results were demonstrated by late-enhancement MRI in five (12%) patients (three patients in Group A and two patients in Group B), which could not be verified by corresponding ESE. Endoluminal ETI is a rare but possible complication, which should be considered following PVAC procedures. MRI of the esophagus is currently not a reliable screening method due to false positive and negative findings compared to ESE.

Three-Dimensional Echocardiography in the Evaluation of Global and Regional Function in Patients with Recent Myocardial Infarction: A Comparison with Magnetic Resonance Imaging

We aimed to compare three-dimensional (3D) and two-dimensional (2D) echocardiography in the evaluation of patients with recent myocardial infarction (MI), using late-enhancement magnetic resonance imaging (LE-MRI) as a reference method. Echocardiography and LE-MRI were performed approximately 1month after first-time MI in 58 patients. Echocardiography was also performed on 35 healthy controls. Left ventricular (LV) ejection fraction by 3D echocardiography (3D-LVEF), 3D wall-motion score (WMS), 2D-WMS, 3D speckle tracking-based longitudinal, circumferential, transmural and area strain, and 2D speckle tracking-based longitudinal strain (LS) were measured. The global correlations to infarct size by LE-MRI were significantly higher (P<0.03) for 3D-WMS and 2D-WMS compared with 3D-LVEF and the 4 different measurements of 3D strain, and 2D global longitudinal strain (GLS) was more closely correlated to LE-MRI than 3D GLS (P<0.03). The segmental correlations to infarct size by LE-MRI were also significantly higher (P<0.04) for 3D-WMS, 2D-WMS, and 2D LS compared with the other indices. Three-dimensional WMS showed a sensitivity of 76% and a specificity of 72% for identification of LV infarct size >12%, and a sensitivity of 73% and a specificity of 95% for identification of segments with transmural infarct extension. Three-dimensional WMS and 2D gray-scale echocardiography showed the strongest correlations to LE-MRI. The tested 3D strain method suffers from low temporal and spatial resolution in 3D acquisitions and added diagnostic value could not be proven.

Strain rate imaging combined with wall motion analysis gives incremental value in direct quantification of myocardial infarct size

The study aimed to evaluate the diagnostic accuracy of a new method for direct echocardiographic quantification of the myocardial infarct size, using late enhancement magnetic resonance imaging (LE-MRI) as a reference method. Echocardiography and LE-MRI were performed on average 31 days after first-time myocardial infarction in 58 patients. Echocardiography was also performed on 35 healthy controls. Direct echocardiographic quantification of the infarct size was based on automated selection and quantification of areas with hypokinesia and akinesia from colour-coded strain rate data, with manual correction based on visual wall motion analysis. The left ventricular (LV) ejection fraction, speckle-tracking-based longitudinal global strain, wall motion score index (WMSI), longitudinal systolic motion and velocity, and the ratio of early mitral inflow velocity to mitral annular early diastolic velocity were also measured by echocardiography. The area under the receiver-operating characteristic curves for the identification of the infarct size >12% by LE-MRI was 0.84, using the new method for direct echocardiographic quantification of the infarct size. The new method showed significantly a higher correlation with the infarct size by LE-MRI both at the global (r = 0.81) and segmental (r = 0.59) level compared with other indices of LV function. Direct quantification of the percentage infarct size by strain rate imaging combined with wall motion analysis yields high diagnostic accuracy and better correlation to LE-MRI compared with other echocardiographic indices of global LV function. Echocardiography performed ~1 month after myocardial infarction showed ability to identify the patients with the infarct size >12%.

Deformation Measurements by Echocardiography versus Late Enhancement Magnetic Resonance Imaging in Patients with Coronary Artery Disease

The aim of this article is to discuss the present and future potential of deformation imaging by echocardiography and scar visualisation by magnetic resonance imaging (MRI) in patients with coronary artery disease (CAD). The two methods are clearly different: one is concerned with function, the other with morphology. Echocardiography, with its versatility of methods and high applicability, will continue to be the workhorse in cardiac imaging of patients with CAD. Important additional information can be extracted from deformation imaging methods, especially due to the high temporal resolution in tissue Doppler. Deformation measurements in 3D images are still limited by their lower resolution compared with 2D but will continue to improve. The standardisation of image analysis and the collaboration within the echocardiographic community to conduct larger studies will be important tasks in the attempt to establish evidence for the new methods. Late enhancement MRI is a method with unique properties and will continue to be an important alternative in selected patients and settings, as well as an invaluable research tool.

Prevalence of Unrecognized Myocardial Infarction Detected With Magnetic Resonance Imaging and its Relationship to Cerebral Ischemic Lesions in Both Sexes

The purpose of this study was to investigate the prevalence of unrecognized myocardial infarction (UMI) detected with magnetic resonance imaging (MRI) and whether it is related to cerebral ischemic lesions on MRI in an elderly population-based cohort. There is a correlation between stroke and recognized myocardial infarction (RMI) and between stroke and UMI detected with electrocardiography, whereas the prevalence of stroke in subjects with MRI-detected UMI is unknown. Cerebral MRI and cardiac late-enhancement MRI were performed on 394 randomly selected 75-year-old subjects (188 women, 206 men). Images were assessed for cerebral ischemic lesions and myocardial infarction (MI) scars. Medical records were scrutinized. Subjects with MI scars, with or without a hospital diagnosis of MI, were classified as RMI or UMI, respectively. UMIs were found in 120 subjects (30%) and RMIs in 21 (5%). The prevalence of UMIs (p = 0.004) and RMIs (p = 0.02) was greater in men than in women. Men with RMI displayed an increased prevalence of cortical and lacunar cerebral infarctions, whereas women with UMI more frequently had cortical cerebral infarctions (p = 0.003). MI scars are more frequent in men than in women at 75 years of age. The prevalence of RMI is related to that of cerebral infarctions.

Dual-Energy Computed Tomography for the Detection of Late Enhancement in Reperfused Chronic Infarction

To evaluate the performance of late enhancement dual-energy CT (LE-DECT) for the detection of infarcted myocardium as compared with 1.5-T late enhancement magnetic resonance imaging (LE-MRI) in a porcine model of reperfused chronic myocardial infarction (MI), using histopathology as standard of reference. In 8 healthy minipigs, MI was induced by 30-minute balloon occlusion of the left anterior descending coronary artery. Sixty-one ± 4 days after left anterior descending coronary artery occlusion, LE-DECT was performed 5, 10, and 15 minutes subsequent to contrast material injection. Therefore, a dual-source CT scanner (Somatom Definition, Siemens Healthcare, Forchheim, Germany) was used in dual-energy mode with the following protocol: tube potential/current 140 kV/95 mAs on tube A and 100 kV/165 mAs on tube B, collimation 2 × 32 × 0.6 mm, 1.5 mL/kg contrast material injected at 3 to 4 mL/s. Myocardial iodine distribution was calculated from the dual-energy data and superimposed on the gray scale multiplanar reformats of the heart in short-axis view. Fifty ± 12 minutes after LE-DECT imaging, 1.5-T LE-MRI (Magnetom Avanto, Siemens Healthcare, Forchheim, Germany) was performed 10 minutes successive to injection of contrast material using phase-sensitive inversion recovery sequences. For all pigs investigated, 2,3,5-triphenyltetrazolium chloride staining and histopathology of stained-tissue samples were acquired. Two experienced radiologists assessed all imaging studies in a random manner and were blinded to the results of the other techniques for the presence of late enhancement (LE). The American Heart Association 17-segment model was used to compare the results of LE-DECT, 100 kV grayscale LE images, LE-MRI, and histopathology. Size of MI was calculated for histopathological findings, LE-MRI, LE-DECT, and 100 kV grayscale LE images 10 minutes after contrast agent injection. Agreement between infarct size assessed with imaging modalities and histopathology was evaluated with Bland-Altman analysis. Of the 136 myocardial segments in 8 minipigs, histopathology found MI in 27 segments. Diagnostic per-segment sensitivities and specificities for 100 kV grayscale LE images, LE-DECT images, and MR images obtained 10 minutes after contrast agent injection for both the readers were 0.62, 0.77, 0.79 and 0.97, 0.92, 0.94, respectively. Although sensitivities were higher for LE-DECT and LE-MRI than for 100 kV grayscale images, no statistically significant difference for the diagnostic accuracies of 100 kV grayscale LE images, LE-DECT images, and MR images (0.9, 0.89, 0.9) existed 10 minutes successive to contrast agent injection (all P > 0.05). Infarct size for LE-MRI, LE-DECT, and 100 kV grayscale LE images correlated well with histopathological findings (r = 0.97, 0.96, and 0.94; all P < 0.01). This feasibility study shows a high accuracy and a good correlation of LE-DECT and LE-MRI to histopathology for the detection of LE in a porcine model of reperfused chronic MI.

Low-Gradient Aortic Valve Stenosis: Myocardial Fibrosis and Its Influence on Function and Outcome

This prospective cohort study in patients with aortic stenosis (AS) aimed to identify surrogates of myocardial fibrosis that are easy to derive in clinical practice, allow the differentiation of low-gradient severe AS from moderate AS, and have an impact on clinical outcome. In patients with symptomatic aortic AS, a characteristic subgroup (i.e., up to one-third) exhibits severe AS with a concomitant low mean valve gradient either with preserved or reduced ejection fraction (EF). It is hypothesized that these patients tend to have an advanced stage of myocardial fibrosis and poor clinical outcome. Eighty-six patients with moderate or severe AS were examined by echocardiography including conventional aortic valve assessment, mitral ring displacement, and strain-rate imaging. Replacement fibrosis was quantified by late-enhancement magnetic resonance imaging. Biopsy samples were taken from patients with severe AS (n = 69) at aortic valve replacement. All patients were followed for 9 months. Patients were divided into 4 groups according to aortic valve area (<1.0 cm(2)), mean valve gradient ≥40 mm Hg, and EF (<50%): group 1, moderate AS (n = 17); group 2, severe AS/high gradient (n = 49); group 3, severe AS/low gradient/preserved EF (n = 11); and group 4, severe AS/low gradient/decreased EF (n = 9). At baseline, a significant decrease in mitral ring displacement and systolic strain rate was detected in patients with low-gradient AS. In low-gradient groups, a higher degree of interstitial fibrosis in biopsy samples and more late-enhancement magnetic resonance imaging segments were observed. A close inverse correlation was found between interstitial fibrosis and mitral ring displacement (r = -0.79, p < 0.0001). Clinical outcome was best for patients in group 1, whereas mortality risk increased substantially in groups 2 through 4. In severe AS, a low gradient is associated with a higher degree of fibrosis, decreased longitudinal function, and poorer clinical outcome despite preserved EF. Mitral ring displacement differentiates between moderate AS and low-gradient/severe AS with preserved EF.

Right Atrial Scar Detection after Catheter Ablation: Comparison of 2D and High Spatial Resolution 3D-late Enhancement Magnetic Resonance Imaging

To prospectively compare the diagnostic performance of two-dimensional (2D) and high spatial resolution three-dimensional (3D) late enhancement magnetic resonance imaging (MRI) for the detection of scar tissue caused by catheter ablation of the right atrium in patients with atrial flutter. Forty-seven patients were enrolled. In 16 patients, imaging of the cavotricuspid isthmus was performed before and after catheter ablation, 16 subjects were imaged before, and 15 after catheter ablation, resulting in a total of 63 examinations. MRI included a standard 2D breathhold and a high-resolution navigator-gated 3D T1-weighted gradient-echo inversion-recovery sequence in right and left anterior oblique views. Two readers assessed the subjective image quality on a 4-point scale (1 = excellent) and the presence of late enhancement (blinded/ in consensus). The average image quality was 1.6 for both imaging approaches. In consensus reading, the sensitivity was 83% versus 100%, specificity 97% versus 89%, accuracy 90% versus 94%, positive predictive value 96% versus 89%, negative predictive value 86% versus 100% for 2D and 3D, respectively. The interobserver agreement was 0.86 for 2D and 0.78 for 3D imaging. For the noninvasive identification of scars in the cavotricuspid isthmus after right atrial flutter, ablation 2D imaging was more consistent, whereas 3D sequences showed superior sensitivity for the depiction of late enhancement.

Aborted myocardial infarction in intracoronary compared with standard intravenous abciximab administration in patients undergoing primary percutaneous coronary intervention for ST-elevation myocardial infarction

Backgound Abciximab reduces major adverse cardiac events (MACEs) in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). Intracoronary (IC) abciximab bolus application might be more effective than a standard intravenous (IV) bolus. So far the occurrence of aborted MI, a new therapeutic target of effective treatment in STEMI, has not been evaluated in IC versus IV abciximab administration in STEMI patients undergoing primary PCI. Methods To investigate the extent of aborted MI, 154 patients undergoing primary PCI were randomized to either IC (n = 77) or IV (n = 77) bolus abciximab administration with subsequent 12-hour intravenous infusion. For assessment of infarct size and extent of microvascular obstruction, all patients underwent late enhancement magnetic resonance imaging (MRI). Aborted MI was defined by major (≥ 50%) ST-segment resolution and a lack of subsequent cardiac enzyme rise ≥ 2 the upper normal limit. We also assessed the occurrence of true aborted MI defined as the absence of myocardial necrosis in MRI. Results The incidence of aborted MI was significantly higher in the IC group (p = 0.04); true aborted MI was only observed in the IC abciximab group (p = 0.01). At multivariable logistic regression analysis, IC abciximab application was a significant independent predictor of true aborted MI (p = 0.03). Aborted MI patients had an excellent prognosis at 6-month follow-up with no MACE as compared to 24 events in patients with non-aborted MI. Conclusions IC bolus application of abciximab in STEMI patients undergoing primary PCI results in a higher incidence of aborted MI and subsequent improved clinical outcome.

Usefulness of Radial Strain Mapping by Multidetector Computer Tomography to Quantify Regional Myocardial Function in Patients With Healed Myocardial Infarction

We introduce and evaluate strain mapping by multidetector computer tomography as a new noninvasive method for assessment of myocardial function. In patients (n = 16) with healed myocardial infarction, peak systolic radial strain was measured by automated pixel pattern matching analysis of multiple left ventricular 64-slice multidetector computer tomographic short-axis recordings. For comparison, radial strain and myocardial infarct extent were measured by tagged magnetic resonance imaging (MRI) and late enhancement MRI, respectively. In a linear mixed model analysis, myocardial infarct extent was a strong predictor of segmental strain by multidetector computer tomography (beta = -0.44, p <0.0001). Strain was significantly different among noninfarcted (0%), nontransmurally infarcted (0% to 50%), and transmurally infarcted (>50%) segments (p <0.001) and between infarcted and noninfarcted border zone segments (p <0.001). There was a close relation between strain by multidetector computer tomography and by tagged MRI (mean difference -7.4 +/- 11.7%, r = 0.68, p <0.0001). Mean time-to-peak systolic strain was 324 +/- 42 ms by multidetector computer tomography and 335 +/- 56 ms by tagged MRI (mean difference 11 +/- 40 ms). In conclusion, to our knowledge this is the first study to demonstrate that regional myocardial function can be quantified by multidetector computer tomographic imaging, indicating that assessment of radial strain by multidetector computer tomography might be a useful tool in the evaluation of patients with cardiovascular diseases.

P-135 Surgical Strategy for Ischemic Cardiomyopathy Based on the Assessment of Myocardial Viability by Late-Enhancement Magnetic Resonance Imaging

P-135 Surgical Strategy for Ischemic Cardiomyopathy Based on the Assessment of Myocardial Viability by Late-Enhancement Magnetic Resonance Imaging