Antonildes N Assunção

A computational framework to characterize and compare the geometry of coronary networks

This work presents a computational framework to perform a systematic and comprehensive assessment of the morphometry of coronary arteries from in vivo medical images. The methodology embraces image segmentation, arterial vessel representation, characterization and comparison, data storage, and finally analysis. Validation is performed using a sample of 48 patients. Data mining of morphometric information of several coronary arteries is presented. Results agree to medical reports in terms of basic geometric and anatomical variables. Concerning geometric descriptors, inter-artery and intra-artery correlations are studied. Data reported here can be useful for the construction and setup of blood flow models of the coronary circulation. Finally, as an application example, similarity criterion to assess vasculature likelihood based on geometric features is presented and used to test geometric similarity among sibling patients. Results indicate that likelihood, measured through geometric descriptors, is stronger between siblings compared with non-relative patients. Copyright

Decreased glycolytic metabolism in non-compaction cardiomyopathy by 18F-fluoro-2-deoxyglucose positron emission tomography: new insights into pathophysiological mechanisms and clinical implications

Aims The pathophysiological mechanisms of left ventricular non-compaction cardiomyopathy (LVNC) remain controversial. This study performed combined 18F-fluoro-2-deoxyglucose dynamic positron emission tomography (FDG-PET) and 99mTc-sestamibi single-photon emission computed tomography (SPECT) studies to evaluate myocardial glucose metabolism and perfusion in patients with LVNC and their clinical implications. Methods and results Thirty patients (41 ± 12 years, 53% male) with LVNC, diagnosed by cardiovascular magnetic resonance (CMR) criteria, and eight age-matched healthy controls (42 ± 12 years, 50% male) were prospectively recruited to undergo FDG-PET with measurement of the myocardial glucose uptake rate (MGU) and SPECT to investigate perfusion-metabolism patterns. Patients with LVNC had lower global MGU compared with that in controls (36.9 ± 8.8 vs. 44.6 ± 5.4 μmol/min/100 g, respectively, P = 0.02). Of 17 LV segments, MGU levels were significantly reduced in 8, and also a reduction was observed when compacted segments from LVNC were compared with the segments from control subjects (P < 0.001). Perfusion defects were also found in 15 (50%) patients (45 LV segments: 64.4% match, and 35.6% mismatch perfusion-metabolism pattern). Univariate and multivariate analyses showed that beta-blocker therapy was associated with increased MGU (beta coefficient = 10.1, P = 0.008). Moreover, a gradual increase occurred in MGU across the beta-blocker dose groups (P for trend = 0.01). Conclusion The reduction of MGU documented by FDG-PET in LVNC supports the hypothesis that a cellular metabolic pathway may play a role in the pathophysiology of LVNC. The beneficial effect of beta-blocker mediating myocardial metabolism in the clinical course of LVNC requires further investigation.

On the search of arterial geometry heritability

BACKGROUND Geometrical risk factors for CAD have been previously proposed before. To date, however, the effect of those factors is not conclusive, and remains as an open research field. Here, we hypothesize that some of these factors have a genetic component explaining inter-individual variability. OBJECTIVE To detect heritability indicators of the coronary arterial geometry. MATERIALS AND METHODS A patient sample of 48 individuals, consisting of 24 siblings, was used. Three dimensional geometry of the LAD, LCx and RCA were reconstructed from standard CCTA. Arterial models were characterized in terms of 20+ geometric descriptors (phenotypes). A comprehensive statistical analysis to detect potential heritability of such phenotypes was employed. Heritability was assessed by means of several statistical indexes. Finally, the association of phenotypes to stenotic lesion is also reported. RESULTS The RCA scored positive indications for heritability in 15+ phenotypes, while the LAD in 10 and the LCx in only 3 phenotypes. Association between presence of lesion and phenotypes was higher in the LAD, 10+ phenotypes, while for the LCx only 2 phenotypes were significantly associated, and none association was found for the RCA. CONCLUSION The RCA showed potential heritability for the largest number of phenotypes, followed by the LAD. The LCx presents the weaker association of morphology among siblings. Regarding lesion-geometry associations, the there are hints of an underlying relation in the LAD, the LCx featured a weaker association and the RCA showed none. This difference could be related to the different hemodynamic environments in these arteries.

Myocardial extracellular volume fraction and myocardial fibrosis by cmr in patients with severe aortic stenosis

Background Severe aortic stenosis (AS) induces diffuse interstitial myocardial fibrosis (MF). CMR late gadolinium enhancement (LGE) technique is useful to detect focal MF. The amount of MF is associated with worse long-term prognosis after aortic valve replacement surgery (AVR). Measurements of T1 relaxation times before and after gadolinium administration allow determination of myocardial extracellular volume fraction (ECV) in order to assess diffuse MF. In this study we investigated ECV and LGE prevalence and extent in severe AS, and compare them to left ventricular (LV), aortic valve (AV) function and MF by biopsy.

Myocardial perfusion in patients with suspected coronary artery disease: comparison between 320-MDCT and rubidium-82 PET

ObjectivesDespite advances in non-invasive myocardial perfusion imaging (MPI) evaluation, computed tomography (CT) multiphase MPI protocols have not yet been compared with the highly accurate rubidium-82 positron emission tomography (82RbPET) MPI. Thus, this study aimed to evaluate agreement between 82RbPET and 320-detector row CT (320-CT) MPI using a multiphase protocol in suspected CAD patients.MethodsForty-four patients referred for MPI evaluation were prospectively enrolled and underwent dipyridamole stress 82RbPET and multiphase 320-CT MPI (five consecutive volumetric acquisitions during stress). Statistical analyses were performed using the R software.ResultsThere was high agreement for recognizing summed stress scores ≥ 4 (kappa 0.77, 95% CI 0.55–0.98, p < 0.001) and moderate for detecting SDS ≥ 2 (kappa 0.51, 95% CI 0.23–0.80, p < 0.001). In a per segment analysis, agreement was high for the presence of perfusion defects during stress and rest (kappa 0.75 and 0.82, respectively) and was moderate for impairment severity (kappa 0.58 and 0.65, respectively). The 320-CT protocol was safe, with low radiation burden (9.3 ± 2.4 mSv).ConclusionsThere was a significant agreement between dipyridamole stress 320-CT MPI and 82RbPET MPI in the evaluation of suspected CAD patients of intermediate risk. The multiphase 320-CT MPI protocol was feasible, diagnostic and with relatively low radiation exposure.Key Points• Rubidium-82 PET and 320-MDCT can perform MPI studies for CAD investigation.• There is high agreement between rubidium-82 PET and 320-MDCT for MPI assessment.• Multiphase CT perfusion protocols are feasible and with low radiation.• Multiphase CT perfusion protocols can identify image artefacts.

Myocardial T1 mapping and extracellular volume quantification in patients with left ventricular non-compaction cardiomyopathy.

Aims From pathophysiological mechanisms to risk stratification and management, much debate and discussion persist regarding left ventricular non-compaction cardiomyopathy (LVNC). This study aimed to characterize myocardial T1 mapping and extracellular volume (ECV) fraction by cardiovascular magnetic resonance (CMR), and investigate how these biomarkers relate to left ventricular ejection fraction (LVEF) and ventricular arrhythmias (VA) in LVNC. Methods and results Patients with LVNC (n = 36) and healthy controls (n = 18) were enrolled to perform a CMR with T1 mapping. ECV was quantified in LV segments without late gadolinium enhancement (LGE) areas to investigate diffuse myocardial fibrosis. Patients with LVNC had slightly higher native T1 (1024 ± 43 ms vs. 995 ± 22 ms, P = 0.01) and substantially expanded ECV (28.0 ± 4.5% vs. 23.5 ± 2.2%, P < 0.001) compared to controls. The ECV was independently associated with LVEF (β = -1.3, P = 0.001). Among patients without LGE, VAs were associated with higher ECV (27.7% with VA vs. 25.8% without VA, P = 0.002). Conclusion In LVNC, tissue characterization by T1 mapping suggests an extracellular expansion by diffuse fibrosis in myocardium without LGE, which was associated with myocardial dysfunction and VA, but not with the amount of non-compacted myocardium.

Rare association of endomyocardial fibrosis and Chagas heart disease

Chagas heart disease (CD) and endomyocardial fibrosis (EMF) are distinct and uncommon cardiomyopathies that can lead to a very poor prognosis. Both diseases are mostly found in African and South- and Central American countries. The patient presented in this case was from an area in Brazil endemic for Chagas disease. CD results from infection by the protozoan Trypanossoma cruzi and is associated with typical electrocardiographic and echocardiographic findings, including posteroinferior wall motion abnormalities in the left ventricle, as well as apical aneurysm. On the other hand, the underlying cause and mechanisms of EMF remain unclear. Obliteration of one or both ventricular apices might be seen. …

Gender and myocardial fibrosis by CMR are independent predictors of myocardial dysfunction in patients with Chagas' heart disease

LVD was present in 45.3% of patients and was more frequent in male than in female (32.9% vs. 67.1%, p<0,001). The presence of MF was greater in male than in female group (42.4% vs. 57.6%, respectively, p<0,001). Quantified MF was significantly higher in males (16.8% vs. 7.4%, p<0.001). Functional class (FC-NYHA) was also significantly greater in males (Table 1 and 2). There was a good and significant negative correlation between LVEF and MF (r=-0.69, p<0.001). A multivariate model using logistic regression showed that gender and MF are independent predictors of LVD, with an OR=6.17 for males (p=0.02) and 1.27 (p<0.001) for MF. Conclusions

Age-related creatinophosphokinase and myocardial fibrosis changes in patients with muscular dystrophy

Background Duchenne (DMD) and Becker (BMD) muscular dystrophy (MD) are characterized by progressive peripheral muscular damage. The cardiac involvement is high and often complicated by severe heart failure and high mortality. Cardiovascular magnetic resonance (CMR) can identify early stages of cardiomyopathy, as presence of myocardial fibrosis (MF). Several studies have shown negative correlation between creatinophosphokinase (CPK) levels and worst stages of peripheral muscular dystrophy, but have not evaluated their possible association with myocardial damage. Our objective was to investigate CPK levels and magnitude of myocardial damage in patients with MD. Methods

Myocardial fibrosis comparison by cmr between genetically positive HCM patients with MYBPC3 and MYH7 gene mutations

Background Advances in tissue characterization with late gadolinium enhancement (LGE) by cardiovascular magnetic resonance (CMR) have highlighted the importance of myocardial fibrosis (MF) in hypertrophic cardiomyopathy (HCM) by confirming that its presence and extent predicts adverse outcomes. Despite of the identification of several genes related to HCM, few studies have investigated the association between genotype and MF. In this study, we sought to investigate the relationship between two most common gene mutations in HCM and the extension of MF by LGE.