ROBERTO NERY DANTAS JUNIOR
Projetos de Pesquisa
Unidades Organizacionais
LIM/65, Hospital das Clínicas, Faculdade de Medicina
4 resultados
Resultados de Busca
Agora exibindo 1 - 4 de 4
- Myocardial T1 mapping and extracellular volume quantification in patients with left ventricular non-compaction cardiomyopathy(2018) ARAUJO-FILHO, Jose A. B.; ASSUNCAO JR., Antonildes N.; MELO, Marcelo D. Tavares de; BIERE, Loic; LIMA, Camila R.; DANTAS JR., Roberto N.; NOMURA, Cesar H.; SALEMI, Vera M. C.; JEROSCH-HEROLD, Michael; PARGA, Jose R.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 +/- 43ms 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 (beta = -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 noncompacted myocardium.
- Decreased glycolytic metabolism in non-compaction cardiomyopathy by F-18-fluoro-2-deoxyglucose positron emission tomography: new insights into pathophysiological mechanisms and clinical implications(2017) MELO, Marcelo Dantas Tavares de; GIORGI, Maria Clementina Pinto; ASSUNCAO JR., Antonildes Nascimento; DANTAS JR., Roberto Nery; ARAUJO FILHO, Jose de Arimateia; PARGA FILHO, Jose Rodrigues; BIERRENBACH, Ana Luiza de Souza; LIMA, Camila Rocon de; SOARES JR., Jose; MENEGUETTI, Jose Claudio; MADY, Charles; HAJJAR, Ludhmila Abrahao; KALIL FILHO, Roberto; BOCCHI, Edimar Alcides; SALEMI, Vera Maria CuryAims The pathophysiological mechanisms of left ventricular non-compaction cardiomyopathy (LVNC) remain controversial. This study performed combined F-18-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 mu mol/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.
- A combined deep-learning approach to fully automatic left ventricle segmentation in cardiac magnetic resonance imaging(2019) MORENO, Ramon A.; REBELO, Marina F. S. de Sa; CARVALHO, Talles; ASSUNCAO-JR, Antonildes N.; JR, Roberto N. Dantas; VAL, Renata do; MARIN, Angela S.; BORDIGNOM, Adriano; NOMURA, Cesar H.; GUTIERREZ, Marco A.In clinical practice, cardiac magnetic resonance imaging (CMR) is considered the gold-standard imaging modality for the evaluation of function and structure of the left ventricle (LV). However, the quantification of LV parameters in all frames, even when performed by experienced radiologists, is very time consuming mainly due to the inhomogeneity of cardiac structures within each image, the variability of the cardiac structures across subjects and the complicated global/regional temporal deformation of the myocardium during the cardiac cycle. In this work, we employed a combination of two convolutional neural networks (CNN) to develop a fully automatic LV segmentation method for Short Axis CMR datasets. The first CNN defines the region of interest (ROI) of the cardiac chambers based on You Only Look Once (YOLO) network. The output of YOLO net is used to filter the image and feed the second CNN, based on U-Net network, which segments the myocardium and the blood pool. The method was validated in CMR exams of 59 individuals from an institutional clinical protocol. Segmentation results, evaluated by metrics Percentage of Good Contours, Dice Index and Average Perpendicular distance, were 98,59% +/- 4,28%, 0,93 +/- 0,06 and 0,72 mm +/- 0,62 mm, respectively, for the LV epicardium, and 94,98% +/- 14,04%, 0,86 +/- 0,13 and 1,19 mm +/- 1,29 mm, respectively, for the LV endocardium. The combination of two CNNs demonstrated good performance in terms of the evaluated metrics when compared to literature results.
- Clinical evaluation of left ventricular function and morphology using an accelerated k-t sensitivity encoding method in cardiovascular magnetic resonance(2019) ASSUNCAO- JR., Antonildes Nascimento; DANTAS- JR., Roberto Nery; VAL, Renata Margarida do; GIANOTTO, Priscilla; MARIN, Angela dos Santos; GOLDEN, Mark; GUTIERREZ, Marco Antonio; PARGA, Jose Rodrigues; NOMURA, Cesar HigaObjectivesTo provide clinical validation of a recent 2D SENSE-based accelerated cardiovascular magnetic resonance (CMR) sequence (accelerated k-t SENSE), investigating whether this technique accurately quantifies left ventricle (LV) volumes, function, and mass as compared to 2D cine steady-state free precession (2D-SSFP).MethodsHealthy volunteers (n=16) and consecutive heart failure patients (n=26) were scanned using a 1.5T MRI system. Two LV short axis (SA) stacks were acquired: (1) accelerated k-t SENSE (5-6 breath-holds; temporal/spatial resolution: 37ms/1.82x1.87mm; acceleration factor = 4) and (2) standard 2D-SSFP (10-12 breath-holds; temporal/spatial resolution: 49ms/1.67x1.87mm, parallel imaging). Ascending aorta phase-contrast was performed on all volunteers as a reference to compare LV stroke volumes (LVSV) and validate the sequences. An image quality score for SA images was used, with lower scores indicating better quality (from 0 to 18).ResultsThere was a high agreement between accelerated k-t SENSE and 2D-SSFP for LV measurements: bias (limits of agreement) of 2.4% (-5.4% to 10.1%), 6.9mL/m(2) (-4.7 to 18.6mL/m(2)), -1.5 (-8.3 to 5.2mL/m(2)), and -0.2g/m(2) (-11.9 to 12.3g/m(2)) for LV ejection fraction, end-diastolic volume index, end-systolic volume index, and mass index, respectively. LVSV by accelerated k-t SENSE presented good agreement with aortic flow. Interobserver and intraobserver variabilities for all LV parameters were also high.ConclusionThe accelerated k-t SENSE CMR sequence is clinically feasible and accurately quantifies LV volumes, function, and mass, with short acquisition time and good image quality.