ROBERTO NERY DANTAS JUNIOR
Projetos de Pesquisa
Unidades Organizacionais
LIM/65, Hospital das Clínicas, Faculdade de Medicina
10 resultados
Resultados de Busca
Agora exibindo 1 - 10 de 10
- Diagnostic Performance of a Machine Learning-Based CT-Derived FFR in Detecting Flow-Limiting Stenosis(2021) MORAIS, Thamara Carvalho; ASSUNCAO-JR, Antonildes Nascimento; DANTAS JUNIOR, Roberto Nery; SILVA, Carla Franco Grego da; PAULA, Caroline Bastida de; TORRES, Roberto Almeida; MAGALHAES, Tiago Augusto; NOMURA, Cesar Higa; AVILA, Luiz Francisco Rodrigues de; PARGA FILHO, Jose RodriguesBackground: The non-invasive quantification of the fractional flow reserve (FFRCT) using a more recent version of an artificial intelligence-based software and latest generation CT scanner (384 slices) may show high performance to detect coronary ischemia. Objectives: To evaluate the diagnostic performance of FFRCT for the detection of significant coronary artery disease (CAD) in contrast to invasive FFR (iFFR) using previous generation CT scanners (128 and 256-detector rows). Methods: Retrospective study with patients referred to coronary artery CT angiography (CTA) and catheterization (iFFR) procedures. Siemens Somatom Definition Flash (256-detector rows) and AS+ (128-detector rows) CT scanners were used to acquire the images. The FFRCT and the minimal lumen area (MLA) were evaluated using a dedicated software (cFFR version 3.0.0, Siemens Healthineers, Forchheim, Germany). Obstructive CAD was defined as CTA lumen reduction >= 50%, and flow-limiting stenosis as iFFR <= 0.8. All reported P values are two-tailed, and when <0.05, they were considered statistically significant. Results: Ninety-three consecutive patients (152 vessels) were included. There was good agreement between FFRCT and iFFR, with minimal FFRCT overestimation (bias: -0.02; limits of agreement:0.14-0.09). Different CT scanners did not modify the association between FFRCT and FFRi (p for interaction=0.73). The performance of FFRCT was significantly superior compared to the visual classification of coronary stenosis (AUC 0.93vs.0.61, p<0.001) and to MLA (AUC 0.93vs.0.75, p<0.001), reducing the number of false-positive cases. The optimal cut-off point for FFRCT using a Youden index was 0.85 (87% Sensitivity, 86% Specificity, 73% PPV, 94% NPV), with a reduction of false-positives. Conclusion: Machine learning-based FFRCT using previous generation CT scanners (128 and 256-detector rows) shows good diagnostic performance for the detection of CAD, and can be used to reduce the number of invasive procedures.
- Siamese pyramidal deep learning network for strain estimation in 3D cardiac cine-MR(2023) GRAVES, Catharine V.; REBELO, Marina F. S.; MORENO, Ramon A.; DANTAS-JR, Roberto N.; JR, Antonildes N. Assuncao; NOMURA, Cesar H.; GUTIERREZ, Marco A.Strain represents the quantification of regional tissue deformation within a given area. Myocardial strain has demonstrated considerable utility as an indicator for the assessment of cardiac function. Notably, it exhibits greater sensitivity in detecting subtle myocardial abnormalities compared to conventional cardiac function indices, like left ventricle ejection fraction (LVEF). Nonetheless, the estimation of strain poses considerable challenges due to the necessity for precise tracking of myocardial motion throughout the complete cardiac cycle. This study introduces a novel deep learning-based pipeline, designed to automatically and accurately estimate myocardial strain from three-dimensional (3D) cine-MR images. Consequently, our investigation presents a comprehensive pipeline for the precise quantification of local and global myocardial strain. This pipeline incorporates a supervised Convolutional Neural Network (CNN) for accurate segmentation of the cardiac muscle and an unsupervised CNN for robust left ventricle motion tracking, enabling the estimation of strain in both artificial phantoms and real cine-MR images. Our investigation involved a comprehensive comparison of our findings with those obtained from two commonly utilized commercial software in this field. This analysis encompassed the examination of both intra- and inter-user variability. The proposed pipeline exhibited demonstrable reliability and reduced divergence levels when compared to alternative systems. Additionally, our approach is entirely independent of previous user data, effectively eliminating any potential user bias that could influence the strain analyses.
- Myocardial perfusion in patients with suspected coronary artery disease: comparison between 320-MDCT and rubidium-82 PET(2018) DANTAS JR., Roberto Nery; ASSUNCAO JR., Antonildes Nascimento; MARQUES FILHO, Ismar Aguiar; FAHEL, Mateus Guimaraes; NOMURA, Cesar Higa; AVILA, Luiz Francisco Rodrigues; GIORGI, Maria Clementina Pinto; SOARES JR., Jose; MENEGHETTI, Jose Claudio; PARGA, Jose RodriguesDespite 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 ((RbPET)-Rb-82) MPI. Thus, this study aimed to evaluate agreement between (RbPET)-Rb-82 and 320-detector row CT (320-CT) MPI using a multiphase protocol in suspected CAD patients. Forty-four patients referred for MPI evaluation were prospectively enrolled and underwent dipyridamole stress (RbPET)-Rb-82 and multiphase 320-CT MPI (five consecutive volumetric acquisitions during stress). Statistical analyses were performed using the R software. There 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). There was a significant agreement between dipyridamole stress 320-CT MPI and (RbPET)-Rb-82 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. aEuro cent Rubidium-82 PET and 320-MDCT can perform MPI studies for CAD investigation. aEuro cent There is high agreement between rubidium-82 PET and 320-MDCT for MPI assessment. aEuro cent Multiphase CT perfusion protocols are feasible and with low radiation. aEuro cent Multiphase CT perfusion protocols can identify image artefacts.
- Ischemic stroke caused by large-artery atherosclerosis: a red flag for subclinical coronary artery disease(2023) ARAUJO, Ana Luiza Vieira de; SANTOS, Raul D.; BITTENCOURT, Marcio Sommer; DANTAS, Roberto Nery; OSHIRO, Carlos Andre; NOMURA, Cesar Higa; BOR-SENG-SHU, Edson; OLIVEIRA, Marcelo de Lima; LEITE, Claudia da Costa; MARTIN, Maria da Graca Morais; ALVES, Maramelia Miranda; SILVA, Gisele Sampaio; SILVA, Victor Marinho; CONFORTO, Adriana BastosBackgroundThe coronary calcium score (CAC) measured on chest computerized tomography is a risk marker of cardiac events and mortality. We compared CAC scores in two multiethnic groups without symptomatic coronary artery disease: subjects in the chronic phase after stroke or transient ischemic attack and at least one symptomatic stenosis >= 50% in the carotid or vertebrobasilar territories (Group(athero)) and a control group (Group(control)). MethodsIn this cross-sectional study, Group(athero) included two subgroups: Group(ExtraorIntra), with stenoses in either cervical or intracranial arteries, and Group(Extra&Intra), with stenoses in at least one cervical and one intracranial artery. Group(control) had no history of prior stroke/transient ischemic attacks and no stenoses >= 50% in cervical or intracranial arteries. Age and sex were comparable in all groups. Frequencies of CAC >= 100 and CAC > 0 were compared between Group(athero) and Group(control), as well as between Group(ExtraorIntr), Group(Extra&Intra), and Group(control), with bivariate logistic regressions. Multivariate analyses were also performed. ResultsA total of 120 patients were included: 80 in Group(athero) and 40 in Group(control.) CAC >0 was significantly more frequent in Group(athero) (85%) than Group(control) (OR, 4.19; 1.74-10.07; p = 0.001). Rates of CAC >= 100 were not significantly different between Group(athero) and Group(control) but were significantly greater in Group(Extra&Intra) (n = 13) when compared to Group(control) (OR 4.67; 1.21-18.04; p = 0.025). In multivariate-adjusted analyses, ""Group(athero)"" and ""Group(Extra&Intra)"" were significantly associated with CAC. ConclusionThe frequency of coronary calcification was higher in subjects with stroke caused by large-artery atherosclerosis than in controls.
- 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.
- Myocardial microstructure assessed by T1 mapping after on-pump and off-pump coronary artery bypass grafting(2023) DALLAZEN, Anderson Roberto; REZENDE, Paulo Cury; HUEB, Whady; HLATKY, Mark Andrew; NOMURA, Cesar Higa; ROCHITTE, Carlos Eduardo; BOROS, Gustavo Andre Boeing; RIBAS, Fernando Faglioni; RIBEIRO, Matheus de Oliveira Laterza; SCUDELER, Thiago Luis; DANTAS, Roberto Nery; RAMIRES, Jose Antonio Franchini; KALIL FILHO, RobertoBackground: The correlation between the release of cardiac biomarkers after revascularization, in the absence of late gadolinium enhancement (LGE) or myocardial edema, and the development of myocardial tissue damage remains unclear. This study sought to identify whether the release of biomarkers is associated with cardiac damage by assessing myocardial microstructure on T1 mapping after on-pump (ONCAB) and off-pump coronary artery bypass grafting (OPCAB). Methods: Seventy-six patients with stable multivessel coronary artery disease (CAD) and preserved systolic ventricular function were included. T1 mapping, high-sensitive cardiac troponin I (cTnI), creatine kinase myocardial band (CK-MB) mass, and ventricular dimensions and function were measured before and after procedures. Results: Of the 76 patients, 44 underwent OPCAB, and 32 ONCAB; 52 were men (68.4%), and the mean age was 63 +/- 8.5 years. In both OPCAB and ONCAB the native T1 values were similar before and after surgeries. An increase in extracellular volume (ECV) values after the procedures was observed, due to the decrease in hematocrit levels during the second cardiac resonance. However, the lambda partition coefficient showed no significant difference after the surgeries. The median peak release of cTnI and CK-MB were higher after ONCAB than after OPCAB [3.55 (2.12-4.9) vs. 2.19 (0.69-3.4) ng/mL, P=0.009 and 28.7 (18.2-55.4) vs. 14.3 (9.3-29.2) ng/mL, P=0.009, respectively]. Left ventricular ejection fraction (LVEF) was similar in both groups before and after surgery. Conclusions: In the absence of documented myocardial infarction, T1 mapping did not identify structural tissue damage after surgical revascularization with or without cardiopulmonary bypass (CPB), despite the excessive release of cardiac biomarkers.
- Radiation dose reduction by adjusting bolus tracking parameters in a 320-detector row scanner(2018) MATSUMOTO, Jacqueline Kioko Nishimura; ASSUNCAO JR., Antonildes Nascimento; DANTAS JUNIOR, Roberto Nery; ARAUJO-FILHO, Jose de Arimateia Batista; ANDRADE, Solange de Sousa; NOMURA, Cesar Higa; PARGA, Jose RodriguesBackground: The importance of bolus tracking (BT) regarding total effective radiation dose (ERD) in the era of advanced coronary computed tomography angiography (CTA) has been ignored. We aimed to investigate whether adjusting BT parameters reduces ERD. Methods: Adults consecutively referred to CTA (n = 289) in a 320 detector-row scanner were distributed into four BT protocols according to delay time and time between intermittent scans, as follows: A (n = 70, delay 10s, intermittent scans 1s); B (n = 79, delay 10s, intermittent scans 2s); C (n = 68, delay 15s, intermittent scans 1s); and D (n = 72, delay 15s, intermittent scans 2s). Image quality was assessed. Results: The overall ERD in BT and AP were 0.32 +/- 0.14 mSv and 6.06 +/- 0.66 mSv, respectively. ERD in BT was different among protocols (A: 0.44 +/- 0.14 mSv; B: 0.32 +/- 0.10 mSv; C: 0.28 +/- 0.14 mSv; D: 0.23 +/- 0.09 mSv; p < 0.001), with no loss in image quality. Adjusted for potential confounders (heart rate, tube current and acquisition window), protocol D provided the highest reduction in total ERD (beta = -0.33, p = 0.004). Conclusion: Delaying initiation of BT images (and acquiring them less frequently) reduces radiation dose and does not impair image quality.
- 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.
- Association between perivascular inflammation and downstream myocardial perfusion in patients with suspected coronary artery disease(2020) NOMURA, Cesar H.; ASSUNCAO-JR, Antonildes N.; GUIMARAES, Patricia O.; LIBERATO, Gabriela; MORAIS, Thamara C.; FAHEL, Mateus G.; GIORGI, Maria C. P.; MENEGHETTI, Jose C.; PARGA, Jose R.; DANTAS-JR, Roberto N.; CERRI, Giovanni G.Aims To investigate the association between pericoronary adipose tissue (PCAT) computed tomography (CT) attenuation derived from coronary computed tomography angiography (CTA) and coronary flow reserve (CFR) by positron emission tomography (PET) in patients with suspected coronary artery disease (CAD). Methods and results PCAT CT attenuation was measured in proximal segments of all major epicardial coronary vessels of 105 patients with suspected CAD. We evaluated the relationship between PCAT CT attenuation and other quantitative/qualitative CT-derived anatomic parameters with CFR by PET. Overall, the mean age was 60 +/- 12 years and 93% had intermediate pre-test probability of obstructive CAD. Obstructive CAD (>= 50% stenosis) was detected in 37 (35.2%) patients and impaired CFR (<2.0) in 32 (30.5%) patients. On a per-vessel analysis (315 vessels), obstructive CAD, non-calcified plaque volume, and PCAT CT attenuation were independently associated with CFR. In patients with coronary calcium score (CCS) <100, those with high-PCAT CT attenuation presented significantly lower CFR values than those with low-PCAT CT attenuation (2.47 +/- 0.95 vs. 3.13 +/- 0.89, P = 0.003). Among those without obstructive CAD, CFR was significantly lower in patients with high-PCAT CT attenuation (2.51 +/- 0.95 vs. 3.02 +/- 0.84, P = 0.021). Conclusion Coronary perivascular inflammation by CTA was independently associated with downstream myocardial perfusion by PET. In patients with low CCS or without obstructive CAD, CFR was lower in the presence of higher perivascular inflammation. PCAT CT attenuation might help identifying myocardial ischaemia particularly among patients who are traditionally considered non-high risk for future cardiovascular events.
- 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.