Background:Myocardial perfusion reflects the macro- and microvascular coronary circulation. Recen... more Background:Myocardial perfusion reflects the macro- and microvascular coronary circulation. Recent quantitation developments using cardiovascular magnetic resonance (CMR) perfusion permit automated measurement clinically. We explored the prognostic significance of stress myocardial blood flow (MBF) and myocardial perfusion reserve (MPR, the ratio of stress to rest MBF).Methods:A two center study of patients with both suspected and known coronary artery disease referred clinically for perfusion assessment. Image analysis was performed automatically using a novel artificial intelligence approach deriving global and regional stress and rest MBF and MPR. Cox proportional hazard models adjusting for co-morbidities and CMR parameters sought associations of stress MBF and MPR with death and major adverse cardiovascular events (MACE), including myocardial infarction, stroke, heart failure hospitalization, late (>90 day) revascularization and death.Results:1049 patients were included with...
Background: Automated analysis of cardiac structure and function using machine learning (ML) has ... more Background: Automated analysis of cardiac structure and function using machine learning (ML) has great potential, but is currently hindered by poor generalizability. Comparison is traditionally against clinicians as a reference, ignoring inherent human inter- and intraobserver error, and ensuring that ML cannot demonstrate superiority. Measuring precision (scan:rescan reproducibility) addresses this. We compared precision of ML and humans using a multicenter, multi-disease, scan:rescan cardiovascular magnetic resonance data set. Methods: One hundred ten patients (5 disease categories, 5 institutions, 2 scanner manufacturers, and 2 field strengths) underwent scan:rescan cardiovascular magnetic resonance (96% within one week). After identification of the most precise human technique, left ventricular chamber volumes, mass, and ejection fraction were measured by an expert, a trained junior clinician, and a fully automated convolutional neural network trained on 599 independent multicen...
Detecting early cardiac involvement in Fabry disease (FD) is important because therapy may alter ... more Detecting early cardiac involvement in Fabry disease (FD) is important because therapy may alter disease progression. Cardiovascular magnetic resonance (CMR) can detect T1 lowering, representing myocardial sphingolipid storage. In many diseases, early mechanical dysfunction may be detected by abnormal global longitudinal strain (GLS). We explored the relationship of early mechanical dysfunction and sphingolipid deposition in FD. An observational study of 221 FD and 77 healthy volunteers (HVs) who underwent CMR (LV volumes, mass, native T1, GLS, late gadolinium enhancement), ECG and blood biomarkers, as part of the prospective multicentre Fabry400 study. All FD had normal LV ejection fraction (EF 73%±8%). Mean indexed LV mass (LVMi) was 89±39 g/m in FD and 55.6±10 g/m in HV. 102 (46%) FD participants had left ventricular hypertrophy (LVH). There was a negative correlation between GLS and native T1 in FD patients (r=-0.515, p<0.001). In FD patients without LVH (early disease), as n...
Fungicide penetration of the peanut (Arachis hypogaea) canopy to target soilborne pathogens is di... more Fungicide penetration of the peanut (Arachis hypogaea) canopy to target soilborne pathogens is difficult due to the dense foliage present when mid- to late-season applications are made. To assess the effect of application timing and volume on leaf spot and stem rot control as well as peanut yield, pyraclostrobin (0.21 kg a.i./ha) or chlorothalonil (1.26 kg a.i./ha), a systemic and a contact fungicide, respectively, were applied four times on cv. Georgia Green during the day (on unfolded leaves) or at night (on folded leaves) at 187, 243, or 355 liters/ha. Night application of pyraclostrobin, across spray volumes, gave the best stem rot control and pod yield increase. Pyraclostrobin applied during the day at higher spray volumes also slightly increased control of stem rot, apparently by improving canopy penetration. Neither application timing nor spray volume affected leaf spot control with pyraclostrobin. Higher spray volumes for the chlorothalonil applications tended to improve con...
Background:Myocardial perfusion reflects the macro- and microvascular coronary circulation. Recen... more Background:Myocardial perfusion reflects the macro- and microvascular coronary circulation. Recent quantitation developments using cardiovascular magnetic resonance (CMR) perfusion permit automated measurement clinically. We explored the prognostic significance of stress myocardial blood flow (MBF) and myocardial perfusion reserve (MPR, the ratio of stress to rest MBF).Methods:A two center study of patients with both suspected and known coronary artery disease referred clinically for perfusion assessment. Image analysis was performed automatically using a novel artificial intelligence approach deriving global and regional stress and rest MBF and MPR. Cox proportional hazard models adjusting for co-morbidities and CMR parameters sought associations of stress MBF and MPR with death and major adverse cardiovascular events (MACE), including myocardial infarction, stroke, heart failure hospitalization, late (>90 day) revascularization and death.Results:1049 patients were included with...
Background: Automated analysis of cardiac structure and function using machine learning (ML) has ... more Background: Automated analysis of cardiac structure and function using machine learning (ML) has great potential, but is currently hindered by poor generalizability. Comparison is traditionally against clinicians as a reference, ignoring inherent human inter- and intraobserver error, and ensuring that ML cannot demonstrate superiority. Measuring precision (scan:rescan reproducibility) addresses this. We compared precision of ML and humans using a multicenter, multi-disease, scan:rescan cardiovascular magnetic resonance data set. Methods: One hundred ten patients (5 disease categories, 5 institutions, 2 scanner manufacturers, and 2 field strengths) underwent scan:rescan cardiovascular magnetic resonance (96% within one week). After identification of the most precise human technique, left ventricular chamber volumes, mass, and ejection fraction were measured by an expert, a trained junior clinician, and a fully automated convolutional neural network trained on 599 independent multicen...
Detecting early cardiac involvement in Fabry disease (FD) is important because therapy may alter ... more Detecting early cardiac involvement in Fabry disease (FD) is important because therapy may alter disease progression. Cardiovascular magnetic resonance (CMR) can detect T1 lowering, representing myocardial sphingolipid storage. In many diseases, early mechanical dysfunction may be detected by abnormal global longitudinal strain (GLS). We explored the relationship of early mechanical dysfunction and sphingolipid deposition in FD. An observational study of 221 FD and 77 healthy volunteers (HVs) who underwent CMR (LV volumes, mass, native T1, GLS, late gadolinium enhancement), ECG and blood biomarkers, as part of the prospective multicentre Fabry400 study. All FD had normal LV ejection fraction (EF 73%±8%). Mean indexed LV mass (LVMi) was 89±39 g/m in FD and 55.6±10 g/m in HV. 102 (46%) FD participants had left ventricular hypertrophy (LVH). There was a negative correlation between GLS and native T1 in FD patients (r=-0.515, p<0.001). In FD patients without LVH (early disease), as n...
Fungicide penetration of the peanut (Arachis hypogaea) canopy to target soilborne pathogens is di... more Fungicide penetration of the peanut (Arachis hypogaea) canopy to target soilborne pathogens is difficult due to the dense foliage present when mid- to late-season applications are made. To assess the effect of application timing and volume on leaf spot and stem rot control as well as peanut yield, pyraclostrobin (0.21 kg a.i./ha) or chlorothalonil (1.26 kg a.i./ha), a systemic and a contact fungicide, respectively, were applied four times on cv. Georgia Green during the day (on unfolded leaves) or at night (on folded leaves) at 187, 243, or 355 liters/ha. Night application of pyraclostrobin, across spray volumes, gave the best stem rot control and pod yield increase. Pyraclostrobin applied during the day at higher spray volumes also slightly increased control of stem rot, apparently by improving canopy penetration. Neither application timing nor spray volume affected leaf spot control with pyraclostrobin. Higher spray volumes for the chlorothalonil applications tended to improve con...
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Papers by Joao Augusto