Volumetric Quantification of Myocardial Perfusion Using Analysis of Multi-Detector Computed Tomography 3D Datasets

Abstract Multi-detector computed tomography (MDCT) assessment of myocardial perfusion is based on visualization of 2D slices. To overcome the subjective nature of this analysis, we developed a new technique for quantification of myocardial perfusion from MDCT 3D datasets and tested it against nuclear myocardial perfusion imaging (MPI Introduction While MDCT is increasingly used as an alternative to invasive coronary angiography, recent studies have demonstrated its potential to provide perfusion information, which could be a valuable addition in the diagnosis of coronary artery disease (CAD). These studies reported hypoenhanced areas corresponding to scar visualized in patients post myocardial infarction (MI), and in animals with acute MI We recently developed a new quantitative index of perfusion that was designed to take into account these differences, and tested it on 2D slices. The addition of this analysis improved the diagnostic accuracy of MDCT evaluation of CAD, especially in patients with high calcium scores and stents Methods We studied 44 patients who underwent CT coronary angiography (CTCA) for the evaluation of CAD. These patients were divided into a study group of 29 patients (age: 62±10, 23 males) who also had MPI within 57±72 days (14 patient with normal MPI both at rest and stress and 15 patients with perfusion defects on MPI), and a control group of 15 patients (age: 58±16, 8 males) who had normal MPI both at rest and stress and no significant stenosis on CTCA. Patients who underwent coronary interventions between MPI and CTCA were excluded. MDCT imaging All CTCA studies were clinically indicated and performed according to a standard protocol. Images were obtained using an MDCT scanner (64-channels, Philips) with retrospective ECG-gating. A nonionic iodinated contrast agent was used (40-80 ml iv at 5-6 ml/sec)

Automated left ventricular diastolic function evaluation from phase-contrast cardiovascular magnetic resonance and comparison with Doppler echocardiography

International audienceBACKGROUND: Early detection of diastolic dysfunction is crucial for patients with incipient heart failure. Although this evaluation could be performed from phase-contrast (PC) cardiovascular magnetic resonance (CMR) data, its usefulness in clinical routine is not yet established, mainly because the interpretation of such data remains mostly based on manual post-processing. Accordingly, our goal was to develop a robust process to automatically estimate velocity and flow rate-related diastolic parameters from PC-CMR data and to test the consistency of these parameters against echocardiography as well as their ability to characterize left ventricular (LV) diastolic dysfunction. RESULTS: We studied 35 controls and 18 patients with severe aortic valve stenosis and preserved LV ejection fraction who had PC-CMR and Doppler echocardiography exams on the same day. PC-CMR mitral flow and myocardial velocity data were analyzed using custom software for semi-automated extraction of diastolic parameters. Inter-operator reproducibility of flow pattern segmentation and functional parameters was assessed on a sub-group of 30 subjects. The mean percentage of overlap between the transmitral flow segmentations performed by two independent operators was 99.7 ± 1.6%, resulting in a small variability ( 0.71) and receiver operating characteristic (ROC) analysis revealed their ability to separate patients from controls, with sensitivity > 0.80, specificity > 0.80 and accuracy > 0.85. Slight superiority in terms of correlation with echocardiography (r = 0.81) and accuracy to detect LV abnormalities (sensitivity > 0.83, specificity > 0.91 and accuracy > 0.89) was found for the PC-CMR flow-rate related parameters. CONCLUSIONS: A fast and reproducible technique for flow and myocardial PC-CMR data analysis was successfully used on controls and patients to extract consistent velocity-related diastolic parameters, as well as flow rate-related parameters. This technique provides a valuable addition to established CMR tools in the evaluation and the management of patients with diastolic dysfunction

Assessment of acute myocardial infarction: current status and recommendations from the North American society for cardiovascular imaging and the European society of cardiac radiology

There are a number of imaging tests that are used in the setting of acute myocardial infarction and acute coronary syndrome. Each has their strengths and limitations. Experts from the European Society of Cardiac Radiology and the North American Society for Cardiovascular Imaging together with other prominent imagers reviewed the literature. It is clear that there is a definite role for imaging in these patients. While comparative accuracy, convenience and cost have largely guided test decisions in the past, the introduction of newer tests is being held to a higher standard which compares patient outcomes. Multicenter randomized comparative effectiveness trials with outcome measures are required

A Tutorial on EEG Signal Processing Techniques for Mental State Recognition in Brain-Computer Interfaces

International audienceThis chapter presents an introductory overview and a tutorial of signal processing techniques that can be used to recognize mental states from electroencephalographic (EEG) signals in Brain-Computer Interfaces. More particularly, this chapter presents how to extract relevant and robust spectral, spatial and temporal information from noisy EEG signals (e.g., Band Power features, spatial filters such as Common Spatial Patterns or xDAWN, etc.), as well as a few classification algorithms (e.g., Linear Discriminant Analysis) used to classify this information into a class of mental state. It also briefly touches on alternative, but currently less used approaches. The overall objective of this chapter is to provide the reader with practical knowledge about how to analyse EEG signals as well as to stress the key points to understand when performing such an analysis

Comparison of various methods for the estimation for aortic characteristic impedance in time domain from velocity-encoded magnetic resonance and applanation tonometry data

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Numerical modeling of arterial pulse wave propagation to characterize aortic hemodynamic: Validation using magnetic resonance data

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Evaluation of aortic flow alterations using MRI: Associations with left ventricular remodeling

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Non-invasive determination of ascending aortic impedance

Background: Non-invasive studies of ascending aortic (AA) impedance, using Doppler flow and carotid tonometry have not confirmed the aging changes demonstrated with invasive electromagnetic flow/micromanometer catheters in humans. Aim: To determine AA impedance from cardiac magnetic resonance imaging (CMRI) flow recorded non-invasively and carotid pressure tonometry, and compare results with previously reported invasive data and realistic arterial model (O’Rourke and Avolio, Circ Res 1980;46;363–372). Methods: Fifty apparently normal subjects (aged 21–70 years; 28 males) underwent velocity-encoded CMRI of the thoracic aorta using a 1.5T system (Signa, GEMS, Waukesha, USA). AA flow was measured non-invasively by subtracting simultaneous forward and backward flow velocity across the AA cross-section. Impedance was determined by relating in modulus and phase, corresponding frequency components of the AA flow waveforms with tonometric carotid pressure waveforms (used as surrogate of AA pressure) and recorded sequentially after CMRI. Data were presented in 5 age groups: 21–30, 31–40, 41–50, 51–60 and 61–70 years. Results: Values of impedance modulus and phase were similar to those previously reported for invasive studies, and with impedance modulus being higher in older than younger subjects up to 3 Hz (reflecting higher peripheral resistance in older subjects, and impedance phase crossed from negative to positive values between 3 and 4.5 Hz. Characteristic impedance (taken as average modulus 5–6 Hz) was 710 dyne.s.cm⁻³. Values of AA impedance fall within the range calculated for a realistic model of the arterial system between age 20 and 80 years. Conclusion: AA impedance values calculated non-invasively from AA CMRI flow waveforms and carotid pressure waveforms show the same pattern as seen with invasive studies in older and younger subjects and lie within the same range as predicted form models at age 20 to 80 years. Better correspondence is expected when AA pressure waveforms can be measured in the magnet room simultaneously with AA flow acquisition.2 page(s

Automatic Detection and Classification of High-Frequency Oscillations in Depth-EEG Signals

International audienceGoal: Interictal high-frequency oscillations (HFOs [30-600 Hz]) have proven to be relevant biomarkers in epilepsy. In this paper, four categories of HFOs are considered: Gamma ([30-80 Hz]), high-gamma ([80-120 Hz]), ripples ([120-250 Hz]), and fast-ripples ([250-600 Hz]). A universal detector of the four types of HFOs is proposed. It has the advantages of 1) classifying HFOs, and thus, being robust to inter and intrasubject variability; 2) rejecting artefacts, thus being specific. Methods : Gabor atoms are tuned to cover the physiological bands. Gabor transform is then used to detect HFOs in intracerebral electroencephalography (iEEG) signals recorded in patients candidate to epilepsy surgery. To extract relevant features, energy ratios, along with event duration, are investigated. Discriminant ratios are optimized so as to maximize among the four types of HFOs and artefacts. A multiclass support vector machine (SVM) is used to classify detected events. Pseudoreal signals are simulated to measure the performance of the method when the ground truth is known. Results: Experiments are conducted on simulated and on human iEEG signals. The proposed method shows high performance in terms of sensitivity and false discovery rate. Conclusion: The methods have the advantages of detecting and discriminating all types of HFOs as well as avoiding false detections caused by artefacts. Significance: Experimental results show the feasibility of a robust and universal detector. © 1964-2012 IEEE