GPU Implementation of the Improved CEEMDAN Algorithm for Fast and Efficient EEG Time-Frequency Analysis

Time-frequency analysis of EEG data is a key step in exploring the internal activities of the human brain. Studying oscillations is an important part of the analysis, as they are thought to provide the underlying mechanism for communication between neural assemblies. Traditional methods of analysis, such as Short-Time FFT and Wavelet Transforms, are not ideal for this task due to the time-frequency uncertainty principle and their reliance on predefined basis functions. Empirical Mode Decomposition and its variants are more suited to this task as they are able to extract the instantaneous frequency and phase information but are too time consuming for practical use. Our aim was to design and develop a massively parallel and performance-optimized GPU implementation of the Improved Complete Ensemble EMD with the Adaptive Noise (CEEMDAN) algorithm that significantly reduces the computational time (from hours to seconds) of such analysis. The resulting GPU program, which is publicly available, was validated against a MATLAB reference implementation and reached over a 260× speedup for actual EEG measurement data, and provided predicted speedups in the range of 3000-8300× for longer measurements when sufficient memory was available. The significance of our research is that this implementation can enable researchers to perform EMD-based EEG analysis routinely, even for high-density EEG measurements. The program is suitable for execution on desktop, cloud, and supercomputer systems and can be the starting point for future large-scale multi-GPU implementations.

Event-Related Spectral Perturbation, Inter Trial Coherence, and Functional Connectivity in motor execution: A comparative EEG study of old and young subjects

INTRODUCTION

The motor-related bioelectric brain activity of healthy young and old subjects was studied to understand the effect of aging on motor execution. A visually cued finger tapping movement paradigm and high-density EEG were used to examine the time and frequency characteristics.

METHODS

Twenty-two young and 22 healthy elderly adults participated in the study. Repeated trials of left and right index finger movements were recorded with a 128-channel EEG. Event-Related Spectral Perturbation (ERSP), Inter Trial Coherence (ITC), and Functional Connectivity were computed and compared between the age groups.

RESULTS

An age-dependent theta and alpha band ERSP decrease was observed over the frontal-midline area. Decrease of beta band ERSP was found over the ipsilateral central-parietal regions. Significant ITC differences were found in the delta and theta bands between old and young subjects over the contralateral parietal-occipital areas. The spatial extent of increased ITC values was larger in old subjects. The movement execution of older subjects showed higher global efficiency in the delta and theta bands, and higher local efficiency and node strengths in the delta, theta, alpha, and beta bands.

CONCLUSION

As functional compensation of aging, elderly motor networks involve more nonmotor, parietal-occipital, and frontal areas, with higher global and local efficiency, node strength. ERSP and ITC changes seem to be sensitive and complementary biomarkers of age-related motor execution.

Heartbeat classification based on single lead-II ECG using deep learning

The analysis and processing of electrocardiogram (ECG) signals is a vital step in the diagnosis of cardiovascular disease. ECG offers a non-invasive and risk-free method for monitoring the electrical activity of the heart that can assist in predicting and diagnosing heart diseases. The manual interpretation of the ECG signals, however, can be challenging and time-consuming even for experts. Machine learning techniques are increasingly being utilized to support the research and development of automatic ECG classification, which has emerged as a prominent area of study. In this paper, we propose a deep neural network model with residual blocks (DNN-RB) to classify cardiac cycles into six ECG beat classes. The MIT-BIH dataset was used to validate the model resulting in a test accuracy of 99.51%, average sensitivity of 99.7%, and average specificity of 98.2%. The DNN-RB method has achieved higher accuracy than other state-of-the-art algorithms tested on the same dataset. The proposed method is effective in the automatic classification of ECG signals and can be used for both clinical and out-of-hospital monitoring and classification combined with a single-lead mobile ECG device. The method has also been integrated into a web application designed to accept digital ECG beats as input for analyses and to display diagnostic results.

Inter trial coherence of low-frequency oscillations in the course of stroke recovery

OBJECTIVE

The aim was to find a sensitive method to highlight the remodeling of the brain's bioelectric activity in post-stroke repair.

METHODS

Fifteen mild upper limb paretic stroke patients and age-matched healthy controls were included. Repeated trials of finger tapping around the 10th and 100th days after stroke onset were recorded with a 128-channel EEG. Power spectra and Inter Trial Coherence (ITC) calculations were synchronized to tappings. ITC was correlated with motor performance.

RESULTS

ITC, in low frequency bands, designates the motor related bioelectric activity in channel space in both healthy subjects and patients. Ten days after stroke onset, delta-theta ITC was severely reduced compared to baseline, while three months later ITC reorganized partially over the ipsilesional central-parietal areas reflecting the improvement of motor networks. Decreased ITC in the central-parietal area remained significant compared to controls. Delta band ITC over the dorsolateral-prefrontal cortex correlates with the performance on Nine Hole Peg Test. At post-recovery, non-paretic hand tappings show significantly decreased delta-theta ITC over the supplementary motor area, which reflects network remodeling.

CONCLUSIONS

Inter Trial Coherence is a useful measure of brain reorganization during stroke recovery.

SIGNIFICANCE

Delta- theta ITC is a sensitive indicator of impaired motor execution.

Treatment of Cystitis by Hungarian General Practitioners: A Prospective Observational Study

Background: Lower urinary tract infections (LUTIs) are amongst the most common community acquired infections with frequent antibiotic prescribing.

Objectives: To assess empiric antibiotic choice in different types of lower urinary tract infections. We also aimed to identify determinants of fluoroquinolone prescribing, as well as to determine the rate of short antibiotic courses. The frequencies of executing laboratory tests and recommending analgesics/anti-inflammatory drugs were also assessed.

Methods: A prospective observational study was performed in 19 different Hungarian primary care practices. Participating general practitioners (GPs) filled out data sheets for each patient with a suspected urinary tract infection. Details of drug use were evaluated. Comparison of different LUTI groups were made by descriptive statistics and univariate analysis. Possible determinants of fluoroquinolone prescribing were assessed by logistic regression.

Results: Data sheets of 372 patients were analyzed. The majority of patients (68.82%) had acute uncomplicated cystitis. While antibiotics were prescribed for almost every patient (uncomplicated cases: 92.58%, complicated cases: 94.83%), analgesics/anti-inflammatory drugs were recommended at a rate of 7.81% in uncomplicated, and 13.79% in complicated cystitis cases. Ciprofloxacin was the most commonly prescribed antibacterial agent in both types of cystitis. Short-term antibiotic therapy was prescribed in one third of relevant cases. Logistic regression found a weak association between fluoroquinolone use and patient’s age and presence of complicating factors.

Conclusions: Many aspects of suboptimal cystitis management were identified (e.g. unnecessarily broad spectra agents, too long antibiotic courses). In this study, patient characteristics has weakly influenced fluoroquinolone prescribing. Based on these results there is considerable room for improvement in primary care antibiotic therapy of cystitis in Hungary.

Improved EOG Artifact Removal Using Wavelet Enhanced Independent Component Analysis

Electroencephalography (EEG) signals are frequently contaminated with unwanted electrooculographic (EOG) artifacts. Blinks and eye movements generate large amplitude peaks that corrupt EEG measurements. Independent component analysis (ICA) has been used extensively in manual and automatic methods to remove artifacts. By decomposing the signals into neural and artifactual components and artifact components can be eliminated before signal reconstruction. Unfortunately, removing entire components may result in losing important neural information present in the component and eventually may distort the spectral characteristics of the reconstructed signals. An alternative approach is to correct artifacts within the independent components instead of rejecting the entire component, for which wavelet transform based decomposition methods have been used with good results. An improved, fully automatic wavelet-based component correction method is presented for EOG artifact removal that corrects EOG components selectively, i.e., within EOG activity regions only, leaving other parts of the component untouched. In addition, the method does not rely on reference EOG channels. The results show that the proposed method outperforms other component rejection and wavelet-based EOG removal methods in its accuracy both in the time and the spectral domain. The proposed new method represents an important step towards the development of accurate, reliable and automatic EOG artifact removal methods.

QUIMaS (Queen's University Image Management System): a museum photographic database

This paper reports on the construction of an interactive image management system. The system's operation is improved by image processing techniques and parallel processing technology.

Although image processing is largely a well understood problem, the technology for supporting it is still immature. Basically, it is a highly computationally intensive activity, and the purpose of our project was to address this very problem using parallel processing technology in the form of transputers. More specifically, we will describe the use of a transputer network in the development of an image database consisting of a collection of historical museum photographs.

During the first phase of the project, we developed a prototype system consisting of a small number of photographs using a simple hardware configuration. It made use of the hard disk of the PC to store the photographs and was implemented using a single transputer. During the second phase, the full hardware configuration was implemented, including the building up of the database of around 1,000 photographs. The final system consists of an IBM-compatible PC equipped with the necessary image processing and mass storage facilities (650 Mb hard disk) and linked to a network of six transputers. The user interface is provided through a serial mouse and a keyword menu. Users are able to retrieve images in three different modes: (i) a predefined keyword list, which is arranged in a hierarchical fashion to select images relating to a particular subject or geographical area; (ii) the Browse mode allows the user to display a set of up to twelve photographs in miniature ‘stub’ format at one go (this is similar to the turning of the pages of an album). Individual items can then be selected and displayed in full size, if necessary; (iii) if the museum reference number is known, the user can type in the number to retrieve the relevant item.

Section 1 will provide a brief review of the background to the project and the use of transputer technology in image processing. The selection and documentation of the photographs are described in Section 2. Section 3 describes the hardware and software configuration of the single-transputer-based prototype, and the full image database system implemented on a network of transputers.

The organisation of the database, both textual and image data, is explained in Section 4. This is followed by a description of the processing techniques for image enhancement and compression, and a discussion of the results of both compression and decompression processes. The final section will discuss the menu-based, mouse-driven user interface, including the various search facilities and display modes used to view images from the database.

Treatment of acute cystitis in Hungary: comparison with national guidelines and with disease-specific quality indicators

BACKGROUND

The aim of this study was to compare Hungarian antibiotic use in acute cystitis with the internationally developed disease-specific quality indicators and with the national guidelines.

METHODS

The aggregated national-level data on systemic antibiotic use was purchased from the National Health Fund Administration. The study period was January-June 2007. Antibiotic use in acute cystitis was evaluated by means of the defined daily dose (DDD) methodology. Quality indicators of antibiotic prescribing proposed by the European Surveillance of Antimicrobial Consumption (ESAC) team were the usage rate of recommended antibacterials and the usage rate of quinolones. Adherence to the available national guidelines was determined.

RESULTS

For acute cystitis, 1.06 DDD per 1000 inhabitant-days antibiotic use was recorded. The ESAC recommended antibiotic use in cystitis (23.3%) was well below the recommended range (80-100%). The consumption of fluoroquinolones was 56.2%, which exceeded the recommended range (0-5%) more than 10 times. The adherence rate to the Hungarian guidelines ranged between 59.3% and 74.2%.

CONCLUSIONS

As both investigated disease-specific quality indicators were well outside the acceptable ranges, some inappropriateness of antibiotic use in cystitis seems to be present. Adherence rates to the different national guidelines were also moderate, but due to the general recommendation of quinolones, values should be interpreted with caution. New transparent guidelines - issued by the Hungarian Society of Family Physicians - should be introduced in Hungary, recommending quinolones only for second-line therapy.

Does the type of bladder augmentation influence the resolution of pre-existing vesicoureteral reflux? Urodynamic studies

AIMS

The type of bladder augmentation on pre-existing vesicoureteral reflux (VUR) was assessed. The effects of urodynamic changes on the resolution of VUR following augmentation cystoplasty performed with various gastrointestinal segments were examined. It was queried whether elimination of high-pressure bladder is sufficient to resolve pre-existing reflux.

METHODS

A retrospective record review of patients who underwent bladder augmentation between 1987 and 2004. Patients were divided into two groups. Group I included patients who had a simultaneous augmentation and ureteral reimplantation. Group II included patients with reflux in whom only a bladder augmentation was performed. Pre-and post-augmentation urodynamic results were compared in both groups. The outcome of VUR and the role of various gastrointestinal (GI) segments on the resolution of VUR were studied.

RESULTS

Sixty-three patients underwent bladder augmentation during the study period. Twenty-six of them had VUR before augmentation. There were 10 patients in Group I and 16 patients in Group II. In Group I, VUR ceased in all patients, while in group II, VUR resolved in 14 patients and persisted in two patients. Small and large bowel segments used for augmentation had no effect on the resolution of VUR but the results of gastrocystoplasties were less favorable. Urodynamically there was no significant difference between the various augmentation cystoplasties.

CONCLUSIONS

Bladder augmentation alone without simultaneous antireflux repair is usually sufficient for the resolution of pre-existing reflux. The various GI segments used for augmentation have no effect on urodynamic results and the resolution of VUR.

Cutaneous vesicostomy revisited--the second 15 years

The aim of this paper was to review the authors' experience with cutaneous vesicostomy (CV) over the last 15 years including indications, results, and complications of CV.

MATERIALS AND METHODS

The records of 31 patients treated by CV between 1987 and 2002 were reviewed. There were 20 boys and 11 girls. The two main primary pathologies were neuropathic bladder (19 patients) and posterior urethral valve (PUV) (7 patients). All patients underwent a Blocksom-type operation at a mean age of 23 months (range 14 days-9 years). Pre- and postoperative conventional uromanometry was performed in 18 patients (58%) and bladder function was assessed.

RESULTS

In 23 patients (74%) the CV provided a successful diversion with improvement of the upper urinary tract and/or stabilization of the renal function. In 5 patients (16%) with PUV, the improvement was temporary. In 3 patients (10%) the CV did not result in an improvement. Twenty-four patients underwent CV closure after a mean duration of 23 months (range, 1 month-7 years) of diversion. In 2 patients with myelomeningocele (MMC) and severe somato-mental developmental delay, CV was not closed and is being considered as a permanent treatment option. Urodynamic studies in 5 PUV patients showed impaired compliance and high intravesical pressure following a successful valve ablation and closure of CV. In the neuropathic bladder group the bladder function improved following closure of CV and commencement of anticholinergic medication and clean intermittent catheterization (CIC). Our augmentation ratio in the neuropathic bladder group was 22%. Complications of CV included: stenosis in 7 patients (22%), prolapse in 2 (6%), and cellulitis in 2 (6%). The revision rate was 16%.

CONCLUSIONS

In young infants CV had a less favourable result in the PUV patients than in cases with high-pressure neuropathic bladder with upper tract dilatation and severe urinary tract infection (UTI), where CV provided decompression and prevented deterioration of the renal function. Cutaneous vesicostomy has stood the test of time in our changing paediatric urological practice and it remains a valuable weapon in the armoury of paediatric urologists in selected patients.