New Publications are available for Sonic and ultrasonic radiation (medical uses)
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New Publications are available now online for this publication.
Please follow the links to view the publication.Unsupervised textural segmentation of SonoElastographic breast images
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0462
Breast Cancer, the most common malignancy in women and the second leading cause of death for women all over the world. By earlier detection of cancer, the better treatment can be provided. SonoElastography, a new medical imaging technique reduces un necessary biopsies compared to mammography and conventional ultrasonography. The diagnosis and treatment of the cancer rely on segmentation of SonoElastographic images. Texture features are widely used in classification problems, i. e. mainly for diagnostic purposes where the Region Of Interest (ROI) is delineated manual ly. It has not yet been considered for SonoElastographic segmenta tion. SonoElastographic images of 15 patients taken using Siemens Acuson Antares are considered for experimentation. The images contain both benign and malignant tumors. From the experimental procedure it is proposed that the combination of texture features, Local Binary Pattern (LBP), Contrast and Variance are best suited for segmentation of SonoElastographic breast images. The images are first enhanced using sticks filter to remove noise, to improve contrast, and emphasize tumor boundary. Then extract the features to segment the breast image. The resultant images undergo some post-processing steps to remove the spurious spots. The segmented image is thinned to mark the tumor boundary. The results are then quantified with the help of an expert radiologist. The proposed work can be used for further diagnostic process, to decide if the segmented tumor is benign or malignant.Research on image filtering method to combine mathematics morphology with adaptive median filter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1152
As a imaging technology of no-traditional lamp-house irradiation ,ultrasound medical imaging with its many advantages, such as no harm to the human body, real-time, cheap and easy to use, is widely used in clinic. But the ultrasonic imaging speckle noise make it difficulties to distinguish between normal tissue and pathological tissue. According to the character of noise in the medical ultrasonic image , an new method of the medical ultrasonic imaging filter based on mathematics morphology and adaptive filtering is proposed after analysis of speckle noise and general filter, and an experiment is made to validate. The experimental method is as follows : Firstly the Rayleigh noise is imposed on the original image , and then the median filter and the adaptive median filter are used on the contaminated image. Secondly the morphological filter is used to improve image quality and enhance the contrast , after the adaptive median filter is used on the image, to retain more necessary details. Finally the three noise filtering methods are compared from the images denoise and evaluation . And the results indicate that the new method is superior to other ones.Estimation of tissue elasticity by image processing of simulated B-mode ultrasound images
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1682
Elastography and strain imaging often use ultrasound to measure mechanical properties of soft tissues. These techniques generally examine radiofrequency signals from an ultrasound scanner. This study investigates the feasibility of strain estimation directly from an ultrasound B-mode image, using segmentation and shape analysis. Several thousand computer generated tissue mimicking phantoms with stiff inclusions were produced and analysed, evaluating the change in shape when the phantom is subjected to 1-D compression in order to estimate strain. The resulting stiffness measurements are accurate to within 8% of the actual values. (6 pages)Blind source separation to extract foetal heart sounds from noisy abdominal phonograms: a single channel method
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080431
A method for extracting foetal heart sounds (FHS) from noisy single channel abdominal phonograms is proposed. First, an appropriate matrix of delays is constructed; then multiple independent components are calculated using FastICA; finally, components are projected back onto the measurement space and those associated to FHS are subjectively selected. Three single channel phonograms, obtained from different subjects were analysed. Preliminary results are promising and showed successfully extractions of FHS (S1, S2). Future work will increase the number of subjects, evaluate the extraction quality, look for more information about foetal well-being, find an objective way to select FHS, and explore ICA implementations that utilise temporal structure such as Temporal Decorrelation source SEParation (TDSEP). (4 pages)Effective ultrasound data processing - a seismic exploration perspective
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080440
Many similarities exist between the seismic exploration technique and diagnostic medical ultrasound. The data processing associated with seismic exploration typically involves the application of numerous advanced algorithms, many of which may be utilised effectively in ultrasound. This paper briefly reviews the seismic exploration technique and investigates application of some typical seismic processing algorithms to medical ultrasound data. In particular, ensemble averaging, time-variant spectral whitening, predictive deconvolution and image reconstruction algorithms are considered, and shown to be very effective in enhancing the ultrasound image. (4 pages)Spectral analysis of backscattered ultrasound field from hydroxyapatite granules
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080469
Microcalcifications (MCs) are of great importance in breast cancer early diagnosis and sometimes they do represent the unique evidence of cancer disease (up to 47%). Their visualization in ultrasound (US) is limited by a number of factors the most important of which are speckle and system limited spatial resolution. MCs are modelled as hydroxyapatite (HA) microgranules and sound scattering from HA microgranules can be solved by mean of Faran model. Agar based phantoms have been manufactured to simulate human soft tissues with cylindrical shape and a commercial echo-scanner (Technos Mpx di ESAOTE s.r.l., Genova, Italia) has been used to perform the scan of the phantom. This work concerns with phantoms and the analysis of US data for the visualization of HA microgranules under multiple angle scan. A reconstruction method was hence used to get a 2D map of reflectivity from the target and further Fourier analysis was applied to radio frequency (RF) data. (4 pages)Motion compensated complementary coding for medical ultrasound
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080646
Ultrasonic imaging using complementary coded pulses offers the SNR improvements of signal coding without the filter side-lobes introduced by single transmit codes. The effects of the transducer and motion in the medium, however, can introduce mismatch artefacts and high side-lobes due to misalignment. A method for filtering and motion compensation of complementary coded signals appropriate for use in medical imaging scenarios is presented in this paper. The method has been shown by simulation to reduce side-lobes to levels that compare favourably to systems using FM-coded signals of similar length and bandwidth while increasing coding gain and range resolution.Restoration of medical ultrasound images via modified homomorphic deconvolution
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080366
Compared with other medical imaging devices, ultrasound imaging suffers from its poor resolution. Therefore, in order to obtain the important diagnostic image detail, restoration procedure need to be performed. The paper describes a modified homomorphic deconvolution which is used to improve the quality of medical ultrasound image. The proposed deconvolution performs the homomorphic filtering based on the estimation of the point-spread function (PSF). Especially, the application of a non-local means (NL-means) algorithm makes PSF estimation more precise for rejecting the white-Gaussian noise (WGN) effectively. We validate our method for different radio-frequency (RF) images with resolution improvement.A fast algorithm for automated independent process separation from single channel biomedical signal recordings: fastIPA
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080430
Independent component analysis (ICA) has found many uses in source separation in biomedical signals. We highlight a methodology and put forward an algorithm which allows single channel ICA to be performed on single channel biomedical signal recordings. The algorithm uses a fast, deflationary approach to efficiently extract independent processes underlying the single channel recordings. We show that for processes which are reasonably spectrally disjoint the algorithm can separate out individual sources. We show examples of this using brain signal recordings and abdominal foetal recordings. (4 pages)An anisotropic diffusion filter for ultrasonic speckle reduction
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080332
Anisotropic diffusion has been widely used to reduce speckle noise from ultrasound images. However, in traditional anisotropic diffusion methods, usually four directions neighborhood are used, which have many disadvantages, such as the sensitivity to the noise, the loss of image details and false contours. In this paper, we modify the standard SRAD (speckle reducing anisotropic diffusion) algorithm in the discrete domain by considering larger neighborhoods in its computation; then we adopt a confine term to keep the closest equivalence between the filtered image and the original image. Experimental results show that, in the presence of speckle nose, this proposed method could effectively preserve edges and detailed structures while suppressing speckle noise These preliminary results indicate that the proposed speckle reduction method could improve image quality and the visibility of small structures and fine details in the medical ultrasound images.Wavelet energy based compression of phonocardiogram (PCG) signal for telecardiology
http://dl-live.theiet.org/content/conferences/10.1049/ic_20070692
This paper presents a novel phonocardiogram (PCG) signal compression method based on Wavelet transform. The proposed compression method uses energy based thresholding for retaining significant coefficients, uniform scalar zero zone quantizer (USZZQ) for quantizing the amplitudes of the significant coefficients and differencing coder for integer significance map (ISM). This method is tested using the PCG records taken from qdheart and eGeneralMedical databases. The performance of the compression method is assessed in terms of compression ratio (CR), percentage root mean square difference (PRD), Wavelet energy based diagnostic distortion (WEDD) measure and mean opinion score (MOS). The compression method is evaluated with PCG signals of more than 100 records with normal sounds, murmurs, stenosis, noise and other pathologies. High compression ratios with lower distortions are achieved with the proposed method.Patient compatibility of devices
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060300
This paper discusses the patient compatibility of medical devices. A device is said to be patient compatible if it meets the regulatory requirements of safety, functionality and is according to the Annex 1 of the European Medical Device Directive. As it is accepted that medical devices constitute a risk, the benefits of the device should outweight the risks. The risk should be minimised hence a risk management programme must be undertaken. The relevance of device encapsulation is also discussed. If some materials are not biocompatible, they must be covered or encapsulated. A case study on an intravascular ultrasound (IVUS) coronary catheter is presented.Occlusal sound analysis revisited
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060392
We present a review of the gnathosonics technique, several improvements and a revision of concepts. Then, we present a method of nonlinear signal processing and heuristic features extraction. (4 pages)Estimating boundaries of primary heart sounds for diagnosing heart valve disorders
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060354
Estimation of the boundaries of primary heart sounds (S1 & S2) aids the characterization of murmurs present in the heart sound cycle for diagnosing heart valve disorders. The work presents an effective boundary estimation algorithm. Extensive incorporation of biomedical domain features facilitates the development of a computationally efficient algorithm using fundamental time-domain signal analysis techniques. The accuracy of algorithm is established over complex heart sound patterns pertaining to various heart valve disorders. (4 pages)Ultrasound image segmentation using watersheds and region merging
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060512
This paper presents an efficient hybrid image segmentation scheme for biomedical ultrasound images based on watershed transformation and region merging. It consists of four major stages. These stages are pre-processing, multiscale morphological gradient, watershed segmentation and finally region merging. The proposed scheme is tested using a set of medical ultrasound images. Experimental results show that our proposed method is capable of producing accurate contours in medical ultrasound images.Improved assessment of pulsatile blood flow during resuscitation using Doppler ultrasound
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060357
Early defibrillation is critical for successful resuscitation of a sudden cardiac arrest patient. Defibrillators currently do not assess the patient's heartbeat or blood circulation and the responder has to manually check for the pulse, a procedure known to be very inaccurate. Previously we had developed an ultrasound Doppler based approach to determine the presence of blood flow in the context of resuscitation. Here we extend our earlier work to develop a generalized pulsation index based on a spectral analysis of the Doppler signal. This new method has the advantage to better distinguish between states of pulse and pulselessness, since it aims at capturing the essentially non-sinusoidal behaviour of cardiac activity. In turn, this leads to better sensitivity and specificity for pulsatile flow assessment. The method was demonstrated on data from pigs undergoing cardiac arrest and defibrillation. (4 pages)Eigenhearts for diagnosis of congestive heart failure (CHF)
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060390
Common cardiac diseases such as cardiomyopathy, coronary artery diseases, and valve diseases, result in abnormal myocardial movement, which could eventually lead to heart failure, also called congestive heart failure (CHF). CHF is a disease in which the heart's ability to pump blood efficiently is lost. Possible presence of this disease and location of the abnormal activity can be diagnosed from patient's scan images, by determining the wall motion abnormalities. In this paper, a new principal component analysis (PCA) technique, Eigenhearts, is presented to diagnose the abnormal contractility of heart wall. Experiments were carried out using a preliminary set of simulated scan data and the results are discussed. (4 pages)A bootstrap approach to testing for an association between bursts in the neonatal EEG and changes in cerebral blood flow
http://dl-live.theiet.org/content/conferences/10.1049/ic_20050324
In normal premature neonates, a pattern of EEG, known as trace discontinu, is common, which contains bursts of relatively high voltage, in an otherwise lower voltage background. The current work investigates whether these bursts are associated with changes in the velocity of blood, measured by transcranial Doppler ultrasound in the middle cerebral artery. A measure of consistency in the response from repeated bursts is proposed, and in order to test its significance, a bootstrap method was devised. With this method signals that are interrupted by `missing samples', where segments of the signal are lost due to excessive noise or artifact (as was the case in our recordings), can also be analysed. Monte Carlo simulation studies demonstrate the potential of this approach. In tests on 12 recordings from premature babies it was found that 3 had significantly consistent responses, with a peak in cerebral blood flow velocity some 5-12 seconds after the onset of the bursts. Overall, the results suggest that there is an association between bursts and blood-flow, at least in some subjects, but the causal mechanisms require further studies.Improved detection of embolic signals using multi scale wavelet filtering, AR and ANN, for TCD ultrasound
http://dl-live.theiet.org/content/conferences/10.1049/ic_20050332
Transcranial Doppler ultrasound can be used to detect emboli in blood flow in the brain. The presence of emboli is an indication of high risk of stroke. Embolic signals have characteristic transient chirps suitable for wavelet analysis. We have implemented an on-line intelligent wavelet pre-filter combined with a new frequency based neural network classification system (NFS) to produce a new online detection system. Initial results show an improvement in accuracy compared with the widely used FS-1 system. Our system makes, use of multi-scale wavelet denoising using an adaptive coefficient threshold. The pre-filtering system is combined with a detection system which uses a two layer neural classifier and a new auto-regressive event detector. For conditions such as carotid stenosis an improvement of 20% in detection accuracy was obtained. Our online (real time) intelligent wavelet amplifier and its matrix optimised form uses the matched filter properties of multiple coefficients from multiple wavelets to significantly enhance embolic signals and improve classification performance.A computer based simulator for ultrasound guided needle insertion procedures
http://dl-live.theiet.org/content/conferences/10.1049/cp_20050104
A system for the simulation of needle insertion procedures under ultrasound guidance is presented. This is a core skill in interventional radiology, currently acquired on an apprenticeship basis. The system is designed to improve the early stages of training, and detect people with poor natural ability. The simulator is based on a volumetric data set which is non-rigidly aligned to a physical mannequin surface. Magnetic 3D position sensors allow the generation of 'virtual ultrasound' images based on the position of a mock ultrasound probe and needle. The calibration procedures required for this are presented. Metrics for skill measurement are presented and evaluated, and it is shown that a set of 10 novice users increase their skill levels after structured practice.A reduced forward operator for acoustic scattering problems
http://dl-live.theiet.org/content/conferences/10.1049/cp_20050327
This paper describes the development of a reduced forward operator for solving acoustic scattering problems that arise in ultrasonic imaging applications. The reduction, inspired by the contrast source inversion technique, is obtained by decoupling the interaction between locations in the computational domain at which contrast is present and those positions at which there is a zero contrast. The decoupling is achieved by multiplication by a diagonal matrix whose entries reflect the presence or absence of contrast at the associated point. Numerical results confirm that the reduced operator produces convergent results in less iterations.Frequency domain blind source separation
http://dl-live.theiet.org/content/conferences/10.1049/ic_20040612
Blind source separation (BSS) has attracted dramatic research interests in the past decade due to its potential applications in signal processing, telecommunications, and medical imaging. Among the open issues in BSS is how to recover the source signals from the linear convolutive mixtures which are observed by an array of sensors, and this remains a challenging problem. An effective solution is to transform the convolutive model into the frequency domain so that a series of complex-valued instantaneous BSS can be applied independently to each frequency bin. This has simplified the separation problem with a better convergence performance. However, a crucial problem, called the permutation problem, should be solved before gaining a good separation performance. This talk gives an outline of our approach to the frequency domain BSS with emphasis on the solutions to the permutation problem. Some recent results, together with a comparative discussion of the state-of-the-art approaches will be presented. (14 pages)An ultrasonic-based enuresis treatment device
http://dl-live.theiet.org/content/conferences/10.1049/cp_20040588
Primary nocturnal enuresis is characterised by an involuntary discharge of urine which happens unconsciously during the night. Enuresis can be treated by means of a conditioning device that wakens the wearer once the bladder volume has reached a preestablished threshold of capacity. Existing research using this preemptive technique indicates good results. However, deep sleep and inability to waken limits its effectiveness. The paper describes an intelligent ultrasonic-based bladder volume monitor and alarm system which enables investigation of multiple complex wakening sounds and stimuli. The proposed system also accurately logs all events for support of on-going research.PhiSAS: a low-cost medical system for the observation of respiratory dysfunction
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020042
Respiratory illness is recognised internationally as one of the commonest medical disorders affecting the world's populous, and is especially a major problem that affects the third world. The World Health Organisation (WHO) pursues an extensive health program that is aimed at reducing the plight of respiratory disorders by treatment and education. As with the majority of third-world health care programs, the effectiveness is limited by the availability of resources and finance. PhiSAS (Physiological Signal Analysis System) is a novel system developed for the observation of lung sounds. The system consists of a Personal Computer (PC) supported with dedicated software and hardware. Lung sounds can be recorded via chest microphones into the computer system for storage in digital form. This data can then be retrieved for post-processing using an array of software-based Digital Signal Processing (DSP) techniques that can mathematically manipulate lung sounds to extract important features. Data and results can be presented audibly by sound playback, or graphically by using spectrographs. The spectrograph is a representation of lung sound spectral energy with respect to time and frequency. PhiSAS has the ability to present three types of analysis based on conventional and novel mathematical techniques: Fourier, Wavelet and Time-Frequency Analysis. The purpose of the PhiSAS system is to provide objective analysis of lung sounds. The practice of auscultation (the art of listening to body sounds) has been practiced by physicians since the days of Hippocratic medicine. However, many physicians believe that respiratory auscultation performed with a stethoscope offers little scientific value due to the way it is practiced. For example, observations can be subjective depending on the physicians hearing ability and experience. Moreover, descriptions of lung sounds are described using onomatopoeic references that are ambiguous. By exploiting advances in low-cost PC technology and techniques in signal analysis, the physician can express sound observations in a more precise scientific manner. (5 pages)Heart sound segmentation by hidden Markov models
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020297
The segmentation of phonocardiogram (PCG) signals is the first step in the automatic diagnosis based on heart sounds. The majority of attempts to segment PCG signals depend on a reference provided by simultaneous electrocardiogram recordings. The algorithm proposed in this paper is based on the analysis of the PCG signal only and does not require an ECG reference signal. In this paper we propose the tracking of the log spectral components that vary slowly with frequency (the low-time components). That is Cepstral analysis is used to provide the features selected to represent the heart sounds. The algorithm utilises a hidden Markov Model to identify the S1 and S2 components of the heart sound, which delimit the systolic and diastolic cycles. The parameters of a simple hidden Markov model with single Gaussian distribution for continuous observations are learned from a training set of heart sounds. Once the parameters of the model are obtained PCG signals from different sets are used to test the segmentation procedure. (4 pages)Speckle reduction techniques in B-mode ultrasound images
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020288
The traditional 1D spilt spectrum processing (SSP) method suffers from a relatively high-resolution loss limitation, inherent to the method. There is a trade-off between speckle reduction and resolution loss. On the other hand, the new 2D SSP with directive filters perform well. In this method, the filters are chosen to have a bandwidth larger than that of the ultrasound pulse and this helps to maintain image resolution. Even though SSP is a single-image method, it tackles the speckle reduction problem in a similar way to frequency compounding (a multi-image method), where a set of images from the same structure is acquired by using ultrasound pulses with different frequencies for each image. Likewise, the use of directive filters in the (single image) 2D SSP method has a similarity with angle compounding method (a multi-image method), where a number of images are acquired from different scanning angles in order to decorrelate the speckle. However, practical difficulties with the use of angle compounding methods in a medical context are overcome by the new 2D SSP with directive filters, which requires only a single image. The zero adjustment processing (ZAP) is a very powerful method, and is the only technique that can recover the apparent energy loss suffered in destructive interference, and promises well for further development. The hybrid method was used to demonstrate the synergy between different techniques, and the concept certainly looks ripe for further development. (6 pages)A novel approach for non-stationary medical signal analysis using Hilbert spectrum
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020292
This paper discusses a novel method to study the nonlinear and non-stationary processes and to investigate the time-varying frequency of the practical medical signals. The aim of this contribution is to explore the role that both empirical mode decomposition and Hilbert transform can be used to play in such medical signals. A Hilbert transform is applied to each intrinsic mode function to obtain the global time-frequency distribution of the underlying signal with a point of view of instantaneous frequency. Two kinds of clinical phonocardiogram signals with normal and abnormal cardiac functions were analyzed by using the proposed method. The instantaneous frequency distributions of the PCG signals were also compared with the results by using the wavelet transform. Both simulation and experimental results were presented and discussed to demonstrate the power and effectiveness of the proposed new approach. (6 pages)Comparison of transformation methods to determine frequency specific cochlear hearing loss based on TEOAE
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020294
In this paper, we aim to determine frequency-specific cochlear hearing loss (HL) by means of transient evoked otoacoustic emissions (TEOAE). Exemplarily, the differentiation of three groups of frequency-specific HL is performed by parametrisation of the time-domain TEOAE responses based on three transforms, namely discrete wavelet transformation, wavelet packets and Gabor frames. Using an SNR-like criterion, the various transforms are tested for their ability to differentiate between the three groups of hearing ability. This differentiation is evaluated on a large group of data from patients. The separability results for each transform method are checked against the data of a second control group. (6 pages)Fuzzy, Weighted-Offset, Multiscale Edge Detection for automatic echocardiographic LV boundary extraction
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020289
This paper describes a new Fuzzy, Weighted-Offset, Multiscale Edge Detection algorithm for cardiac left ventricular (LV) epicardial and endocardial boundary detection on short axis (SA) echocardiographic images. The proposed method uses the `centre-based' approach, previously described in S.K. Setarehdan and J.J. Soraghan, 1999, IEEE Transaction on Biomedical Engineering. Vol. 46, No. 11, 1364 - 1378. The Edge-detection stage uses a new Fuzzy Weighted Offset Multiscale Edge Detection (FWOMED) technique in order to identify a single moving point for each one of the epicardial and endocardial boundaries over the N radii in an echocardiographic frame. This technique achieves optimal edge detection through non-decimated wavelet decomposition of the original signal followed by a fuzzy based decision technique, which is applied across the scales. Finally, a uniform cubic B-spline approximation is used to define the closed LV boundaries. The performance of this technique is compared to Mallat's (S. Mallat and S. Zhong, 1992, IEEE Trans. PAMI, Vol. 14, No. 7, 710-723.) multiscale edge detection technique, for a range of test data sets comprising different synthetic noisy signals. (6 pages)Long-term objective cough recognition and quantification
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020298
The application of advanced digital signal processing (DSP) and spectral estimation techniques to the analysis of cough has produced many benefits in recent years. The ability to recognise the characteristic features of a signal defined to be a cough and to distinguish these from the features of other signals such as speech and background noise have allowed accurate cough identification, counting and frequency determination to be carried out in increasingly natural every-day environments. This work requires an algorithm that identifies cough sounds from patients over extended periods of time and produces a series of statistical measurements for comparing the effectiveness of different anti-tussive drug treatments. To achieve the required specificity and sensitivity, the properties of sounds characteristic of different conditions: asthma, cystic fibrosis, cryptogenic fibrosing alveolitis, and chronic obstructive pulmonary disease were analysed and used to adapt the algorithm to detect sound characteristic of coughs. The accuracy of the detector has been assessed. A sensitivity of 80.8% and specificity of 99.3% were achieved for overnight recordings. (4 pages)Bone fracture imaging study with an acoustic technique
http://dl-live.theiet.org/content/conferences/10.1049/cp_20000341
Imaging studies of bones are important for orthopaedic doctors to know the physical condition of the bones, to enable them to decide about the treatment of a particular abnormality. Generally, the X-ray technique is used by clinicians to assess the condition of the bone, but this method is cumbersome and has diagnostic limitations, particularly in the case of minor fractures. In order to overcome this problem, an acoustic stress wave technique is developed for the study of bone imaging. This technique is quick, less expensive and reliable for evaluating the inner structure of the bone, layer by layer, non-destructively and non-invasively. This paper describes a comparative study of imaging patterns in normal and fractured bones.Introducing transmission line matrix (TLM) modeling and its application in medical ultrasound
http://dl-live.theiet.org/content/conferences/10.1049/cp_20000340
Transmission line matrix (TLM) modeling is a numerical technique for modeling wave propagation. It was used originally for modeling electromagnetic waves. P.P.M. So et al. (1991) introduced the inverse TLM, which is TLM in time reversal. In this paper, we introduce TLM modeling and inverse TLM modeling and explain how it would be used for modeling ultrasound waves. Some applications of TLM modeling in medical ultrasound systems are also proposed.Determination of the shock wave intensity from a laser lithotriptor using a bi-laminar hydrophone
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990493
Kidney stones have been treated for some years with extracorporeal shock wave lithotripsy (ESWL) with marked success but this therapy is contraindicated under certain circumstances. In addition, some types of kidney stone do not respond to ESWL and the reason for this is not fully understood although the materials from which the stone are formed is thought to be a crucial factor. An alternative technique uses a laser, which discharges into the urine surrounding the stone and thereby initiates a shock wave. The interaction of this shock wave with the stone is only poorly understood. In order to examine this situation further, artificial stones were created whose material and elastic properties were calculated by ultrasonic methods. The shock wave induced pressures within the stone could then be calculated once the shock wave intensity had been measured. Measuring the shock wave intensity was performed by the use of a bi-laminar hydrophone. The variation in the shock intensity as a function of the laser discharge-hydrophone separation was measured which permitted the intensity at the point of discharge to be estimated. Pressures up to 500 MPa have been measured which is well in excess of the fracture strength of the stones. (5 pages)An efficient algorithm for 3-D image reconstruction over parallel and distributed architectures
http://dl-live.theiet.org/content/conferences/10.1049/cp_19990324
We have designed an efficient parallel algorithm for performing 3D image reconstruction. In this framework, we have considered 3-D image to be reconstructed from a series of 2-D images, produced using ultrasonography, computer tomography, etc. The paper discusses a general parallel algorithm for 3D image reconstruction over CRCW, CREW and EREW PRAM models. We have developed efficient implementations of this algorithm over a vector machines, a distributed system comprising of a cluster of workstations and various interconnection network like a mesh network and a reconfigurable bus network. The performance of the above algorithms are tested using simulation experiments performed for 3D image reconstruction of the vitreous region of the eye using ophthalmic ultrasonograms. A novel approximation scheme has also been proposed for a drastic improvement in performance for specific kinds of image. The results indicate the time complexities of the algorithms are in resonance with the expected theoretical values and image obtained has a uncompromising level of accuracy.Fetal echocardiographic image segmentation using neural networks
http://dl-live.theiet.org/content/conferences/10.1049/cp_19990374
This paper discusses supervised and unsupervised neural network approaches to fetal echocardiographic image segmentation. The obtained results were compared with images segmented by a known unsupervised clustering technique (i.e. k-means). The visual aspect of the segmented images was evaluated with respect to its visual quality by an expert. A subset of the segmented images showed sufficient detail of the internal heart anatomy to allow medical diagnosis. The visual observation was matched closely by our unsupervised image segmentation approach, using the modified Hubert index.A nonlinear processing technique for removing coherent interference artefacts
http://dl-live.theiet.org/content/conferences/10.1049/ic_19980436
Ultrasound pulses propagating through human tissue appear to retain most of their initial coherence, and are coherently scattered from the many inhomogeneities within a tissue. A complex echo field is generated which exhibits many interference effects, the most familiar of these manifests itself as the ubiquitous speckle artefact. Speckle pervades almost all medical ultrasound pulse-echo signals and imposes a fundamental limit on signal and image quality. It is commonly assumed that the removal of speckle will produce a great advantage in a large number of practical applications. The novel approach developed here provides a general descriptive framework for interference effects, and is based on a description of interference by the presence of what we have termed structure zeros in the analytic continuation of the real data into the complex frequency, and complex time domains. The structure zeros may be uniquely identified if the form of the interrogating ultrasound pulse is precisely known. In practice, the latter requirement cannot be satisfied, and the presence of noise introduces a further element of uncertainty, but the structure zeros which make the dominant contribution to signal corruption may be unambiguously identified (via a sensitivity index) when short data segments are considered. Appropriate manipulation of the structure zero locations results in a specific, desired correction to the signal. (5 pages)Time-frequency analysis of heart murmurs in children
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970032
Examination of heart sounds (phonocardiology) facilitates diagnosis of defects which manifest themselves as irregularities in the heart sound. Simply by listening to such sounds a trained physician can diagnose a variety of heart complaints, e.g. Atrial Septal Defects (ASDs) or colloquially “holes in the heart”. Such defects may not manifest themselves on ECGs. Any abnormality in a heart sound is generically termed a murmur. It is common practice for GPs to examine young children to check for the presence of a heart murmur. However, heart murmurs are relatively common in paediatric patients, the vast majority of these murmurs are nonpathological and the murmur will vanish, with no ill effects, over time. The problem arises in that GPs can detect the presence of a murmur, but cannot distinguish an “innocent” murmur from a pathological one. This classification task can be performed by specialist physicians simply listening to heart sounds. The goal of this work is to develop computer based methods capable of performing the task of the trained physician, i.e. the classification of heart murmurs. Heart sounds are clearly nonstationary signals and hence the natural analysis methods are those of time-frequency and/or time-scale. In this application there is no evidence to suggest that the analysis technique would benefit from a multiresolution type analysis, so the authors concentrate on time-frequency, rather than time-scale, methods. The study of heart sounds via time-frequency analysis has been undertaken by other authors. (4 pages)Time-frequency analysis of systolic murmurs
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970035
Many pathological conditions produce systolic murmurs which may or may not be audible during auscultation. The significance of murmurs during auscultation generally alert the examiner for further investigations such as Doppler test, ultrasonic imaging or even cardiac catheterisation. This approach, however has not proved efficient. An alterative approach is to acquire heart sound data directly into computer memory using various suitable interface circuits. The systolic period can be isolated and time-frequency analysis can be applied. Analysis show some interesting results which may, or may not, be related to the severity of aortic stenosis. (2 pages)The development of a sideways looking laser ultrasound probe for use in laser angioplasty procedures
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970682
A set of laser ultrasound directivity patterns have been presented for samples irradiated within a water medium. The forward-going pattern for aluminium was used to validate the experimental technique and showed reasonable agreement with theory. The backwards-going patterns measured in gelatine showed significant sideways going energy at angles of approximately 70° from the surface normal. This effect was particularly marked for small laser spot sizes but had little dependence on optical absorption coefficient over the range investigated. A pattern was measured for healthy fixed aorta and the pattern showed similar features to the pattern measured in gelatine under similar conditions. Hence, the results indicate that there is the possibility of designing a sideways imaging system using laser-generated ultrasound. (6 pages)Laser ultrasound for investigation of arteriosclerotic arterial tissue
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970680
Angioplasty has become a common procedure for reducing the effects of constrictions in human arteries caused by the build up of fatty deposits, thrombosis and calcification (arteriosclerosis). An intraluminal laser ultrasound probe has been designed and constructed. The probe allows the use of a small pulsed laser to generate ultrasound on the tissue surface and to determine the nature of the tissue to be treated. Its design is also compatible with that required for a therapeutic laser beam to be delivered to the same site. The results obtained at both 532 nm and over the range of wavelengths covered by the optical parametric oscillator show that variations in the optical absorption characteristics within a tissue sample caused significant differences in the detected acoustic signal. This suggests that the acoustic signal obtained by optical absorption within the tissue can be used to gain information on the structure of the tissue sample. As the wavelength of the laser used was increased, waveforms suggested that the optical absorption of tissue decreased, leading to an increase in the amplitude of the signals from within the tissue if absorption centres were present. The results suggest that laser ultrasound can be used to determine the nature of arterial tissue samples and to distinguish between healthy and diseased arterial tissue. (6 pages)Cardiac left ventricular volume changes assessment by long axis echocardiographical image processing
http://dl-live.theiet.org/content/conferences/10.1049/cp_19970916
This paper describes a new multiresolution based left ventricular endocardium (LVE) extraction system. By this approach, the LVE extraction from both 2-chamber and 4-chamber apical views, which is the most crucial step for automatic LV volume changes measurement based on the American Society of Echocardiography (ASE) recommendations, is possible. The complete automatic system comprising fuzzy centre detection, non-uniform radial data sampling, wavelet based edge detection, and postprocessing and boundary extraction is described. The results for real echocardiographic images are also presented.Classical image processing vs. computer vision techniques in automated computer-assisted detection of follicles in ultrasound images of ovary
http://dl-live.theiet.org/content/conferences/10.1049/cp_19970954
A complete understanding of follicle dynamics inside ovary is crucial for the field of genetic engineering. Monitoring follicles over entire cycle is especially important in human reproduction. In Gore et al. (see Human Reproduction, no.10, p.2313-19, 1995) is stated that the outcome of a pregnancy is dependent upon the quality of the embryo. This, in turn, is dependent in part upon the quality of the female gamete oocyte contained in the dominant follicle (dominant follicles are those that grow and have potential to ovulate at the end of the follicular phase) and, therefore, the quality of the follicle itself which supports oocyte growth and maturation. Not all dominant follicles ovulate and of those that do, not all are of sufficiently high quality to result in pregnancy.Fully automatic left ventricular myocardial boundary detection in echocardiographic images: a comparison of two modern methods
http://dl-live.theiet.org/content/conferences/10.1049/ic_19960640
The echo images in 2D echocardiography have poor noise characteristics and low spatial and grey-value resolutions. Numerous attempts have been made to develop automated algorithms for quantitative analysis and boundary extraction in these images, but as yet none have been developed adequately to be used clinically. This report presents two modern approaches for automatic extraction of the left ventricular (LV) epicardial and endocardial boundaries from short-axis (SA) echocardiographic data, and compares their performance. Both methods use the radial search algorithm in the extraction process. In the AMRBDS (automatic multiresolution boundary detection system), the first stage uses fuzzy logic and the spatial and intensity information of the input image to estimate the LV centre point (LVCP). Then, a novel multiresolution edge detection technique based on the wavelet transform is applied to each one of the radial intensity profiles to extract the most probable and unique LV edge points along them. Median post-filtering and cubic B-spline techniques are employed to produce the final LV boundaries. In the AANNBDS (automatic artificial neural networks boundary detection system), an MLP (multilayer perceptron) is used to detect the most appropriate centre point of the LV. A second MLP is trained to classify each pixel on the radial lines as an inner, outer or non-edge point. Finally, knowledge guided snakes are employed to extract the LV borders by minimization of the snakes' energy function. (6 pages)Obstetrics and technology
http://dl-live.theiet.org/content/conferences/10.1049/ic_19961024
Most of the technological developments in obstetrics have been focussed on improving access to and assessment of the fetus. The great majority of these developments have included ultrasound in one form or another. The five technologies in obstetrics upon which the author concentrates are: (1) real-time ultrasound imaging of the fetus; (2) antenatal fetal heart rate monitoring using Doppler ultrasound; (3) umbilical artery blood flow recording with Doppler ultrasound; (4) intrapartum fetal heart rate recording with either Doppler ultrasound or a scalp electrode; (5) intrapartum fetal electrocardiogram recording. (6 pages)Robotic aided transurethral resection of the prostate
http://dl-live.theiet.org/content/conferences/10.1049/ic_19960624
A new robot was purpose built for prostatectomy. This was designed to be constrained to work within a small volume only, approximately the size of a large prostate. No movement is possible outside of this region, removing the possibility of trauma in the case of a malfunction. The robot is powered by four motors. This robot has shown that automated prostate resection is possible. The use of an integrated ultrasound system enables a prostate resection model to be generated quickly at the time of surgery, and the robot is capable of resecting the prostate accurately using this model. Although the process is automated, the surgeon is still in control of the robot. Initial results are promising, however, the system is still under trial and requires a larger patient database and the results of long term tests to prove its effectiveness. (3 pages)High intensity focused ultrasound: applications in urology
http://dl-live.theiet.org/content/conferences/10.1049/ic_19960621
High intensity focused ultrasound therapy (HIFU) is a novel method of providing precise, non-contact, irradiation free, deep tissue ablation. In the field of urology, clinical data currently available indicate that the technique may be useful in the treatment of benign prostatic hypertrophy. Development of treatments of localised prostate, bladder and renal cancer are yet to be proven and may require improvements in technology before the full potential can be determined. (3 pages)Neural network and conventional classifiers to distinguish between first and second heart sounds
http://dl-live.theiet.org/content/conferences/10.1049/ic_19960638
A technique to distinguish between the first and second heart sounds without the need for a reference ECG is described. The choice of features for presentation to classifiers is discussed and several types of classifier are introduced. Comparative results for each of the classification techniques are given for data sets obtained from both normal and pathological cases. A misclassification rate of 5.76% is obtained using a neural network classifier whereas conventional classifiers are shown to give a relatively poor performance. (6 pages)Methods for assessing snoring
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951589
Snoring has traditionally been assessed in clinical practice from subjective accounts by the snorer and his/her partner. The authors have developed a technique for measuring snoring quantitatively and have compared the measurements with a subjective assessment. (3 pages)An intravascular ultrasound imaging system
http://dl-live.theiet.org/content/conferences/10.1049/ic_19950774
The authors discusses the design of an intravascular ultrasound imaging system. In particular they consider the bus data rate requirement, the bus interface, the choice of processor-the ADSP 21060 is considered appropriate-and its multiprocessing features. (5 pages)Spectral analysis of Carpentier-Edwards prosthetic heart valve sounds in the aortic position using SVD-based methods
http://dl-live.theiet.org/content/conferences/10.1049/ic_19950278
The authors examine the performance of spectral estimation techniques when analysing the spectral content of Carpentier-Edwards (C-E) prosthetic heart valve sounds. The performance of the following methods is analysed: the fast Fourier transform (FFT), Burg algorithm (BA), sinusoidal signal identification, several algorithms for autoregressive moving average modelling, and Prony's spectral method (PSM). Synthesised second heart sounds were generated to allow a vigorous comparison between all the methods. From the results achieved, it is concluded that parametric methods based on singular value decomposition are generally more appropriate than the FFT and BA algorithm. Amongst these parametric methods, PSM achieves the best results. Results also show that spectral analysis of closing sounds produced by C-E valve in the aortic position represents a useful technique for monitoring the condition of the prosthetic heart valves. (4 pages)