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Effect of despeckle filtering on classification of breast tumors using ultrasound images

Kriti, Virmani Jitendra, Agarwal Ravinder

Biocybernetics and Biomedical Engineering

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2019

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Vol. 39, no. 2

536--560

EN

Ultrasound is the most widely used imaging modality for screening of breast tumors. However, due to the presence of speckle noise in an ultrasound image, the diagnostic information gets masked and the interpretation of the breast abnormalities becomes difficult for the radiologist. The texture of the tumor region and the shape/margin characteristics are considered to be important parameters for the analysis of the breast tumors. In the present work, exhaustive experimentation has been carried out for the design of CAD systems for classification of breast tumors by considering (a) original images only, (b) despeckled images only and (c) both original and despeckled images together (hybrid approach). Total 100 breast ultrasound images (40 benign and 60 malignant) have been used for the analysis. Initially, these images have been despeckled using six filters namely Lee sigma, BayesShrink, DPAD, FI, FB and HFB filters. Total 162 features (149 texture and 13 morphological features) have been computed from both original and despeckled breast ultrasound images and SVM classifier has been used extensively for the classification. The results of the study indicate that the hybrid approach of CAD system design using texture features computed from original images combined with morphological features computed from images despeckled by DPAD filter yield optimal performance for classifica-tion of benign and malignant breast tumors with a classification accuracy of 96.0%. From the promising results of the study it can be concluded that the proposed hybrid CAD system design could be used as a second opinion tool in clinical setting.

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Assessment of despeckle filtering algorithms for segmentation of breast tumours from ultrasound images

Kriti, Virmani Jitendra, Agarwal Ravinder

Biocybernetics and Biomedical Engineering

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2019

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Vol. 39, no. 1

100--121

EN

In the present work, the performance assessment of despeckle filtering algorithms has been carried out for (α) noise reduction in breast ultrasound images and (b) segmentation of benign and malignant tumours from breast ultrasound images. The despeckle filtering algorithms are broadly classified into eight categories namely local statistics based filters, fuzzy filters, Fourier filters, multiscale filters, non-linear iterative filters, total variation filters, non-local mean filters and hybrid filters. Total 100 breast ultrasound images (40 benign and 60 malignant) are processed using 42 despeckle filtering algorithms. A despeckling filter is considered to be appropriate if it preserves edges and features/structures of the image. Edge preservation capability of a despeckling filter is measured by beta metric (β) and feature/structure preservation capability is quantified using image quality index (IQI). It is observed that out of 42 filters, six filters namely Lee Sigma, FI, FB, HFB, BayesShrink and DPAD yield more clinically acceptable images in terms of edge and feature/structure preservation. The qualitative assessment of these images has been done on the basis of grades provided by the experienced participating radiologist. The pre-processed images are then fed to a segmentation module for segmenting the benign or malignant tumours from ultrasound images. The performance assessment of segmentation algorithm has been done quantitatively using the Jaccard index. The results of both quantitative and qualitative assessment by the radiologist indicate that the DPAD despeckle filtering algorithm yields more clinically acceptable images and results in better segmentation of benign and malignant tumours from breast ultrasound images.

3

Obrazowanie gruczołu piersiowego ze stymulatorami serca

Sobczyk J., Gaweł G., Pusz-Sapa A., Przypek A., Król M., Babiarz E., Stępień S., Jachymek S.

Inżynier i Fizyk Medyczny

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2018

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Vol. 7, nr 1

57--60

PL

Początki implantacji stymulatorów serca sięgają późnych lat 50. XX wieku. Od tamtej pory odnotowano ogromny postęp w tej dziedzinie, a z roku na rok rośnie liczba osób z wszczepioną aparaturą do elektrostymulacji serca. Choć urządzenia te nie ograniczają znacząco życia pacjenta, mogą pojawić się trudności podczas badań diagnostycznych. Uwagę zwracają badania obrazowe gruczołu piersiowego u kobiet z wszczepionym stymulatorem serca. Rozważając bezpieczeństwo wykonywania badań u takich pacjentek, należy wziąć pod uwagę umiejscowienie stymulatora, źródła energii w poszczególnych badaniach oraz technikę ich wykonania.

EN

The beginning of pacemakers implantation dates back to the late 1950s. Since then, great progress has been made in this area and the number of people with implanted cardiac electro-stimulation devices is growing every year. Although these devices do not significantly constrain the patient’s life, difficulties may arise during diagnostic tests. Attention is drawn to the imaging of the breast gland of women with an implanted cardiac pacemaker. Considering the safety of tests performance on such patients – the location of the pacemaker, the source of energy in individual studies and the technique of their implementation, should be taken into account.

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Modeling Breast Ultrasound; on the Applicability of Commonly Made Approximations

Taskin U., Ozmen N., Gemmeke H., van Dongen K. W. A.

Archives of Acoustics

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2018

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Vol. 43, No. 3

425--435

EN

To design breast ultrasound scanning systems or to test new imaging methods, various computer models are used to simulate the acoustic wave field propagation through a breast. The computer models vary in complexity depending on the applied approximations. The objective of this paper is to investigate how the applied approximations affect the resulting wave field. In particular, we investigate the importance of taking three-dimensional (3-D) spatial variations in the compressibility, volume density of mass, and attenuation into account. In addition, we compare four 3-D solution methods: a full-wave method, a Born approximation method, a parabolic approximation method, and a ray-based method. Results show that, for frequencies below 1 MHz, the amplitude of the fields scattering off the compressibility or density contrasts are at least 24 dB higher than the amplitude of the fields scattering off the attenuation contrasts. The results also show that considering only speed of sound as a contrast is a valid approximation. In addition, it is shown that the pressure field modeled with the full-wave method is more accurate than the fields modeled using the other three methods. Finally, the accuracy of the full-wave method is location independent whereas the accuracy of the other methods strongly depends on the point of observation.