Speckle in Ultrasound Computerized Reflection Mode Tomography
Soon after the first use of Ultrasound B-Scanners, a phenomenon was observed in the images of texture, which has been under investigation up to now: Macroscopic homogeneous texture areas are represented in the B-Scan-images not as a single homogeneous grey-level, but as very “granular” areas with characteristic “granule-size”. This phenomenon is commonly called “speckle”. Several different approaches were done to investigate this problem. Two of them, the analytical statistical methods of Burckhardt /3/and Wagner et al. /4/, are extended in this paper in order to investigate speckle in ultrasound computerized reflection mode tomography (UCTR). UCTR can be explained as a numerical superposition of several B-Scans of a cross-sectional plane obtained from different aspect angles. The superposition consists of a summation and an additional inverse filtering procedure, which is equivalent to the deconvolution in X-ray-CT. UCTR has been investigated theoretically (/1/, /2/) and has also been used for clinical in-vivo imaging of female breast /5/, muscles, and thyroid gland /2/. Section 2 summarizes the theory of UCTR. Section 3 shortly reviews the results of speckle in B-Scans from Burckhardt /3/ and Wagner et al. /4/ Sections 4, 5 and 6 presents results of first and second order statistics of speckle in the summation image, and shows measurements of correlation-coefficients of two B-Scans with different aspect-angles.
KeywordsPoint Spread Function Aspect Angle Inverse Filter Spatial Frequency Domain Speckle Size
Unable to display preview. Download preview PDF.
- /2/.Roehrlein G, Ermert H.: Limited angle reflection mode computerized tomography. Acoustical Imaging, Vol. 14, Plenum Press 1985, New York and London, edts. A.J. Berkhout et al.Google Scholar
- /3/.Burckhardt D.B.: Speckle in ultrasound B-mode scans. IEEE Trans, on Sonics and Ultrasonics, Vol. SU-25, No. 1, January 1978, pp. 1–6Google Scholar
- /5/.Hassler D.A., Trautenberg E.A., Friedrich M., Sparrenberg A.: Breast-scanner for clinical evaluation of ultrasonic computed tomography in reflection mode. Proc. of WFUMB 85, Sydney, 14–19 July 1985, Pergamon Press, pp. 360–361Google Scholar
- /6/.Papoulis A.: Probability, Random Variables and Stochastic Processes. McGraw-Hill, Hamburg, 1965Google Scholar
- /7/.Gehlbach S.M.:Quantitative analysis of acoustic speckle. Ultrasonic Imaging, Vol. 5, No. 2, 1983, p. 190Google Scholar