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A method to quantify the motion of the heart from digitized sequences of two-dimensional echocardiograms (2-D) echos was recently proposed. This method computes on every point of the 2-D echoes, the 2-D apparent velocity vector (or optical flow) which characterizes its interframe motion. However, further analysis is required to determine what part of this motion is due to translation, rotation, contraction, and deformation of the myocardium. A method to locally obtain this information is presented. The proposed method assumes that the interframe velocity field U(xy), V(x,y) can be locally described by linear equations in the form U(x,y)=a+Ax+By; V(x,y)=b+Cx+Dy. The additional constraint was introduced in the computation of the local velocity field by the method of projections onto convex sets. Since this constraint is only valid locally, the myocardium must be first divided into sectors and the velocity fields computed independently for each sector.

Ultrasound B-scan images of the thyroid obtained from 10 patients with Hashimoto disease were digitized and processed by a computer method of image analysis that segments complex B-scan images into regions of homogeneous texture. The method was first applied to B-scan images of the normal thyroid and it consistently classified the normal tissue into a unique region. When applied to Hashimoto disease B-scan images, the same method segmented the thyroid into two regions. Detailed analysis of these regions revealed that their gray-level histograms were very different from that of the normal thyroid in eight cases. In two cases the histogram of one of the regions was similar to that of the previous eight cases, whereas the histogram and the tissue of the other region were similar to those of the normal tissue. This paper shows how these results can be interpreted according to the natural history of the Hashimoto disease.

SUMMARY. The effects of torso inhomogeneities on electrocardiographic potentials were investigated via computer simulation, using a 23-dipole heart model placed within a realistically shaped human torso model. The transfer coefficients relating the individual dipoles to the torso surface potentials, as well as the body surface potential maps, the vectorcardiogram, and the 12-lead electrocardiogram resulting due to normal activation of the heart model, were calculated for each of the following torso conditions: homogeneous, homogeneous + skeletal muscle layer, homogeneous + muscle layer + lungs, and homogeneous + muscle layer + lungs + intraventricular blood masses. The effects of each inhomogeneity were deduced by comparing results before and after its inclusion. For individual dipole transfer coefficients we confirm the validity of the "Brody effect," whereby the high conductivity blood masses augment radially oriented dipoles and diminish tangentially oriented ones. With regard to the vectorcardiogram, the electrocardiogram, and the body surface potential maps, the major qualitative effects were an augmentation of the head-to-foot component of the vectorcardiogram due to the lungs, and a smoothening of notches in the electrocardiogram (temporal filtering) and of isopotential contours in the body surface potential maps (spatial filtering) with a consequent loss of information, due to the blood masses, muscle layer, and, to a lesser extent, the lungs. Besides the above qualitative effects of the inhomogeneities, there were also large quantitative effects on the surface potentials, namely, magnitude increases due to the blood masses and magnitude decreases due to the muscle layer, that-if unaccounted for-could compromise the inverse solution of these potentials for the cardiac dipole sources. (Ore Res 52: 45-56, 1983)

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