The schematic principle of MACI. The principle of transforming an ultrasound image sequence (a) into a score plot (c) by means of the wavelet transform (b). (a) A multivariate image space made up of a series of images from an ultrasound loop. (b) The congruent images are stored as the rows of an ordinary two-way data table. This means that each row corresponds to a point, or frame, in time; the columns contain the wavelet coefficients. (c) A two-component score plot of the table of wavelet coefficients in which the second score vector is plotted against the first score vector. Each circle in this plot represents one image or one time point in the ultrasound sequence.