We undertook this study to investigate if a single measure of foeal or regional wall motion abnormalities eould be devised. Sinee it ean be shown that the global ejeetion fraetion does not neeessarily deerease until a substantial fraetion of the myoeardium has been damaged, and sinee global parameters are easily influeneed by non-myoeardial variables such as after-Ioad, pre-Ioad and heart rate, it seemed that a more preeise measure of foeal damage was needed. Our approaeh is based on the hypothesis that in the absenee of foeal damage, eaeh myoeardial segment has a eonstant relative eontribution to the global ejeetion fraetion. While global, non-eardiae faetors whieh influenee the global ejeetion fraetion will also influenee all segments, th ey will not influenee the relative (amongst segments) eontraetion of the segments. Henee, all data eould be normalized to a "normaI" global ejeetion fraetion. The first step of the method is analogous to the eireumferential profile methods in Thallium myoeardial perfusion seintigraphies~ after the (automatie) delineation of the left ventrieular borders and the isolation of left ventrieular aetivities by interpolation from those borders, 255 radii evenly spaeed over 360 degrees are defined, originating in the center of mass of the left ventriele computed in the end-diastolie frame. Along those radii eounts are integrated over the outer half, between center and border, in the end-diastolie image, and over the identieal pixels in the end-systolie image. From those data 256 radial ejeetion fraetions are computed. From 12 middle-aged volunteers a normal resting and a normal stress profile is then computed, with a standard deviation value for eaeh radial value. The index of regional or foeal wall motion abnormality is computed from the eumulative differenee between eorresponding points in the test

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Information processing in medical imaging

A new method is described that modifies the original concept of parametric or functional imaging. While the conventional parametric image replaces a temporal sequence of images with a single static image based upon a selected parameter, in the new approach fixed zonal areas and bands are established within the imaged organ, and the mean value for each zone is computed. It is shown that parametric images can be quantified and objectively compared in this way. The algorithm has been implemented to analyze renal studies.

Zonal parametric imaging: concept and application to renal angiography;

A new method is described that modifies the original concept of parametric or functional imaging. While the conventional parametric image replaces a temporal sequence of images with a single static image based upon a selected parameter, in the new approach fixed zonal areas and bands are established within the imaged organ, and the mean value for each zone is computed. It is shown that in this way parametric images can be quantified and objectively compared. Examples for various organs are given.

D. P. Harrington

Papers

Zonal Parametric Imaging