Computer-aided analysis of three-dimensional radiopharmaceutical distributions in serial ECT acquisitions

Quantitative techniques are assuming an increasing role in clinical nuclear medicine imaging. Emission computed tomograms (BCT) use such methods, but ;their diagnostic utility depends on effective, meaningful data displays. Algorithms are described which provide quantitative images of radio-labelled tracers in 3-dimensions (3D). the system, developed from autoradiographic studies, creates 3D histograms of regional tracer activity such as Tc-99mMDP and Tc-99mDTPA. Perimeters defining the regions of interest (ROI) for each tomographic slice are manually traced and stored. Standard ROI perimeter4s can also be translated, rotated, or scaled to fit individual data. Pixel values in the ROI are sequentially stored by a raster-scan algorithm which assigns 3D coordinates to each value for later quantitative analysis. A 2D pixel distribution histogram is generated for each ROI by summing all pixel values within the intersection of the perimeter and either horizontal or vertical bins. The position of each histogram in space is assigned according to the thickness and depth of each acquisition plane. A triangulation algorithm then generates polygons which connect the histogram from sequential sections to create a 3D surface. By color coding the height of the surface, quantitative comparisons can be made between tracer distributions in 3D structures. This display system providesmore » a powerful tool for interpreting quantitative nuclear medicine procedures in radionuclide distribution within selected structures. Separate ECT acquisitions can be compared by normalizing pixel values.« less