Quantitative and regional evaluation methods for lung scintigraphs

For the evaluation of perfusion lung scintigraphs with regard to the quantitative valuation and also with regard to the choice of the regions new criteria were presented. In addition to the usual methods of sectioning each lung lobe into upper, middle and lower level and the determination of the per cent activity share of the total activity the following values were established: the median of the activity distribution and the differences of the per cent counting rate as well as of the median of the corresponding regions of the right and left lung. The individual regions should describe the functional structures (lobe and segment structure). A corresponding computer program takes over the projection of lobe and segment regions in a simplified form onto the scintigraph with consideration of individual lung stretching. With the help of a clinical study on 60 patients and 18 control persons with 99mTc-MAA and 133 Xe-gas lung scintigraphs the following results could be determined: depending on the combination of the 32 parameters available for evaluation and the choice of regions between 4 and 20 of the 60 patients were falsely negatively classified and 1 to 2 of the 18 controls were falsely positive. The accuracy of the Tc-scintigraph proved to be better. All together using the best possible parameter combinations comparative results were attained. (TRV)