Efeitos da filtragem nas relações ventilação-perfusão pulmonares com tomografia por emissão de pósitrons

Abstract

Positronemissiontomography(PET)allowsalocalassessmentofventilationperfusion ratios. However, as PET images are inherently noisy, they must be ltered. In order to evaluate ltering effects, in this study, different sizes of spatial movingaverage lter (N=0, 9, 13 e 18 mm) were applied to data of a previous study with 7 sheep, before and afteran induced bronchoconstriction. Yielded results were consistent with the ones of the previous work which used the same database, for all spatial lter sizes. Maps of pixel classication, ventilation and perfusion showed a pronounced effect of ltering when comparing pixel by pixel. Filters of size N=0 and 18 mm do not result in a good compromise between the robustness of estimates and the space resolution lossatlocallevel.However, when indexes of regional distribution (calculated from tens of pixels) and globals (calculated from all-lung pixels) of ventilation and perfusion were considered, no signicant statistical differences related to lter sizes were found.