title: Distribution of ventilation-to-perfusion ratios analysed in planar scintigrams of emphysematous patients.
abstract: The aim of the present study was to develop and evaluate a method for semi-quantification of ventilation-to-perfusion ratios in small regions in planar pulmonary scintigrams using 99mTc-Technegas (Tetley Manufacturing Ltd, Sydney, Australia) and 99mTc-macro-aggregated human albumin. Eight emphysematous patients and eight healthy volunteers were investigated in the supine position. Anterio-posterior and posterio-anterior images of ventilation and ventilation-and-perfusion were acquired consecutively. Perfusion images were obtained by subtracting the corrected ventilation images from ventilation-and-perfusion images. Lung regions of interest were divided into 2.03 x 2.03 cm regions. The ratio of normalized counts of ventilation-to-perfusion (V/Q) was calculated in each square region. The log (V/Q)s of healthy volunteers were distributed symmetrically and similarly around 0, whereas the corresponding ratios in patients distributed unevenly. The standard deviations of log (V/Q)s were significantly higher in patients than in healthy volunteers. Parametric images of V/Q distribution were constructed to visualize the magnitude and location of 'waste ventilation' and 'shunt' effects. In conclusion, the present semi-quantitative method is validated by confirming the expected dispersed V/Q distribution in emphysematous patients compared to healthy volunteers.
authors.affiliation: Department of Clinical Physiology, University of Göteborg, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden.
authors.forename: J H
authors.initials: JH
authors.lastname: Xu
authors.forename: M
authors.initials: M
authors.lastname: Moonen
authors.forename: A
authors.initials: A
authors.lastname: Johansson
authors.forename: B
authors.initials: B
authors.lastname: Bake
mesh_terms: D000328:Adult; D004646:Emphysema / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin; D014692:Ventilation-Perfusion Ratio; D014797:Vital Capacity
chemical_list: D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin