Radiology - Emphysema Index Based on Hyperpolarized 3He or 129Xe Diffusion MRI: Performance and Comparison with Quantitative CT and Pulmonary Function Tests
Aug 11 2020
Figure 3: Representative axial CT lung images, segmented CT images with voxels having attenuation coefficient levels less than −950 HU and −910 HU displayed in yellow and red, respectively, and corresponding helium 3 (3He) and xenon 129 (129Xe) apparent diffusion coefficient (ADC) maps. In top row, CT image in healthy 60-year-old man shows uniformly dense parenchyma throughout lung and uniformly low ADC values in both 3He and 129Xe ADC maps. In middle row, CT in 75-year-old man with stage III chronic obstructive pulmonary disease (COPD) depicts large areas of lung parenchyma with low attenuation coefficients. Clear visual concordance is present between these areas in CT image and elevated ADC values in corresponding 3He and 129Xe ADC maps. CT RA950 and ADC emphysema indices are well outside healthy range (>0.04), indicating that with all techniques participant is identified as emphysematous. In bottom row, clear difference in performance is seen in 68-year-old woman with stage III COPD. Very few pixels in CT image cross −950 HU threshold, whereas both ADC maps show extensive lung regions with elevated values. Accordingly, both ADC-based emphysema indices for this participant lie well outside healthy range, but CT RA950 does not (RA950 = 0.01; ADC emphysema index = 0.25 and 0.21 based on 3He and 129Xe, respectively). RA950 = fraction of CT lung voxels with attenuation coefficients less than −950 HU.
#RSNA #radiologia #RadRes #imaging #roentgen
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