OBJECTIVE: This study was performed to compare standard- and low-radiation-dose techniques in the CT quantification of emphysema. MATERIALS AND METHODS: The study population consisted of 36 men and 20 women who were current or former heavy smokers and underwent standard-dose (effective tube current, 100-250 mAs) chest CT at our institution within 6 months of having undergone low-dose (effective tube current, 30-60 mAs) chest CT. All CT scans were reconstructed at 5-mm slice thickness with a smooth filter. CT-measured lung volume, mean and median lung attenuation, and percentage of lung volume with attenuation lower than multiple thresholds (emphysema index values) were compared by Pearson correlation, two-tailed and paired Student's t tests, and regression analysis. RESULTS: There were no significant differences in mean attenuation (-848 vs -846 H, p > 0.35) for the low dose and the standard dose or in median lung attenuation (-879 vs -878 H, p > 0.66). Low- and standard-dose emphysema indexes were correlated at all attenuation thresholds (r = 0.86-0.97). Mean emphysema indexes were higher on the low-dose scans, but the mean difference at all thresholds was less than 3%. The differences were significant (p < 0.05) only at the lower index thresholds, correlated with differences in lung volume (r < or = 0.86), and increased with greater differences in dose. CONCLUSION: Low-dose technique has minimal effect on CT quantification of emphysema.
OBJECTIVE: This study was performed to compare standard- and low-radiation-dose techniques in the CT quantification of emphysema. MATERIALS AND METHODS: The study population consisted of 36 men and 20 women who were current or former heavy smokers and underwent standard-dose (effective tube current, 100-250 mAs) chest CT at our institution within 6 months of having undergone low-dose (effective tube current, 30-60 mAs) chest CT. All CT scans were reconstructed at 5-mm slice thickness with a smooth filter. CT-measured lung volume, mean and median lung attenuation, and percentage of lung volume with attenuation lower than multiple thresholds (emphysema index values) were compared by Pearson correlation, two-tailed and paired Student's t tests, and regression analysis. RESULTS: There were no significant differences in mean attenuation (-848 vs -846 H, p > 0.35) for the low dose and the standard dose or in median lung attenuation (-879 vs -878 H, p > 0.66). Low- and standard-dose emphysema indexes were correlated at all attenuation thresholds (r = 0.86-0.97). Mean emphysema indexes were higher on the low-dose scans, but the mean difference at all thresholds was less than 3%. The differences were significant (p < 0.05) only at the lower index thresholds, correlated with differences in lung volume (r < or = 0.86), and increased with greater differences in dose. CONCLUSION: Low-dose technique has minimal effect on CT quantification of emphysema.
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Authors: David S Gierada; Jason C Woods; Richard E Jacob; Andrew J Bierhals; Cliff K Choong; Seth T Bartel; Yulin V Chang; Nitin A Das; Cheng Hong; Barbara A Lutey; Jon H Ritter; Thomas K Pilgram; Joel D Cooper; G Alexander Patterson; Richard J Battafarano; Bryan F Meyers; Dmitriy A Yablonskiy; Mark S Conradi Journal: J Comput Assist Tomogr Date: 2010 Sep-Oct Impact factor: 1.826
Authors: David S Gierada; Andrew J Bierhals; Cliff K Choong; Seth T Bartel; Jon H Ritter; Nitin A Das; Cheng Hong; Thomas K Pilgram; Kyongtae T Bae; Bruce R Whiting; Jason C Woods; James C Hogg; Barbara A Lutey; Richard J Battafarano; Joel D Cooper; Bryan F Meyers; G Alexander Patterson Journal: Acad Radiol Date: 2010-02 Impact factor: 3.173