Purpose To evaluate the effects of adaptive iterative dose reduction using 3D processing (AIDR 3D) for quantification of two measures of emphysema: percentage of low-attenuation volume (LAV%) and size distribution of low-attenuation lung regions.
Method and materials: Fifty-two patients who underwent standard-dose (SDCT) and low-dose CT (LDCT) were included. SDCT without AIDR 3D, LDCT without AIDR 3D, and LDCT with AIDR 3D were used for emphysema quantification. First, LAV% was computed at 10 thresholds from -990 to -900 HU. Next, at the same thresholds, linear regression on a log-log plot was used to compute the power law exponent (D) for the cumulative frequency-size distribution of low-attenuation lung regions. Bland-Altman analysis was used to assess whether AIDR 3D improved agreement between LDCT and SDCT for emphysema quantification of LAV% and D.
Results The mean relative differences in LAV% between LDCT without AIDR 3D and SDCT were 3.73%-88.18% and between LDCT with AIDR 3D and SDCT were -6.61% to 0.406%. The mean relative differences in D between LDCT without AIDR 3D and SDCT were 8.22%-19.11% and between LDCT with AIDR 3D and SDCT were 1.82%-4.79%. AIDR 3D improved agreement between LDCT and SDCT at thresholds from -930 to -990 HU for LAV% and at all thresholds for D.
Conclusion AIDR 3D improved the consistency between LDCT and SDCT for emphysema quantification of LAV% and D.
All Science Journal Classification (ASJC) codes
- Radiology Nuclear Medicine and imaging