Abstract
PurposeTo investigate image quality and bronchial wall quantification in low‐ and ultralow‐dose third‐generation dual‐source computed tomography (CT).MethodsA lung specimen from a formerly healthy male was scanned using third‐generation dual‐source CT at standard‐dose (51 mAs/120 kV, CTDIvol 3.41 mGy), low‐dose (1/4th and 1/10th of standard dose), and ultralow‐dose setting (1/20th). Low kV (70, 80, 90, and Sn100 kV) scanning was applied in each low/ultralow‐dose setting, combined with adaptive mAs to keep a constant dose. Images were reconstructed at advanced modeled iterative reconstruction (ADMIRE) levels 1, 3, and 5 for each scan. Bronchial wall were semi‐automatically measured from the lobar level to subsegmental level. Spearman correlation analysis was performed between bronchial wall quantification (wall thickness and wall area percentage) and protocol settings (dose, kV, and ADMIRE). ANOVA with a post hoc pairwise test was used to compare signal‐to‐noise ratio (SNR), noise and bronchial wall quantification values among standard‐ and low/ultralow‐dose settings, and among ADMIRE levels.ResultsBronchial wall quantification had no correlation with dose level, kV, or ADMIRE level (|correlation coefficients| < 0.3). SNR and noise showed no statistically significant differences at different kV in the same ADMIRE level (1, 3, or 5) and in the same dose group (P > 0.05). Generally, there were no significant differences in bronchial wall quantification among the standard‐ and low/ultralow‐dose settings, and among different ADMIRE levels (P > 0.05).ConclusionThe combined use of low/ultralow‐dose scanning and ADMIRE does not influence bronchial wall quantification compared to standard‐dose CT. This specimen study suggests the potential that an ultralow‐dose scan can be used for bronchial wall quantification.
Highlights
Airway quantification on computed tomography (CT) provides an estimate of bronchial remodeling and inflammation, which is associated with physiological parameters and symptoms in chronic obstructive pulmonary disease (COPD).[1,2,3,4,5,6] The increasing concern on radiation exposure in clinical practice stimulates the new techniques to decrease radiation dose,[7] like peak kilovolt reduction and iterative reconstruction (IR).[8]
signal‐to‐noise ratio (SNR) was significantly correlated with dose level, and advanced modeled iterative reconstruction (ADMIRE) level, but not with kV (0.219, P = 0.003)
Image noise was significantly correlated with dose level, and ADMIRE level (−0.716 and −0.546, P < 0.001), but not with kV (−0.215, P = 0.004)
Summary
Airway quantification on computed tomography (CT) provides an estimate of bronchial remodeling and inflammation, which is associated with physiological parameters and symptoms in chronic obstructive pulmonary disease (COPD).[1,2,3,4,5,6] The increasing concern on radiation exposure in clinical practice stimulates the new techniques to decrease radiation dose,[7] like peak kilovolt (kV) reduction and iterative reconstruction (IR).[8]. Some studies showed no significant side effect of dose reduction on emphysema evaluation.[15,16,17] For example, ultralow‐dose CT at a radiation dose equivalent to 5% of the standard dose (2.33 ± 1.54 mSv), increasing the percentage of low attenuation area, was strongly correlated with standard‐dose CT, could be used to evaluate lung volume and density.[15] the reduction in radiation dose decreases the ability to display distal bronchi. Kirby et al showed that the spatial resolution of 1‐ 2 mm in low‐dose CT (about 1.5 mSv) could identify the bronchi with an inner diameter greater than 2.5 mm.[18] While CT examination at higher radiation dose (11.2 mSv) could show small airways with a diameter of 0.8 mm.[19] In an ex vivo porcine lung specimen study when radiation dose decreased, the number of evaluable bronchial branches decreased, but measurement variability increased.[20] To the best of our knowledge, there are few studies investigating bronchial wall quantification using low/ultralow‐dose CT in the human lung
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
