Abstract
Previous studies demonstrated that regional intensity variations between different lung volumes acquired by HRCT (Aliverti et al,ERJ2013) and by proton-MRI (Pennati et al,Radiology2014) can be used as estimates of regional ventilation.The aim of the study is to compare maps of CT-density difference (ΔHU) with the corresponding maps of proton-signal-density difference in pediatric patients.
Seven infants (age 6-24mo) with cystic fibrosis (CF) were scanned during breath-hold at functional residual capacity (FRC)and total lung capacity (TLC) through HRCT and MRI. FRC was registered onto TLC by the Demons algorithm and maps of ΔHU and of proton-density difference were obtained by voxel-by-voxel subtraction between the two lung volumes.Difference maps were compared by computing the linear correlation between the median values of ΔHU and of proton-density difference in six corresponding regions at five equally-spaced lung levels.
Fig. 1 shows matched HRCT and MRI slices at TLC and FRC,with the corresponding difference maps in a representative infant.In the overall population the average±SD correlation coefficient is R2=0.6±0.2.
Multi-volume HRCT and MRI demonstrate good correlation in CF infants, with significant regional variation,suggesting that proton-density difference may be used to describe ventilation patterns in infants with CF, with no radiation dose.
- Copyright ©ERS 2015