Assessment of Reproducibility and Stability of Different Breath-hold Maneuvres by Dynamic MRI: Comparison Between Healthy Adults and Patients with Pulmonary Hypertension

To assess the stability and reproducibility of different breath-hold levels in healthy volunteers and patients using dynamic MRI (dMRI). In ten healthy volunteers and ten patients with pulmonary hypertension (PH) and normal lung function craniocaudal intrathoracic distances (CCD) were measured during inspiratory and expiratory breath-hold (15 s) (in healthy volunteers additionally at a self-chosen mid-inspiratory breath-hold) using dMRI (trueFISP, three images/s). To evaluate stability and intraobserver reproducibility of the different breath-hold levels, CCDs, time-distance curves, confidence intervals (CIs), Mann-Witney U test and regression equations were calculated. In healthy volunteers there was a substantial decrease of the CCD during the inspiratory breath-hold in contrast to the expiratory breath-hold. The CI at inspiration was 2.84+/-1.28 in the right and 2.1+/-0.68 in the left hemithorax. At expiration the CI was 2.54+/-1.18 and 2.8+/-1.48. Patients were significantly less able to hold their breath at inspiration than controls (P<0.05). In patients CI was 4.53+/-4.06 and 3.46+/-2.21 at inspiration and 4.45+/-4.23 and 4.76+/-3.73 at expiration. Intraobserver variability showed no significant differences either in patients or in healthy subjects. Reproducibility was significantly lower at a self-chosen breath-hold level of the healthy volunteers. DMRI is able to differentiate stability and reproducibility of different breath-hold levels. Expiratory breath-hold proved to be more stable than inspiratory breath-hold in healthy volunteers and patients.