Rationale and Objectives: To determine lobar ventilation patterns in asthmatic lungs with hyperpolarized 3 He magnetic resonance imaging (HP 3 He MRI). Materials and Methods: Eighty-two subjects (14 normal, 48 mild-to-moderate asthma, and 20 severe asthma) underwent HP 3 He MRI, computed tomography (CT), and pulmonary function testing. After registering proton to 3 He images, we segmented the lungs from proton MRI and further segmented the five lung lobes (right upper lobe [RUL], right middle lobe [RML], and right lower lobe [RLL]; left upper lobe and left lower lobe [LLL]) by referring to the lobar segmentation from CT. We classified the gas volume into four signal intensity levels as follows: ventilation defect percent (VDP), low ventilation percent, medium ventilation percent, and high ventilation percent. The local signal intensity variations in the ventilated volume were estimated using heterogeneity score (Hs). We compared each ventilation level and Hs measured in the whole lung and lobar regions across the three subject groups. Results: In mild-to-moderate asthma, the RML and RUL showed significantly greater VDP than the two lower lobes (RLL and LLL) (P ≤.047). In severe asthma, the pattern was more variable with the VDP in the RUL significantly greater than in the RLL (P =.026). In both asthma groups, the lower lobes (RLL and LLL) showed significantly higher high ventilation percent and Hs compared to the three upper lobes (all P ≤.015). Conclusions: In asthma, the RML and RUL showed greater ventilation abnormalities, and the RLL and LLL were more highly ventilated with greater local heterogeneity. These findings may facilitate guided bronchoscopic sampling and localized airway treatment in future studies.
|Original language||English (US)|
|Number of pages||10|
|State||Published - Feb 2018|
Bibliographical noteFunding Information:
This work was supported by the National Institutes of Health UL1TR000427 , NIH/NHLBI U10 HL109168 (The Severe Asthma Research Program), NIH/NCI 5 T32 CA009206 Radiological Science Training Grant, and GE Healthcare, pulmonary imaging center, NIH S10 OD016394 .
© 2018 The Association of University Radiologists
- hyperpolarized gas imaging
- magnetic resonance imaging
- ventilation defect percent
- ventilation heterogeneity