Evaluation of structure-function relationships in asthma using multidetector CT and hyperpolarized He-3 MRI

Area of Science:

• Pulmonary Medicine
• Radiology
• Medical Imaging

Background:

• Asthma is characterized by structural and ventilation abnormalities.
• Multiple detector computed tomography (MDCT) and hyperpolarized gas magnetic resonance imaging (HP MRI) can detect these abnormalities.
• Regional analysis of these imaging techniques is underexplored.

Purpose of the Study:

• To assess regional disease in asthma by correlating HP MRI ventilation defects with MDCT air trapping and bronchoscopic inflammatory markers.
• To evaluate the association between sites of ventilation defect on HP MRI and hyperlucency on MDCT.
• To compare inflammatory cell counts in lung lobes with varying HP MRI defect volumes.

Main Methods:

• HP MRI (helium-3) and MDCT were performed on the same asthma patients.
• Supervised segmentation of lung lobes allowed for regional comparison of ventilation defects and hyperlucency.
• Spatial overlap between HP MRI defects and MDCT hyperlucency was quantified.
• Bronchoscopic assessment compared inflammatory cell differences in lung lobes with high vs. low HP MRI defect volumes.

Main Results:

• Significant overlap was observed between HP MRI ventilation defects and MDCT hyperlucency, indicating associated airway obstruction and air trapping.
• Increased neutrophil counts in bronchoalveolar lavage directly correlated with higher HP MRI defect volumes (r=0.68 for percent, r=0.61 for absolute count).

Conclusions:

• HP MRI and MDCT demonstrate overlapping regional abnormalities in asthma.
• These imaging modalities show promise for guiding regional assessment of ventilation defects and air trapping.
• This approach may aid in managing heterogeneous obstructive lung diseases like asthma.