Characterization and detection of physiologic lung changes before and after placement of bronchial valves using hyperpolarized helium-3 MR imaging: preliminary study

Rationale and objectives: The aim of this study was to determine the efficacy of hyperpolarized (3)He (HHe) ventilation and apparent diffusion coefficient (ADC) HHe magnetic resonance imaging (MRI) in detecting changes in lung function and microstructure in emphysematous lung after bronchial valve (BV) placement.

Materials and methods: One patient diagnosed with emphysema had nine BVs placed in upper lobe bronchi. Imaging was performed before and 6 months after BV placement. Coronal HHe ventilation MRI was used to assess volume changes in the ventilated portions of the lung. Coronal ADC HHe MRI, acquired with b value pairs of 0 and 1.6 s/cm(2) during a second 10-second breath-hold, was used to compute ADC values.

Results: HHe ventilation MRI revealed decreased ventilation in the treated segments of the upper lobes after BV placement. Increased ventilation in the lower lobes and two untreated segments of the left upper lobes were also observed, with an upward shift of the major fissure of the right lung. Whole-lung mean ADC decreased by 6.3% from baseline, from 0.48 ± 0.196 to 0.45 ± 0.176 cm(2)/s (toward healthier values) following BV placement.

Conclusions: HHe ventilation MRI detected an increase in whole-lung volume and an interlobar fissure shift indicative of increased ventilation of lower relative to upper lobes. Reduced ADC values suggest increased ventilation to healthy lower lobes at the expense of more diseased, expanded alveolar spaces in the upper lobes distal to BV placement. These results suggest that this ionizing radiation-free method of examining the lungs may offer functional and structural information useful in BV intervention planning.