Hyperpolarized ¹²⁹Xe MRI, ^99mTc scintigraphy, and SPECT in lung ventilation imaging: a quantitative comparison

Area of Science:

• Pulmonary Medicine
• Medical Imaging
• Radiology

Background:

• Current lung imaging relies on scintigraphy and SPECT using radioactive tracers.
• Hyperpolarized Xenon-129 MRI (XeMRI) is a newer, FDA-approved technique offering higher spatial resolution.
• XeMRI provides functional lung imaging comparable to existing methods.

Purpose of the Study:

• To compare the efficacy of Hyperpolarized Xenon-129 MRI (XeMRI) against Technetium-99m (99mTc) scintigraphy and SPECT.
• To evaluate XeMRI's utility in patients with asthma and COPD.
• To assess the correlation between XeMRI, SPECT, and standard spirometry.

Main Methods:

• 59 subjects (healthy, asthma, COPD) underwent 99mTc scintigraphy/SPECT, spirometry, and HP XeMRI.
• Image registration allowed for direct voxel-wise signal comparison.
• Ventilation defect percentage (VDP) was calculated and compared across imaging modalities and with spirometry.

Main Results:

• Voxel-wise signal comparison showed moderate correlation between scintigraphy and XeMRI (median r=0.698) and lower correlation between SPECT and XeMRI (median r=0.398).
• Ventilation defect percentage (VDP) showed strong correlation (r=0.853, p<0.05) between XeMRI and SPECT.
• VDP effectively differentiated asthma and COPD patients from controls and correlated significantly with spirometry measures (FEV1, FEV1/FVC, FEF 25-75).

Conclusions:

• HP XeMRI provides functional lung imaging information equivalent to 99mTc SPECT and spirometry.
• XeMRI's non-invasive nature makes it suitable for longitudinal studies.
• XeMRI holds potential for evaluating novel treatments for various lung ailments.