ABSTRACT
RATIONALE: Severe COVID-19 viral infection results in parenchymal pneumonia involving the terminal bronchi and alveolar cells;viral re-production results in damaged and destroyed cells, causing whole lung inflammation resulting in failed gas exchange and respiratory failure that leads to end-stage organ failure. Hyperpolarized 129Xe gas MRI is non-invasive, radioactive-free tool can examine COVID-19 damage to the lungs with spatial-resolution similar to the CT-resolution. We hypothesize, that the high-resolution 129Xe MRI can be used for the assessment of the lung structure and function in COVID-19 survivors (CS). In this pilot study conducting with a small number of CS, we measured the Ventilation-Defect-Percent (VDP) a sensitive indicator of lung function, using highresolution (voxel-size=3x3x3mm3) 129Xe MRI. This should improve our understanding on the effects of COVID-19 on the lungs. METHODS: Three CS with written informed consent provided, underwent spirometry and 1H/129Xe MRI scanning (NCT04584671), performed on a 3.0T scanner. Traditional or low-resolution coronal xenon images (3x3x15mm3), were acquired in a <16 sec breath-hold after inspiration of 1.0L of gas (129Xe/4He-30/70) from functional-residual-capacity using acquisition parameters reported elsewhere.2 Pre- and post-salbutamol data set acquired for each subject. Isotropic-voxel high-resolution-images with 3x3x3mm3 were reconstructed by using the key-hole approach.3 Hyperpolarized 129Xe gas (polarization=35%) was obtained from a turn-key 129Xe polarizer system. Proton MRI was performed as described.1 Image SNR and VDP values were calculated as elsewhere.4 RESULTS: Figure 1 reports CS information and imaging results. The calculated VDPs for the highresolution data were lower than the low-resolution data. The pre- and post-salbutamol values were similar except for CS-1, where the post-salbutamol value was larger. The SNR values are reported on Figure1.DISCUSSION: The good quality of the high-res 129Xe images permitted a precise VDP calculation, which are comparable to those reported elsewhere.5 The North-American xenon consortium expects 129Xe MRI to be FDA approved any moment now, which allow for better diagnoses, treatment planning and treatment assessment of CS. This increases the potential of the 129Xe MRI clinical translation for better treatment of patients with different diseases. CONCLUSION: The preliminary results using 129Xe MR imaging demonstrated accurate lung damage assessment. The results from this pilot study will inform future guidelines on therapies and treatment planning, resulting in improved outcomes for COVID-19 patients.