Feasibility, tolerability and safety of pediatric hyperpolarized 129Xe magnetic resonance imaging in healthy volunteers and children with cystic fibrosis

Hyperpolarized Xe-129 is a promising contrast agent for MRI of pediatric lung function, but its safety and tolerability in children have not been rigorously assessed. To assess the feasibility, safety and tolerability of hyperpolarized Xe-129 gas as an inhaled contrast agent for pediatric pulmonary MRI in healthy control subjects and in children with cystic fibrosis. Seventeen healthy control subjects (ages 6-15 years, 11 boys) and 11 children with cystic fibrosis (ages 8-16 years, 4 boys) underwent Xe-129 MRI, receiving up to three doses of Xe-129 gas prepared by either a commercially available or a homebuilt Xe-129 polarizer. Subject heart rate and SpO(2) were monitored for 2 min post inhalation and compared to resting baseline values. Adverse events were reported via follow-up phone call at days 1 and 30 (range +/- 7 days) post-MRI. All children tolerated multiple doses of Xe-129, and no children withdrew from the study. Relative to baseline, most children who received a full dose of gas for imaging (10 of 12 controls and 8 of 11 children with cystic fibrosis) experienced a nadir in SpO(2) (mean -6.0 +/- standard deviation 7.2%, Paecurrency sign0.001); however within 2 min post inhalation SpO(2) values showed no significant difference from baseline (P=0.11). There was a slight elevation in heart rate (mean +6.6 +/- 13.9 beats per minute [bpm], P=0.021), which returned from baseline within 2 min post inhalation (P=0.35). Brief side effects related to the anesthetic properties of xenon were mild and quickly resolved without intervention. No serious or severe adverse events were observed; in total, four minor adverse events (14.3%) were reported following Xe-129 MRI, but all were deemed unrelated to the study. The feasibility, safety and tolerability of Xe-129 MRI has been assessed in a small group of children as young as 6 years. SpO(2) changes were consistent with the expected physiological effects of a short anoxic breath-hold, and other mild side effects were consistent with the known anesthetic properties of xenon and with previous safety assessments of Xe-129 MRI in adults. Hyperpolarized Xe-129 is a safe and well-tolerated inhaled contrast agent for pulmonary MR imaging in healthy children and in children with cystic fibrosis who have mild to moderate lung disease.