Safety of repeated hyperpolarized helium 3 magnetic resonance imaging in pediatric asthma patients

BACKGROUND: Hyperpolarized helium 3 magnetic resonance imaging ((3)He MRI) is useful for investigating pulmonary physiology of pediatric asthma, but a detailed assessment of the safety profile of this agent has not been performed in children. OBJECTIVE: To evaluate the safety of (3)He MRI in children and adolescents with asthma. MATERIALS AND METHODS: This was a retrospective observational study. (3)He MRI was performed in 66 pediatric patients (mean age 12.9 years, range 8–18 years, 38 male, 28 female) between 2007 and 2017. Fifty-five patients received a single repeated examination and five received two repeated examinations. We assessed a total of 127 (3)He MRI exams. Heart rate, respiratory rate and pulse oximetry measured oxygen saturation (SpO(2)) were recorded before, during (2 min and 5 min after gas inhalation) and 1 h after MRI. Blood pressure was obtained before and after MRI. Any subjective symptoms were also noted. Changes in vital signs were tested for significance during the exam and divided into three subject age groups (8–12 years, 13–15 years, 16–18 years) using linear mixed-effects models. RESULTS: There were no serious adverse events, but three minor adverse events (2.3%; headache, dizziness and mild hypoxia) were reported. We found statistically significant increases in heart rate and SpO(2) after (3)He MRI. The youngest age group (8–12 years) had an increased heart rate and a decreased respiratory rate at 2 min and 5 min after (3)H inhalation, and an increased SpO(2) post MRI. CONCLUSION: The use of (3)He MRI is safe in children and adolescents with asthma.