Unsedated cerebrovascular reactivity imaging is well-tolerated in children

Unsedated MRI use in pediatric clinical and research settings is often feasible, but advanced imaging techniques like cerebrovascular reactivity (CVR) may affect tolerability of unsedated MRIs. Exogenous carbon dioxide (CO₂) provides a CVR vasodilatory challenge, but its impact on unsedated children's MRI tolerability is unknown.

We hypothesized that children would tolerate MRI with exogenous CO₂ as well as children undergoing only MRI.

Children with and without sickle cell disease and/or reactive airway disease participated in prospective, single-site unsedated MRI observational studies and completed a post-scan questionnaire. A RespirAct® device delivered CO₂ during the scan for MRI-measured CVR. Head displacement across frames quantified motion. Tolerability was defined as MRI study completion without lasting symptoms or serious adverse events.

One-hundred children participated, with a median age of 14.0 years [11.0, 16.3]. Sickle cell disease and/or reactive airway disease was present in 35% (35/100) and 16% (16/100), respectively. CVR sessions occurred in 75 participants, while 25 had MRI only. All children tolerated and completed the scans; 77% (58/75) had usable CVR data. Motion was similar between those with and without CVR (P=0.33). Children undergoing CVR were more likely to report symptoms, mainly shortness of breath (42/75 vs 3/25; P<0.001), compared to MRI only. Eleven children reported mild, temporary symptoms post-CVR scan; all resolved within a few hours. No serious adverse events occurred. Three children (CVR group) reported unwillingness to repeat the scan.

Children tolerate MRI with exogenous CO₂ for CVR measurement with mild, predictable transient symptoms.