PURPOSE: To assess the safety of hyperpolarized 3Helium magnetic resonance (3HeMR) imaging. MR imaging of inhaled hyperpolarized 3He gas provides insight into pulmonary structure and physiology. Although 3He is an FDA investigational contrast agent not approved for clinical use, safety concerns of 3HeMR imaging have received little attention.
METHODS: Physiologic monitoring data obtained during hyperpolarized 3HeMR imaging in 100 consecutive subjects (57 male 43 female ages 52.9 ± 13.6 years range 18–74 years)were retrospectively reviewed. Subjects were normal volunteers, National Lung Screening Trial participants, and asthma, emphysema, or lung cancer patients. Subjects inhaled 1–3L of 300–400 ml hyperpolarized 3He combined with 600–2700 ml N2, and performed breath-holds (maximum duration 15 seconds) during MR scanning. Pre/Post-scan pulse, blood pressure, respiratory rate, pulse oxygen saturation (SpO2), and transient temporal changes in SpO2 within the first minute after inhalation were compared using two-tailed paired t tests. Potential factors associated with the degree of change in SpO2 were evaluated by analysis of variance. Subgroup analyses according to clinical classification were performed.
RESULTS: No serious adverse events occurred during the scans or the 24-hour follow-up period. A statistically-significant but small post-scan decrease in mean heart rate (from 78±13 to 73±11, P<0.001)was found in the entire cohort, but not seen in the normal or emphysema subgroups. Standard doses of approximately 300–400 ml of 3He combined with 600–700 ml N2 were administered at least once for 10 seconds or less to 75 of the subjects and accounted for 82% of the doses. A transient decrease in mean SpO2 of 3.6% was observed in the first minute after these doses (P< 0.001), reaching a nadir < 90% at least once in 19 subjects. ANOVA showed no association between the occurrence or degree of desaturation and clinical status or number of doses administered.
CONCLUSION: Hyperpolarized 3HeMR imaging can be safely performed in subjects with airway obstructive disease.
CLINICAL IMPLICATIONS: Because of unpredictable transient desaturation, subjects should be screened for co-morbidities, and excessive breath-hold times avoided.
DISCLOSURE: Barbara Lutey, No Financial Disclosure Information; Product/procedure/technique that is considered research and is NOT yet approved for any purpose. Hyperpolarized 3Helium is considered an investigational contrast agent that is not yet approved for clinical use.