Hyperpolarized 3He MR imaging: physiologic monitoring observations and safety considerations in 100 consecutive subjects.
OBJECTIVE
To evaluate the safety of hyperpolarized helium 3 ((3)He) magnetic resonance (MR) imaging.


METHODS
Local institutional review board approval and informed consent were obtained. Physiologic monitoring data were obtained before, during, and after hyperpolarized (3)He MR imaging in 100 consecutive subjects (57 men, 43 women; mean age, 52 years +/- 14 [standard deviation]). The subjects inhaled 1-3 L of a gas mixture containing 300-500 mL (3)He and 0-2700 mL N(2) and held their breath for up to 15 seconds during MR imaging. Heart rate and rhythm and oxygen saturation of hemoglobin as measured by pulse oximetry (Spo(2)) were monitored continuously throughout each study. The effects of (3)He MR imaging on vital signs and Spo(2) and the relationship between pulmonary function, number of doses, and clinical classification (healthy volunteers, patients with asthma, heavy smokers, patients undergoing lung volume reduction surgery for severe emphysema, and patients with lung cancer) and the lowest observed Spo(2) were assessed. Any subjective symptoms were noted.


RESULTS
Except for a small postimaging decrease in mean heart rate (from 78 beats per minute +/- 13 to 73 beats per minute +/- 11, P < .001), there was no effect on vital signs. A mean transient decrease in Spo(2) of 4% +/- 3 was observed during the first minute after gas inhalation (P < .001) in 77 subjects who inhaled a dose of 1 L for 10 seconds or less, reaching a nadir of less than 90% at least once in 20 subjects and of less than 85% in four subjects. There was no correlation between the lowest Spo(2) and pulmonary function parameters other than baseline Spo(2) (r = 0.36, P = .001). The lowest mean Spo(2) varied by 1% between the first and second and second and third doses (P < .001) and was unrelated to clinical classification (P = .40). Minor subjective symptoms were noted by 10 subjects. No serious adverse events occurred.


CONCLUSIONS
Hyperpolarized (3)He MR imaging can be safely performed in healthy subjects, heavy smokers, and those with severe obstructive airflow limitation, although unpredictable transient desaturation suggests that potential subjects should be carefully screened for comorbidities.
Lutey
Barbara A
BA
Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, 510 S Kingshighway Blvd, St Louis, MO 63110, USA.
Lefrak
Stephen S
SS
Woods
Jason C
JC
Tanoli
Tariq
T
Quirk
James D
JD
Bashir
Adil
A
Yablonskiy
Dmitriy A
DA
Conradi
Mark S
MS
Bartel
Seth T
ST
Pilgram
Thomas K
TK
Cooper
Joel D
JD
Gierada
David S
DS
D000368:Aged; D000704:Analysis of Variance; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006371:Helium / Q000009:adverse effects; D006801:Humans; D008171:Lung Diseases / Q000175:diagnosis* / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D010092:Oximetry; D012449:Safety
D006371:Helium