Sodium imaging intensity increases with time after human ischemic stroke.
OBJECTIVE
Establishing time of onset is important in acute stroke management. Current imaging modalities do not allow determination of stroke onset time. Although correlations between sodium magnetic resonance imaging signal intensity within ischemic lesions and time of onset have been shown in animal models, the relation to onset time has not been established in human stroke. Utilizing high-quality sodium images, we tested the hypothesis that sodium signal intensity increases with time from symptom onset in human ischemic stroke.


METHODS
Twenty-one stroke patients (63 +/- 15 years old) were scanned 4 to 104 hours after symptom onset. Follow-up images were obtained in 10 patients at 23 to 161 hours after onset, yielding a total of 32 time points. A standard stroke imaging protocol was acquired at 1.5 Tesla, followed by sodium magnetic resonance imaging at 4.7 Tesla. Relative sodium signal intensity within each lesion was measured with respect to the contralateral side.


RESULTS
The sodium image quality was sufficient to visualize each acute lesion (lesion volume range, 1.7-217cm(3)). Relative sodium signal intensity increased nonlinearly over time after stroke onset. Sodium images acquired within 7 hours (n = 5) demonstrated a relative increase in lesion intensity of 10% or less, whereas the majority beyond 9 hours demonstrated increases of 23% or more, with an eventual leveling at 69 +/- 18%.


CONCLUSIONS
Increases of sodium signal intensity within the ischemic lesion are related to time after stroke onset. Thus, noninvasive imaging of sodium may be a novel metabolic biomarker related to stroke progression. Ann Neurol 2009;66:55-62.
Hussain
Muhammad S
MS
Division of Neurology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.
Stobbe
Robert W
RW
Bhagat
Yusuf A
YA
Emery
Derek
D
Butcher
Kenneth S
KS
Manawadu
Dulka
D
Rizvi
Nasir
N
Maheshwari
Perkash
P
Scozzafava
James
J
Shuaib
Ashfaq
A
Beaulieu
Christian
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000150:complications / Q000175:diagnosis*; D001931:Brain Mapping; D016001:Confidence Intervals; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D012975:Sodium Isotopes; D020521:Stroke / Q000175:diagnosis* / Q000209:etiology; D013997:Time Factors
D012975:Sodium Isotopes