Comprehensive MR imaging protocol for stroke management: tissue sodium concentration as a measure of tissue viability in nonhuman primate studies and in clinical studies.
OBJECTIVE
To investigate sodium magnetic resonance (MR) imaging for monitoring tissue viability in stroke.


METHODS
A comprehensive MR imaging protocol used to measure apparent diffusion coefficient and perfusion parameters was extended to include sodium imaging. Tissue sodium concentration was estimated by using a two-compartment model. This protocol lasted less than 45 minutes. These parameters were followed over the first 6 hours in a nonhuman primate model (n = 2) of acute embolic stroke without or with thrombolytic therapy. This protocol was used in patients in whom acute (< 24 hours, n = 11) or nonacute (> or = 24 hours, n = 31) stroke was ultimately confirmed.


RESULTS
The animal model showed abnormal diffusion and perfusion parameters in the lesion immediately after embolization, and these remained abnormal for over 6 hours. Tissue sodium concentration increased with time (5.7 mmol/L/h) unless halted with thrombolytic therapy. Regions with sodium concentrations over 70 mmol/L were histochemically verified as being infarcted. In patients in whom stroke older than 6 hours was clinically confirmed, sodium concentrations over 70 mmol/L were found in the appropriate brain regions.


CONCLUSIONS
Tissue sodium concentration provides a sensitive measure of tissue viability that is complementary to the diagnostic role of diffusion and perfusion imaging for ischemic insult.
Thulborn
K R
KR
MR Research Center, Presbyterian University Hospital, St. Pittsburgh, PA 15213-2582, USA. keith@mrctr.upmc.edu
Gindin
T S
TS
Davis
D
D
Erb
P
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001921:Brain / Q000473:pathology; D001923:Brain Chemistry; D020520:Brain Infarction / Q000175:diagnosis / Q000473:pathology; D005260:Female; D006801:Humans; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012964:Sodium / Q000032:analysis*; D020521:Stroke / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D015912:Thrombolytic Therapy; D013997:Time Factors; D014022:Tissue Survival
D012964:Sodium