Clinical-diffusion mismatch predicts the putative penumbra with high specificity.
OBJECTIVE
Perfusion-diffusion (PWI-DWI) mismatch may represent the ischemic penumbra. The complexities associated with perfusion-weighted imaging (PWI) have restricted its use. Mismatch between stroke severity, assessed with the National Institutes of Health Stroke Scale (NIHSS), and the volume of the diffusion-weighted imaging (DWI) lesion (clinical-diffusion mismatch; CDM) has been suggested as a surrogate for PWI-DWI mismatch. We compared CDM with PWI and DWI in acute stroke.


METHODS
Seventy-nine hemispheric stroke patients were imaged within 24 hours of symptom onset and subacutely (3 to 5 days). CDM was defined as NIHSS > or =8 and DWI < or =25 mL. DWI lesion and PWI (Tmax+4s) volumes were measured by planimetric techniques. Acute PWI-DWI mismatch was examined as a continuous variable (mismatch volume=PWIvol-DWIvol) and a categorical variable (mismatch=PWIvol-DWIvol/DWIvol x 100>20%). Early infarct expansion was calculated as DWI(subacute vol/DWI(acute vol).


RESULTS
In the 54 sub-6-hour patients, CDM detected PWI-DWI mismatch with a specificity of 93% (95% confidence interval [CI], 62% to 99%), a positive predictive value of 95% (95% CI, 77% to 100%), but a sensitivity of only 53% (95% CI, 34% to 68%). Alternate DWI and NIHSS cutpoints did not improve test performance characteristics. In addition, subacute DWI expansion was significantly greater in patients with CDM (P=0.01) compared with those without.


CONCLUSIONS
CDM (NIH > or =8, DWI < or =25 mL) predicts the presence of PWI-DWI mismatch with high specificity and low sensitivity. CDM also predicts DWI expansion. CDM may be a useful selection tool in acute stroke therapies, including thrombolysis.
Prosser
Jane
J
Department of Neurology, Royal Melbourne Hospital, University of Melbourne, Melbourne, Australia.
Butcher
Ken
K
Allport
Louise
L
Parsons
Mark
M
MacGregor
Lachlan
L
Desmond
Patricia
P
Tress
Brian
B
Davis
Stephen
S
D000368:Aged; D004058:Diffusion; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy*; D015912:Thrombolytic Therapy / Q000379:methods*; D013997:Time Factors