Usefulness of z-score mapping for quantification of extent of hypoattenuation regions of hyperacute stroke in unenhanced computed tomography: analysis of radiologists' performance.
OBJECTIVE
The purpose of this study was to evaluate the usefulness of z-score mapping method on neuroradiologists' performance in quantification of the extent of hypoattenuation regions of hyperacute stroke on unenhanced computed tomographic (CT) images by using the Alberta Stroke Programme Early CT Score system.


METHODS
Twenty-one patients with infarction (<3 hours) were retrospectively selected. Five neuroradiologists interpreted CT images first without and then with z-score maps by using the Alberta Stroke Programme Early CT Score system. Their performances in the quantification of the extent of hypoattenuation were compared.


RESULTS
Average accuracies for the quantification without and with the z-score maps were 82.6% and 86.6%, respectively (P < 0.0001). The average area under the receiver operating characteristic curve for detection of focal hypoattenuation significantly increased from 0.883 to 0.925 (P = 0.01) by use of z-score maps.


CONCLUSIONS
The use of z-score mapping method has the potential to help neuroradiologists quantify the extent of hypoattenuation regions of hyperacute stroke on unenhanced CT images.
Takahashi
Noriyuki
N
Department of Radiological Technology, Graduate School of Health Sciences, Niigata University, Niigata, Niigata, Japan. kiyurino1189@happy.odn.ne.jp
Tsai
Du-Yih
DY
Lee
Yongbum
Y
Kinoshita
Toshibumi
T
Ishii
Kiyoshi
K
Tamura
Hajime
H
Takahashi
Shoki
S
D000368:Aged; D000369:Aged, 80 and over; D002983:Clinical Competence; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D020521:Stroke / Q000000981:diagnostic imaging* / Q000473:pathology; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*