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Acute Ischemic Stroke :

Infarct

Core Estimation on CT Angiography

Source Images Depends on CT

Angiography Protocol

Benjamin Pulli , MD

Purpose:

To test whether the relationship between acute ischemic

Pamela W . Schaefer , MD

infarct size on concurrent computed tomographic (CT)

Reza Hakimelahi , MD

angiography source images and diffusion-weighted (DW)

Zeshan A. Chaudhry , MD

magnetic resonance images is dependent on the parame-

Michael H. Lev , MD

ters of CT angiography acquisition protocols.

Joshua A. Hirsch , MD

This retrospective study had institutional review board ap-

Materials and

R. Gilberto González , MD , PhD

proval, and all records were HIPAA compliant. Data in 100

Methods:

Albert J. Yoo , MD

patients with anterior-circulation acute ischemic stroke and

large vessel occlusion who underwent concurrent CT angi-

ography and DW imaging within 9 hours of symptom onset

were analyzed. Measured areas of hyperintensity at acute

DW imaging were used as the standard of reference for

infarct size. Information regarding lesion volumes and CT

angiography protocol parameters was collected for each pa-

tient. For analysis, patients were divided into two groups on

the basis of CT angiography protocol differences (patients in

group 1 were imaged with the older, slower protocol). Inter-

method agreement for infarct size was evaluated by using the

Wilcoxon signed rank test, as well as by using Spearman cor-

relation and Bland-Altman analysis. Multivariate analysis was

performed to identify predictors of marked ( 20%) overesti-

mation of infarct size on CT angiography source images.

Results:

In group 1 ( n = 35), median hypoattenuation volumes on

CT angiography source images were slightly underestimated

compared with DW imaging hyperintensity volumes (33.0

vs 41.6 mL, P = .01; ratio = 0.83), with high correlation ( r

= 0.91). In group 2 ( n = 65), median volume on CT angi-

ography source images was much larger than that on DW

images (94.8 vs 17.8 mL, P , .0001; ratio = 3.5), with poor

correlation ( r = 0.49). This overestimation on CT angiog-

raphy source images would have inappropriately excluded

from reperfusion therapy 44.4% or 90.3% of patients el-

igible according to DW imaging criteria on the basis of a

100-mL absolute threshold or a 20% or greater mismatch

threshold, respectively. Atrial ﬁ brillation and shorter time

from contrast material injection to image acquisition were

independent predictors of marked ( 20%) infarct size over-

estimation on CT angiography source images.

From the Division of Neuroradiology (B.P., P.W.S., R.H.,

CT angiography protocol changes designed to speed imag-

Conclusion:

M.H.L, R.G.G., A.J.Y.) and Interventional Neuroradiology

ing and optimize arterial opaciﬁ cation are associated with

(Z.A.C., J.A.H., A.J.Y.), Massachusetts General Hospital,

Harvard Medical School, 55 Fruit St, Gray 241, Boston, MA

signiﬁ cant overestimation of infarct size on CT angiogra-

02114. Received May 2, 2011; revision requested June 1;

phy source images.

revision received July 27; accepted August 11; ﬁ nal version

accepted August 30. A.J.Y. supported by Neuroradiology

RSNA, 2011

Education and Research Foundation/Boston Scientiﬁ c

Fellowship in Cerebrovascular Disease Research. Address

correspondence to A.J.Y. (e -mail: ).

Supplemental material :

/suppl/doi:10.1148/radiol.11110896/-/DC1

RSNA, 2011

593

Radiology: Volume 262: Number 2—February 2012

Acute Ischemic Stroke : Infarct Core Estimation On Ct Angiography Source Images Depends On Ct Angiography Protocol

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