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NEURORADIOLOGY:

Infarct Core Estimation on CT Angiography Source Images Depends on Protocol

Pulli et al

Figure 3

Figure 3: (a) Scatterplot shows correlation between infarct volume on CT angiography source images (CTA-SI) and that on DW images (DWI)

for protocol 1 ( ) ( r = 0.912) and protocol 2 ( ) ( r = 0.494). (b) Bland-Altman plot shows agreement between infarct volume on CT angiog-

raphy source images and that on DW images for protocol 1 ( ) (mean, 0.82) and protocol 2 ( ) (mean, 5.0). Dotted line = line of equality.

Figure 4

Figure 4: Graphs show (a) absolute difference and (b) ratio between infarct volume on CT angiography source images (CTA-SI) and that on

DW images (DWI) versus mean time to imaging of the anterior circulation (AC) territory. At imaging times of less than 38 seconds, volume is

overestimated at DW imaging in the majority of cases. Dashed line = line of equality.

of the ischemic territory independently

the basis of a mismatch between infarct

have been inappropriately excluded from

predicted signiﬁ cant lesion overestima-

size on CT angiography source images

treatment on the basis of absolute

tion on CT angiography source images.

and mean transit time abnormality on

thresholds. It needs to be stated, how-

If conﬁ rmed, these ﬁ ndings would

perfusion CT images. In particular, in-

ever, that neither the mismatch concept

have major implications for clinical prac-

farct overestimation on CT angiography

nor absolute infarct size at DW imag-

tices that use CT angiography source

source images could lead to inappropri-

ing is currently recommended outside

images to evaluate brain parenchyma

ate exclusion of patients who may ben-

approved clinical trials as a method of

and estimate infarct core size and for

eﬁ t from treatment. With our current,

selecting patients for treatment. Impor-

clinical trials ( 29–31 ) that are designed

rapid CT angiography protocol, approx-

tantly, many centers are using similar

to select patients for thrombolysis on

imately 45%–60% of patients would

protocols to ours, including protocols

600

Radiology: Volume 262: Number 2—February 2012

Acute Ischemic Stroke : Infarct Core Estimation On Ct Angiography Source Images Depends On Ct Angiography Protocol Page 8