Early Ischemic Stroke: Comparison of Diffusion Weighted Images and ADC maps

Choi, Soo Jung; Choi, Choong Gon; Kim, Jae Kyun; Kim, Jung Hoon; Lee, Jae Hong; Lee, Ho Kyu; Suh, Dae Chul; Kim, Jong Sung

Abstract

PURPOSE: The purpose of this study was to compare the clinical utility of diffusion-weighted images(DWI) withthat of apparent diffusion coefficient(ADC) maps for detecting early ishemic strokes.
MATERIALS AND METHODS
In22 patients with infarct, lesion conspicuity as seen on T2-weighted images(T2WI), low diffusion-weightedimages(DWI ; b value 300 sec/mm2), high DWI(b value 1000 sec/mm2), and ADC maps was retrospectively compared. Theinfarct was hyperacute (< 6 hours) in six, acute (< 48 hours) in six, and subacute (< 2 weeks) in ten. All imageswere obtained using an echo-planar spin echo sequence; lesion conspicuity was graded from 0 to 2 by tworadiologists. Signal intensity was analysed in 17 patients[hyperacute (n=5); acute (n=4); and subacute (n=8)].Lesion-to-controlateral normal side signal intensity ratio(SIR) and contrast-to-noise ratio(CNR) were measured andcompared between four different types of images. RESULT: With regard to lesion conspicuity, high DWI wassuperior to the other images for detecting hyperacute strokes(Grade 2, 6/6). In such cases, an ADC map showedgrade 0 lesion conspicuity in one case, grade 1 in three, and grade 2 in two. There was no significant differencein lesion conspicuity in acute and subacute strokes between DWI(low & high) and T2WI(Grade 2, 16 in each). An ADCmap in acute and subacute stroke showed Grade 1 in four cases and Grade 2 in 12. Signal intensity analysis of SIRand CNR showed that high DWI was also superior to the other images for detecting hyperacute ischemic strokes(p <0.05, n=5), and superior to an ADC map in acute and subacute stroke(p < 0.05, n=12).
CONCLUSION
Diffusion-weighted images with a high b value could be more useful than ADC maps and conventional T2-weightedimages, especially for the detection of hyperacute strokes.