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Free keywords:
STEAM, stroke, DWI, susceptibility, artifacts
Abstract:
Introduction: Diffusion-weighted imaging in stimulated echo acquisition mode (STEAM-DWI) is an interesting
alternative with less susceptibility artifacts compared to the most commonly used diffusion-weighted echo-planar
imaging (EPI-DWI). Sensitivity and specificity of a novel STEAM-DWI, described by Merrem et al. 2017 [1], were
assessed in patients with ischemic stroke.
Methods: EPI- and STEAM-DWIs were performed in patients with suspected subacute stroke between 01 July
2019 and 30 June 2020 using 3-T MRI. Three neuroradiologists independently and separately rated STEAM-DWI
images with respect to (i) signs of an acute/subacute stroke, (ii) the number, size and localization of infarctions
and, (iii) the presence of artifacts.
Results: In 55 (23 right, 23 left, 9 both hemispheres) of 85 patients a subacute stroke was confirmed using EPI-
DWI. The cerebral vascular territories were affected as follows: anterior cerebral artery 8 %, middle cerebral
artery 48 %, posterior cerebral artery 27 %, brainstem 7 %, cerebellum 10 %. In 53 of 55 (96 %) cases the stroke
was detected by usage of STEAM-DWI, in 35 of 37 patients microembolic events were noticed (95 %). Results
showed a sensitivity and specificity of 100 % (70/70) for major infarcts (>9 mm2 in-plane) and a sensitivity of up
to 94 % (121/129) for detecting subacute microembolic lesions. No susceptibility artifacts were noticed in
STEAM-DWI.
Conclusion: Compared to standard EPI-DWI, STEAM-DWI offers a more robust alternative for diagnosing subacute
strokes in areas affected by susceptibility artifacts.
