Neuroimaging plays a key role in assessing the detection of acute hemorrhage, diagnosis of infarct core, detection of steno-occlusive arteries, mismatch between infarct core and penumbra, and collateral circulation in patients with acute cerebral ischemic stroke. The recent announcement of randomized clinical trials that demonstrated the usefulness of intra-arterial mechanical thrombectomy and the guidelines of 2018 Guidelines for the Early Management of Patients with Acute Ischemic Stroke from American Heart Association/American Stroke Association led to a larger role of neuroimaging and required new neuroimaging strategy for acute cerebral ischemic stroke. In this review, we summarize the recommendation on neuroimaging from the 2018 Guidelines, and review pros and cons between CT and MR and fast scanned stroke MR. Based on the new guidelines and recent research, we discuss the appropriate neuroimaging strategy for acute cerebral ischemic stroke patients.
Acute ischemic hyperintensity on fast and conventional FLAIR. Acute ischemic hyperintensity (left column, arrows) in a diffusion-restricted area is well demonstrated in both conventional FLAIR (middle column, scan time: 128 s) and fast FLAIR [right column: (EPI-FLAIR, top, scan time: 45 s), (ETL-FLAIR, middle row, scan time: 74 s), and (TR-FLAIR, bottom, scan time: 79 s)]. DWI = diffusion-weighted imaging, EPI = echo planar imaging, ETL = echo train length, FLAIR = fluid-attenuated inversion recovery imaging, TR = repetition time
Fast and conventional GRE. A microbleed in the right thalmus (arrows) is well-demonstrated on both conventional GRE (right, scan time: 141 s) and fast GRE [EPI-GRE (middle, scan time: 29 s) and parallel-GRE (left, scan time: 54 s)]. EPI = echo planar imaging, GRE = Gradient echo
Fast CE-MRA and TOF-MRA. Both TOF-MRA (left, scan time: 274 s) and fast CE-MRA (right, scan time: 39 s) demonstrate an occlusion in the right middle cerebral artery (arrows). CE = contrast-enhanced, MRA = magnetic resonance angiography, TOF = time-of-flight
AHA/ASA 2018 Recommendation of Imaging Protocols
뇌 영상 가이드라인 | 권고 수준 COR | 근거 수준 LOE | 개정 상태 |
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Adapted from Power et al. Stroke 2018;49:e46-e110 (14). Only Korean translated table is permitted from the American Heart Association.
Class I (strong recommendation), Benefit >>> Risk.
Class IIa (moderate recommendation), Benefit >> Risk.
Class IIb (weak recommendation), Benefit ≥ Risk.
Class III: no Benefit (moderate recommendation), Benefit = Risk,
Class III: harm (moderate recommendation), Benefit = Risk.
Level A, high quality evidence.
Level B-R, moderated quality evidence, randomized.
Level B-NR, moderated quality evidence, nonrandomized.
Level C-LD, limited data.
Level C-EO, consensus of expert opinion based on clinical experience. AHA/ASA = American Heart Association/American Stroke Association, COR = class of recommendation, CTA = CT angiography, CTP = CT perfu sion, DW = diffusion-weighted, EVT = endovascular treatment, LOE = level of evidence, MCA = middle cranial artery, MRP = MRI perfusion
Comparison between CT and MRI in Acute Ischemic Stroke
CT | MRI | |
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Examples of Scan Parameters for 1.5 Tesla Fast MR
FLAIR | GRE | MRA | |||||||
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Conventional | EPI | ETL | TR | Conventional | EPI | Parallel | Conventional CE-MRA | Fast CE-MRA | |
Scan time (second) 128 45 74 79 141 29 54 74 39 CE-MRA = contrast-enhanced MR angiography, EPI = echo planar imaging, ETL = echo train length, FLAIR = fluid attenuated inversion recovery, GRAPPA = generalized autocalibrating partial parallel acquisition, GRE = Gradient echo, NAV = number of signal averaging, TE = echo time, TR = repetition time