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Abstract
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.
References
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Fig. 1.
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
Fig. 2.
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
Fig. 3.
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
Table 1.
AHA/ASA 2018 Recommendation of Imaging Protocols
| 뇌 영상 가이드라인 | 권고 수준 COR | 근거 수준 LOE | 개정 상태 |
|---|---|---|---|
| 1. 허혈성 뇌 경색이 의심돼 내원한 모든 환자는 도착과 동시에 뇌 영상 검사를 시행해야 한다. 대부분의 경우, | I∗ | B-NR†† | 2013권고안으로 |
| 비 조영 증강 CT (noncontrast CT) 가 초기 치료 결정에 필요한 정보를 제공할 것이다. | 부터 개정됨 | ||
| 2. 정맥 내 혈전 용해술(IV alteplase) 또는 동맥 내 재개통술(mechanical thrombectomy)의 대상이 될 수 있는 환자의 적어도 50%가 응급실 내원 후 20분 안에 뇌 영상 검사를 할 수 있도록 시스템을 갖추어야 한다. | I∗ | B-NR†† | 새 권고 사항 |
| 3. 정맥 내 혈전 용해술(IV alteplase)의 치료반응에 영향을 줄 수 있는 급성 CT 저음영(acute CT hypoattenuation)의 정도와 크기에 대한 특정한 역치값에 대한 증거는 여전히 불충분하다. 따라서 급성초기 허혈성 저음영을 제외하면 정맥 내 혈전 용해술 치료 대상인 환자에 대해서 급성 초기 허혈성 저음영초기 허혈성 저음영을 제외하면 정맥 내 혈전 용해술 치료 대상인 환자에 대해서 급성 초기 허혈성 저음영 (CT hypoattenuation or early ischemic change)의 정도와 크기를 치료를 유보하는 기준으로 삼아서는 안된다. | III: No Benefit§ | B-R∗∗ | 2015 권고안으로 부터 개정됨 |
| 4. CT 동맥 고음영 소견(CT hyperdense MCA sign)을 제외하면 치료 대상인 환자에 대해서 CT 동맥 고음영소견을 정맥 내 혈전 용해술(IV alteplase) 치료를 유보하는 기준으로 삼아서는 안된다. | III: No Benefit§ | B-R∗∗ | 새 권고 사항 |
| 5. 정맥 내 혈전 용해술(IV alteplase) 치료 전에 뇌 미세출혈(cerebral microbleeds)을 배제하려는 목적으로 시행하는 정례적인 MR (routine MR)은 권고되지 않는다. | III: No Benefit§ | B-NR†† | 새 권고 사항 |
| 6. 증상발생시점이 불명확하거나 기상 시 발견된 뇌졸중(awoke with stroke) 환자에서 정맥 내 혈전 용해술 (IV alteplase) 치료 결정을 위해 뇌영상의 기준(imaging criteria)을 적용하는 것은 임상시험외에는 | III: No Benefit§ | B-NR†† | 2015 권고안과차이 없음. |
| 7. 관류 영상을 포함한 다중기법의 CT, MR (multimodal CT and MR) 검사로 인해 정맥 내 혈전 용해술(IV alteplase) 치료가 지연되어서는 안된다. | III: Harm‖ | B-NR†† | 새 권고 사항 |
| 8. 동맥 내 재개통술 적응증에 해당하는 환자들에게 초기 영상학적 검사 중 비 침습적 혈관 조영술(CTA 및MRA)이 권장되지만, 정맥 내 혈전 용해술(IV alteplase) 치료를 지연시켜서는 안된다. 전문적인 의료 그룹(professional medical societies)의 가이드라인을 따라 정맥 내 혈전 용해술(IV alteplase) 치료 대상이되는 환자들에서 초기 영상학적 검사 중에 비 침습적 혈관 조영술이 시행되지 않았다면 그 검사 전에정맥 내 혈전 용해술(IV alteplase) 치료를 먼저 시행하는 것이 권고된다. 그리고 비 침습적 혈관 조영술은가능한 빨리 시행해야 한다. | I∗ | A¶ | 2015 권고안으로 부터 명료한부터 명료한 표현으로 수정됨 |
| 9. 동맥 내 재개통술 대상인 환자에서 큰 뇌 혈관 폐색 (large vessel occlusion)이 의심된다면 혈중 크레아티닌 검사를 하지 않았을 경우라도 이전에 신장 기능 장애의 기왕력이 없다면 CT 혈관 조영술을 시행하는 것이 합리적이다. | IIa† | B-NR†† | 새 권고 사항 |
| 10. 동맥 내 재개통술의 잠재적 후보 환자들에서 뇌 혈관뿐 아니라 두개 외경동맥(extracranial carotid artery) 과 척추동맥에 대한 영상 검사는 치료 환자 선별과 계획에 유용한 정보를 줄 수 있으므로 합리적이다. | IIa† | C-EO§§ | 새 권고 사항 |
| 11. CT 그리고 CTA, 또는 MR 그리고 MRA 검사 외 관류영상과 같은 추가적인 영상은 6시간 이내 환자에서는 동맥 내 재개통술 대상자 선정을 위한 검사로 권고되지 않는다. | III: No Benefit§ | B-R∗∗ | 새 권고 사항 |
| 12. 증상 발생 추정 시점부터 6시간부터 24시간 사이의 환자가 전방 순환의 큰 뇌혈관 폐색이 확인되었다면동맥 내 재개통술 대상자 선정을 위해 관류 CT, 확산 강조 MR, 혹은 관류 MR 검사를 추천한다. 하지만동맥 내 재개통술을 위한 환자 선정은 DAWN과 DEFUSE-3 임상 시험에서 동맥 내 재개통술이 이득을보였던 뇌 영상을 포함한 기준 범위 내에서 엄격히 적용돼야 한다. | I∗ | A¶ | 새 권고 사항 |
| 13. 동맥 내 재개통술의 대상자 선정을 위해 측부 순환 상태를 임상적 결정에 포함시키는 것은 합리적일 수 있다. | IIb‡ | C-LD‡‡ | 2015 권고안으로 부터 개정됨 |
Adapted from Power et al. Stroke 2018;49:e46-e110 (14). Only Korean translated table is permitted from the American Heart Association.
§§ 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
Table 2.
Comparison between CT and MRI in Acute Ischemic Stroke
Table 3.
Examples of Scan Parameters for 1.5 Tesla Fast MR
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
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