Mikael Häggström: Copied from CC-BY article

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|author1=[[User:Mikael Häggström|Mikael Häggström]]
|author2=Authors if integrated Creative Commons article<ref name=Mirza2016>{{cite web|url=http://www.smgebooks.com/neuroimaging/chapters/NI-16-06.pdf|title=Neuroimaging in Acute Stroke|author=Shazia Mirza and Sankalp Gokhale|date=2016-07-25}}<br>[https://creativecommons.org/licenses/by/4.0/ Attribution 4.0 International (CC BY 4.0)]</ref>
|author3=
}}

Several studies have been conducted to determine the “best” imaging modality in acute stroke,
but the reality is that both CT and MRI will co-exist and complement each other for a long time.
The main drawbacks to CT are that an ischemic brain stroke may not appear in a CT scan for
up to 48 hours period, and that CT does not image the vertebra-basilar (up to 15% of strokes).
While the MRI does provide superior quality of images and anatomical details, in an acute setting
its advantages address the above-mentioned two drawbacks of CT. Important contraindications
to MRI are patients with magnetic material in their body such as pacemakers, pins, a vital point
to note as neurologically altered or aphasic patients may be unable to provide this information to
their providers.<ref name=Mirza2016/>

The sensitivities and specificities were 100% and 86%, respectively, for diffusion-weighted
MR imaging versus 18% and 100% for conventional MR imaging and 45% and 100% for CT .
New guidelines from the American Academy of Neurology state that doctors should use a diffusion
MRI scan to diagnose stroke instead of a CT scan which was published in the July 13, 2010, issue
of Neurology®, the medical journal of the American Academy of Neurology.
The imaging modality of choice will depend upon the specific situation: cost, availability,
clinical setting, contraindications etc. and it remains the purview of a well-educated provider to
determine the imaging to effectively guide the therapeutic goals.<ref name=Mirza2016/>

{|class="wikitable"
|+ Table 1: CT vs MRI<ref name=Mirza2016/>
! Characteristic !! CT !! MRI
|-
| Availability || Easily available in the emergency department || Not available in all emergency departments
|-
| Time || 5 mins || 15 mins
|-
| Perfusion study: volume assessed || 2–4 cm || Entire brain visualized
|-
| Side effects: Contrast
| Iodinated contrast has toxic effects on kidney, cannot be used in renally compromised patients, risk of anaphylaxis.
| Gadolinium: minimal toxicity on kidneys, risk of nephrogenic and systemic fibrosis
|-
| Side effects: Ionizing radiation || YES: increases risk of cancer || No ionizing radiation
|-
| Side effects: Claustrophobia || - || +++
|-
| Drawback: motion artefact || + || +++
|-
| Contraindication: Pacemaker, shrapnel, metal plates || - || +++
|-
!colspan=3| Purpose
|-
| Chronic hemorrhage || +/- || +++
|-
| Acute ischemic stroke || - || ++
|-
| Angiography || ++ || +++
|-
| Vertebro-basilar visualization || - || ++
|-
|colspan=3| Abbreviations: ICH: Intracerebral hemorrhage, SAH: Sub arachnoid hemorrhage, EDH: Extradural hemorrhage, SDH: Subdural hemorrhage. AVM: Arterio-venous malformation, TCD: transcranial Doppler, CDUS: Carotid duplex ultrasound, DSA: Digital subtraction Angiography.
|}

==See also==
*[[CT of the head in stroke]]
*[[MRI of the head in stroke]]

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