Administrators, Editors, Administrators
3,484
edits
Changes
Jump to navigation
Jump to search
NCCT is performed as a first line in neuroimaging as it is usually considered gold standard inruling out hemorrhage despite MRI being equivalent to Non-contrast CT in this regard due to theease of availability, rapid results, and safety in both stable and unstable patients .Advancements in technology enabling thinner slices (sub millimeter) and enhanced tissuedifferentiation allows for a role of NCCT in arterial occlusion and early infarction with has avariable detection rate of about 65% in cases imaged within 6 hours. A description of thesesigns is below.<ref name=Mirza2016/>
{{multiple image
| direction = horizontal
| width = 200
| footer = Figure 5D: This patient had subarachnoid hemorrhage on non-contrast CT scan. Images D1, D2,
D3 are 3-D reconstructions from CTA (to identify source of hemorrhage) which show aneurysm
like pouching (red arrows) in the PCOM (2) and ACOM (3,4). On conventional angiography (1),
these aneurysms were proved to be the infundibulum of vessels. The diagnosis of aneurysms <3
mm on CTA is often tenuous and requires angiographic confirmation.<ref name=Mirza2016/>
| image1 = Volume rendered CT angiography of posterior communicating artery aneurysm.png
| alt1 =
| caption1 =
| image2 = Volume rendered CT angiography of subtle anterior communicating artery aneurysm.png
| alt2 =
| caption2 = }}
→Reporting: Template
==Non-contrast CT==
;Hyperdense artery/MCA sign
At cut near top of the lateral ventricles: M4 - anterior third of cortex; M5 - middle third of
cortex; M6 - posterior third of cortex.<ref name=Mirza2016/>]]
A major reason for quantifying the volume in ischemic involvement is because extensive cerebral ischemia further increases the risk of secondary hemorrhage if thrombolysis is given.
Alberta Stroke Program Early CT score (ASPECTS) is a 10-point quantitative topographic CT
scan score developed in 2001 offering a reproducible grading system to score early ischemia inanterior circulation strokes to better direct treatment and reduce the variability of observations. Using two standard axial CT slices; one at the level of the thalamus and basal ganglia, andone just rostral to the basal ganglia, the MCA territory is divided into 10 regions,each accounting
for one point in the total score, for each involved area, a point is subtracted. This score correlated
inversely with the NIHSS (National Institutes of Health Stroke Score) with clinicians agreeing it
superior and more systematic compared to the conventional 1/3 MCA rule to exclude thrombolytic
treatment . The ASPECTS method is not without its limitations; such as difficulty in scoring
due to age related periventricular white matter changes or streak artifacts in the base of the skull
or tilt and motion artifacts. (ASPECTS diagram).<ref name=Mirza2016/> {|class="wikitable"|+ CT findings that generally contraindicate thrombolysis<ref name="FrankGrotta2013">{{cite journal|last1=Frank|first1=Benedikt|last2=Grotta|first2=James C.|last3=Alexandrov|first3=Andrei V.|last4=Bluhmki|first4=Erich|last5=Lyden|first5=Patrick|last6=Meretoja|first6=Atte|last7=Mishra|first7=Nishant K.|last8=Shuaib|first8=Ashfaq|last9=Wahlgren|first9=Nils G.|last10=Weimar|first10=Christian|last11=Lees|first11=Kennedy R.|title=Thrombolysis in Stroke Despite Contraindications or Warnings?|journal=Stroke|volume=44|issue=3|year=2013|pages=727–733|issn=0039-2499|doi=10.1161/STROKEAHA.112.674622}}</ref>|-| Edema, dense middle cerebral artery sign, loss of insular ribbon, lenticular hypodensity, acute infarction, sulcal effacement, or ASPECT-score of 8 or 9|-| Mass effect, infarction of >1/3 of the middle cerebral artery territory, midline shift, or ASPECT-score of ≤7|-| ASPECT-score of ≤7|}
==Computed tomography angiography (CTA)==
File:CT angiography of a vascular malformation with intraventricular hemorrhage.png|Figure 5A: Sagital reformatted images from CT angiogram identify an enhancing vascular malformation (arrow), which was the etiology of the intraventricular hemorrhage.<ref name=Mirza2016/>
File:CT angiography of basilar tip aneurysm.png|Figure 5B: Computed tomography angiogram in the axial projection demonstrates a focal basilar tip artery aneurysm (arrow).<ref name=Mirza2016/>
File:Volume rendered CT angiography of anterior communicating artery aneurysm.png|Figure 5C: [[Volume rendering]] of cerebal computed tomography angiogram (CTA) with
skull surface overlay demonstrates an anterior communicating artery aneurysm (1). Dedicated images from CTA of the Circle of Willis isolate the aneurysm (arrow) (2).<ref name=Mirza2016/>
File:Volume rendered CT angiography of posterior communicating artery aneurysm.png|Figure 5D: This patient had subarachnoid hemorrhage on non-contrast CT scan. Left image is a maximum intensity projection and right is a volume rendering CTA (to identify source of hemorrhage) which show aneurysm like pouching (red arrows) in the PCOM (2). On conventional angiography, these aneurysms were proved to be the infundibulum of vessels. The diagnosis of aneurysms <3 mm on CTA is often tenuous and requires angiographic confirmation.<ref name=Mirza2016/>
File:Volume rendered CT angiography of subtle anterior communicating artery aneurysm.png|Two more volume renderings of the same case, also showing an aneurysm-like pouching in the ACOM.<ref name=Mirza2016/>
</gallery>
CTA Source Images: CTA SI using the images in a CTA, cerebral perfusion can be assessed as
</gallery>
==Subsequent MRI==MRI is more sensitive than seldom performed after CT of stroke in detecting ischemic changesSwedish practice, similar to CT with respect to<ref>{{NU Hospital Group}}</ref> but can offer additional diagnostics:[[File:Stroke imaging algorithm.png|thumb|350px|center|Algorithm.]] diagnosing hemorrhage, and it remains {{Main|MRI of the gold standard for imaging head in acute focal neurologicalstroke}} deficits . Multimodal MRI (different imaging sequences) provides detailed visualization ==Reporting==Report even the absence of:*Intracranial hemorrhagebrain and vessel anatomy, including perfusion data with a higher sensitivity and specificity than*Delineable infarctionCT to detect stroke mimics . The complete MR imaging protocol requires approximately 15to 20 minutes to performIn case of angiography, and an additional 10 minutes for patient positioning and transfer, asreport:well as calculation *Normal/Unremarkable contrast filling of larger vessels of the apparent diffusion coefficient cerebrum and mean transit time maps cerebellum (or pathology thereof). MRIcomes with an advantage of decreased exposure to radiation with higher costs, lesser availability,claustrophobia experienced by patients as a drawback, along with absolute contraindicationssuch as metallic implants or pacemakers.<ref name=Mirza2016/>{{Reporting}}
{{Bottom}}
