101 ct neuroimaging
TRANSCRIPT
Basic 101 on CT Neuroimaging(from neurology point of view)
Dr Ahmad Shahir MawardiNeurology Department Hospital Kuala Lumpur25th May 2016
Content
• Basics of CT Neuroimaging • Neuro anatomy on CT• Common neurological conditions
Expectation(s)
• Able to – do on-call confidently– intreprete important CT findings
What not to expect(s)
• interprets CT scan like a 'pro'• pass medical examination with flying colours
The Eyes Don't See What the Mind Don't Know
CT scan Intrepretation (Abnormal)
1. Lesion(s) (hyperdense/Hypodense)2. Location3. Age of lesion (acute/subcute/chronic)4. + Cause, + complications
e.g• Acute infact at the left internal capsule• Acute communicating hydrocephalus
Pitfalls
• Pt name (make sure you have the right pt!)
• Age• Date• CT (brain)• Plane/View• Plain vs contrast• Findings
Part I
Basic of CT Neuroimaging
Basics of CT Neuroimaging
• Orientation• Region/Planes• Windows• Density• Slice thickness• Contrast enhancement
Basics of CT Neuroimaging: Orientation
Basics of CT Neuroimaging: Orientation
Basics of CT Neuroimaging: SYMMETRYMIRROR IMAGE
CT brain – 2 identical half
Basics of CT Neuroimaging: Planes
Basics of CT Neuroimaging: Planes
A
S
C
Basics of CT Neuroimaging: Window
Basics of CT Neuroimaging: Density
• Hypodense• Hyperdense• Isodense
Basics of CT Neuroimaging: Density
HYPERDENSITIES
Most common:•Blood•Calcification•Exception to the rule:
– Pineal gland– Choroid plexus
Left temporal epidural haematoma
HYPODENSITY
Most common:
•Infarction•Fluid
– edema, infection, tumour
•Hydrocephalus•Air
Basics of CT Neuroimaging: Density
The Density of Blood Changes with Time!
Basics of CT Neuroimaging: slice thickness
• Scanogram– Plane used for
scanning– Anatomic extent of
series of scans
• Slice thickness may vary (5-10 mm)
CT brain: Contract vs non-contrast
• Contrast:– Vascular lesion– Tumor– Sites of infection
• CTA (stenosis)• CTV (CVT)• Leptomenigeal
enhancement (meningitis)
• Ring enhancing lesion
Ring enhancing lesion
• Tumour – Primary (GBM, lymphoma) – Metastasis
• Infections:– Abscess– HIV associated:
toxoplasma, crytococcus– TB/ tuberculoma– Neurocysticercosis
• Resolving hematoma (10-21 days)
• Radiation necrosis• Postoperative change• Aneurysm • Multiple sclerosis/ADEM (MRI)
Ring enhancing lesion
Part II
NeuroAnatomy
Identification of structures
Lateral View of Brain
Ventricular System
Cross-sectional Anatomy
• Grey/White interface, Subcortical white matter
Cross-sectional Anatomy
• Paired of crescent-shape = Twin bananas
Cross-sectional Anatomy
Basal ganglia
Cross-sectional Anatomy
• Third ventricle, Basal ganglia, Superior cerebellar cistern
Physiologic Calcification
Brain Anatomy
Cross-sectional Anatomy
• Third ventricle, Smiley face
Cross-sectional Anatomy
• Midbrain, Interpeduncular cistern
Cross-sectional Anatomy
• Star shape ~ Circle of Willis, • Fourth ventricle, Temporal horn ~ slit
Cross-sectional Anatomy
• Base of skull, Midline bony prominence, • Prepontine cistern, Pretrous bone, Frontal sinus
Cross-sectional Anatomy
• Orbits, Ethmoid air cell
Part III
Common neuropathological findings
Common neuropathological findings
• Stroke• Haemorrhage• Hydrocephalus• Leptomeningeal enhancement• CNS infections
Ischemic stroke
• Location:– Cortical infarction– Lacunar infarction– Watershed / Borderzone infarction
• Timing:– Hyperacute changes– Early changes– Established changes
• Complications:– Haemorrhagic transformation– Cerebral oedema
Cortical signs
• Aphasia• Neglect (may be spatial, sensory, visual, auditory)• Alteration of consciousness• Visual field cut
Stroke: Cortical Infarction
• Follows vascular territory– ACA– MCA– PCA– Mixed
• Wedge shape• May have complications
– Haemorrhagic transformation
– Cerebral oedema
• Usually embolic aetiology
Lacunar Infarction
• Sites (BITCP)– Basal Ganglia (Caudate, Putamen)– Internal capsule– Thalamus– Pons– Cerebellum
• 3-15 mm in diameter• Distal distribution of penetrating arteries
– Lenticulostriate– Thalamoperforators– Pontine perforators– Recurrent artery of Heubner
• Fibrinoid degeneration
Penetrating arteries/ perforators
Lacunar Infarction
Lacunar Infarction
Borderzone Infarction
• Cortical Borderzone
• Internal Borderzone
• Pathology / Occlusion of proximal vessels – ICA
Hyperacute changes
• Dense MCA sign• Dot sign• Loss of gray-white
differentiation• Loss of sulcation• NORMAL
• As early as 2-6 hours from onset
6 hours 24 hours 40 hours
ASPECTS score
What ASPECTS tell us
• Functional Outcome• Risk of bleeding
Intracerebral Haemorhage
• Typical hypertensive sites:– Lenticulostriate vessels
• Basal Ganglia (Caudate, Putamen)• Internal capsule• Thalamus (a/w intravent. Ext)• Pons• Cerebellum
– Complications:• Mass effect• Obstructive hydrocephalus
Intracerebral Haemorrhage• Atypical sites!!!:
– Cerebral Amyloid Angiopathy• 15% of ICH in pts > 60 yrs old
– AVMs• Intracerebral haemorrhage or SAH
• Ix: CTA
Venous Infarction
• Thrombosis of cerebral veins– Evidence of thrombosis – Dense cord sign,
Delta / Empty delta sign– Complications of CVT – SAH, Atypical infarcts.
Haemorrhage
Haemorrhage
Epidural Haematoma
• Biconvex• restricted by dural tethering at
the cranial sutures
Subdural Haematoma
• Crescent-shaped
• They do not cross the midline because of the meningeal reflections
Subarachnoid haemorrhage
Subarachnoid haemorrhage
Hydrocephalus
Ventriculomegaly a/w raised ICP
•Communicating/Non-obstructive:– Impaired reabsorption of CSF fulid in the absence of any CSF flow
obstruction
•Non-Communicating/Obstructive:– CSF-flow obstruction
• Foramen of Monro• Aqueduct of Sylvius• Fourth Ventricle obstruction
Hydrocephalus
• Acute - “Ballooned” ventricles with periventricular low density “ halo”- 3rd ventricle - rounded
• Chronic – “Ballooned” ventricles without periventricular halo- 3rd ventricle – normal app
• Obstructive:– Basal cisterns, sulci compressed /
obliterated
Hydrocephalus Hydrocephalus ex-vacuo
Tuberculous Meningitis
1.Meningeal enhancement:
2. Infarction (20.5 – 30.8%):- thalamus, basal ganglia, internal capsule
3. Hydrocephalus
4. Tuberculomas -Infrequently seen except in miliary TB
5. Vascular changes-uniform narrowing of large segments -small segmental narrowing -irregular beaded appearance -complete occlusion.
Postgrad Med J 1999;75:133 140 doi:10.1136/pgmj.75.881.133
TB Meningitis: Tuberculomas
Contrast-enhanced CT•showing multiple tuberculomas in a patient with tuberculous meningitis
Postgrad Med J 1999;75:133 140 doi:10.1136/pgmj.75.881.133
Meningioma
Right Temporal Glioblastoma
High grade glioma – usually Glioblastoma
Brain Abscess
Herpes Encephalitis
• Predilection for limbic system:– Temporal lobes– Insular cortex– sub frontal area– cingulate gyri.
• Initially unilateral --> "sequential bilaterality" is highly suggestive of HSE1.
Toxoplasmosis Primary CNS Lymphoma
Thank You
Hydrocephalous
Subarachnoid hemorrhage