Dr. Mohamed Wael Samir

Prof. of Neurosurgery

Ain Shams University

CT Brain

Intending Learning Objectives (ILOs)

Discuss the radiation hazards of CT Demonstrate the usage of different contrast agents safely Identify normal anatomical landmarks on CT brain Interpretation of CT perfusion in cerebral ischemia Interpretation of CT angiogram of cranial and cervical vasculature.

Facts

Radiation Dose Considerations

Single Radiographs Effective Dose, mrem (mSv)Skull (PA or AP)1 3 (0.03)Skull (lateral)1 1 (0.01)Chest (PA)1 2 (0.02)Chest (lateral)1 4 (0.04)Chest (PA and lateral)5 6 (0.06)Thoracic spine (AP)1 40 (0.4)Thoracic spine (lateral)1 30 (0.3)Lumbar spine (AP)1 70 (0.7)Lumbar spine (lateral)1 30 (0.3)

CT study Effective Dose, mrem (mSv)CT head1 200 (2.0)Lumbar spine series6 180 (1.8)Thoracic spine series6 140 (1.4)Cervical spine series6 27 (0.27)

Contrast Facts

Types: Ionic: Nonionic: Dimer or monomer

Dose: safety issues:

Idiosyncratic (nondose dependent), allergylike reactions: Acute Late:

Dose-dependent (nonidiosyncratic) Reactions: CVS: CIN: Thyroid function

Drug interactions:

Contrast Medium

Trade Name Molecular Weight (Dalton)

Iodine Conc

(mgI/mL)

Osmolality

(mOsm/kg water)

Viscosity at 20°C

(cP)

Viscosity at 37°C

(cP)

Ionic CM, monomer (High osmolar CM)

Iothalamate3 Conray 60% 809 282 1,400 6.02 4.0

Nonionic CM, monomer (Low osmolar CM)

Iohexol Omnipaque

821 300-&350 672844

11.820.4

6.310.4

Iopromide Ultravist 791 300& 370 607774

9.222.0

4.910.0

Serum Creatinine Levels (in mg/dL) Indicating an Estimated Glomerular Filtration Rate of less than 60 mL/min/1.73 m2

Age (years) 20 30 40 50 60 70 80

Men (not African American) 1.57 1.47 1.39 1.34 1.30 1.26 1.23

Women (not African American) 1.21 1.13 1.08 1.03 1.00 0.97 0.95

Men (African American) 1.86 1.73 1.65 1.58 1.53 1.49 1.46

Women (African American) 1.44 1.34 1.27 1.22 1.18 1.15 1.12

Preventive Measures for CMEN

Facts

Superior frontal sulcus

Precentral sulcus

Central sulcus

Precentral gyrus

Postcentral gyrus

Superior frontal gyrus

Lateral ventricle (anterior horn)

Third ventricle

Foramen of Monro

Lateral ventricle (trigone with

choroid plexus)

Pineal gland

Caudate nucleus (head)

Corpus callosum (genu)

Thalamus

Lentiform nucleus

Internal capsule

insular cistern

Quadrigeminal and ambient cisterns

Quadrigeminal plate (colliculus)

External capsule

Insula

Interhemispheric cistern

insular cistern

3rd ventricle

Hypothalamus

Midbrain

Aqueduct

Cerebral peduncle

Ambient cistern

Quadrigeminal cisternVermis of cerebellum

Sylvian fissure

Interpeduncular cistern

Optic chiasm

Lateral ventricle (temporal horn)

Sphenoid ridge

Petrous ridgeFourth ventricle

Pons

Dorsum sella

Prepontine cistern

Frontal air sinus

Orbital roof

Frontal lobe

Greater wing of sphenoid

Ant. clinoid

Pituitary fossa

Cavernous carotid

Basilar artery

Cerebello pontine cistern

Pons

4th ventricle

Cerebellar hemisphere

VII / VIII complex

Vermis

Straight gyrus and olfactory bulbEthmoid sinus

Sphenoid sinus

OrbitOptic nerve

SOF

Temporal lobe

Mastoid air cells

EAC

Medulla

Cerebello medullary fissure

Crista galle

SOFOptic foramen

Auditory canal

SOF

Optic foramen

Orbit

Paranasal sinuses

Petrous bone

Skull Base

CT Perfusion

Principles of CT perfusion (CTP)

CBF

50-80 ml/100 gm/min normal

15-20 ” Neurological

dysfunction

<10 ” infarction

CT Brain with Stroke window

Infarct signs on NCCT

B C

CTP

1) Mean Transition Time (MTT) or time to peak (TTP) 2) Cerebral Blood flow (CBF) , 3) Cerebral Blood Volume (CBV),

A B C

CT Angiogram

Initial Angiographic Appearance of Intracranial Vascular Occlusions in Acute Stroke

Cutoff morphology:

Initial Angiographic Appearance of Intracranial Vascular Occlusions in Acute Stroke

Tram track (nonocclusive or recanalized clot):

Initial Angiographic Appearance of Intracranial Vascular Occlusions in Acute Stroke

The tandem morphology:

Initial Angiographic Appearance of Intracranial Vascular Occlusions in Acute Stroke

Tapered morphology :

Initial Angiographic Appearance of Intracranial Vascular Occlusions in Acute Stroke

meniscus or flattened shape to clot (recent) versus reverse meniscus (older) :

Initial Angiographic Appearance of Intracranial Vascular Occlusions in Acute Stroke

Delayed (antegrade) flow :

Initial Angiographic Appearance of Intracranial Vascular Occlusions in Acute Stroke

Retrograde collateral flow :

Initial Angiographic Appearance of Intracranial Vascular Occlusions in Acute Stroke

Aneurysms:

CTA:sagittal MPRCTA:3D color VR

References

Sits

(Information adapted from www.radiologyinfo.org