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Imaging of the CNS. Contents. Diagnostic tools Anatomical localization: Brain Diseases: - Infection - Tumor - Trauma - Stroke - Cord compression. Tools. Plain film CT MR Angiography. Plain radiography. 5 densities. Air Fat Soft tissue (water,muscles,etc) - PowerPoint PPT Presentation
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Imaging of the CNS
Contents• Diagnostic tools• Anatomical localization: Brain• Diseases:
- Infection- Tumor- Trauma- Stroke- Cord compression
Tools
• Plain film• CT• MR• Angiography
Plain radiography
5 densities
• Air• Fat• Soft tissue
(water,muscles,etc)• Bone, calcification• Metallic
Advantage & I/C
Adventage
- Convenience
- Safe
- Fast
- Availability
Indication- Fracture skull- Increase ICP- Intrasellar mass- Osteolytic/
osteoblastic lesion- Calcifying pathology
View and positioning
PA
• Petrous pyramid อยู่��ภายู่ในกระบอกตา
• Frontal bone and parietal bone• Frontal sinus • Nasal cavity• Mandible• Roof of orbits
Lateral skull
• Cranial vault• Suture : coronal and
lambdoid • Occipital bone • Sellar turcica• Floor of cranial fossa• Clivus • Nasopharyngeal soft tissue• Sphenoid air sinus• lateral of calvarium• lateral of mandible• Cervical spine 1st-2nd
LateralOuter table
Inner table
Diploic space
External occipital protuberance
Suture
Sphenoid air sinus
Sellar turcica
Caldwell view
• Orbital wall• Frontal and ethmoid
sinuses• Mandible
Ethmoid sinusMaxillary sinus
Orbital wallCaldwell view
Towne’s view
• Occipital bone• Lamdoid suture• Foramen magnum• Petrous ridge และ
mastoid sinuses• Zygomotic arch• Mandible ส่�วน head,
neck และ rami
Waters’ view
• Facial bone• Orbital roof• Maxillary, frontal
and ethmoid sinus
Waters’ view
Maxillary sinus
Orbital wallFrontal sinus
Water’ s view
Caldwell view
Paranasal sinuses
Paranasal sinusitisParanasal sinusitis
Air-fluid level at both maxillary and both frontal sinuses
Linear fracture skull right parietal bone
Nasal bone
Outer table destruction : histiocytosis X
Fx nasal bone
Normal sella turcica
Posterior clinoidAnterior clinoid
Dorsum sellae
Floor of sella
ICP
“loss of dorsum sella sign”
Pituitary tumor
“Double floor sign”
Large intrasella mass
2
3
1
“ballooning sella”
CECT
CT : Pituitary tumour
CT scan
CT /Spiral CT/ MDCT
CT scan
Advantage- Axial imaging- Reconstruction, reformatted to coronal,
sagittal planes- Providing contrast- noncontrast study- Differentiation tissues by densities(HU)- Additional software: CTA, CTV, 3D, CTP
etc.
Indication
• Trauma case• 1st line imaging of Stroke• Infection• Tumor• Intracranial calcification• C/I: pregnancy, contrast enhancement
injection: limited in patient with azotemia
Attenuation number of CT (HU)Hounsfield Units
• CSF = 0-20 HU.• Gray matter = 40 HU.• White matter = 23-46 H• Clot blood & hematoma = 70-100 HU.• Calcification and bone = +100-200 HU.• Fat = -100-200 HU.• Air = >- 600 HU.• Density ของ lesion ใดๆจะด�เที�ยู่บก�บ gray matter
Normal CT brain
Basal ganglia
Gray matter
White matter
Thalamus
cerebellum
Normal CT brain : Ventricular system
4th ventricle
Temporal horn
Frontal horn
Occipital horn
Lateral ventricle
Physiologic calcification• Pineal gland
– Age > 10 year– Size < 10 mm.
• Basal ganglia– Middle aged – Young aged :
hypoxia or abnormal serum Calcium
• Choroid plexus• Dura
– Falx cerebri– Calcification of
diaphragmatic sellae
Enhancement by contrast media
• Abnormal blood brain barrier (BBB)
• Identify vascular and dural structures
• Differential pathology by pattern of enhancement
DSA
ANGIOGRAM – MCA BIFURCATION ANEURYSM
MCA aneurysm
25-YEAR-OLD NORMOTENSIVE MAN WITH UNEXPLAINED ICH
LT ICA ANGIOGRAM – AVM
Indication
• Gold standard for vascular imaging ( ex. Aneurysm, AVM)
• Arterial / venous• Risk=1%• C/I : azotemia, pregnancy
MRI machine
MRI
• Magnet Field : 0.5-3Tesla• Pulse sequences : Spin Echo ( SE)• Parameters : T1 : T2 : TR : TE
Advantage MRI
1. Multiplanar imaging
( axial/coronal/sagittal/any planar)
2. No radiation
3. No bony artifact
4. Safer contrast agent (Gadolinium)
5. Best for analysis: posterior fossa and leptomeningeal lesions
MRI- three planars
Axial Coronal Sagittal
Contraindications
• Implantable Cardiac defibrillator• Pace Maker• wt. > 136 Kg • Severe Claustrophobia• Pregnancy (+/- )• Cochlear Implant• Aneurysm Clips• Ferromagnetic eye prosthesis /
F.B.
SIGNAL INTENSITY(SI)
• BRAIN : GM
: WM
• Muscles • Nerve :dorsal root
:ventral• CSF• Fat• Pituitary: anterior
posterior
T1W T2W
intermediate high
high low
intermediate
intermediate intermediate
intermediate intermediate
low high
high low
Intermediate intermediate
high high
Tissue
T1WI
T2WI
MRI of brain tumor
T1W T2W T1W-GD