Basic Cranial CT Flashcards
Views in skull x rays
Straight PA Caldwells PA Grangers Waters Towne lateral
CT Scan values of clotted blood
+ 100
CT Scan values of bones
+ 1000
CT Scan values of unclotted blood
+60
CT Scan values of brain
+ 24-40
CT Scan values of CSF
+5
CT Scan values of water
0
CT Scan values of fat
-100
CT Scan values of air
- 1000
A T2 sequence, the normal fluid is suppressed only pathologic fluid remains
FLAIR
Imaging modality of choice for hyperacute stroke
DWI and ADC
Usually hyperacute stroke can only be seen after how many hours in CT scan?
6 hours
How many hours does MRI detects hyperacute stroke?
1-2 hrs.
Structures that are mostly affected by infarct (large distribution infarct)
Cortical and subcortical areas
What type of infarct is this?
- hyperdense vessel on NECT
- loss of gray-white matter distinction in 1st 3 hrs.
- parenchymal density on NECT
Acute
Best diagnostic clue in subacute infarct
Gyral edema and enhancement, occasional with hemorrhagic transformation within basal ganglia, cortex
Imaging modality of choice for early infarcts
MRI
Extensive hypodense in white matter, usually associated with?
- diventricular and deep white matter ischemic changes
- neurodegenerative disease
- white matter disease (demyelinating disease)
Blood supply of parasaggital portion of frontal lobe
Anterior cerebral artery
Percentage of population with complete circle of willis
25%
4 extra axial locations in intracerebral hemorrhages
- parenchymal
- epidural
- subdural
- subarachnoid
Best diagnostic clue in parenchymal hemorrhage
Acute intracerebral hematoma without history of trauma
Etiology of parenchymal hemorrhage in elderly patients
Hypertension Cerebral amyloid angiopathy Neoplasm Coagulopathy Venous occlusion Cerebral vascular malformation
Etiology of parenchymal hemorrhage in younger patients
Drug use
Vasculitis
Venous thrombosis
Cerebral vascular malformation
Most spontaneous hemorrhages caused by _?
Hypertension
Basal ganglia/ external capsule hematoma are common is patients with?
Hypertension
Lobar/ subcortical hematoma is caused by?
Cerebral amyloid angiopathy
Cerebral vascular malformation
Venous occlusion
Give the following percentage distribution of hypertensive hemorrhage
Putamen/ external capsule: 60-65% Thalamus: 15-25% Pons: 5-10% Cerebellum: 2-5% Subcortical white matter: 1-2%
Arteries or vessels in lacunar infarcts
Reticulostriate artery
Thalamostriate artery
Best diagnostic clue in epidural hematoma
Hyperdense biconvex extra axial mass on NECT acute phase
Best diagnostic clue in subdural hemorrhages
Crescent-shaped, homogenously hyperdense CT, extra-axial collection that spreads diffusely over affected hemisphere
Cause of epidural hemorrhage
Rupture of middle meningeal artery
Cause of subdural hemorrhage
Tearing of bridging vein
Cresentic, crosses the sutures but not dural attachments
Subdural hemorrhage
Biconvex or lentiform, crosses the dural attachments but not the sutures
Epidural hemorrhage
Subdural or epidural? Has higher mortality
Subdural
Most common cause of subdural hemorrhage
Trauma
2nd most common cause of subdural hemorrhage
Ruptured aneurysm
Preferred modality for trauma
CT scan
What are the supratentorial tumors
Glioma Meningioma Oligodendroglioma Lymphoma Meningioma Tumors in sellar/parasellar (pituitaru adenoma- most common)
Give the infeatentorial tumors
Schwannoma Meningioma Epidermoid tumors Hemangioblastoma Brainstem glioma Metastasis
Most common intra axial posterior fossa tumor in adults
Metastatic tumor
Butterfly appearance
Gliomablastoma
Most common extra axial neoplasm of adults
Meningioma
