Head/Brain Flashcards
axial images of the brain are parallel or perpendicular to what positioning line?
parallel to the IOML
What recon WW and WL is/are made for the Brain/Head?
standard/soft tissue and, for trauma, bony recon
For the brain, what are the WW and WL for:
- gray/white matter (standard/tissue)
- bony (trauma)
- hemorrage/hematoma
- actue ischemia
- WL 35, WW 100
- WL 400, WW 3000
- WL 75, WW 150
- WL 35, WW 25
Indications for a brain/head CT w/o contrast:
- congenital abnormalities
- hydrocephalus
- mass/tumor
- primary neoplasm of the brain
- metastatic lesions
- endocrine pathology
The IAC CT scan should have a coronal recon of what slice thickness?
1-2mm with a small display field of view (DFOV)
For CT of the Orbits, what are the positioning line and orientation to it?
parallel to the IOML
What is the slice thickness for Orbits? What recons are obtained/created?
- 1-3mm
2. axial, oblique sagittal and oblique coronal (to best visualize the optic nerve)
What are the WL and WW for soft tissue and bone recons of the Orbits/Facial Bones/Sinuses?
ST: WL 40, WW 400
Bone: WL 400, WW 3000
What are 3 indications for Brain/Head scan with contrast?
- neoplasm
- inflammatory process
- vascular abnormalities
What is an example protocol for CTA Brain? (contrast plus delay, collimation size, technique, amount of overlap)
- axial brain scan w/o contrast first
- 50-75 mL of contrast; 15-20 sec delay
- Helical scan, 0.625 mm collimation
- 120 kVp, 300 mA, 0.4 sec
- 0.75 mm of slice overlap w/cor and sag MPR, MIP, and 3D
CTA Brain can be done for acute stroke. What superior anatomy and inferior anatomy must be included?
Circle of Willis to Aortic Arch
What does the CT Perfusion of the Brain study evaluate?
the level of blood flow throughout brain tissue
What is Cerebral Blood Volume? Cerebral Blood Flow? And Mean Transit Time? What are the normal ranges of each?
CBV: the quantity of blood within a 100 g of brain tissue; normal is 4-5 mL/100 g
CBF: the quantity of blood that moves through 100 g of brain tissue per minute; normal is 50-60 mL/100 g /min
MTT: the average transit time (in sec) for blood to pass through a given region of brain tissue (varies between venous and arterial)
What is the Central Volume Principle?
the relationship between CBV, CBF, and MTT.
CBF = CBV / MTT
The primary goal of a CT Perfusion study is to differentiate between infarct core and penumbra. What is the difference between the two?
- infarct core is damaged beyond repair
2. penumbra is ischemic but still viable; it surrounds the infarct core
