Neuroimaging Flashcards
In a MRI:
T1W, highlights ______ , the CSF is ____ = _____ signal
T2W, highlights _____, the CSF is ______ = ____ signal
FLAIR (fluid attenuated recovery) is like a T__W, but …..
Most lesions appear _____ = ____ signal or T_W or FLAIR MRI sequences
T1W, highlights ANATOMY, the CSF is DARK = LOW signal
T2W, highlights PATHOLOGY, the CSF is BRIGHT = HIGH signal
FLAIR (fluid attenuated recovery) is like a T2W, but
the visually distracting high signal of CSF is removed from the images
Most lesions appear BRIGHT= HIGH signal or T2W or FLAIR MRI sequences
In acute hemorrhage,
It appears ______ on CT, whether inside or outside the brain; as time passes, any edema subsides and the hematoma becomes ___ and then ____ on CT.
In acute hemorrhage,
It appears HYPERENSE/BRIGHT on CT, whether inside or outside the brain; as time passes, any edema subsides and the hematoma becomes ISODENSE and then HYPODENSE/DARK on CT.
Left image: Intra Midline shift pushing the mdlinet
Right image: subarachnoid hemorrhage , blood in the subarachnoid space – filling the sulci, edema will subside, the hematoma becomes ISOdense (same density as the brain) then hypodense(dark or black on CT)
Edema appears as…
_____ on CT
____ on MRI T2W / FLAIR
Edema mainly invovled the ____matter, often sparing the cortical gyri “fingers”
Contrast enhances lesions with a _______, as well as normal vascualr structures
What could occur as a result of edema?
Edema appears as…
hypodensity/lucency on CT
increased/high signal intensity on MRI T2W / FLAIR
Edema mainly invovled the WHITE MATTER, often sparing the cortical gyri “fingers”
Contrast enhances lesions with a LEAKY BBB, as well as normal vascualr structures
What could occur as a result of edema? subfalcine or lateral brain shifts
Lateral compression or shifting of the lateral ventricles
unilaterally obscured sulci or gray-white junction
Hydrocephalus = ventricular ______ without loss of brain tissue, related to
Could be due to …(2)
Hydrocephalus = VENTRICULAR ENLARGEMENT without loss of brain tissue, related to IMPAIRED CSF FLOW
Could be due to …
Aqueductal Stenosis - enlarged lateral, 3rd ventricles (not 4th)
Scarring or block of subarachnoid vili - enlarged lateral, 3rd AND 4th ventricles
What are common CNS infections and how would each appear on brain imaging?
Abscess: cavitary, encapsulated lesion (“walled off”) with surrounding edema; better visualized when the capsule is delineated by contrast / ring enhancing lesion
causes: bacterial/TB, fungal, parasitic
Encephalitis (brain) or myelitis (spinal cords): focal edema with variable enhancment, usually viral
Meningitis: leptomeningeal enhacement ay occur
Brain tumors:
Primary could be ___ [solitary/multiple]
Metastaic could be ___ [solitary/multiple], shaped ____ and at ____ junction of brain
Epidural spinal cord metastasis…
arise from _____ and encroach upon the spinal cord in its canal
Brain tumors:
Primary could be SOLITARY, hemorrhagic or heterogenous
Metastaic could be solitary OR multiple, shaped SPHERICAL and at GRAY-WHITE junction of brain
Epidural spinal cord metastasis.
arise from teh VERTEBRAL BONE/BODY and encroach upon the spinal cord in its canal
