Neuro Imaging Flashcards
What type of scan is usually first line for neuro due to fast scanning times and availability
CT
What is better seen on CT
Anatomy of the skull
On a non-contrast CT what usually shows up as white
Bone or blood
What type of MRI is considered standard and best for differentiating fat from water
T1
What type of MRI is most sensitive for detecting brain pathology
T2
Anatomical MRI is ____ weighted while functional MRI is ___ weighted
T1
T2
Water appears black on _____ weighted images and white on ____ weighted images
T1
T2
Which type of imaging is best for acute hemorrhage
CT
Which type of imaging is best for diffuse axonal injury
MRI
What is the study of choice in head trauma and more sensitive for detecting fractures
CT
What imaging is used as the initial study in strokes
CT
What imaging study is more sensitive for brain masses
MRI
What is usually used to evaluate for aneurysms
CT
When is contrast dye used?
When evaluating for intracranial mass or vascular pathology
What is the study of choice when tumor is being imaged
MRI brain with and without contrast
What kind of imaging uses contrast to provide pictures of the blood vessels (eval for aneurysms, vertebral artery injuries, or vascular malformations)
CT angiogram
When is MR angiography used
If the patient has decreased renal function, contrast dye allergy, pregnant or breastfeeding patients
What should you use to view skull fractures?
Bone windows
What type of skull fractures are more likely to occur in temporal and parietal bones?
Linear skull fractures
What kind of skull fracture is associated with underlying brain injury and results from a high energy blow to a small area of the skull?
Depressed skull fractures
What is the imaging study of choice for facial fractures?
CT
What is the most common type of orbital fracture?
Blow out fracture
What is a traumatic accumulation of blood between the inner table of the skull and the stripped off dural membrane?
Epidural hematoma
70-80% of EDHs are located where?
In the temporoparietal region
CT looks like a balloon, young person, bright red blood
EDH
Which type of hematoma cannot cross the suture line
EDH
Most EHDs are due to injury to which artery
Middle meningeal artery
High-density, extra-axial, biconvex lens-shaped mass lesion on CT. Found in the temporoparietal region.
Epidural hematoma
13 yo male patient presents to ED after falling off his bike and hitting the left side of his head. Parents report he passed out for a minute, but has been acting fine since. He reports headache. Within 5 minutes of talking to him, he starts to act sleepy, his words become confused, and you notice his left pupil is larger than the right. Dx?
EDH
False localizing sign where the patient will experience ipsilateral weakness due to midline shift of the brain stem shift forces in contact with the opposing tentorium
Kernohan’s notch
T or F: epidural hematomas are more common than subdural hematomas
False. Subdural are more common
Commonly occurs in elderly and looks like a banana on imaging
Subdural hematoma
Often seen in deceleration injuries such as car crashes or falls
Subdural hematoma
Hemorrhage into potential space between dura mater and arachnoid
Subdural hematoma
Which hematoma is associated with a high mortality rate
SDH
Bridging veins are usually the source of __________ hematoma
Subdural
Acute SDH appears _______ on non-contrast CT while chronic SDH appears _______ on CT ___ weeks after injury
White
Dark
3
84 year old female had a ground level fall 3 days ago after dialysis treatment and struck her head. No loss of consciousness. She has been complaining of headache since then. This morning she was not acting like herself and was very sleepy with slurred speech. Dx?
Subdural hematoma
72 yo female who has history of a fib and on Coumadin therapy tripped and fell while walking home. She hit her head on the lawn. What brain injury she most at risk for?
Subdural hematoma
SDH clinical presentation (small-moderate)
Small bleed, asymptomatic or mild headache, confused, mild weakness on contra lateral side, sleepy
SDH clinical presentation (severe)
Obtunded, contralateral hemiplegia, dilated/fixed contralateral pupil
Symptoms will start within ____ hours of injury for acute SDH, ____ days for subacute SDH, and ________ or longer in chronic SDH
72
3-20days
3 weeks or longer
MCC of subarachnoid hemorrhage
Trauma
MCC of spontaneous subarachnoid hemorrhage
Ruptured aneurysm
Thunderclap headache, altered level of consciousness, unchallenged rigidity, cranial nerve palsy or neuro deficit, hx of smoking or Htn
Subarachnoid hemorrhage
Most frequent CNS aneurysm
Berry aneurysm
Gold standard test for SAH and alternative choice
CTA head
MRA as alternative if pt can’t have contrast
_________ develops from a congenital weakening of the arterial wall, usually at the Circle of Willis
Berry aneurysm
Treatment for traumatic SAH vs aneurysmal SAH
Traumatic- monitor in ICU, consider external ventricular drain
Aneurysmal-nimodipine, BP control, daily sodium level, daily transcranial Doppler, surgical clipping/coiling
Acceleration/deceleration forces diffusely injure axons deep to cortex, most often from MVA
Diffuse axonal injury
Study of choice for DAI
MRI
You see loss of normal differentiation between gray and white matter, effacement of normal sulci, ventricular compression and herniation on brain imaging. What should you be concerned for?
Cerebral edema
Common injury following trauma that is often due to shearing of small intracerebral vessels
Coup
Acceleration/deceleration injuries that occur when the brain is propelled in the opposite direction and strikes inner surface of the skull
Contrecoup
What do you see on a CT of someone with intraparenchymal hematoma
Multiple small, well-demarcated areas of high attenuation within parenchyma surrounded by a ring of hypo-attenuation, compression/shift of ventricles is common
_______________ is often secondary to large IPH and or SAH
Intraventricular hemorrhage
What is an acute loss of neurologic function that occurs when blood supply to an area is lost or compromised
Stroke
What are the uses for CT for a stroke patient
Determine if there is another cause of the neuro impairment, identify presence of blood to differentiate ischemic vs. hemorrhagic, identify and characterize the infarct
Thromboembolic disease secondary to atherosclerosis
Ischemic stroke
What is the timeline for CT findings for ischemic stroke
12-24 hrs- indistinct area of low attenuation in a vascular distribution
>24 hrs- better circumscribed with mass effect
72 hrs- contrast enhancement occurs when mass effect is waning or gone
>4 weeks- no mass effect, well-circumscribed low attenuation lesion with no contrast enhancement
What are signs of acute stroke on CT
Insular ribbon sign, obscured lentiform nucleus, dense artery sign
Which CVA vascular distribution is most common and has the most significant symptoms
MCA
Most hemorrhagic strokes are related to _________ and occur in the __________
Hypertension
Basal ganglia
Freshly extravasated whole blood will be seen as _________ on non-enhanced CT and becomes ________ for about 3 days. After the 3rd day the clot _________ in density. After ____ months only a small hypo density may remain.
Increased density
Denser
Decrease
2 months
What is the most common primary supratentorial, intro-axial mass in adults
Astrocytomas/Gliomas
Which intracranial tumor is classified as WHO Grade IV and has the worst prognosis
Glioblastoma Multiforme
Glioblastoma multiforme is more common in _________
Males ages 65-75
You get a CT back that shows a tumor with necrosis, tumor infiltrates surrounding brain tissue, crossing the white matter of the corpus callosum, and produces vasogenic edema and mass effect. What should you be concerned about?
Glioblastoma multiforme
T or F: There are usually multiple metastases in the brain, but they can be solitary
True
Metastases are typically _________or ________ on non-enhanced CT. With IV contrast, it can enhance in a pattern of ____________
Hypodense or isodense
Ring-enhancement
What are the most common primary malignancies to produce brain lesions
Lung cancer, breast cancer, melanoma
What is the most common extra-axial mass
Meningiona
Meningioma arises from _________, often attached to dura with a “____________”
Arachnoid
“Dural tail”
Meningiomas usually occur in what group of people
Middle-aged women
Multiple meningiomas may be associated with _____________
Neurofibromatosis type 2
On CT, greater than half of ___________ are hyper dense, may contain calcification and enhance markedly with contrast
Meningiomas
The most common symptom of acoustic neuroma is ___________
Hearing loss
What kind of mass occurs most commonly along the course of the eight cranial nerve within the internal auditory canal
Acoustic neuroma (schwannoma)
What is the most sensitive imaging study for acoustic neuroma
MRI
What kind of tumor is often benign, presents with vision changes, and may be associated with hormonal disturbances
Pituitary tumor
Large ________ tumors often displace the optic nerves and look like a snowman
Pituitary tumors
Obstructive extra-ventricular hydrocephalus with dilation of the fourth ventricle
Communicating
Obstructive intraventricular hydrocephalus where the fourth ventricle is normal in size
Noncommunicating
A 60 year old patient presents to the ER with urinary incontinence, loss of balance, and confusion. Their brain CT shows enlarged ventricles with flattened sulci. What is the diagnosis?
Normal pressure hydrocephalus (“wet, wobbly, wacky”)
T or F: atrophy implies loss on gray matter only
False. It implies loss of gray AND white matter
Why do the ventricles dilate in patients with cerebral atrophy?
Because the loss of normal cerebral tissue produces a vacant space.
What is the study of choice for MS
MRI
MS lesions have a predilection for what areas
Periventricular area, corpus callosum, and optic nerves
You look at your patient’s T2 weighted MRI and see lesions that produce discrete, globular foci of high signal intensity. What do these findings indicate?
MS
22 yo male was using an electric scooter when he crashed and fell off. His friends report he struck his head, was unconscious for a minute and then was able to get up. He was not wearing a helmet. He is currently in the ER and is alert and oriented and able to move his face and extremities. He tells you he is getting sleepy. What is on the ddx? What imaging do you order?
Epidural hematoma, CT?
55 yo male found down and unresponsive. He is intubated and in the ICU when you arrive. His wife tells you that he had been complaining of horrible headache an hour before she found him. He has taken some ibuprofen with no relief. What is on the ddx? What would you order for imaging?
Subarachnoid hemorrhage, Non-contrast CT head
75 year old female with new onset right sided weakness. She ran out of her BP meds a few days ago. Her BP is currently 179/113. The right side of her face is droopy and she has difficulty moving her right arm. What do you suspect? What do you order?
Ischemic stroke, Head CT first for rapid results, then. MRI
41 yo male with a cc of a worsening headache. It usually gets better with Tylenol, but has been more persistent over the past few weeks. Denies any recent trauma. His medical history is significant for hypertension and hyperlipidemia. He has borderline diabetes. His BP is 134/85. Dx?
Meningioma
Classic presentation of EDH
Brief loss of consciousness during accident, but then they recover and appear relatively normal for several hours before getting rapid onset neuro deterioration
Symptoms of EDH
Obtundation, ipsilateral dilated or blow pupil, contralateral weakness, nausea and vomiting, seizure, increased ICP (htn, bradycardia, irregular respirations)
T or F: less than 20% of EDH patients actually experience a lucid period between the trauma and subsequent neuro deterioration
True
