Imaging the brain and spinal cord Flashcards
List some imaging modalities for the brain and spinal cord
Computed tomography (CT)
Magnetic resonance imaging (MRI)
X-ray (plain film)
List the different cross sections of imaging
Axial
Coronal
Sagittal
What is meant by spatial resolution?
Good for looking at bones
What is meant by contrast resolution?
Good for looking at different tissues - can distinguish between different types
What are the most important MRI images sequences?
T1 and T2
What is a T1 weighted MRI scan?
Static fluid appears black
What is a T2 weighted MRI scan?
Static fluid is white
What static fluid is best to look at to determine the weighting of a MRI scan?
CSF
What is contrast?
Used to increase contrast resolution
Given intravenously or enteral before scan
Is either more or less dense than surroundings (CT or X ray) or paramagnetic (MRI)
What are the pros of Xray?
Cheap, quick, easy for patient
Good spatial resolution
Low radiation dose
What are the cons of Xray?
Poor contrast resolution
Planar imaging
What are the pros of CT?
Quick, widely available
Cross sectional images
High contrast resolution
What are the cons of CT?
Radiation dose
IV contrast risks
What are the pros of MRI?
Contrast resolution
Specific applications
No radiation
What are the cons of MRI?
Limited availability
Patient experience
Expense
Magnet/contrast risks
Which imaging modalities are used to view the skull?
CT
X-ray
Describe a blowout trauma
Soft tissue found in the sinus
Bone fragment displaced
What is the falx cerebri?
Separates the cerebral hemispheres
What is the tentorium cerebelli?
Separates cerebrum from cerebellum
Where are the dural venous sinuses?
Lie between the outer (periosteal) and inner (meningeal) layers of the dura
Contrast is not used in which weighted MRI scan?
T2 - fluid is already white
What is the function of the cerebral hemispheres?
Language, reasoning, motor and sensory function
What comprises the basal ganglia?
Caudate nucleus and lentiform nucleus
What is the purpose of the basal ganglia?
Action selection and movement regulation
What is the purpose of the thalamus?
Sensory relay station
What is the purpose of the cerebellum?
Motor coordination, balance and precision
What is the purpose of the brain stem?
Life support: heart rate and breathing
What can be seen on a CT scan in the case of a blunt trauma to the head?
Extradural haematoma (damage to meningeal artery/vein) Midline shift
How can a blunt trauma to the head be imaged?
By taking a bone window followed by a soft tissue window
Describe the ventricles and their function
4 Ventricles
Choroid plexus lines ventricles- production of CSF
Ventricles connect with central canal of spinal cord via 4th ventricle allowing CSF circulation
Network of 4 cavities in the brain
Give an image modality used to view the ventricles
MRI T2 weighted with no contrast - CSF appears white
Describe what may be seen in a case of chronic headache using axial CT
Obstructive hydrocephalus with dilatation of both lateral ventricles due to colloid cyst at foramen of monro
Describe the arteries of the brain
Aorta - internal carotid arteries and vertebral arteries - circle of willis
Describe an image modality used to view the arteries of the brain
MRA (magnetic resonance angiogram) - Angiogram with 3D contrast
DSA (digital subtraction angiography) - X-ray with contrast
Describe an image modality used to view the veins of the brain
DSA (digital subtraction angiography) - X-ray with contrast
What might be seen on a CT scan of a patient with an ischemic MCA stroke?
Cerebral edema
Midline shift
What is used to determine the cause of a stroke?
Angiogram (DSA - LATERAL)
Useful for spotting atherosclerotic plaques in the internal carotid artery
What is more sensitive than CT for acute stroke?
MRI (diffusion)
Which imaging modality is good for assessing the bones in the spine?
X-ray
CT (bones and joints)
Which imaging modality is good for assessing the soft tissue detail in the spine?
MRI
