Anatomical Imaging Flashcards
Xray:
Electrons hitting anode = image
Different tissues absorb electrons differently
Usually used in trauma ,degenerative diseases or post operative procedures
Fluoroscopy
Continuous XR radiation passes through body onto fluorescent screen creating moving image = moving XR
Could be used in swallow studies, IR, arthrography or cardiac cath
Angiography
Form of fluoroscopy used to evaluate vasculature
Used for aneurysms etc.
Pros of Angiography:
Fast
Diagnostic and therapeutic
Cons of angiography:
Invasive
Need contrast
Uses radiation
Angiography requires …
Injection of contrast into vasculature (barium or iodine)
Myelography:
Uses fluoroscopy and needs intrathecal (spinal) injection of contrast, invasive
Pros of Myelography:
Defines subarachnoid space
Identifies spinal block
Cons of Myelography:
Invasive
Could worsen CSF leak, headache
Radiation
Contrast
CT:
Series of XRs scanned axially and resliced in any plane
Read caudal up
Hounsfield units (HU:)
Measure of radiodensity for CT
All densities compared to water which is 0 HU
Hyperdense (high HU) appears…
Hypodense (low HU) appears …
White
black
CT used for (head and neck relevant) :
Skull and vertebrae path Ventricle studies Masses Hemorrhage, ischemia Calcification
Pros of CT:
Fast
Inexpensive
Good at detecting large pathology
Cons of CT:
Less detail than MRI
Radiation exposure
Low sensitivity in posterior fossa
Use CT contrast for …
Neoplasm Infection Vascular disease Inflammatory disease More than 3 hours after symptoms onset
Do not use CT contrast if …
Trauma Hemorrhage Hydrocephalus Dementia Epilepsy Within 3 hours of symptoms
CT contrast:
Indicates whether BBB is intact. Enhancement/whiter of contrast = not intact BBB
Structures that enhance IV contrast:
Cerebral blood vessels Meninges Pineal gland Pituitary gland Choroid plexus
CT angiography:
Uses IV contrast bolus. Arteries digitally reconstructed into 2d and 3d images
Pros of CT angiography:
Non invasive
Examine vessels from origin
Cons of CT Angiography:
Contrast
Radiation
Lower resolution
MRI:
Uses magnet alignment of atoms in tissue to form an image
Hyperintense structure appears … in MRIHypointense structure appears .… in MRI
White
Black
Uses of MRI:
Further eval CT findings, tumors, infection, joint imaging (TMJ)
Pros of MRI:
High level of detail
Safe to use in pregnancy
Vessel imaging can be obtained without use of contrast
Cons of MRI:
Time consuming
Contraindications (metal devices in body)
Expensive
Not good for claustrophobic patients
T1 weighted MRI
CSF appears
White matter appears
Good for?
Dark = hypointense
White = hyperintense
Imaging normal anatomy
T2 weighted MRI
CSF appears …
White matter appears …
Good for ….
Bright = hyperintense (white looking brain)
Dark = hypointense
Visualizing pathology
T2 FLAIR MRI
Removes CSF from T2
Enhances high protein fluid (edema/abscesses)
Ultrasound:
Noninvasive
Transducer emits US waves into body and it turns into an image
US used for?
Evaluation of carotid arteries and placement of central lines
Pros of US:
Non invasive
Cheap
No radiation
Cons: of US:
Learning curve
