Diagnostic Imaging (Exam 1) Flashcards
What is an X-Ray?
Plain film or conventional radiograph, it is a negative
What are the positions for radiographs?
AP
PA
Lateral
Oblique
Sunrise
Open Mouth
More dense objects the (BLANK) absorption of x-ray and (BLANK) exposure of film
greater, less
More dense of a tissue the (BLANK) x-rays penetrate the tissue to expose the film
Less
Radiolucent:
(BLANK) Density
(BLANK) Exposure of film
Bright or Dark?
Low Density
High Exposure
Dark
Radiopague
(BLANK) Density
(BLANK) Exposure of film
Bright or Dark?
High Density
Low Exposure
Bright
What are the ABC’s of X-ray interpretation?
Alignment & Adequacy
Bone
Cartilage, Joints, Soft Tissues
When and why are X-rays ordered for a patient with suspected NM injury?
- Depends on severity of injury
- Rule out/establish bony integrity
- Check for other systems
What are some ways of early examination of the human brain?
Animal Studies
Post-mortem
X-rays
Electrocephalography
What is a pneumoencephalography?
X- Ray imaging following an injection of air into subarachnoid space to displace CSF & improve signal contrast
What is a pneumoencephalography used for?
Visualize ventricular anomalies
What is a cerebral angiography?
X-ray imaging of the blood vessels of the brain following injection of a contrast agent
What is a cerebral angiography used for?
Visualize anomalies and occlusions
What is a myelography?
X-ray imaging following injection of contrast into CSF to improve contrast/imaging in vertebral column/spinal cord, subarachnoid space, nerve roots
What are some modern techniques for neuroimaging?
CT
MRI
Neuroangiograohy
How does a CT work?
- Uses X-ray beam and a row of detectors on opposite sides of the head.
- The X-ray source and detector rotate around the head
- Pt is moved through scanner and process is repeated
How can you determine the density of tissue through a CT?
X-ray are partially absorbed by tissue encounters and the amount of absorption depends on the density of the tissue it passed through
What is the benefit of the CT rotating the x-ray source?
X-ray is passed through same structures at many different angles
Describe the typical CT imaging planes?
Not in true horizontal plane but angles upward anteriorly
(BLANK) structures are hyper dense and appear (BLANK)
- Dense (bone, calcification)
- White
(BLANK) structures are hypodense and appear (BLANK)
- Less dense structures (air)
- Black
(BLANK) structures are Isodense and appear (BLANK)
- Intermediate density structures
- Gray
Is a CT with intravenous contrast appropriate if an intracranial hemorrhage is suspected? And why?
No, b/c this adds more fluid which increases pressure which could increase bleeding
What is injected during a CT with intravenous contrast?
Iodine
What becomes hyper dense during CT with intravenous contrast?
Areas of increased vascularity or breakdown of blood-barrier
What is window width?
Range of radio densities displayed on an image
What is window level?
Central density displayed on an image
General: What is an MRI?
Noninvasive technique that uses magnetic energy & radio frequency pulses to generate images
General: How does an MRI generate an image?
- Pt placed in static magnetic field
- Radiofrequency pulse applied at right angles to magnetization
- Radiofrequency pulse stops
What determines the intensity of a MRI signal?
- Proton density
- T1 (longitudinal) proton relaxation times
- T2 (transverse) proton relaxation times
Sequence of events during image acquisition creates contrast using what 2 key parameters?
Time to echo (TE)
Time to repetition (TR)
What is time to echo and time to repetition?
TE: time at which signal is captured
TR: time at which radiofrequency pulse is repeated to again displace the protons
how will hyper intense and hypo intense structures appear?
Hyper: brighter
Hypo: darker
in T1 images tissues that rapidly release energy are (BLANK) and tissues slow to release energy are (BLANK)
Rapid: brighter (fat)
Slow: Darker (water)
in T2 images tissues that rapidly release energy are (BLANK) and tissues slow to release energy are (BLANK)
Rapid: darker (fat)
Slow: Brighter (water)
What does a doppler ultrasound measure and detect?
Measure: flow and lumen diameter of blood vessels
Detects: Artery stenosis & vasospasm
What is done during a CT angiography and what does it detect?
Process: Inject contrast with spinal CT scan
Detects: Major artery stenosis, arterial dissection, aneurysms and vascular malformations
What does a MRA detect?
Narrowing in large vessels, some aneurysms and vascular malformations
What is electroencehphalography?
Recording of electrical potential generated in the brain using electrodes
What is a SPECT/PET?
Single photon/position emission computed tomography
How do Nuclear scan work?
Patient is made radioactive with an isotope
What is a diagnostic ultrasound?
High frequency sound waves create an image of living tissues
When are diagnostic ultrasound commonly used?
Abdominal imaging, obstetrics, vascular studies, and head ultrasound of infants
