Anatomical Imaging of the Head and Neck

Question 1

How is an x-ray produced?

Answer 1

Produced by sudden deceleration of electrons hitting the anode

Question 2

What are the indications for using an x-ray?

Answer 2

Trauma (fractures), degenerative diseases (RA), and post-operative

Question 3

What are the types of xrays?

Answer 3

PA, AP, lateral

Question 4

How is a fluoroscopy/angiography produced?

Answer 4

Continuous x-ray radiation passes through the body onto a fluorescent screen creating a moving x-ray image

Question 5

What are the indications for using a fluoroscopy?

Answer 5

Swallow study, interventional radiology, arthography, and cardiac catheterization

Question 6

What is injected into the vasculature for contrast in a angiography?

Answer 6

Barium or iodine

Question 7

What are the indications for angiography?

Answer 7

Aneurysm, vascular malformations, fistulae, stenosis, thrombosis, dissection, stenting, and thrombolysis

Question 8

What are the pros and cons of angiography?

Answer 8

Pros: fast, diagnostic, and therapeutic

Cons: invasive, contrast, radiation

Question 9

How is a myelography produced?

Answer 9

Uses fluoroscopy with an intrathecal injection of contrast

Question 10

What are the indications for a myelography?

Answer 10

Spinal stenosis, nerve root compression, and CSF leak

Question 11

What are the pros and cons of myelography?

Answer 11

Pros: defines subarachnoid space and identifies spinal block

Cons: invasive, CSF leak, headache, radiation, and contrast

Question 12

How is a computed tomography produced?

Answer 12

Series of x-rays scanned axially; x-rays are digitally resliced in any plane; scans are read as if looking at the patient from the feet

Question 13

How is the radiodensity measured on a CT?

Answer 13

Measured in Hounsfield Units (HU); all densities are compared to water; water is 0 HU; hyperdense is white, hypodense is black

Question 14

What are CT scans used for?

Answer 14

Skull, skull base, vertebrae, ventricles, intracranial masses, mass effect, hemorrhage, ischemia, and calcification

Question 15

What are the indications for a CT scan?

Answer 15

Trauma, bone lesions, hydrocephalus, masses, mass effect, nausea, vomitting, headache, visual symptoms, stroke, mental status change, focal neurological defects, and lesion characterization

Question 16

What are the pros and cons of a CT scan?

Answer 16

Pros: fast, relatively inexpensive, and good at detecting large pathologies

Cons: less detail than MRI, radiation exposure, and low sensitivity in posterior fossa

Question 17

When is contrast on a CT indicated?

Answer 17

Neoplasm, infection, vascular disease, inflammatory disease, more than 3 hours after onset of symptoms

Question 18

When is contrast on a CT contraindicated?

Answer 18

Trauma, hemorrhage, hydrocephalus, dementia, epilepsy, and within 3 hours of symptoms

Question 19

What structures will enhance in the brain with IV contrast?

Answer 19

Cerebral blood vessels, meninges, pineal gland, pituitary gland, and choroid plexus

Question 20

How is a CT angiography produced?

Answer 20

Rapid IV contrast bolus; scanned during arterial phase; digitally reconstructed into 2D and 3D images

Question 21

What are the uses of CT angiography?

Answer 21

Atherosclerosis, dissection, aneurysm, and trauma

Question 22

What are the pros and cons of CT angiography?

Answer 22

Pros: non-invasive, examine vessels from origin

Cons: contrast, radiation, lower resolution

Question 23

How is an MRI produced?

Answer 23

Patient lies in large magnet which aligns all the protons in the body; radiowaves are then passed through the patient and the returning signals are converted into an image

Question 24

What are the different radiodensities of an MRI?

Answer 24

Hyperintense - white

Hypointense - black

Question 25

What are the uses of an MRI?

Answer 25

Further evaluation of CT findings, tumors, infection, and joint imaging

Question 26

What are the pros and cons of an MRI?

Answer 26

Pros: high level of detail, safe to use in pregnancy, and vessel imaging can be obtained without the use of contrast Cons: time consuming, contraindications (metal/implantable diseases), expensive, and claustrophobia

Question 27

What is a T1 weighted MRI?

Answer 27

CSF is dark (hypointense), white matter is bright (hyperintense); good for imaging normal anatomy

Question 28

What is a T2 weighted MRI?

Answer 28

CSF is bright (hyperintense), white matter is dark (hypointense); good for visualizing pathology

Question 29

What is a T2 flair MRI?

Answer 29

Removes CSF from T2; enhances fluid with high protein content (edemal/abscesses) *FLAIR = Fluid Attenuated Inversion Recovery*

Question 30

How is an ultrasound produced?

Answer 30

Transducer emits ultrasound waves into the body; transducer then functions as a receiver that records the energy

Question 31

What are the uses of ultrasound?

Answer 31

Evaluation of carotid arteries and placement of central lines

Question 32

What are the pros and cons of an ultrasound?

Answer 32

Pros: non-invasive, cheap, no radiation Cons: learning curve