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Bone Path > Advanced Imaging Quiz > Flashcards

Advanced Imaging Quiz Flashcards

1
Q

Probable indicators for plain film imaging

A 
Trauma
Unexplained weight loss
night pain
Neurmotor deficits
Inflammatory arthritis
history of malignancy
Fever of unknown origin (>100 F)
Abnormal blood finding
Deformity
Failure to respond to treatment
Medicolegal implications
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2
Q

Possible indicators for plain film imaging

A 
>50 years old
Drug/alcohol abuse
Corticosteroid use
Unavailability of alternate imaging or previous studies
Outdated previous studies
Research
Constitutional/systemic symptoms
Recent immigration
Therapeutic risk assessment or response
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3
Q

What are disadvantages to plain film imaging?

A
  1. Not sensitive (need 30-50% of bone destruction)
  2. No axial images
  3. Quality dependent on positioning and technique
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4
Q

What are indications for tomography?

A
  1. Requires a specific area to be visualized

2. Often an area that is difficult to see on plain film but is still clinically relevant

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5
Q

What is tomography?

A

Radiographic “slices” taken with a moving camera and film

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6
Q

What are advantages of tomography?

A
  1. The thin “slices” of bony anatomy visualized show detail (great for osseus structures)
  2. Minimal radiation exposure
  3. Cost effective
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7
Q

What are the disadvantages of tomography?

A
  1. Can only visualize small specific areas

2. Soft tissues are seen as well as in plain film

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8
Q

How much more contrast resolution is there with computed tomography when compared to plain film?

A

100x

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9
Q

Does CT use film?

A

No, a detector collects numeric information on remnant radiation that passes through the body

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10
Q

How thick are the slices in CT?

A

0.5mm to 10 mm thick

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11
Q

how many transmission measurements per slice in CT?

A

~800,000

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12
Q

Can a CT gantry be angled?

A

Yes usually 15-30 degrees, which allows for better visualization of the skull and intervertebral discs

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13
Q

What is each block of the matrix in CT called?

A

a voxel (a volume element: LxWxD)

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14
Q

What is a pixel?

A

A two dimensional representation of a voxel (picture element: LxW)

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15
Q

What is the range for housfield units (HU)?

A

-1000 to +1000 (CT). The computer gives each voxel a numerical value (HU)

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16
Q

What are the housfield units for various known substances?

A 
Water: 0 HU
Blood: +40 HU
CSF: +15 HU
Air: -1000 HU
Fat: -100
Cortical Bone: +1000 HU
Metallic objects: +1000
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17
Q

What is a bone window in CT?

A
  1. A tech tells to computer to display HU numbers that allow details of osseus structures to be seen.
  2. The cortex and medullary bone will be distinctly different
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18
Q

What is a soft tissue window in CT?

A
  1. A tech tells to computer to display HU numbers that allow details of soft tissue structures to be seen.
  2. Cortex and medullary bone have similar densities
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19
Q

What are contraindications or risks for CT?

A
  1. Metallic objects will create artifacts
  2. Radiation exposure
  3. Sensitivity to iodine contrast agent
  4. Claustrophobia (not as severe as MRI)
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20
Q

What are indications for CT with trauma cases?

A
  1. Involvement of complex osseus structures
  2. Post-traumatic calcifications
  3. Fresh blood
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21
Q

What are indications for CT with infection cases?

A
  1. Cortical violation may be seen

2. MRI will show ST and marrow changes better

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22
Q

What are indications for CT with vascular cases?

A
  1. Intracranial and intrathoracic vessels

2. MRA may also be used

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23
Q

What are indications for CT with neoplasms?

A
  1. Better seen on MRI

2. May be used as a adjunct when MRI not available

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24
Q

What are indications for CT with arthritis cases?

A

DJD of the spinal canal (stenosis)

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25
Q

What are indications for CT withdisc herniation cases?

A
  1. Best with MRI

2. With myelographic contrast CT may add diagnostic accuracy

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26
Q

What are indications for CT with chest and abdomen cases?

A

Usually the modality of choice! (d/t breathing artifacts in MRI)

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27
Q

What are indications for CT with sinus cases?

A

Chronic sinusitis evaluation

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28
Q

What are the KVp and mAs settings for most CT studies?

A

KVp: 120-140
mAs: 200-800

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29
Q

Where does CT not produce very good images

A

Posterior fossa of the skull and low pelvis

30
Q

What are the advantages of CT?/

A
  1. Excellent bony detail and god ST images
  2. Image can be manipulated and changed to show specific areas of interest with various levels of contras
  3. 3D image reconstruction possible
31
Q

What are the disadvantages of CT?

A
  1. Relatively high radiation dose
  2. High coast
  3. Reformatted images not as good as original
32
Q

What are general characteristics of MRI?

A
  1. No radiation
  2. Expensive
  3. Great soft tissue detail
  4. Multiplanar imaging
33
Q

What are the components of an MRI unit?

A
  1. Supraconducting magnet
  2. Table for patients to lie on
  3. Faraday cage to shield out extraneous radiofrequencies
  4. Operator console
  5. Computer to analyze and create images
34
Q

What contributes to better images with MRI?

A

Greater magnet strength or software packages

35
Q

How dos MRI work?

A

It uses magnets to align the nuclear spin of atoms in the body. A radio signal is activated and knocks the nuclei out of alignment. When they realign they produce a signal that is read by the coil

36
Q

What is precession?

A

The rotation motion a given proton experiences as it wobbles about the axis of an external magnetic field

37
Q

What are the 2 periods associated with an MRI?

A
  1. Period of excitation

2. Period of listening for a radio frequency (relaxation)

38
Q

What are the 4 components of the signal in an MRI?

A
  1. Hydrogen activity
  2. Two relaxation times of magnetized protons (T1 and T2)
  3. Motion or flow
  4. Differential response of fat and water protons
39
Q

What are the 2 times associated with MRI image creation?

A
  1. Echo time (TE): time interval from 90 degree radiofrequency (RF) pulse and echo detection (msec)
  2. Relaxation time (TR): time between 90 egrees RF pulses (msecs)
40
Q

What are factors for MRI that determine image appearance?

A
  1. Number of hydrogen protons in tissues being imaged (spin density)
  2. T1 relaxation time
  3. T2 relaxation time
41
Q

What will appear bright/white on a T1 weighted image?

A

Fat!

42
Q

What will appear bright/white on a T2 weighted image?

A

Water!

43
Q

How will ligaments and tendons look on T1 and T2 images?

A

They will produce little to no signal, thus they will appear dark grey or black

44
Q

How will cortical bone appear on T1 and T2 images?

A

as a signal void (black)

45
Q

What is a T1 image good for? (Short TE and TR)

A
  1. Fat (bright)
  2. Precise anatomy
  3. Medullary bone
  4. Spinal cord
  5. Low signal cortical bone
  6. CSF intermediate
46
Q

What is a T2 image good for? (long TE and TR)

A
  1. Water image
  2. CSF is bright
  3. Less precise detail
  4. Normal discs are bright
47
Q

What does STIR stand for?

A

Short T1 Inversion Recovery (MRI)

48
Q

What does GRASS stand for?

A

Gradient Recalled Acquisition in Steady State (MRI)

49
Q

What does FLASH stand for?

A

Fast Low-Angle Shot

50
Q

When is gadolinum used as a contrast agent

A
  1. With MRI
  2. Goes to areas of increased vascularity
  3. Only on T1 images (before and after)
51
Q

What are MRI images best for?

A 
Patients with soft tissue abnormalities
Non-acute cranial lesions
Spinal cord pathology
Disc lesions
Marrow replacement process (neoplasm, AVN, bone edema)
52
Q

Contraindications for MRI?

A
  1. First trimester of pregnancy
  2. More than 300 lbs (maybe open MRI?)
  3. Ferromagnetic artifacts (surgical clips)
  4. Pacemakers/defibrillators/implanted TENs
  5. Cochlear implants, some prosthetic heart valves and penile implants
53
Q

What are limitation of MRI?

A
  1. Many contraindications
  2. Patient physical size is an issue
  3. Claustrophobia (talking, music, movie glasses help)
  4. Lying completely still for 30 mins-1 hour
  5. Loud tapping noises
54
Q

What are common artifacts for MRI?

A

Patient motion and metal

55
Q

What is myelography?

A

Injection of contrast agent into subarachnoid space which is used to indirectly visualize lesions in the spinal canal

56
Q

What are indications for myelography

A
  1. Disc herniations (spinal canal lesions)
  2. tumor
  3. Hematoma
  4. Osteophyte
  5. Inflammation
  6. Developmental anomaly
  7. Gold standard for spinal stenosis (pre-surgical)
57
Q

What has mostly replaced myelography?

A

MRI

58
Q

What are disadvantages of myelography?

A
  1. Invasive
  2. Infection risk
  3. Reactions (HA, arachnoditis, allergic)
  4. Patient must be monitored 3 hours post procedure
59
Q

What is meant by nuclear imaging

A

Imaging types that use intravenous injections of radionuclides which are taken up selectively by tissue displaying increased metabolic rates or vascularity

60
Q

What are the most common radionuclides used in nuclear medicine?

A
  1. Technetium-99***
  2. Gallium-67
  3. Indium-111
61
Q

What are the 3 phases of scintigraphy?

A
  1. Flow phase
  2. Blood pool
  3. Delayed/Bone scan phase
62
Q

Scintigraphy has high _______ and low ______

A

Sensitivity, specificity

63
Q

What are advantages of bone scans?

A
  1. Entire body can be evaluates for diffuse disease area
  2. Very sensitive
  3. Only 3-5% bone destruction is needed
64
Q

What are disadvantages of bone scans?

A
  1. Not specific
  2. Hot areas do not specify disease process
  3. Invasive injection and radioactivity risks
65
Q

What is a discography?

A
  1. Injection of radiopaque contrast agent into intervertebral disc to provoke pain
  2. May demonstrate dessicated or herniated discs
66
Q

What are complications from discography?

A
  1. Invasive
  2. Infection risk
  3. Damage to discs
  4. Usefullness dependent on doctors skill
67
Q

How is SPECT similar to scintigraphy?

A
  1. It uses a similar principle but utilizes CT to display the tracer in selected image planes (better localization)
  2. Appearance is almost identical to planar bone scan
68
Q

What are SPECT scans for?

A

Confirming fatigue/stress fractures (pars)

69
Q

What is a Positron Emission Tomography (PET) scan?

A

A type of imaging that utilizes radiopharmaceuticals that emit positrons. When a positron collides with an electron, both particles are annihilated, producing two gamma rays

70
Q

Which has the best resolution: SPECT, PET or Scintigraphy?

A

PET scans

71
Q

What are PET scans best for?

A
  1. Excellent at soft tissue tumor localization
  2. Ascertaining lymph node involvement
  3. Developing brains
  4. Parkinson’s brain scans
72
Q

What are indications for Ultrasound?

A
  1. Fetus/OB work
  2. Gallbladder diseases and stones
  3. Stone in general
  4. Thyroid issues (nodes)
  5. Diagnose some infections and cancers
  6. Guide needles or tumor treatment
  7. Evaluate blood vessels and tendons/ligaments
  8. Abnormalities in the scrotum and prostate

Bone Path (4 decks)

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