Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Oms > advanced imaging > Flashcards

advanced imaging Flashcards

1
Q

Conventional ct vs cbct vs mri image

A

Conventional ct: see outline of bony structures and soft tissue. Bone appear white.

Cbct: outline of bony structures, appear white. Soft tissue homogenous grey

MRI: bone appear dark, soft tissue appear white

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the most commonly used generation of ct

A

3rd gen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Features of the third gen ct

A

No translation
Rotate-rotate movement
Fan beam
Faster scan times

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is pitch (ct)

A

How much the table travels per x ray tube rotation aka image thickness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Advantage and disadvantage of lower pitch

A

Better spatial resolution

Higher radiation dose (overlapping of anatomy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Compare CT and CBCT in terms of image acquisition and equipment

A

Similar components (detector, x ray source) which patient located in the middle

CT multiple rotations, CBCT one rotation

CT beam fan shaped, CBCT beam cone shaped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does pre patient collimator do

A

Restrict the size of the x ray beam entering the patient’s body, specifying thickness of cross sectional slice. Minimise radiation dose to patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does post patient collimator in ct do

A

Restrict x ray beam from entering detector assembly at arbitrary angles. This reduces the amount of scatter —> improve image contrast (hence soft tissue contrast on CT better)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Hounsfield unit

A

Representation of tissue density relative to water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which views are available on CT

A

Orthogonal ie axial, sagittal, coronal

Oblique, surface render, MIP
No serial cross sectional, no panoramic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which modality has bone and soft tissue windows

A

Ct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the average radiation dose of head ct

A

534-1100usv

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Contrast agents are used for what modality

A

CT and mri

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do contrast agents do

A

Enhance soft tissue and vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Contrast agents contraindicated in patients with

A

Iodine allergy

Renal impairment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Indications for CT

A

Evaluate pathology eg soft and bony tissue involvement

Infection — soft tissue, osteomyelitis

Spitch

Evaluate trauma

Craniofacial evaluation

Paranasal sinuses and temporal bone evaluation

Investigate symptoms of headache, stroke (symptom investigation not indication for CBCT)

17
Q

Principles of mri image acquisition (what does the magnetic field do)

A

In their natural state, atoms spin in random directions around their individual magnetic fields

Magnets in MRI scanner align hydrogen nuclei to the stronger MRI magnetic field

Radio frequency pulses emitted by MRI scanner intermittently. Hydrogen nuclei respond to RF pulses absorb and release energy at different intensities.

MRI coil detects these signals and processed by algorithm to form image

18
Q

What is high SI in T1 pulse timing

A

MRI. High SI = white. T1 is weighted +/- contrast

Fat, blood, contrast, melanin, protein

(CSF dark)

19
Q

What is high SI in T2 weighted image

A

Fluid, CSF, kidney, gallbladder

20
Q

Strengths of mri

A

No ionising radiation
Excellent soft tissue detail
Use of of paramagnetic contrast agents can enhance soft tissue

21
Q

Limitations of mri

A

Long scanning time 1.5-2hours

Expensive

Susceptible to metal artefacts which can severely distort appearance of MRI image, making diagnosis difficult

22
Q

Contraindications for mri

A

Metal containing implants eg pace maker, cochlear implant. If patient unable to provide good history may do x ray to check

Metallic foreign body eg bullet shrapnel

Braces and dental implants not contraindicated as tend not to be magnet but can cause image distortion

Pregnant, strength of magnetic field biological effect on fetus

Impaired renal function — contrast risk of nephrogenic systemic fibrosis or side effect from contrast agents

Claustrophobic

23
Q

Indications for mri

A

Soft tissue pathology

Malignant spread to lymph nodes

Edematous changes

Perineural involvement

Evaluation of TMJ articular disc

Evaluate vascular lesions

Plenav

24
Q

What is the main use of nuclear medicine

A

Provide functional information (rather than morphological information), using radionuclides which are taken up and metabolised. Measure radioactivity of radionuclides.

25
Q

Bone scans are 2d or 3d

A

2d

26
Q

What are the application of bone scans

A

Bone activity eg Paget’s disease, condylar hyperplasia

Skeletal tumours, metastases

Infection, osteomyelitis

Fracture

Eg orthognathic surgery for patient with hemimandibular hypertrophy, see whether jaw growth has stopped

27
Q

How do pet scans work

A

Positive emission tomography scans use fluorodeoxyglucose, taken up by glucose metabolising cells

28
Q

Applications of PET scan

A

Diagnose and stage cancer and metastases

Infection, osteomyelitis

29
Q

Oblique lateral mandible x ray can be used in evaluation of

A

Mandibular trauma

30
Q

What is waters view used for

A

Paranasal sinuses and zygomatic arch

Oms (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions