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Flashcards in Introduction to Radiology Deck (46):
1

What is radiology?

Use of medical imaging to diagnose and treat diseases within the body.

2

What are the types of medical imagine that is used most commonly in radiology?

X-ray (Mammography and fluoroscopy included)

CT

MRI

UltraSound

Nuclear medicine (PET/SPECT)

3

What kind of radiation are X-rays?

Electromagnetic generated by firing electrons at a metal anode within vacuum tube

4

How can an image be generated by X-ray?

X-ray is either passed through the body (very high energy)

Can be absorbed by the body

Can be scattered in tissue

These interactions generate x-ray image

5

What do less dense objects look like on x-ray?

They are black (Air or gas)

6

What do more dense objects look like on x-ray?

They appear white for example: bone or metal

7

What would X-ray imaging show in bones?

Trauma

Degenerative diorders

Pathological processes such as cancer

8

What would x-ray imaging show in soft tissue?

Infection (common first request)

Blockages (Bowel obstruction, constipation, etc)

Trauma (Pneumothorax, pneumoperitoneum)

Pathological changes (CCF, cancer)

9

How is a mammography different to typical X-ray?

Specialized x-ray equipment for breast tissue

Uses low intensity X-rays (25 - 30kV)

Requires compression of the breast to reduce overlap of structures and to reduce X-ray dose

10

What is fluoroscopy?

Live x-ray imaging used for theatre imaging and functional studies/assessments (Dysphagia)

Oftem employs the use of contrast

11

What is x-ray contrast?

Use of high attentuating solution intravenously or orally to observe structures filled with that liquid

12

What fluid is used for IV contrast?

Iodine based solutions

13

What fluid is used for oral contrast?

Barium based solutions

14

What is important to note regarding use of IV contrast?

Can cause serious allergic reactions and extravasation.

It can be toxic to the kidneys when processed by them.

15

What are the advantages and disadvantages of using X-ray?

Pros:

Fast

Easily available

Cheap

Excellent for bony pathology

Cons:

Radiation dose (can be problematic in pregnant women and children)

2D, overlapping structures

Relatively poor soft tissue visualization

16

How does CT help solve the issues associated with using X-ray?

It takes x-ray images around the patient creating a 3D image allowing visualization of neighbouring structures and to create 3D models.

17

How are images of a CT scan shown?

Transverse view (Looking up from patient's feet)

Coronal (From the front)

Sagittal (From the left side)

18

What are the uses of CT scans?

Many uses:

Soft tissue (Volumetric scans for cancer detection, first line imagine for stroke)

Bones (Occult fractures and degenerative diseases)

Angiography with contrast imagine COW to see blockages in cerebral vessels.

19

What does a non-enhanced CT scan allow us to see?

Stones in the kidney, ureter and CBD

Calcifications in the liver and pancreas

Fat in liver tumours

Fat in adrenal adenoma or myelolipoma

20

What does contrast dye allow us to see on CT scan?

15 - 20 seconds: Demarcation of vessels and allows detection of aortic dissection as well as arterial bleeding

35 - 40 seconds (late arterial phase): hypervascular lesions, stomach, bowel, pancreas parenchyma, spleen, kidney outer cortex, liver Hepatic Cell Carcinoma, FNH, adenoma, bowel ischaemia, pancreatic cancers

21

What is the phase after 35 - 40 seconds of injecting dye for CT scan called?

Late arterial phase

22

What is the phase 15 - 20 seconds after dye injection called?

Early arterial phase

23

What is the phase called after 70 - 80 seconds of dye injection?

Hepatic phase

24

What does the hepatic phase indicate?

enhances hepatic parenchyma

Hypovascular liver lesions: cysts, abscesses, and most metastases

25

What is the phase called after 100 seconds of injecting dye?

Nefrogenic phase

26

What is enhanced after 100 seconds of dye?

Renal parenchyma including medulla

Renal cell carcinomas can be detected at this stage

27

What is the phase called after 6 minutes of dye injection?

Delayed phase

28

What shows in the delayed phase on CT?

Fibrotic lesions

Enhancement of kidneys and urinary collecting system

Liver cholangiocarcinoma

Fibrotic metastases

Breast cancer

Kidney transitional cell carcinoma

29

What are the advantages and disadvantages of using CT scans?

Pros:

3D modelling, windowing and reformatting of images

Analysis of impact on neighbouring structures

Fast, available, relatively cheap

Cons:

Dose

Patient compliance is important (staying still)

Contrast concerns

30

How does MRI work?

Uses powerful magnet to align magnetic moments of protons in tissue then flips them with RF pulse and image is formed by measuring energy emitted as protons return to alignment.

31

What is MRI used for?

1st line imaging choice for brain and spinal cord problems

Musculoskeletal imaging (cartilage, tendon, and ligament tears)

32

What is used for emergency situations when looking for bony abnormalities?

CT scans because they are faster and superior for bone. If not possible MRI can be used.

33

What are the cons for using MRIs?

Long scan times

Clautrophobic atmosphere

Noisy

Metal extremely prone to force generated by magnet. (prostheses, metallic foreign bodies, conductors, etc)

Not available 24 hours

Not available everywhere

Longer scan times/patient compliance issues

Expensive

34

What are the advantages and to using MRI?

High quality images of soft tissue structures such as ligaments and cartilage

3D imaging

No radiation dose

35

How does ultrasound work?

Uses sound wave pulses to generate images.

Waves echo off interfaces between structures and return to detector to generate images

Images describe echogenicity

36

What are ultrasounds used for?

All soft tissue imaging (muscles, tendons, ligaments)

Blood flow analysis (doppler imaging)

Abdominal organ pathology

Antenatal imaging

37

What are the pros and cons of using ultrasounds?

Pros:

Good for soft tissue and measuring blood flow

No dose

Cheap

Easily accessible

Cons:

Can't image well through air

Poor resolution

Difficult to interpret without extensive training

38

What is nuclear medicine (PET/SPECT)?

Use of radioactive substances to generate images

39

What are the most common radioisotopes used for PET scans?

PET = FDG

PLANAR/SPECT = Technitium 99m (gamma emitter)

40

How are nuclear imaging techniques used?

Combined with CT/MRI to provide high resolution images.

41

What is NM used for?

Staging and identifying cancer

Bone scans

Lung function

Thyroid

42

When are PET and SPECT used?

PET is very expensive so used when better contrast and spatial resolution is required

PET uses positron emitting isotope

SPECT is cheaper and uses gamma emitting isotope.

43

What is interventional radiology?

Use of imaging to direct minimally invasive procedures

44

What types of procedures use interventional radiology?

Vascular procedures - Stenting, Angioplasty, aneurysm coiling, embolization

Joint/nerve injections - Facet joints, nerve roots, steroid joint injections.

Radiofrequency ablation

Biopsies, fine needle aspirates

45

Does high detail imaging necessarily mean improved outcomes?

No, indidental findings can trigger unnecessary anxiety

46

What must be considered with image modalities?

Risk versus benefit - will the image alter diagnosis or treatment? Will further imaging be needed anyway?

Radiation dose (minimise dose)

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