Lecture 15 - Medical Imaging Flashcards

1
Q

Types of imaging that use X-Rays

A

X-ray
Fluoroscopy
CT

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2
Q

Basic principle on how X-Rays work

A

Electrons accelerated towards detector and patient
Some X-rays pass through patient hitting detector (BLACK)
Some X-rays attenuated by patient (absorbed scattered) GOES WHITE

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3
Q

What colour will dense structures appear on X-Ray images and why

A

White
X-rays attenuated and don’t reach detector

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4
Q

What colour will non dense structures appear on X-rays and why?

A

BLACK
X-rays pass through patient and reach detector

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5
Q

Densities visible on X-ray from Darkest (least dense) to Lightest/Whitest (Most DENSE)

A

AIR
FAT
WATER
SOFT TISSUE/MUSCLE
BONE
METAL

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6
Q

Clinical uses of X-Ray

A

Chest - Infection, pulmonary oedema, pleural effusion,pneumothorax

Abdomen/pelvis - Perforation, colitis, obstruction

MSK - Fracture, dislocation, effusion, soft tissue injury

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7
Q

Adv of X-ray

A

Quick
Portable
Cheap
Simple

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8
Q

Disadvantage of X-ray

A

Ionising radiation
Poor soft tissue imaging
1 plane
Cant see all pathology

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9
Q

What is Fluroscopy

A

Continuos pulsed X-Rays creating real time moving images

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10
Q

Clinical use of FLuroscopy

A

Diagnostic and Interventional
Angiography (Vascular) - stenting, embolisation
GI - (BArium swallowed and observed)

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11
Q

Fluroscopy adv

A

Real time study can assess function and carry out intervention
Quick

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12
Q

Fluroscopy disadvantage

A

High ionising radiation dose (continual pulsing X-rays)
Clinician doing intervention exposed to radiation
Then all X-Ray disadvantages

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13
Q

What is Computed Tomography (CT)/How does it work?

A

X-ray tube and detectors move around patients creating cross sectional images

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14
Q

What PLane are CT Scans read in?

A

Transverse plane

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15
Q

CT uses

A

MANY
Diagnosis
Monitor conditions
Interventional

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16
Q

ADV CT

A

Quick
Can scan most body parts
Good spatial resolution

17
Q

Disadvantage CT

A

Radiation from ionising x-rays
Doesn’t portray (delineate) soft tissues well
affected by movement of patients (artefacts)
Patient holds breath (might be unable)

18
Q

Positron Emission Tomography (PET)

A

Involves release of Gamma rays (Ionising radiation)

19
Q

What does a patient need to be given in Positron Emission Tomography (PET) ?

A

A radiopharmaceutical

20
Q

2 Components of a radiopharmaceutical

A

Pharmaceutical - Takes compound to target tissue

Radionuclide - Decays and releases Gamma radiation. (E.g Flurine 18)

21
Q

CLinical use of PET

A

Oncology -Detection, staging, response to treatment

Neurological - Early diagnosis of Alzheimer’s

Cardiac - Identify poorly perfumed myocardium

Infectio/INflammation - Vasculitits, unknown origin pyrexia

22
Q

PET ADV

A

Good contrast + spatial arrangement
Anatomy and function analysis

23
Q

PET DISADVANTAGE

A

Radiation dose to patient (GAMMA)
Radiation to others
Radioactive waste produced
Expensive
Actual uptake of radiopharmaceutical

24
Q

MRI (magnetic Resonance Imaging) How it works

A

Strong magnetic field aligns H atoms
Strong radio frequency pulse applied which knocks the H atoms
This creates a detectable magnetic field which induces an electrical current in the coils in the MRI machine producing an image

25
Q

Hyper intense meaning for MRI

A

Bright

26
Q

Hypointense meaning MRI

A

Dark

27
Q

Clinical uses of MRI

A

MANY
Neurological Imaging (CNS)
Cardiac
Paediatric/pregnancy (No ionising radiation)

28
Q

MRI ADV

A

NO RADIATION
Good contrast resolution

29
Q

MRI DISADVANTAGE

A

Expensive
Time COnsuming
Features stopping patients having MRI (Contraindications) Claustrophobia, metal items , pacemakers, cochlear implants

30
Q

Ultrasound (How it works)

A

High freq sound waves emitted
Sound waves travel through tissues and reflected back from boundaries with different densities
Echoes detected and converted into electrical signal then image

31
Q

Hyperechoic meaning

A

More reflection of ultrasound waves so white on image

32
Q

Hypoechoic meaning

A

Less reflection of ultrasound waves = Dark image

33
Q

What is Acoustic Shadowing?

A

Sound waves get completely reflected back so structures behind it hard to see

34
Q

Ultrasound clinical uses

A

MANY
Obstetrics - Pregnancy dating, Fetal anomaly, placental location
Solid organs
Breast
MSK - Muscles, tendons, ligaments joints
Interventions

35
Q

Ultrasound ADV

A

No radiation
Cheap
Portable
Dynamic (Can see movement)

36
Q

Ultrasound Disadvantage

A

NO BONE OR GAS PENETRATION
Difficult with obese/frail/unwell patients (can’t move)