Modalities Of Diagnostic Techniques And Regional Anatomy

Question 1

Diagnostic modalities

Answer 1

Basic medical investigations: blood, urine, stool etc
Histopathology
Liver function tests, kidney function tests, pulmonary function tests
Electrocardiograph ECG, electroencephalograph EEG (brain)
Endoscopies
Imaging- X-rays, ultrasonography (USG), echocardiography, CT scan, MRI scan, PET scan

Question 2

Ionising radiation

Answer 2

From outside: X-rays (radiography), fluoroscopy(uses X-rays, real time, dynamic image), CT
From inside: nuclear imaging, PET (positron emission tomography)

Question 3

Non-ionising radiation

Answer 3

USG- uses sound waves
MRI-magnetic resonance imaging (uses magnetic fields)

Question 4

Contrast radiography

Answer 4

Method of studying organs using X-rays and the administration of a special dye- contrast medium
Barium swallow- highlight upper digestive system

Question 5

Ultrasound

Answer 5

For soft tissues and glandular tissue
Non-invasive, no radiations, relatively low cost
Enlarged lymph nodes
Thyroid disorders
Salivary gland tumours and calculi
Doppler ultrasound: monitors blood flow
Pregnancy follow up
Can evaluate pelvic viscera for pathologies

Question 6

CT scan

Answer 6

For imaging of soft tissues as well as bones
Bone window good for diagnosing fractures

Question 7

MRI

Answer 7

Better soft tissue discrimination
Exquisite anatomical details
Very good for nervous system
When protons in the magnetic field align, fire electromagnetic pulse so protons move , depending on density they slowly realign, very dense they take a long time to realign

Question 8

Thorax scanning

Answer 8

High resolution CT: for lung details
CT pulmonary angiography: look for presence of pulmonary embolism
PET/CT: powerful nuclear medicine molecular imaging technique for staging primary lung cancer
Mammography: breast cancer screening

Question 9

Cardiac diagnostic techniques

Answer 9

CT coronary angiography: visualisation of coronary arteries by injecting dye
Cardiac MRI
Echocardiography: type of a ultrasound
Doppler echocardiography
Interventional cardiac procedures like stenting

Question 10

Abdominal ultrasound

Answer 10

To diagnose pain or enlargement and evaluate the viscera

Question 11

Fluoroscopy

Answer 11

Continuous X-ray beam produces a moving image to monitor examinations such as barium meals, barium enemas etc

Question 12

Endoscopy

Answer 12

Scopy is visualisation, endo is internal/mucosa
Fibre optic endoscopes are passed through orifices like nostrils, mouth, anus etc
Can visualise the pathology
Can take a tissue sample for further investigation: biopsy
Can treat: resection (cutting out tissue, part of organ), cauterisation (burn skin or flesh to stop bleeding or infection) etc
Oesophagoscopy, gastroscopy, bronchoscopy, colonoscopy

Question 13

Musculoskeletal imaging

Answer 13

All modalities can be used
Digital X-ray is fastest and cheapest

Question 14

Plain X-rays

Answer 14

2D of 3D organ
Posterior to anterior PA X-ray
X-rays are a beam of photons
Body tissues attenuate X-rays to varying degrees depending on density of tissues
Image captured on screen or film
Abdominal X-rays AXR:
Pros: quick, low radiation dose, no prep needed
Cons: limited interpretation

Question 15

CT scans abdomen

Answer 15

3D X-rays
X-ray tube and detector plate are on a rotator this allows lots of 360 X-ray to be produced from all over body
Images are processed and reconstructed by computers
More detail
Gold standard of acute abdominal imaging
Quick readily available
Radiation dose is higher can be hindered by artifact

Question 16

Ultrasound physics

Answer 16

Uses high frequency sound waves to obtain images from inside the body
Unlike CT and plain radiography no ionising radiation
Frequency higher than the human auditory limit of 20KHz
Voltage applied to crystal array, when they get electrified they cause vibrations
US transducer converts electric signals into mechanical vibrations and vibrations back into electrical signals which forms he picture depending on density of tissues
If material is solid, particles are denser and so ultrasounds are reflected back so show up as white
If material is fluid it transmits sound waves so fluid comes across black
Air is even stronger reflector so cant see anything behind it (ultrasound gel)

Question 17

Different types array in ultrasound

Answer 17

Linear array- produces a rectangular field of view
Curvilinear array- produces a wide sector field of view
Phased array- small footprint, produces a sector field of view

Question 18

FAST scan

Answer 18

Focussed
Assessment
Sonography
Trauma
A&E use this, abdominal trauma quickly need a scan, dont want to move patient. Portable ultrasound-look for free fluid in abdomen. Scan in lower& upper quadrants 4 scans

Question 19

Things to assess on a chest x ray CXR

Answer 19

Heart size- cardiomegaly
Mediastinal mass
Pulmonary plethora- increased pulmonary perfusion
Aortic enlargement

Question 20

Pneumothorax

Answer 20

Air in pleural cavity
More radiolucent, black