Imaging

Question 1

Anatomical imaging

Answer 1

Plain films
Contrast angiography
Ultrasound
CT / MRI

Question 2

Functional imaging

Answer 2

Radionuclide Imaging
MRI functional imaging
Ultrasound

Question 3

Problems with vascular imaging

Answer 3

Soft tissue contrast
Functional significance of lesions
Is treatment effective

Question 4

What are the ideal properties of a man-made contrast agent in radiology?

Answer 4

Has an attenuation the same as the surrounding tissues
Inexpensive
Inert
Equal distribution in and out of selected body compartments
Painless
Easy to use

Question 5

Iodinated Contrast

Answer 5

Differential X Ray attenuation
Inert
Stable in selected body compartments
Painless
Easy to use
Cheap

Question 6

Problems with Iodinated Contrast

Answer 6

Major Reactions
Renal Dysfunction
Disturbance of Thyroid Metabolism
Disturbance of Clotting
Seizures
Pulmonary oedema

Question 7

Parenteral Iodinated Contrast side effects

Answer 7

Metallic Taste
Feeling of warmth
Arterial injections
Micturition (urination)
discomfort
Rarely nausea
Previous contrast allergy
Asthma / atopy
Poor renal function
Remember
Metformin (interaction)

Question 8

Catheter Angiography

Answer 8

Vessel punctured and catheterised
Sterile procedure
Contrast injected using pump injector
Rapid series of images acquired

Question 9

Interventional Radiology can be used for..

Answer 9

Minimal invasive treatment of lots of things
Angiography / Angioplasty
Embolisation
Catheter thrombolysis
Drainage of abscesses
Nephrostomy
Vertebroplasty

Question 10

When to use Angioplasty

Answer 10

Short stenoses or occlusions
Sessile (fixed)/ concentric plaques (all around)
Iliac > sfa > popliteal > crural
“Not as long lasting as surgery but not as dangerous”

Question 11

Carbon Dioxide

as a contrast

Answer 11

A negative contrast agent

Useful in patients with poor renal function or sensitivity to iodinated contrast agents

Question 12

Angioplasty : Problems

Answer 12

Occlusion
Dissection
Embolisation
Rupture
Infection

Question 13

Limitations of CT

Answer 13

Leaks
Won’t identify small volume leaks
Snapshot images, cannot exclude intermittent bleeding

Blockages
Can’t always differentiate between acute and chronic thrombosis

Anatomy
Can be difficult to convey anatomy to non-radiologists

Question 14

Contrast Reactions

Answer 14

Dose-related / chemotoxic
Nausea 
Itching
Flushing
(Seizures, arrhythmias)

Management is usually supportive, if mild

Anaphylaxis / anaphylactoid (IgE / non-IgE mediated)

• Hypotension
• Pulmonary oedema
• Bronchospasm
• Convulsions

Management is as per anaphylaxis
Or antihistamines / salbutamol if less severe

Question 15

Ultrasound

Answer 15

piezoelectric crystal produces waves via electricity

Question 16

B-Mode US

Answer 16

(Brightness / 2D mode)
Scans an anatomical plane,
gives anatomical representation of structures

Used in almost all ultrasound practice

Question 17

M-mode US

Answer 17

Motion mode

Less commonly used – fixed plane over time

Can be used to assess heart valve movement, and heart chamber dimension / function

Question 18

Doppler Imaging

Answer 18

Flow alters frequency of ultrasound waves returning to the probe

Can be used to show direction / velocity of flow

Used clinically primarily for detection of DVT

Question 19

Ultrasound Contrast

Answer 19

Indications
Contrast made from microbubbles
Inert gas, surrounded by a shell

Characterising lesions (dynamic pattern of uptake)
Assessment of organ perfusion, e.g. in liver cirrhosis
Delineating organ edges, e.g. for irregularity of heart valves

Alternative to CT / MRI, if unable to tolerate, or allergic to other forms of contrast

Question 20

Spiral CT

Answer 20

Enables acquisition in single breath hold
Less motion artefact
Better coordination with IV contrast
Much quicker -> higher patient throughput
Enable multiplanar image reconstruction (coronal, axial, sagittal)
Can reduce patient radiation dose (depending on other technical factors)

Question 21

CT (Hounsfield) units

Answer 21

Standardised arbitrary unit, representing the density of structures

Air = -1000
Fat= -60 to -120
water= 0
Soft tissue= 20 to 70
bone= 1000

Question 22

Windowing in CT

Answer 22

Windowing changes the shading of pixels to make easier for human eye to appreciate particular structures
Window level refers to the CT unit assigned as the midpoint of the scale

Window range refers to the range of values around this, which are shaded, before complete black or white