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Medicine > Radiology > Flashcards

Radiology Flashcards

1
Q

Outline how you would interpret a chest XR.

A

DRIPE ABCDE

Details/ Date and time

Rotation
Inspiration
Projection (often PA)
Exposure

Airways (trachea, carina, bronchi, hilar, diaphragm)
Breathing (lungs and pleura)
Circulation (heart size and borders)
Disability (bones)
Everything else

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2
Q

What is the width of the carina supposed to be?

A

<100 degrees

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3
Q

How many ribs should be able to be counted posteriorly?

A

10 posterior ribs bilaterally

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4
Q

Outline how you would review the airways in a CXR.

A

Trace down the trachea, check trachea is straight and narrow
Check the carina bifurcates at <100 degrees

Check for foreign bodies/obstructions

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5
Q

Outline how you would do the ‘B’ section of a CXR.

A

Check both lungs are expanded and symmetrical in all 3 zones

Can you see posterior 10 ribs

Check density

Check lung vessels branch out progressively and uniformly

Check costophrenic angles
Check hemidiaphragms

Check cardiac borders

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6
Q

Outline circulation in a CXR.

A

Check position (1/3 R: 2/3 L)

Check size (CTR <50%)

Check the aortic arch and pulmonary trunk

Check mediastinal width

Look at hilar vessels

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7
Q

Outline how you would assess Disability in a CXR.

A

Check each posterior (horizontal) rib on one side of chest, compare to other side

Check each lateral and anterior rib on both sides

Check clavicles and shoulders

Check vertebral bodies (pedicles x2 and disc spaces)

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8
Q

What else is there to check in ‘everything’ in a CXR?

A

Pneumoperitoneum
Subcutaneous emphysema
Gastric bubble
Hiatus hernia
Surgical clips
Check lung apices
Retrocardiac/retrodiaphragmatic pathology

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9
Q

What is Falciform ligament sign?

A

Aka Silver sign - falciform ligament outlined in a large pneumoperitoneum

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10
Q

What is football sign?

A

Massive pneumoperitoneum where abdominal cavity outlined by gas from perforated viscus

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11
Q

Give 3 potential causes of Football Sign

A

Bowel obstruction with secondary perforation
Volvulus
Hirschsprung disease
Meconium ileus
Intestinal atresia

Iatrogenic (endoscopic perforation)
Trauma

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12
Q

What is Rigler sign?

A

Double-wall sign - sign of pneumoperitoneum on AXR when gas outlining both sides of bowel wall

Seen in a large pneumoperitoneum (>1000mL)

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13
Q

What are the 5 basic densities?

A

Air
Fat
Fluid
Bones
Metal

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14
Q

What two forms of X-ray generation are there?

A

1) Characteristic X Ray generation: electron fired fast into W anode with electron ejected and outer shell electron replacing inner electron with loss of energy emitted as a photon

2) Bremsstrahlung (braking radiation): electron fired near nucleus which slows down and deflected with energy lost, emitted as a bremsstrahlung X-ray photon

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15
Q

How do X rays travel?

A

X-rays travel in straight lines with body parts further away from the detector magnified as these are struck first.

Area closer to the detector is least magnified

Object in patient struck first is magnified most.

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16
Q

How might you use magnification in an X-Ray to your advantage?

A

If someone had a pathology in the right side of the posterior mediastinum, below the level of the diaphragm, can take a left lateral image which magnifies the right ribs, displacing them posteriorly and revealing the previously hidden pathology

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17
Q

The denser the tissue, the more the X-ray beam is…

A

Attenuated

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18
Q

What are the 5 X-ray densities?

A

Air
Fat
Soft tissue
Bone
Metal

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19
Q

What is the average radiation dose per person in the UK?

A

2.6mSv per year (2.2 is background, 0.4 is medical exposure)

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20
Q

What is the dose of radiation involved in a chest X-Ray?

A

0.02mSv

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21
Q

What is the amount of radiation involved in a CT-abdomen?

A

10mSv (=4.5 years of background radiation)

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22
Q

What is the inverse square law?

A

Strength of the X-ray beam is inversely proportional to the square of the distance from the source (X).

Thus, increase distance = reduced intensity

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23
Q

What is the density of a CT image measured in?

A

Density of each pixel measured in Hounsfield Units (HU)

Air is -1000 HU, water is 0 HU and bone is 500 HU

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24
Q

What is ‘windowing’?

A

Windowing is the range of Hounsfield units included in a study thus may allow identification of different pathologies without having to re-image the patient.

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25
Q

How are tissue densities described in US?

A

Based on echogenicity, derived from high-frequency sound waves penetrating tissue and bouncing back internal structures, with echogenicity determined by how much should is reflected.

Bone = hyperechoic (shows as white)

Fluid = hypoechoic (shows as black)

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26
Q

How does MRI work?

A

MRI manipulated energy of a proton (hydrogen nuclei) with positive charge and makes protons align with own magnetic field, releasing energy to be collected and turned into an image

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27
Q

What are the indications for a CT head?

A

Altered mental status
Head trauma (penetrating trauma/GCS <13/ GCS<15 2 hours/ vomiting 2+ times/focal neurological deficit)
CSF leak
Headache (thunderclap/papilloedema/deficit/cancer/known triggers e.g position, sex, activity)
Dangerous mechanism of injury
Amnesia (lasting more than 5 minutes)
Loss of consciousness (lasting more than 5 minutes)

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28
Q

When might you want a contrast-enhanced CT?

A

Suspicion of:
Brain metastases
Meningioma
Brain abscesses
Meningitis
Multiple sclerosis
Lymphoma

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29
Q

What are the indications for an MRI head?

A

Confirmation of intracranial tumour
Chronic headache
Seizure disorder
Focal neurological deficit (MS?)

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30
Q

What are the benefits of an MRI head?

A

No radiation
Multiplayer assessment of brain
Detailed images of the brain
Different sequences allow assessment of different pathology

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31
Q

What are the limitations of MRI head?

A

Longer (20-40 minutes)
Less available
Patients may be claustrophobic

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32
Q

How are MRI images described?

A

Described by signal intensity - hyper intense or hypo intense

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33
Q

What is the difference between T1 and T2 imaging?

A

T1 timing of radiofrequency pulse sequences highlight fat tissue within the body

T2 timing of radiofrequency pulse sequences highlight fat AND water within the body

T1 = 1 tissue type bright = fat

T2 = 2 tissue types bright = fat and water

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34
Q

What are the two types of relaxation occurring following radiofrequency impulses in MRI?

A

Realignment of protons with magnetic field

Dephasing of spinning protons (loss of resonance)

T1 correlates to speed of realignment

T2 correlates to speed of proton spin dephasing

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35
Q

What is midline shift?

A

Finding observed in axial slices when midline of intracranial anatomy has shifted due to pushing/pulling forces either side of the intracranial compartment

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36
Q

What is mass effect?

A

Effect of a tumour on the surrounding brain

A lesion within the skull will compress and/or displace adjacent structures

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37
Q

What may cause mass effect?

A

Tumours
Cerebral abscess
Infarction/oedema
Haemorrhage

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38
Q

What is hydrocephalus?

A

Intracranial ventricular system enlarged due to increased pressure

May be obstructed CSF flow or increased CSF

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39
Q

What radiographic feature is shown in hydrocephalus?

A

Midline shift/mass effect

Dilatation of ventricular system - lateral ventricles dilate first

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40
Q

What is a brain mass lesion?

A

Umbrella term for pathological processes changing the brain when imaged

These may range from an abscess to a brain tumour.

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41
Q

What is cerebral oedema?

A

Additional fluid within the brain parenchyma as a response to injury

Takes two forms:
Vasogenic (white matter, surrounds a mass - abscess/tumour)
Cytotoxic (grey and white matter, ischaemia/infarction)

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42
Q

How would cerebral oedema appear in T2 images?

A

High signal on T2-weighted images (MRI)

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43
Q

What is an intracranial haemorrhage?

A

Bleeding within intracranial cavity including intra-axial and extra-axial haemorrhage

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44
Q

What are the radiographic features of an intracranial haemorrhage?

A

Acute haemorrhage is hyper dense on CT

Chronic blood approaches density of CSF thus density decreases

Sizeable haemorrhage may cause mass effect and midline shift

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45
Q

What is an extra-axial collection?

A

Collection of fluid within the skull, outside the brain

May be CSF, blood or pus and may exist in the extradural, subdural or subarachnoid space.

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46
Q

What is a Hounsfield unit?

A

Dimensionless unit used in CT, deduced from a linear transformation of measured attenuation coefficients

Transformation based on arbitrarily assigned densities of air and pure water

Water = 0HU

Air = -1000HU

at STP

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47
Q

What is STP?

A

Standard temperature (=0 degrees) and pressure (10^5)

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48
Q

What is the spectrum of hounsfield units?

A

air = -1000 HU

water = 0

very dense bone = +2000 HU

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49
Q

What is STIR imaging?

A

Short Tau Inversion Recovery - highly water sensitive and timing of pulse sequence acts to suppress signal from fatty tissues thus only water is bright

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50
Q

What approach would you use to interpret an MRI?

A

Details

Planes (MRI): axial; coronal; sagittal; oblique

Sequences (MRI): T1 and compare to other sequences

Abnormalities: Use DSCAM - distribution; shape; colour (intensity); associated changes; morphology)

Clinical question: relate findings to original question

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51
Q

What are the two types of relaxation of a proton following radiofrequency pulses?

A

Realignment (of protons with magnetic field)

Dephasing (loss of resonance)

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52
Q

Which form of proton relaxation predominantly relates to T1 signal?

A

T1 signal relates to the speed of realignment with the magnetic field

Greater speed of realignment = higher T1 signal

T1 = fat

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53
Q

Which form of proton relaxation is related to T2 signal?

A

T2 signal is related to the speed of proton spin dephasing - the slower the dephasing, the greater the T2 signal

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54
Q

What specialised MRI sequences are there? Name one

A

STIR image (Short Tau Inversion Recovery)

FLAIR (Fluid Attenuation Inversion Recovery)

T2* (gradient echo)

DWI (Diffusion Weighted images)

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55
Q

What is a STIR image?

A

Short Tau Inversion Recovery is where signal is suppressed from fatty tissues in T1 thus water will appear bright

Abnormal low signal in T1 but high in STIR = fluid

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56
Q

What is a FLAIR image?

A

Fluid attenuation inversion recovery

This is where free fluid suppressed and compared with the T2 image thus high signal on T2 suppressed and still high on FLAIR, suggests a lesion e.g. Demyelination

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57
Q

What is T2* (gradient echo) images?

A

Highlights the presence of blood

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58
Q

What is DWI?

A

Diffusion weighted images - increased signal means reduced diffusion (in DWI) which suggests cell death

Possibilities may be infarction, cancer, abscess

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59
Q

What is contrast used for?

A

May enhance a lesion if more vascular; do pre and post-contrast to compare

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60
Q

How may you determine where an extra-axial collection is?

A

Determine location by…

Subarachnoid - extends into sulci and into basal cisterns

Subdural - crescentic (banana)

Extradural - lens-like (egg)

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61
Q

What shape is produced by an extradural haemorrhage?

A

convex shape

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62
Q

What is the best initial investigation for a suspected extradural haemorrhage?

A

CT head non-contrast

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63
Q

Why do extradural haematomas have such a classical shape?

A

Dura tightly adheres to intracranial bony sutures therefore does not travel between and cross suture lines

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64
Q

What is a subdural haemorrhage?

A

Collection of blood between the dura and arachnoid layers of the meninges - usually related to head trauma.

A subdural haemorrhage moves freely in the cranial cavity hence the crescentic shape

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65
Q

What is the shape of a subdural haemorrhage?

A

Crescentic

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66
Q

How may a subdural haemorrhage present?

A

Head injury
Vascular malformations
Confusion

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67
Q

What is the best initial investigation for a suspected extra-axial haemorrhage?

A

Non-contrast CT head

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68
Q

What is the presentation of a SAH?

A

Headache - thunderclap
Neck stiffness
Confusion
Reduced consciousness

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69
Q

What radiographic features might be seen on a CT non-contrast?

A

Hyperdense (bright) on CT
blood in basal cisterns and sulci

CT angiogram should identify and characterise any aneurysm

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70
Q

What is the gold standard test to assess the extent of an aneurysm in a SAH?

A

DSA (digital subtraction angiography)

Allows better visualisation of blood vessels by acquiring a mask image (image of the same area pre-contrast). Same area has images produced at a set rate, with the subsequent image getting the mask image subtracted out. Smaller structures require less contrast to fill the vessel than others thus images appear in the presence of a very pale grey background which produces a high contrast to blood vessels (appearing dark grey)

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71
Q

What is the most important MRI sequence in a stroke?

A

DWI - diffusion restriction is highly sensitive for ischaemia

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72
Q

Should a patient present with Broca’s aphasia, where is the occlusion?

A

MCA, superior division

Superior division supplies the frontal lobe which is most likely affected in Broca’s aphasia.

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73
Q

Which cancers are most likely to metastasise to brain?

A

Lung
Breast
Melanoma
Renal cell
Colorectal

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74
Q

What is the initial test in a suspicion of an intracranial mass?

A

CT head - pre and post-contrast

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75
Q

What is a cerebral abscess?

A

Focal area of infection within brain parenchyma usually containing pus and having a thick capsule

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76
Q

What is the role of imaging in a brain abscess?

A

Diagnostic
Assess mass-effect and other lesions
Surgical/MDT plan

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77
Q

What are the radiographic features of a brain abscess?

A

CT is first line - low density lesion with peripheral enhancement; surrounding low-density white-matter oedema

MRI is more sensitive with pus being bright on T2 image; wall of abscess will increase in signal following contrast; DWI may provide diagnostic clarity

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78
Q

What is the gold-standard investigation for suspected Multiple Sclerosis?

A

MRI

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79
Q

Which MRI sequence best reveals MS?

A

Fluid-sensitive sequence e.g. T2, FLAIR

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80
Q

What is the first line investigation for a suspected skull fracture?

A

CT head

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81
Q

A young adult male, previously well, dove into a shallow pool striking their head on the bottom. They were brought to the emergency department and underwent the non-contrast CT shown…

This shows a vertex extradural haematoma

What does this abnormality represent?

A

Extradural haematoma due to venous bleeding

Damage to superior sagittal sinus and associated with diastasis of sagittal suture with/without concurrent skull fracture

Thus, this extradural haematoma can cross a suture line

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82
Q

What is the vertebral level of the conus medullaris?

A

L1

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83
Q

What is the pathophysiology involved in a spinal cord compression?

A

Mechanical (herniation; fractures)

Malignancy (primary or secondary metastasis)

Infection (discitis; epidural abscesses)

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84
Q

What is the gold-standard investigation in a suspected spinal cord compression?

A

MRI whole spine

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85
Q

What are the two divisions of traumatic brain injury by aetiology?

A

Closed head injury (blunt trauma/blast/NAI)

Penetrating head injury (high-velocity injury/low-velocity injury)

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86
Q

Which group of patients account for the majority of traumatic brain injuries?

A

75% are males, more common in young patients

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87
Q

How may a patient present with a traumatic brain injury?

A

N/V
Confusion

GCS 14-15 = mild

GCS 9-13 = moderate

GCS 3-8 = severe

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88
Q

Outline the Ottawa CT head injury rules.

A

GCS <15 2 hours post-injury
GCS <13
?Skull fracture
2+ episodes vomiting
Age ≥65
Retrograde amnesia ≥30 minutes
Dangerous mechanism

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89
Q

How may you classify a skull fracture?

A

Anatomical (base of skull vs skull vault)

Open vs Closed

Displaced vs non-displaced

Fracture type (linear vs comminuted)

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90
Q

What is the best form of imaging modality for a suspected skull fracture?

A

CT head - sensitive to detection of fractures

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91
Q

How will a skull fracture appear on CT-head?

A

Appear as a discontinuity - may be displaced or non-displaced.

Must be distinguished from suture lines - fractures do not have corticated margins

Furthermore, fractures may be accompanied by fluid collection, surrounding soft tissue swelling

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92
Q

What are the red flags of a headache?

A

Positional change/Early morning
N/V
Photophobia
Neck stiffness
Temporal artery tenderness
Facial neurological deficit
New headache in ≥50 years old

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93
Q

What investigations should be conducted prior to

A

Cranial nerve examination
Fundoscopy
Visual field assessment

Obs
Bloods

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94
Q

What are Dawson’s fingers?

A

White matter changes seen near the ventricles. Usually perpendicular or in a radial distribution.

Phenomenon seen in MS

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95
Q

What criteria is used to diagnose MS?

A

McDonald criteria - dissemination in time and space

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96
Q

Which areas are common areas to check for contusions on CT head?

A

Areas contacting bone at most risk

Anterior horns of temporal lobes almost encased in bone between anterior and middle cranial fossae

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97
Q

What are the predominant symptoms of cauda equina syndrome?

A

Saddle paraesthesia
Bilateral leg weakness
Bladder/bowel/sexual dysfunction

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98
Q

What is the best imaging modality for suspected CES?

A

MRI whole spine

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99
Q

Where should an ETT sit in the trachea?

A

3-5cm

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100
Q

What shape should the AP window be on a CXR?

A

Concave

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101
Q

What is silhouette sign?

A

Two adjacent structures with same density thus loss of normal cardiac silhouette

“loss of silhouette sign”

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102
Q

Loss of normal silhouette at the right paratracheal stripe indicates pathology at?

A

Right upper lobe

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103
Q

Loss of normal silhouette at the left paratracheal stripe indicates pathology at?

A

Left upper lobe

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104
Q

Loss of normal silhouette at the right hemidiaphragm indicates pathology at?

A

right lower lobe

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105
Q

Loss of normal silhouette at the left hemidiaphragm indicates pathology at?

A

Left lower lobe

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106
Q

Loss of normal silhouette at the aortic knuckle indicates pathology at?

A

Left upper lobe

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107
Q

Loss of normal silhouette at the right heart border indicates pathology at?

A

right middle lobe or medial right lower lobe

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108
Q

Loss of normal silhouette at the left hemidiaphragm indicates pathology at?

A

Left lower lobe

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109
Q

Loss of normal silhouette on a lateral CXR at the anterior right hemidiaphragm indicates pathology at?

A

right middle lobe

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110
Q

Loss of normal silhouette on a lateral CXR at the posterior right hemidiaphragm indicates pathology at?

A

right lower lobe

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111
Q

What is an air brocnhogram?

A

Visible bronchioles due to air in bronchioles surrounded by consolidation which results in bronchioles appearing as a translucent tube against hazy opacity

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112
Q

What is deep sulcus sign?

A

Air in pleural space from a pneumothorax collects in locations such as apices if WB or bases

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113
Q

What is continuous diaphragm sign?

A

Chest radiograph sign of free air in the thorax or peritoneum.
May be pneumomediastinum or pneumopericardium if lucency above diaphragm

May be pneumoperitoneum if lucency is below the diaphragm

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114
Q

What is the most common accessory fissure?

A

Azygous fissure is the most common accessory fissure (2% of individuals)

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115
Q

What is the point at which the diaphragm meets the heart on XR?

A

Cardiophrenic angles

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116
Q

What is the difference between the costophrenic angle and costophrenic recess?

A

Costophrenic recess is the area prior to the angle which is the sharp point inferior to the recess

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117
Q

How do you calculate CTR?

A

Cardiac width / Thoracic width

Should be less than 50%

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118
Q

What mediastinal contours should you be aware of on CXR?

A

Aortic knuckle
Left PA
AP window (should be concave)
Paratracheal stripes

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119
Q

How many ribs on an AP CXR suggests hyperinflation?

A

> 7 ribs

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120
Q

What is the Ginkgo leaf sign?

A

Surgical emphysema whereby subcutaneous air outlines fibres of pec major

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121
Q

What is Chilaiditi’s sign?

A

Interposition of the bowel, usually colon, between the inferior surface of the right hemidiaphragm and the superior surface of the liver.

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122
Q

Outline how you would interpret an AXR.

A

ABDO X

Details: Patient; Data; Indication; Other views/imaging modalities

Air (check for air)

Bowel (position; structure; size)

3:6:9 rule

Densities (examine all bones)

Organs (all organs that can be seen)

eXtra objects

123
Q

When may hepatomegaly be inferred on AXR?

A

Extension of right lobe inferior to lobe of right kidney

124
Q

When looking for air in the abdomen in an AXR, what should be checked?

A

Diaphragm

Wall of bowel

Falciform ligament (outlined by gas?)

Liver look less lucent?

125
Q

What is Cupola sign?

A

Radiographic feature seen in Pneumoperitoneum on AXR in a supine patient whereby air accumulates underneath central tendon of diaphragm in midline

Lucency seen over lower thoracic vertebral bodies

126
Q

What is Doge cap sign?

A

Sign of pneumoperitoneum seen on AXR as triangular-shaped gas lucency in the RUQ (Morison’s pouch; Hepato-renal fossa)

Also called Morrison’s pouch sign

127
Q

What is air space opacification?

A

Descriptive term for filling of lung parenchyma with material attenuating XR more than unaffected tissue. Radiological correlate of pulmonary consolidation

128
Q

What are the distributions of air-space opacification?

A

Patchy (non-contiguous)

Lobar (fills a lobe)

Multifocal (multiple points/areas)
- Symmetrical vs asymmetrical
- Perihilar vs Peripheral

129
Q

What is atelectasis?

A

Area of lung collapse

130
Q

What may cause atelectasis?

A

Direct compression (tumour; aneurysm; osteophyte; consolidation)

Passive (lung relaxes from parietal pleura - pleural effusion; pneumothorax)

Dependent (posterior regions where patients not fully expanding lungs whilst lying for long periods)

131
Q

How does atelectasis usually appear?

A

Small volume linear shadows

May also be able to see the cause

132
Q

what is an air bronchogram?

A

Gas-filled bronchi surrounded by alveoli filled with fluid/pus/debris (air-space opacification)

133
Q

What is a pneumothorax?

A

Air in the pleural space

134
Q

What radiographic sign may show pneumothorax?

A

Region of radiolucency on CXR/AXR

Lung margins observed

135
Q

What is the criteria for a large vs small pneumothorax?

A

> 2cm = large

<2cm = small

136
Q

Which artefacts may mimic a pneumothorax?

A

Skin fold artefact (apparent pleural edge is darker cf true pneumothorax which is white)

Clothing
Blankets

Oxygen bags/masks

Pulmonary bullae

Air in other locations (pneumomediastinum; pneumopericardium)

137
Q

What may accumulate in the pleura?

A

Air

Fluid (blood/pus/simple fluid)

138
Q

What are the two types of simple pleural fluid which may accumulate in the pleural space?

A

Pleural effusion may be exudate (high protein) or low protein (transudate)

139
Q

Give 3 causes of a pleural effusion.

A

Lung cancer
Pneumonia
Rheumatoid
TB

140
Q

Give 3 causes of a transudative pleural effusion.

A

CCF
Hypoalbuminaemia
Hypothyroidism
Meig’s syndrome

141
Q

What radiographic features may be seen in a CXR with pleural effusion?

A

Unilateral air-space opacification - usually basal

Blunted costophrenic angles

142
Q

In what CXR view can heart size be assessed accurately?

A

PA

143
Q

What method can be used to assess for an increased cardiothoracic ratio?

A

Measure heart at widest point
Measure thorax at widest point

CTR > 50% = increased cardiothoracic ratio

144
Q

What is pneumomediastinum?

A

Air within the mediastinum

145
Q

What is surgical emphysema?

A

Air/gas located in subcutaneous tissues

146
Q

What radiographic features may be seen on CXR in pneumonia?

A

Air space opacification

Air bronchograms

Complications: cavitation; pleural collections

147
Q

What may cause lobar collapse?

A

Inflammation
Infection
Neoplasm
Iatrogenic
Mechanical

148
Q

What are the radiographic features of a lobar collapse on CXR?

A

Complete collapse of lobe with structures into different places due to volume loss

Mediastinal shift

Increased lung density thus radio-opaque

149
Q

What is pulmonary oedema?

A

Accumulation of fluid in the extravascular compartments of the lung

150
Q

What are the radiographic features of heart failure on CXR?

A

ABCDE

Alveolar opacification
Batwing sign (bilateral perihilar lung shadowing)
Cardiomegaly
Diffuse interstitial thickening/Upper lobe diversion
Effusion (pleural)

151
Q

What are the three main features of a pneumothorax on CXR?

A

Peripheral lucency
Visible lung edge
Absence of lung markings peripheral to lung edge

152
Q

What are the radiographic features of a tension pneumothorax on CXR?

A

Relative lucency of entire hemithorax

Mass effect on ribs, diaphragm and mediastinum - increased rib spacing and depression of the diaphragm to the contralateral side of the chest

153
Q

What are the radiographic features of a pleural effusion on CXR?

A

Opacification with meniscus at the costophrenic angles

Lung collapse (if large)

Mediastinal shift potentially

154
Q

What radiographic signs may be observed on CXR in COPD?

A

Flattened diaphragm due to hyper expansion
Increased lung lucency due to parenchymal loss

Decreased peripheral bronchovascular markings

Bulla

Prominence of hilar vessels (in pulmonary hypertension

155
Q

What types of emphysema may you see when conducting a CT-Chest?

A

Categorised by pattern and extent of emphysema.

Centrilobular (most common) - destruction of parenchyma around terminal bronchiole (which is centre of secondary pulmonary lobule)

Panlobular (A1AT deficiency) -affects all areas of lung lobule

Paraseptal emphysema - emphysema lesions in parenchyma adjacent to pleural surfaces

156
Q

What radiographic signs may be seen in an asthma patient on CXR?

A

Non-specific

May be normal

Possible to see bronchial wall thickening and hyperinflation

CT can show stuff if ABPA, eosinophilic pneumonia or vasculitis

157
Q

What radiographic features may be seen on CXR in a PE?

A

Used to look for alternative causes for symptoms

Westermark sign (sharp pulmonary vessel with distal hypoperfusion)

Hampton hump (shallow wedge-shaped opacity in lung periphery)

158
Q

What radiographic signs are present in a lung cancer on CXR?

A

Enlarged focal lesion

Widened mediastinum

Pleural effusion

Atelectasis

Opacification

159
Q

Which radiographic features are present in mesothelioma on CXR?

A

Opacification in lateral aspect

White out appearance with trachea shifting potentially

Pleural effusion and mediastinal lymphodenopathy may be seen

160
Q

What is the hallmark feature of bronchiectasis on CXR?

A

Tram-track sign (dilated bronchi with thickened walls)

161
Q

What is the hallmark feature of bronchiectasis on CT-Chest?

A

Signet ring sign (enlarged airway with accompanying pulmonary artery)

162
Q

What radiographic features may be present in TB on CXR?

A

Consolidation
Lymphadenopathy
Pleural effusion

Cavitation
Ghon complex (caseating granuloma)

163
Q

What is Nutcracker syndrome?

A

Rare vein compression disorder whereby abdominal aorta and SMA squeeze Left Renal Vein - may cause renal symptoms such as flank pain and haematuria

164
Q

What is SMA syndrome?

A

Duodenum compressed by SMA against abdominal aorta causing blockage and prevention of food into distal SI

165
Q

What is pelvic congestion syndrome?

A

Condition of chronic pain due to enlarged veins in the lower abdomen

This is caused by venous outflow obstruction

Causes may be:
- Tumour
- Fibroids
- Endometriosis

  • Budd-Chiari Syndrome
  • Nutcracker Syndrome
  • May-Turner Syndrome (iliac vein compression syndrome)
166
Q

What is May-Turner Syndrome?

A

Compression of common venous outflow of left lower extremity in the iliofemoral veins (left common iliac vein compression by overlying Right common iliac artery)

Blood stasis occurs which predisposes to blood clots (hypercoagulability)

167
Q

What is a sabre sheath trachea?

A

Diffuse coronal narrowing of intrathoracic portion of trachea with widening of sagittal diameter

Seen in COPD

  • Reduced coronal diameter of intrathoracic trachea
  • Increased sagittal diameter
168
Q

What differences may an AP film produce in a CXR?

A

enhanced cardiac shadow
higher diaphragm
reduced lung volumes

169
Q

How is a 3DCT constructed?

A

CT slices are stacked up as a reformation and provides a 3D image which gives position and orientation of the fracture

170
Q

How does ultrasound work?

A

Probe directs beam of high-frequency sound waves into the body and measures the manner in which sound is reflected back to the transducer from organs and their interfaces

171
Q

What is acoustic impedance in US?

A

Degree of which US is reflected back by different tissues with varying physical density of the tissue and the subsequent velocity of the sound

172
Q

How do you calculate acoustic impedance?

A

Z = pV

Z = acoustic impedance

p = density

V = acoustic velocity

173
Q

What are the benefits of US?

A

Cheap
Quick
Bedside
Internal
Multiple planes

174
Q

What is the unit of measurement to define magnetic flux density?

A

Tesla

1 Tesla = 10,000 Gauss

175
Q

What is relaxation time?

A

Time taken for hydrogen atoms to regain equilibrium state following radiofrequency wave pulsation

176
Q

What are the main differences between T1 and T2 regarding echo time and repetition time?

A

Repetition time is the time taken between RF pulses

Echo time is the time taken between RF pulses exciting hydrogen atoms and the arrival of return signal at the detector

T2 has longer TR and TE cf T1 has shorter TR and TE

177
Q

How does nuclear imaging work?

A

Radionuclide (radioactive isotope) injected into body which is labelled to a substance involved in metabolism of the organ/cancer thus remains their to be imaged.

Radionuclide emits gamma rays which are recorded by a gamma camera for a period of time

178
Q

How does PET scanning work?

A

Positron-producing isotope administered, combined with substance (e.g. glucose) travelling to target organ

Radioactive substance decays, producing positive electrons (positrons) which travel 1-2mm prior to colliding with an electron which results in conversion from mass to energy releasing two gamma rays in opposite directions.

Gamma rays are detected within the ring-shaped PET scanner and a computer produces an image of where radioactive substance has accumulated

179
Q

What may create a false negative in PET scanning?

A

Raised serum glucose
Some cancer types (RCC; BAC; NHL; mucinous GI tumours)

180
Q

What may cause a false positive in a PET scan?

A

Patient discomfort + anxiety
Talking
Injected clot
Injected artefact
Sites of high physiological uptake (renal, spleen, liver, GI, salivary glands)
Uterine/ovarian uptake in a cyclical manner (premenopausal)
Infection
Sarcoidosis (autoimmune conditions)
Flare phenomenon
Osteonecrosis
Malunion fractures
Post-operative
Radiation pneumonitis

181
Q

What is meant by the interspace?

A

Space between posterior segments of adjoining ribs (unless anterior specified)

182
Q

How can you easily identify the first rib on CXR?

A

Find manubriosternal angle and trace back posteriorly

183
Q

How do you check for rotation on a CXR?

A

Look at distance between clavicles and spinous process

184
Q

When increasing the penetration of deep structures by increasing exposure, what method may be used to reduce scattered radiation?

A

Bucky grid

185
Q

How does a bucky grid work to reduce scattered radiation?

A

Alternating beam of strips with varied radiolucent and radio-opaque material.

When X-rays are perpendicular, the rays pass through radiolucent portions fine but when oblique rays strike radio-opaque regions, these are absorbed thus reduced scattered radiation and reduced blackening of the film

186
Q

What is a Bq?

A

Becquerel is the measurement of radioactivity

One disintegration per second

187
Q

Which lung hilum is typically higher and why?

A

Left hilum is higher than the right hilum due to the LPA arching over the left main bronchus

188
Q

In a patient with COPD with a suspected pneumothorax, what investigation should be ordered and why?

A

Must order a CT-Chest in addition to CXR in case ‘pneumothorax’ is an emphysematous bullae - chest drain of a bullae may cause lung collapse

189
Q

How many lobes does the right lung have?

A

3

190
Q

What are the bronchopulmonary segments of the right lung?

A

Superior lobe: 3
Apical, posterior, anterior

Middle lobe: 2
Medial and lateral

Inferior lobe: 5

Superior; lateral basal, medial basal; posterior basal; anterior basal

Mnemonic: A PALM Seed Makes Another Little Palm

191
Q

How many bronchopulmonary segments are present in the left lung?

A

8 bronchopulmonary segments

Superior lobe: 4
Anterior; apical posterior; superior (lingula); inferior (lingula)

Inferior lobe: 4
Superior; Posterior basal; Anteromedial basal; Lateral basal

Mnemonic: ASIA ALPS

192
Q

What are the indications for carotid stenting?

A

Symptomatic with >50% stenosis

193
Q

What might the contraindications of carotid stenting be?

A

Complete occlusion
Major disabling stroke on same side
ICH/SOL
Unstable plaque
Extremely tortuous vessel

194
Q

What are the complications of carotid stent insertion?

A

CVA
Hyperperfusion syndrome

195
Q

How is an intra-aortic balloon pump inserted?

A

Inserted via femoral artery, extend retrogradely to proximal descending thoracic aorta.

Inflate the end of the balloon at diastole and deflate at end of diastole thus provide forward momentum to blood in distal descending aorta but also increased perfusion to vessels arising from aortic arch and ascending aorta

196
Q

What are the two main physiological functions of an intra-aortic balloon pump?

A

Reduces LV afterload through a vacuum effect (pushed blood further along descending aorta)

Increases myocardial perfusion (whilst reducing myocardial oxygen requirements)

197
Q

Where should the intra-aortic balloon pump be located in the arterial system?

A

Proximal descending aorta

Just inferior to the origin of the Left Subclavian artery (level of the AP window)

198
Q

What complications may occur with insertion of an intra-aortic balloon pump?

A

Malpositioning: aortic dissection; too high thus obstructing LSCA; too low thus obstructing splanchnic arteries

Functioning: platelet/RBC destruction; distal embolisation

199
Q

What is endocrine venous sampling?

A

Sampling venous blood from specific endocrine organs used for diagnostic purposes

200
Q

What is inferior petrosal sinus sampling?

A

Evaluate for ACTH-secreting pituitary adenoma

201
Q

What is adrenal venous sampling?

A

Sampling venous blood for identification of primary aldosteronism (Conn syndrome) or Bilateral adrenal hyperplasia

202
Q

Which organs may endocrine venous sampling be used in?

A

Inferior petrosal sinus sampling (ACTH)

Selective venous sampling for primary hyperparathyroidism

Pancreas

Adrenal venous sampling

Ovarian venous sampling

203
Q

Why would you perform a CT-guided thoracic biopsy?

A

Diagnose suspicious lung, pleural or mediastinal lesions

204
Q

What are the indications for a CT-thoracic biopsy?

A

Pulmonary lesion inaccessible to bronchoscopy

Mediastinal/pleural mass

205
Q

What are the contraindications to a CT-guided thoracic biopsy?

A

Poor respiratory function/reserve
Uncooperative patient
Lack of safe access
Uncorrectable bleeding diathesis (disease)

206
Q

How is a CT-biopsy procedure conducted?

A

Complete blood count: platelets >50 000/mm^3

Coagulation profile: INR ≤1.5; normal PT and PTT

207
Q

How is a CT-guided biopsy procedure conducted?

A

Pre-procedure evaluation:
- Complete blood count (platelets >50,000/mm3)
- Coagulation profile (INR, PT, PTT)

  • Review diagnostic CT (check relation to structures - vessels, bleb, bullae, central bronchi, fissures)

Positioning (decubitus preferred - limits respiratory motion, minimises local aeration, comfortable)

Biopsy:
- Radiopaque marker utilised to focus optimal access point, mark this with a pen
- Antiseptic and anaesthetic
- Incision (skin orifice made)
- Biopsy needle introduced
- Activate biopsy gun

Post-procedure care:
- XR (4 hours post-procedure)
- Monitoring
- Document procedure appropriately

208
Q

What are the benefits of a decubitus position for a CT-guided lung biopsy?

A

Reduced respiratory motion
Comfort
Minimises local aeration (reduces pneumothoraces)

209
Q

What are the complications of CT-guided lung biopsy?

A

Pneumothorax (8-64%)

Alveolar haemorrhage (5-16.9%)

Air embolism (0.2%)

210
Q

How does a preoperative pulmonary nodule localisation work?

A

CT-guided procedure where marker applied to small lung lesion to assist in surgical identification and resection

Preprocedural evaluation:
- Platelets
- INR/PT/APTT

  • Positioning
  • Confirm CT
  • Introduce marker (metalic/methylene blue/Tc99m/indocyanine green)
211
Q

What is a thoracentesis?

A

Pleural tap (chest drain) - pleural fluid drained from pleural space for diagnostic ± therapeutic reasons

212
Q

What are the indications for a thoracentesis?

A

Symptomatic pleural effusion

Investigation of cause of pleural effusion

213
Q

How may you determine a pleural effusion is exudative or transudative?

A

Determine protein content of the pleural fluid

> 3g/dL = exudative

<3g/dL = transudative

214
Q

What are some exudative causes of pleural effusion?

A

Lung Ca
Pneumonia
Rheumatoid
TB

215
Q

What are some transudative causes of pleural effusion?

A

CCF
Hypoalbuminaemia
Hypothyroidism
Meig’s syndrome

216
Q

Outline the procedure for a US-guided thoracentesis.

A

Note: May be performed blindly, US-guided or CT-guided

Pre-procedure evaluation:
- History; indication; pathology; prior imaging
- Bloods: Coagulation profile; blood count

Gather equipment:
- US
- Sterile surgical pack
- Long hypodermic needle, syringe and lidocaine
- Scalpel
- 3 way tap
- Dressings

Position:
- Lean forward
- Monitoring
- Access from behind the patient

Insert drain:
- DON
- Subcutaneous and deep infiltrate of local anaesthetic
- Small skin incision with scalpel
- Introduction of thoracentesis needle under US-guidance; travel along superior margin of rib , aspirating whilst advancing until pleural fluid is aspirated
- Connect 3-way tap and drainage bag with airtight dressing
- 50mL fluid required for diagnostic procedure

Post-procedure care:
- Drain until content (either diagnostic or symptoms reduce)
- CXR to confirm absence of pneumothorax
- Safety net with patient

217
Q

What are the potential complications of a thoracentesis?

A

Pain
Cough
Vasovagal reaction
Re-expansion pulmonary oedema
Pneumothorax
Haemothorax
Iatrogenic damage of viscera
Air embolism
Pleural infection/empyema
Trapped lung (non-expanding lung after fluid removal)

218
Q

What is percutaneous transhepatic cholangiography (PTC)?

A

Radiographic visualisation of biliary tree and can be used as the primary step in numerous percutaneous biliary intervention e.g. stent placement

219
Q

What are the indications of PTC?

A

Failed ERCP
Biliary system delineation in presence of intra- and extrahepatic biliary calculi
Identify bile leaks
Percutaneous biliary stent placement
Post-operative stricture dilatation
Stone removal

220
Q

What are the contraindications to PTC?

A

Bleeding diathesis
Gross ascites

221
Q

How is a PTC conducted?

A

Preprocedural evaluation:
- History
- Indication
- Previous imaging
- Coagulation profile
- Blood count

Positioning:
- Supine
- Anaesthetic (LA vs GA)

Procedure:
- US-guidance to guide point of entry of needle
- Long two part 22G needle inserted into peripheral duct, observe bile reflux at needle hub or inject contrast to confirm duct puncture on fluoroscopy
- Inject sufficient dye and identify obstructive pathology
- Images taken in PA, RAO and LAO views

Post-procedural care:
- Routine observations

222
Q

What are the potential complications of a PTC?

A

Bile leakage
Biliary peritonitis
Bleeding
Cholangitis

223
Q

What is a percutaneous transhepatic biliary drainage?

A

PTCG is an IR procedure done on those with biliary obstruction such as cholangiocarcinoma when ERCP is not amenable

Undertaken as part of palliative biliary stent insertion

224
Q

What is a percutaneous cholecystostomy?

A

Insertion of a drainage catheter into the gallbladder lumen via image-guidance

225
Q

When is a percutaneous cholecystostomy indicated?

A

Poor surgical candidate
High risk patients with acute calculous/acalculous cholecystitis
Sepsis of unknown origin in critically ill patients
Access or drainage of biliary tree following failed ERCP/PTC

226
Q

How is a percutaneous cholecystostomy conducted?

A

Preprocedural evaluation:
- History
- Indication
- Previous imaging
- Coagulation profile; Bloods
- Administer prophylactic broad-spectrum ABX 1-4 hours pre-procedure
- Arrange analgesia and sedation according to local protocols

Positioning and set-up:
- Supine position
- Regular monitoring of vital signs
- Clean skin with antiseptic solution and drape

Equipment:
- US machine
- Sterile US probe cover and US gel
- Local anaesthetic
- Relevant needles, guide wires and catheters

Procedure:
- Clean field
- Place sterile drape
- Anaesthetise patient
- Insert catheter using Trocar or Seldinger technique
- Secure catheter to skin
- Attach gravity drainage bag to catheter
- Send bile for Gram stain, culture and count

Post-procedure care:
- Bed rest
- Observations
- Catheter flushed and aspirated
- Cholecystogram performed to help establish satisfactory catheter position
- Catheter removed once tract is mature (3-4 weeks)

227
Q

What is the Seldinger technique used for percutaneous cholecystostomy?

A

Gallbladder punctured with 18/19 gauge needle under US-guidance and 0.035 guide wire used to change needle for a dilator and drain placed within gallbladder

Aspiration of bile/pus from drain confirms satisfactory position

228
Q

What is the Trocar technique used in percutaneous cholecystostomy?

A

Load 8 French locking pigtail catheter over trocar

Advance catheter assembly into Gallbladder lumen under image-guidance

Aspirate bile/pus

Unscrew trocar from catheter and advance catheter over trocar into gallbladder

Remove trocar and lock pigtail

229
Q

What are the complications of a percutaneous cholecystostomy?

A

Catheter displacement
Bile leakage
Biliary peritonitis
Bleeding
Bowel injury
Bradycardia and hypotension from gallbladder manipulation

230
Q

What are the two types of percutaneous liver biopsy?

A

Use of US/CT-guided for accurate

Focal (directed to focal parenchymal lesion)

Non-focal (used in assessment/staging of parenchymal lesion)

231
Q

What are the indications for a image-guided liver biopsy?

A

Cirrhosis
NAFLD (NASH/NAFL)
PBC
Wilson disease
Haemochromatosis

Focal liver lesion assessment

232
Q

What are the contraindications to a liver biopsy?

A

Uncorrectable bleeding diathesis
Ascites
Extrahepatic biliary obstruction

233
Q

How is a percutaneous liver biopsy undertaken?

A

Pre-procedure preparation: history; indication; consent; equipment; prior imaging; blood counts

Position patient:
- Supine
- Oblique
- LLD

Procedure:
- Aseptic technique
- Entrance created with scalpel
- Needle advanced under US guidance
- Documentation of needle position prior to firing
- Identify if sufficient material obtained

Post-procedure:
- Documentation of procedure
- Check if patient is ok
- Inspection of the site
- Observations

234
Q

What are the complications of a liver biopsy?

A

Post-procedural pain
Severe haemorrhage (1%)
Death

235
Q

What are the advantages of US-guided percutaneous drainage?

A

Dynamic study- controls needle insertion
No exposure to ionising radiation
Does not require wide range of stage

236
Q

What are the disadvantages of US-guided percutaneous drainage?

A

Poor visualisation of deeper structures
Bowel gas can obscure visualisation
Large patients may attenuate the sound beam

237
Q

What are the indications for a percutaneous drainage?

A

Diverticular abscess
Crohn’s disease related abscess
Appendicular abscess
Hepatic abscess
Renal abscess
Splenic abscess

238
Q

Outline the technique for the procedure of a US-guided percutaneous drainage?

A

US-guided

May be singe stage (direct entry with catheter) or multiple step

Multiple step requires introducer needle with stiff wire passed then track expanded with dilator and catheter passed over stiff guide wire to penetrate abscess
Locking drain used to secure position and catheter connected to external drainage bag

239
Q

What are the advantages of CT-guided percutaneous drainage?

A

Access areas poorly visualised on US
Vision not obscured by gas
Better vision in large patients
CT table offers more stable positioning
Better in critically-ill patients (intubated patient can be monitored and positioned better)

240
Q

What are the disadvantages of CT-guided percutaneous drainage in a patient?

A

Not truly dynamic like US
Exposes patient to ionising radiation
Wider range of staff required
Harder in uncooperative patient

241
Q

Which vessels are connected in a TIPS?

A

Direct communication formed between hepatic vein and portal vein allowing portal flow to bypass the liver

242
Q

What is the target portosystemic gradient following TIPS formation?

A

<12mmHg

243
Q

What are the indications of a TIPS?

A

Acute variceal bleeding (refractory to medical therapy)
Recurrent variceal bleeding
Ascites (refractory to medical management)
Portal hypertensive gastropathy
Hepatorenal syndrome
Malignant compression of hepatic or portal veins
Budd-Chiari syndrome

244
Q

What are the absolute contraindications to TIPS?

A

Severe chronic liver disease (injured liver may not tolerant nutrient diversion)
Severe encephalopathy (diversion of unfiltered blood will worsen it)
Severe right HF (flow diversion increases pre-load)

245
Q

How is a TIPS procedure conducted?

A

US-guided vascular access to right internal jugular vein
Angigraphic catheter passed into chosen hepatic vein - confirmed with hepatic venography
Curved TIPS puncture needle advanced into hepatic vein
TIPS puncture needle rotated anteriorly and advanced inferiorly through liver parenchyma to location of portal vein branch
Portal venogram performed through TIPS puncture needle to confirm portal vein cannulation
Guidewire advanced through needle and manipulated into splenic or mesenteric vein to ensure portal vein access not lost as liver moves craniocaudally with respiration
Angiographic catheter advanced into portal vein to measure pressure
Track created through liver parenchyma dilated via balloon catheter
Stent deployed over vascular sheath (which is in the portal vein branch)
Portal pressures measured to assess desired reduction into portosystemic gradient
Venography repeated to confirm variceal bleeding ceased with portal pressure reduction

246
Q

Why would the guide wire be advanced all the way into the splenic or mesenteric vein during a TIPS?

A

Liver moves craniocaudally (inferiorly) with respiration therefore portal vein access will not be lost

247
Q

What are the potential complications of a TIPS procedure?

A

Haemorrhage
Hepatic infarction
Gallbladder puncture
Sepsis
Vascular site haematoma
Unintentional arterial access
AKI

Uncontrollable hepatic encephalopathy
Hepatic venous stenosis
Stent occlusion
Stent migration
Stent infection

248
Q

What are the approaches for a liver biopsy?

A

Transjugular

Percutaneous

249
Q

What are the indications for a trans jugular liver biopsy?

A

Massive ascites
Coagulopathy
Hepatic peliosis
Morbid obesity
Failed percutaneous liver biopsy

250
Q

How is the procedure of a trans jugular hepatic biopsy undertaken?

A

US-guided needle into IJV
Wire inserted into SVC and sheath placed over wire
Venous puncture conducted.
Guidewire and catheter used to gain entry into right hepatic vein
Venogram obtained to confirm position in right hepatic vein

Catheter exchanged with sheath over stiff wire
Once sheath is in mid RHV, biopsy needle inserted and 2-3 cores of liver tissue obtained following entering liver parenchyma

251
Q

What are the potential complications of a transjugular liver biopsy?

A

Haemorrhage
Liver capsule rupture
Haemoperitoneum
Pneumothorax
Haemobilia
Fistulisation between hepatic artery and portal vein

252
Q

What is a percutaneous nephrostomy?

A

Kidney drain under image-guidance through the skin

253
Q

What are the indications for a percutaneous nephrostomy?

A

Used when retrograde approaches unsuccessful

Urinary tract obstruction
Urinary diversion
Access for percutaneous procedures e.g. stone treatment; ureteric stenting
Diagnostic testing

254
Q

What are the contraindications to a percutaneous nephrostomy?

A

Uncorrectable bleeding diathesis
Uncooperative patient
Severe respiratory disease
Uncorrected electrolyte abnormality

255
Q

How is a percutaneous nephrostomy procedure undertaken?

A

Aseptic technique
Infiltration of local anaesthetic
Use image-guidance to puncture the calyx at the mid/lower pole
Urine drains freely on removal of stylet from needle
Contrast injected to confirm needle position
Guidewire advanced and pigtail drain placed in renal pelvis over the guide wire

256
Q

What are the potential complications of a percutaneous nephrostomy insertion?

A

Bleeding
Pneumothorax
Bowel injury
Urine leak
Splenic/liver injury
Catheter obstruction
Catheter displacement

257
Q

What are the benefits of ultrasound?

A

Non-ionising
Readily available
Cheap
Straight forward
Few medical staff required
Few contraindications
Real-time imaging
Doppler modality adds physiological data

258
Q

What are the disadvantages to US?

A

Training required
Ultrasound subject to objects of acoustic impedance
US artifacts may degrade image
May be limited by body habitus

259
Q

What is acoustic enhancement in US?

A

Increased echoes deep to structures which transmit sound well

This can be seen in fluid-filled structures e.g. cysts

Fluid only attenuates sound less than surrounding tissue thus time gain compensation overcompensates through the fluid-filled structures causing deeper tissues to be brighter

This shoes as increased echogenicity posterior to the cystic area.

260
Q

What is time gain compensation (TGC)?

A

Compensatory mechanism for attenuation of ultrasound energy with depth.

Allows fine tuning of image which corresponds to a differing depth which reduces the altered time gain which may produce artefacts

261
Q

What is attenuation?

A

Concept that US wave amplitude reduces as it penetrates a tissue
Thus echoes from deep layers have smaller amplitudes, even if same echogenicity

262
Q

What is acoustic shadowing?

A

Imaging artefact with signal reduction posterior to a structure absorbing/reflecting ultrasonic waves

263
Q

What is anisotropy in US?

A

US beam is on a fibrillar structure (e.g. tendon/ligament), organised fibrils may reflect most of the beam away.

Thus the transducer does not receive the returning echo and assumes area will be hypoechoic.

This is dependent upon the angle of beam, perpendicular means maximal return (therefore increase the insonating angle)

264
Q

What impact does the insonating angle have on the level of return in US?

A

Increasing the insonating angle (perpendicular) will yield maximal return of echo and reduce anisotropy

265
Q

What is beam width artefact?

A

Reflective object beyond widened ultrasound beam, after focal zone, creates falsely detected echoes which are displayed as overlapping structure of interest.

E.g. echoes generated by object located in peripheral field are perceived as overlapping object of interest.

266
Q

What is mirror image artefact?

A

Artefact whereby highly reflective surface (e.g. diaphragm) receives primary beam which is reflected once again by another structure (e.g. nodular lesion) then to be reflected again by the diaphragm which is detected by the transducer.

This gives a false assumption that the echo is coming from a deeper structure thus giving a mirror artefact on the other side of the reflective surface

267
Q

How is an ultrasound image generated?

A

Electric current applied to crystal which vibrates and sends off sound wave which is reflected off a structure, then transduced and generates electrical current (Piezoelectric effect)

Thus acts as a speaker and a microphone

268
Q

What are the best Windows in US?

A

Areas where fluid or fluid-dense tissues are in contact with skin:
- Liver
- Heart
- Bladder
- Spleen

269
Q

How do you decide which probe to use on ultrasound?

A

Transducer depends on what you wish to see

Frequency is associated with a transducer

Therefore, high frequency = better resolution but less penetration

low frequency = more penetration but better resolution

270
Q

What radiographic features are seen in a pneumothorax?

A

Visible visceral pleural edge
No lung markings peripheral to this line (radiolucent cf adjacent lung)

Additional features:
- mediastinal shift
- lung collapse
- subcutaneous emphysema

271
Q

What method can be used to estimate percentage volume of pneumothorax from an AP erect radiograph?

A

Collins Method:

% = 4.2 + 4.7 (A+B+C)

272
Q

How does a lateral decubitus radiograph increase chance of observing a pneumothorax?

A

Positioned on ‘well side’, lung will fall away from Cx wall

273
Q

How does an expiratory chest radiograph enable visualisation of a pneumothorax?

A

Lung becomes smaller and denser

Pneumothorax remains same size thus more identifiable

274
Q

What radiographic features may be seen on CXR in PE?

A

Linear/patchy atelectasis
Westermark sign (peripheral oligaemia with proximal dilation of pulmonary arteries)
Air space opacification (pulmonary infarction)
Hampton’s hump (pleura based opacification due to PE and lung infection)
Pleural effusion
Palla sign (enlarged right descending PA)
Elevated diaphragm (due to loss of lung volume)

275
Q

How does a V:Q scan work?

A

IV injection of serum albumin tagged with Technetium-99m which are slightly larger than RBCs and same lumen diameter (>8um) than pulmonary capillaries.

They perfuse the lung and are trapped in capillary branches where they emit gamma radiation - recorded by gamma camera.

Identification of reduced uptake which shows a ‘defect’ highlights area of reduced perfusion.

If this is abnormal, a ventilation scan is performed by inhalation of Xenon-133 however if normal V scan but abnormal Q scan ≈ PE

276
Q

What process can you use to recognise the ages of carpal bone maturity?

A

Start at the capitate, rotate anti-clockwise, omitting the pisiform.

277
Q

What age does the capitate appear on radiograph?

A

2 months

278
Q

What age does the hamate bone develop?

A

4 months

279
Q

What age does the pisiform develop?

A

12 years

280
Q

What age does the triquetrum develop?

A

2 years

281
Q

What age does the lunate develop?

A

4 years

282
Q

What age does the hamate develop?

A

4 months

283
Q

What age does the trapezium develop?

A

6 years

284
Q

What age does the trapezoid develop?

A

6 years

285
Q

What age does the trapezium develop?

A

6 years

286
Q

What age does the lunate develop?

A

4 months

287
Q

What age does the scaphoid develop?

A

6 years old

288
Q

When does the distal radius develop?

A

1 years old

289
Q

What age does the distal ulnar develop?

A

6 years

290
Q

What is the difference between an Os and a Sesamoid bone?

A

An os trigonometry is an accessory bone developing behind another bone connected by a fibrous band

A sesamoid bone is a bone embedded within a tendon/muscle

291
Q

What is the name of the bone embedded within the lateral head of gastrocnemius?

What type of bone is this?

A

Fabella

A sesamoid bone

292
Q

What type of injury is a Segond fracture?

A

Avulsion injury of the lateral tibial plateau and mid-lateral capsule which accompanies ACL rupture

293
Q

Which blood test should be avoided in a pregnant woman query PE? Why?

A

D-dimer should not be ordered.

Order a form of imaging.

D-dimer will be elevated in pregnancy

294
Q

When does the early arterial phase occur?

A

15-20 seconds, contrast still in arteries

295
Q

When does the late arterial phase occur?

A

35-40 seconds

All structures perfused by arteries show optimal enhancement

296
Q

When does the hepatic or late portal phase occur?

A

70-80 seconds

Liver parenchyma enhances through PV

297
Q

When does the nephrogenic phase occur?

A

100 seconds

Renal parenchyma enhances

298
Q

When does the delayed phase occur?

A

6-10 minutes

Washout (equilibrium) phase - washout of contrast in all abdominal structures apart from fibrotic tissue

299
Q

How much contrast is used for someone weighing <75kg in a CT scan?

A

100cc

300
Q

How much contrast is used for someone weighing 75-90kg in a CT scan?

A

120cc

301
Q

How much contrast is used for someone weighing >90kg in a CT scan?

A

150cc

302
Q

What provides optimal enhancement of the liver parenchyma in a CT-Liver (with contrast)?

A

Portal venous phase (70-80 seconds) is ideal for liver parenchyma as 80% blood supply comes from portal vein

Note: A hypervascular tumour is seen best in the late arterial phase as all liver tumours get 100% blood supply from hepatic artery

A hypovascular tumour enhances poorly in the late arterial phase due to being hypovascular and surrounding liver does also enhance poorly in that phase - seen best when surrounding tissue enhances in the hepatic phase.

303
Q

Which CT phase is a pancreatic carcinoma best visualised in?

A

This is a hypovascular tumour therefore best seen in late arterial phase 35-40 seconds p.i. when normal glandular tissue enhances and hypovascular tumour does not

Medicine (18 decks)

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