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MD4003 OSCEs > Imaging: MRI, CT, X-ray > Flashcards

Imaging: MRI, CT, X-ray Flashcards

1
Q

Difference between T1 and T2 weighted MRI?

A

In T2, H2O is bright

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2
Q 
Technical consideration of CT:
View?
Age?
Angle on imagine plane?
Colour range?
A

View: Caudal (so image is looking from the feet)
Age: As age increases there is loss of brain matter so more dark areas seen around edges and ventricles appear more visible
Angle: Diagonal image plane
Colour: Interpretting greyness. Bone= white, air = black.

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3
Q

How to interpret a CT and MRI?

A

[A]

  • Adequacy
  • Alignment
  • Artifact

[B]

  • Bones
  • Blood
  • Brain

[C]
- Cisterns and ventricles

[S]

  • Subcutaneous and soft tissue
  • Surfaces
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4
Q

What is the difference between SDH and EDH?

A

EDH

  • Extradural haemorrhage
  • More common in younger
  • Lemon shaped due to tight bonding between layers of meninges

SDH:

  • Subdural haematoma
  • More common in older
  • More of a diffuse ring around entire brain
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5
Q

Use of contract agents in CT?

A

Rim and edges light up e.g. useful for meningioma

Enhances areas of low density

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6
Q

What is more likely to cause a stroke, leakage or blockage?

A

Blockage of a blood vessel

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7
Q

Order the following in terms of colour appearance in a CT:

Bone, air, blood clot, water, fat, grey mater, CSF, white mater

A 
[White]
Bone
Blood clot
Grey M
White M
CSF
Water
Fat
Air
[black]
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8
Q 
Technical considerations of MR scanning:
View?
Age?
Plane?
Weighting?
Generated by?
A

View: Caudal
Age effect: Atrophy better shown on MR than CT. Need to establish if level of atrophy is due to age and not hydrocephalus
Plane? Any. Can be used to show pacemaker, cochlear implant, metal around eye/head
Weighting? T1 weighed means the spinal fluid is WHITE. T2 weighted means the spinal fluid is white
Generated by emission

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9
Q

Difference in T1 and T2 weighting in MRI?

A

T1 weighed means the spinal fluid is BLACK. T2 weighted means the H2O is WHITE (WW2: Water, white 2 )

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10
Q

What are the different MRI variants?

A 
Diffusion weighted
ADC (Apparents diffusion coefficient)
FLAIR (Fluid attenuated inversion recovery)
GRE (Gradient echo imaging)
EPI (echo planar imaging, reduces motion artifact)
Perfusion
Angiography
Functional (spectrography)
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11
Q

Best way to scan for spinal lesion?

A

MRI scanning

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12
Q

What is SPECT?

A

Single photo emission tomogrpahy

Used radiosotope and gamma rays

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13
Q

What is PET?

A

Positron emission tomography

Requires cyclotron

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14
Q

MRI variants?

A

Diffusion weighted (DWI)
ADC (apparent diffusion co-efficient, uses DWI)
FLAIR (fluid attenuated inversion recovery)
Angiography
Perfusion

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15
Q

Systematic approach to interprettig abdominal CT?

A

“BBC Approach”
Bowel and other organs
Bones
Calcification and artefact

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16
Q

If bowel perforation is being considered, you don’t usually require an abdominal film, instead you need an..

A

Erect chest x-ray, as this allows free gas under the diaphragm to be identified (the patient needs to have sat upright for at least 15-20 minutes prior to the x-ray to allow time for air to rise).

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17
Q

In abdominal x-ray, what is looked at when assessing the bowels?

A

Small and large bowel

  • SI has full width mucosual folds called Kerckring folds or plicae circulares
  • LI has haustra, pouches which protrude into lumen, with plicae semilunaris inbetween

Normal diameters
SI = 3cm
LI= 6cm
Caecum = 9cm

Signs of obstruction in both LI and SI

Features of bowel inflammation

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18
Q

Causes of SI obstruction?

A

Adhesions due to previous abdominal surgery
Abdominal hernias
Intrinsic/extrinsic compression by neoplastic masses

Sign: Dilated loops of the small bowel = coiler spring appearance

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19
Q

Causes of LI obstruction?

A

Colorectal carcinoma *
Diverticular strictures *
Hernias
Volvulus (twisting of the bowel on its mesentry, commonly at the sigmoid and caecum)

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20
Q

Features of inflammatory bowel disease on AXR?

A

Thumb-printing – mucosal thickening of the haustra due to inflammation and oedema causing them to appear like thumb prints projecting into the lumen

Lead-pipe (featureless) colon – loss of normal haustral markings secondary to chronic colitis

Toxic megacolon – colonic dilatation without obstruction associated with colitis

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21
Q

Which bones are commonly visible of AXR?

A 
Ribs
Lumbar vertebrae
Sacrum
Coccyx
Pelvis
Proximal femurs
22
Q

Name examples of calcification that could be identified on AXR?

A

Calcified gallstones in the RUQ
Renal stones/staghorn calculi
Pancreatic calcification

23
Q

When assessing the image quality of a CXR, how is this performed?

A

[RIPE]
Rotation
Inspiration: 5-6 ant ribs, lung apices, both costophrenic angles and lateral rib edges should be visible
Projection
Exposure: Left hemidiaphragm visible along to the edge of the vertebral body and vertebrae visible behind heart

24
Q

What is the approach to interpreting a CXR?

A 
ABCDE
Airway
Breating
Cardiac
Diaphrams
External features
25
When assessing the airway in a CXR, what is assessed?
Trachea -Is it central? Deviation due to pushing (e.g. large pleural effusion or tension pneumothorax) or pulling (e.g. consolidation with lobar collapse) -Are there paratracheal masses or lymphadenopathy Carina and Bronchi -Right main bronchus (RMB) is wider, shorter and more vertical. Common sight for foreign inhaled objects to lodge Hilar structures - (Hilar consist of main pulmonary vasculature and the major bronchi) - Left slightly higher - Usually same size
26
When assessing the breathing in a CXR, what is assessed?
Lung - Compare symmetry of the zones, looking for lung markings Absence of lung markings in pneumothorax Increased airspace shadowing in consolidation and malignancy Pleura - Inspect lung borders - Check for fluid (hydrothorax) or blood (haemothorax) accumulation in pleural space. Sign = opacity
27
Signs of tension pneumothorax?
SoB Tracheal deviation Absence of lung markings
28
What is mesothelioma?
Mesothelioma is a cancer that most commonly starts in the layers of tissue that cover each lung (the pleura). More rarely it starts in the layer of tissue in the abdomen that surrounds the digestive system organs (the peritoneum).
29
When assessing the cardiac in a CXR, what is assessed?
Assess heart size -Should be no more than 50% of the thoracic width If greater = cardiomegaly (due to cardiomyopathy, pulmonary hypertension and pericardial effusion) Assess heart borders - RA at the right border - LV at the left border
30
When assessing the diaphragm in a CXR, what is assessed?
RHS hemi-diaphragm is higher Stomach underlies the left, characteristics gastric bubble Costrophrenic angles: Formed from the dome of each hemi-diaphragm and the lateral chest wall. Loss of acute angle ("costrophrenic blunting") suggests fluid or consolidations
31
When assessing everything else in a CXR, what is assessed?
Mediastinal contours Bones Soft tissues Tubes/valves/pacemakers
32
What are the two mediastinal contours checked in a CXR?
Aortic knuckle: - Left lateral edge of the aorta as it arches back over the left main bronchus. - Loss of definition of the aortic knuckles contours can be caused by an aneurysm. Aorto-pulmonary window: - The aorto-pulmonary window is a space located between the arch of the aorta and the pulmonary arteries. - This space can be lost as a result of mediastinal lymphadenopathy (e.g. malignancy).
33
What are the review areas of a CXR?
``` Lung apices Retrocardiac Behind the diaphragm Peripheral lungs Hilar ```
34
Which artery is commonly involved in EDH?
Middle meningeal artery
35
Main risk in EDH?
Compression of brain --> herniation of the brainstem
36
``` Location of: EDH? SDH? SAH? Intracerebral haemorrhage? ```
EDH: Between dura mater and skull. Common in trauma SDH: Between dura and arachnoid mater. Common in falls in the elderly SAH: Between arachnoid and pia mater. Commonly in aneurysms Intracerebral haemorrhage: In the parenchyma of the cerebrum
37
What are the 4 key cisterns seen in a head CT? | What are you looking for?
Interpeduncular cistern Pontine cistern Cisterna Magna Superior/quadrigeminal cister Checked for effacement, blood and asymmetry
38
In head CT, sign of increased intracranial pressure?
Sulcal effacement
39
When assessing the ventricles in a CT scan on the head, was is observed?
Intraventricular haemorrhage and the choroid plexus -Appears as hyperdensity in ventricular system Hydrocephalus - Can be communicating and non-communicating - Look first at temporal horns Ventricular effacement -Intracranial volume is fixed, made up of: brain, CSF and blood
40
Hyperdense = | Hypodense =
o Hyperdense = bright (e.g. acute haemorrhage, calcification) o Hypodense = dark (e.g. oedema, infarction)
41
Bat's wing in a CXR is a sign of...
``` Pulmonary oedema (due to HF, fluid overload, aspiration) Pneumonia (due to TB, viral pneumonias ```
42
Kerley B lines in CXR are a sign of...
Interstitial oedema
43
Pneumonia shows up as ___ in CXR?
Consolidation
44
What is a tension pneumothorax? Why is it so dangerous? Risks on CXR?
Tension pneumothorax is the progressive build-up of air within the pleural space, usually due to a lung laceration which allows air to escape into the pleural space but not to return. Positive pressure ventilation may exacerbate this 'one-way-valve' effect. Signs of LHS tension pneumothorax: - Expansion of left hemithorax - Increased space between left ribs - Shift of the mediastinal structures to the right - Severe collapse of the left lung
45
What is emphysema? | Sign in CXR?
enlarged air spaces secondary to destruction of the alveolar walls CXR sign: Overexpanded lungs, flat diaphragms over 6th rib anteriorly
46
Panlobular emphysema is sign of...
alpha-1 antitrypsin deficiency (AATD) AAT controls the enzymes which fight lung damage and infections, thus reducing the damage to surrounding healthy lung tissue. When AATD, risk of development of COPD and emphysema
47
Causative agents of pneumonia?
Streptococcus pneumoniae Haemophilus influenzae Mycoplasma pneumoniae --> Consolidation
48
Sign of primary TB on CXR?
Healed pulmonary lesions of primary TB --> Small calcified peripheral pulmonary nodule with calcified hilar lymph node
49
What is TB?
Tuberculosis (TB) is an infectious disease usually caused by the bacterium Mycobacterium tuberculosis (MTB). Tuberculosis generally affects the lungs, but can also affect other parts of the body. Most infections do not have symptoms. Spread through some air droplets
50
Causes of bright red vomit?
Peptic ulcer Oesophagus varices Mallory-weiss syndrome (tear in mucous membrane of the oesophagus)

MD4003 OSCEs (19 decks)

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