intro Flashcards
black on plain x-ray
less dense and thin
radiolucent
white plain x-ray
dense and thick
radio-opaque
two words to describe CT
low and high attenuation
nuclear lingo
low and high uptake
MRI terminology
high and low signal
24-hour x-ray interpretation and availability for questions; radiologist reading your x-rays in
real-time but in a different time zone
allows radiologist in other locations to read your films
teleradiology
nechoic, hyperechoic, hypoechoic, acoustic shadow
are all terms that refer to what type of imagine
Ultrasound (ULA)
view box direction
old–>new–> newest
so the new ones would be viewed on your right
don’t forget pts left if your right
most common imaging you are going to order
plain film
dense materials are
radio-opaque
plain film is good for
bone
lung and pleura pathology
foreign bodies
and air filled structures (lung and bowel)
when would you NOT want to use a plain film
detail, precise location
solid organs
brain
vasculature detail
five densities of x-rays
air, fat, soft tissue, calcium, metal)
plain x-ray CXR indications
upper GI complaints (diaphragm)
trauma
procedures/lines (radio-opaque so you can make sure they are in the right place)
admissions: almost everyone admitted to the ED get a chest x-ray
chest pain
respiratory symptoms
fever
chest pain
face/spine x-ray indications
face fractures and trauma
soft tissues
abdomen indications for plain film
obstructions
foreign bodies
extremities indications for xray
fracture/trauma foreign bodies gas, fluid in soft tissue metabolic Dx bony tumors
x-ray readings 5 things in order
Verify Name, Date ● Verify Study ● Verify Body Part ● Are the images adequate? ● If there is a question of an abnormality, (compare to previous study or other side and use old films)
what color would fat be in plain films
dark-grey (4)
what color would gas be in plain films
black (5)
what color would soft tissue/fluid be in plain films
light-grey (3)
cone calcification would be what color in plain films
nearly white (2)
what color would metal be in plain films
white (1)
Air-fluid levels are only seen if
Air-fluid levels are only seen if X-ray beam is horizontal (parallel to the floor)
orthogonal view
90 degrees view
different views
AP (anteroposterior) or PA (posteroanterior)
■ Lateral
■ Oblique
■ Supine, upright, lateral decubitus
when is magnification is the most important
CXR
why would you use a lordotic film?
Lordotic films will displace clavicles & distort image; useful in assessing upper lobes for TB
how would you know if you’re looking at a lordotic film
clavicles are high riding
each CT study has multiple images _________, “slices”: scroll through on PACS
each study has multiple images (25->100), “slices”: scroll through on PACS
CT & MRI images described using plane of orientation
CT & MRI images described using plane of orientation (coronal, sagittal, or axial/transverse)
why use a contrast like barium in a CT
Contrast (barium) adds density (it’s white ), defines structures
why would you use a CT w/ contrast
adds density and certain things take up contrast
Vasculature (IV)
Tumors (IV)
Abdominal pathology (IV)
Bowel (if swallowed PO)
high attenuation in a CT scan refers to what type of material
dense
appears white
low attenuation on a CT refers to what type
dark
less dense material
what are the Honsfield units of a hyper or hypo attenuation area
Refers to densities
and will tell you what densities are most consistent with what type of material
mantra of Lauri involving CT and contrast
CT contrast Creatinine no metformin for a day no metformin for two dasy
metformin rules with contrast
No Metformin 24hrs before/48hrs after contrast
what are the advantages of a CT
Readily available
Great for bone detail Great for brain & abdomen
Can detect metallic FB 3D available (vs. 2D conventional x-ray)
Can reformat images for clarity, precision
disadvantages of a CT
Radiation dose
Ischemic CVA – misses subtle, new ones
Vertebrobasilar system (cerebellum) – not great here
Renal function for contrast
Replacing traditional medicine (Hx and physical)
Applies a powerful magnetic field to atoms which realign and release energy; radio wave mapped as image
MRI
how do we talk about mRI
high or low signal
T1: water black
or T2: fat black
weighted
Advantages of MRI
Non-ionizing radiation No known side effects Excellent for soft tissue Shows vasculature w/o contrast
Definitive study for brain and spine
Titanium, stainless steel OK
Contrast = gadolinium = no renal damage unless GFR <30ml/min
Safe in pregnancy
disadvantages of MRI
Cost
Not readily available as CT
Claustrophobia (10% failure)
Imaging time, motion artifact
Contraindications for MRI
Contraindications:
- Unstable patients
- Ferrous metal
- Pacemaker
why would you use a MRI
Ligament/tendon injuries (soft tissue)
Spine/spinal cord injury or lesion (tumor, abscess) Brainstem/cerebellar pathology Intracranial masses/tumors – detail, staging CVA(non-contrastCT1s t thenMRI) Multiple sclerosis, Encephalitis Ortho: occult fractures (esp hip, scaphoid), avascular necrosis, tumors, osteomyelitis, stress fractures
Biliary tract - MRCP – gallstone pancreatitis, cholangitis Pregnant pt
what does weighting refer to
how the image is presented w/ respect to pulse sequence paramters that affect proton relaxation time
T1 water s
black (low signal)
ventricles/CSF
T2 CSF would be
white
advantages of ULS
Cheap, safe, portable, instant No radiation Real time guidance for procedures Color doppler use for vasculature Serial exams at bedside Peds – can avoid radiation
ULS terminology
Hyperechoic or Echogenic (bright/white) Hypoechoic or A nechoic (dark/black) Acoustic shadow (band of reduced echoes behind an echo-dense object)
disadvantages of ULS
Operator-dependent
indications of ULS
Trauma (FAST exam) Cardiac (Echo)/Lung Obstetrics & Gynecology Aorta
Biliary System, Kidneys, Bladder, Appendix
IV’s/Central Lines
DVT
Abscess, Foreign Bodies Soft Tissue, Eye
Nerve Blocks
Lumbar Puncture
indications for nuclear studies
PET scan – cancer dx/staging
Bone scan – cancer dx/staging Thyroid scintigraphy – dx and tx of thyroid goiter, nodules, hyperthyroidism, cancer
V/Q scan – PE
HIDA scan – choledocholithiasis
Myocardial perfusion scan – cardiac perfusion studies
x-rays are attenuated more or less by bone compared to tissue
more
more attenuated = more radio opaque
dose dependent biological effects become measurable above ________ and a whole body dose of greater than _____ is universally lethal
dose dependent biological effects become measurable above 50mSv (millisieverts) and a whole body dose of greater than 10Sv (sieverts) is universally lethal
This means that a chest X-ray amounts ________ background radiation and a CT abdomen is equivalent to_____
This means that a chest X-ray amounts to 3 days of background radiation and a CT abdomen is equivalent to 4.5 years!
- Measures should be in place to reduce dose to patients and staff is known as
optimization
Measures to ensure wider regulations are enforced, for example that X-ray machines are correctly installed and used, and that referrals are justified are known as
local rules
Potential benefit of radiation exposure should outweigh risk. is known as
justification
‘inverse square law
the dose to a given area is quadrupled be halving the distance from the radiation source.
how to present during a osce
- Demonstrate a systematic approach
- Describe and summarise the salient abnormalities
- Link the abnormalities to the clinical scenario
- Suggest appropriate management or further investigations
opening line for a osce plain film reading
This is a plain CHEST/ABDOMINAL radiograph of PATIENT’S NAME taken on DATE at TIME, it is a PA/AP/SUPINE/MOBILE image, and I note the side marker is correct…’
‘The image is of adequate quality…’ -
Although you are unlikely to be given a chest X-ray with poor inspiration how would you evaluate if a CXR was appropriate
you should always quickly note if the lungs are hyperexpanded. The quickest way to do this is to see if the hemidiaphragms are flattened, and if you are not sure, then count ribs.
what should you do after noting the obvious abnormality
after noting the obvious abnormality by saying “the first abnormality to comment on..”
then say I am now examining the image systematically
what is the proper evaluation of a CXR systematically
The trachea is central…
‘The hilar structures are normal…
The upper, middle and lower zones of the lungs are symmetrical and clear…
The costophrenic angles and hemidiaphragms are well-defined…
The heart size and contours are normal…
I can see no abnormality of the bones or soft tissues…’
how to describe Equivocal findings in a OSCE
‘I am not sure if the… (anatomical structure)… is abnormal. It appears… (describe the structure)…’
how to finish a plain film evaluation on an OSCE
‘In summary, this X-ray demonstrates evidence of…
‘These findings are consistent with the clinical suspicion of…’.
‘In this situation I would manage the patient by…’
indications of fluroscopy
cardiac angiography GI swallowing studies Cystourethrogram Biopsies
Special lumbar punctures Complex vasculature access Removal of foreign bodies
cardiac angiography GI
what type of imaging would you want
fluroscopy
