Radiology Flashcards
(41 cards)
8 Steps to Interpreting a CXR
- Patient ID
- Type of film (AP or PA)
- Adequacy (penetration, rotation, inspiration)
- Lines and tubes (ETT, OG, chest tube, esophageal balloon)
- Soft tissue
- Bones
- Mediastinum (cardiac silhouette, AP window, trachea, aorta)
- Lungs (lung fields, helium, bronchograms, peri bronchial cuffing)
Correct land marking of ETT on CXR
2cm above carina
Key features of epidural bleed on CT
- Clean mass effect with clear borders between epidural and cranium.
- Lenticular shaped
- Demarcation line against cortex
- Usually associated with skull fractures and torn dural vessels such as the middle meningeal artery.
- Infrequently associated with underlying brain damage but rapid ICP increase can result in secondary brain death.
Key features of subdural bleed on CT
- Non clear (rippled) borders against cranium
- New bleeding shows up as white, while old blood is grey
- Crescent shaped
- Often associated with damage to bridging veins, which drain the cerebral cortical surfaces to dural venous sinuses.
- Often associated with underlying brain damage.
Key features of subarachnoid bleed
- Blood found in ventricles, basal sulci, fissures and/or cisterns.
- Can cause obstructive hydrocephalus (seen as increased ICP and enlarged lateral ventricles)
- Star or spider shaped hyperdensity at level of Circle of Willis.
Key features of intraparenchymal hemorrhage on CT
Intraparenchymal bleeding (white) surrounded by penumbra/edema (grey).
Causes of opacity in a CXR
- Pus
- Blood
- Fluid
- Cells (malignancy)
- Peas and carrots
Steps for interpreting a head CT
Hint: Blood Can Be Very Bad
- Blood (epidural, subdural, SAH, intraparenchymal)
- Cisterns (spaces where arachnoid mater and pia mater are separated)
- Brain (symmetry, grey/white differentation, densification)
- Ventricles (intraventricular bleeding, asymmetry, hydrocephalus)
- Bone (mastoid/sinus air/bleeding, basal fracture)
- On head CT, grey matter has more fat in it so it shows up white while white matter shows up as grey.
What does an EFAST stand for?
Extended Focussed Assessment with Sonography for Trauma.
-It’s a FAST exam, but includes views of both lungs.
What are the five views of the EFAST?
Perihepatic (RUQ) Perisplenic (LUQ) Pelvic (Suprapubic) Pericardial (Subxiphoid) 2 X anterior lung
Does the IVC collapse or distend on a PPV patient on inspiration?
Distends.
On a spontaneous breathing patient, the IVC collapses due to the negative pressure “pulling” blood into the RA.
*Remember, the patient must be supine, in sinus rhythm and on ACV and the IVC must be measured at the level of the hepatic vein in order to be useful. Even then, it’s still representative of a pressure and not a volume.
What is “Gain” when referring to ultrasound?
Amplifies signal in order to make it brighter or darker. Does not improve signal quality.
What is “Depth” when referring to ultrasound?
It’s how far you can see into the tissue. The deeper you go, the greater the lag. Try to concentrate depth on the organ you want to see and no deeper.
What is “Frequency” when referring to ultrasound?
Frequency affects image resolution. The higher frequency probe you have, the higher the quality of image. High frequencies can’t penetrate as deep so you will sacrifice depth for better image quality.
How much fluid is required for a positive FAST in the RUQ region?
200mL (Kanji)
600mL (Perera)… “Hi!”
FAST exam for RUQ (hepatorenal) approach and positive findings…
- Hold probe in long axis view with indicator towards patient’s head.
- Anterior axillary line
- Hepatorenal interface (Morison’s Pouch)
- Right hemothorax (left-posterior side of screen)
- Caudal tip of liver (may need to move down an ICS to view)
FAST exam for LUQ (splenorenal) approach and positive findings…
- Long axis view with indicator towards patient’s head.
- Post-axillary line (knuckles to stretcher)
- Anachoic fluid anterior to spleen (top and left of screen)
- Spleenorenal interface
- Anachoic fluid in 6 to 9 o’clock of spleen indicates left hemothorax. Look for diaphragm.
FAST exam for suprapubic approach and positive findings…
- Will be different for female/male anatomy.
- Use both a long axis (indicator to head) and a short axis view (indicator to pt’s right).
- Be sure to be right above the pubic symphysis and angled 30 degrees inferiorly.
- Observe posterior edge of bladder for men, and posterior of uterus (Pouch of Douglas) for women. Blood will collect in the posterior and inferior aspects.
- Men may have fluid in their seminal vesicles (two tubes of anachoic fluid underneath bladder) or ureters that should not be mistaken for free fluid. These will be seen in short axis view but not in long axis.
- Mirror image of bladder may appear as a deeper free fluid. Ignore it.
Anterior lung view on ultrasound. What are you looking for?
- Ants marching/sliding sign = Good!
- Comet tails = Good!
- Lung point sign = Pneumothorax!
- It’s really that easy!
What are the indications for a FAST exam?
- Abdominal/Thoracic trauma
- Trauma in pregnancy
- Undifferentiated hypotension
List vessels from medial to lateral (NAVEL)
NAVEL
- Nerve
- Artery
- Vein
- Empty space
- Lymphatic
Where do you measure optic nerve sheath diameter?
3mm below posterior eyeball, from inside to inside.
An optic nerve sheath should be less than what?
5mm
It increases with elevated ICP due to transition of pressure within cranial vault compressing and redistributing CSF.
How to get an accurate view of IVC using ultrasound?
- Indicator light to patient’s chin while in subxiphoid view, shift towards liver and use liver as a median to look for blood vessels.
- Observe the IVC enter the RA and look for hepatic vein draining into IVC. This differentiates IVC from aorta. IVC is also on patient’s right.
- IVC should not have more than 50% variability with passive breathing at level of hepatic vein.
