Tag Archives: radiology

picture of the day: orbital compartment syndrome

18 Dec

via this EM Ireland talk on eye injuries:

hopefully, you’ll be able to see some signs clinically (e.g. proptosis, pain with EOM) if you’re worried about retro-orbital hematoma causing orbital compartment syndrome, but if you’re on the fence, you might see this on CT:



signs of orbital compartment syndrome on CT:

  • loss of contour of globe
  • tenting of the globe
  • proptosis


References: EM Ireland post


strength in numbers: subarachnoid hemorrhage

30 Jul

via a recent EP monthly article on acute SAH vs. traumatic tap:


sensitivity of CT for diagnosing aSAH: 93% (95% CI 89-96%)

sensitivity of CT  within 6 hrs of headache onset: 100% (95% CI 97-100%)

sensitivity of CT beyond 6 hrs: 86% (95% CI 78-91%)


traumatic taps in up to 30% of LPs


one study (caveats: required dx of aneurysmal aSAH on CTA, and 8/15 SAH dx by LP were missed on initial CT read):

  • cutoff of <2000 x 10^6/L  CSF RBCs: 93% sensitivity (CI 66-99.7%)
  • cutoff of <2000… RBCs + no xanthochromia: 100% sensitivity (CI 74.7-100%)
  • only 15 cases of aSAH diagnosed by LP at 12 academic centers in 10 years
  • interesting, but not practice changing just yet


Food for thought.


References: epmonthly article, picture

visual aid: mastoiditis

10 Jun

Not usually the focus of most of our head CT’s, but worth remembering what to look for, particularly for those with ear symptoms, and certainly if they have mastoid tenderness



rare complication of otitis media

more common in kids than adults

mastoid lies superior to the middle ear cavity

can have redness, swelling, tenderness over the mastoid process

pus entering mastoid cells under pressure -> dissolution of surrounding bone (not awesome)

infection can spread to nearby structures (e.g. neck, CNS)

treatment: IV abx



(opacification of mastoid air cells–tip: use bone windows)




File it away in the mental Rolodex.


References: uptodate.com; mastoid process; picture 1; picture 2

visual aid: dense MCA sign

6 Mar

was reminded of the useful dense MCA sign by this article in December’s JEM (good pictures, though the article was written by radiologists with variably subtle CT findings):



increased attenuation of [a segment of] the middle cerebral artery 

can give an MCA dot sign when the vessel is seen end-on.

usually seen in 90 min of the event

for more visual aids, check out radiopaedia.org, which has a video link + several cases you can scroll through like a real CT scan.

quick imaging overview with pictures over here as well.


References: JEM article; radiopaedia.org + picture; radiology assistant + picture


quick ortho: MUGR

27 Jan

quick refresher for the upcoming in-service and/or boards:


MUGR (Monteggia=Ulna fx; Galeazzi=Radial fx)


Monteggia Fracture

  • Ulnar fracture, radial head dislocation
  • Mechanism: direct blow to forearm


Galeazzi Fracture

  • Radial fracture, ulnar dislocation
  • Mechanism: FOOSH with flexed elbow


MUGR (Monteggia=Ulna fx; Galeazzi=Radial fx)

  • Proximal to distal (Monteggia=>problem near elbow; Galeazzi=>problem near wrist)


References: Wheeless Monteggia & Galeazzi; monteggia pic; galeazzi pic

CT scans & radiation exposure: crib sheet

6 Oct

via a 2007  article from Radiologic Technology (found on the imagegently.org site), some contextual info and #’s that might help clarify things in your own mind, and help in risk/benefit discussions with patients:


If you only have 5 minutes, read Table 2 in the article.


If you only have 2 minutes, here are some highlights:

X-rays are high energy, ionizing radiation and will break apart DNA molecules. Light sources and microwaves have much lower energies, which are insufficient to break up molecules.

dose from a typical chest CT examination (5 to 10 mSv) is more than 100 times larger than conventional CXR (0.05 mSv)

CT examination exposures generally are higher than 1 year’s worth of background radiation exposure (~3 mSv).

A CT scan with a dose of 10 mSv has an average cancer induction risk of about 1 in 1000, with half of those cancers being fatal (most are expressed decades after the scan).

overall cancer incidence in a population is ~480/1000.

References: article on imagegently.org; picture

wrist X-ray review resource

3 Oct

Came across this very nice site that’s quite handy for brushing up on your wrist bones & X-ray skills.  Personally, I find that the rollover feature (put the cursor over the image to get your cheat-sheet labeling of the bones) very useful.

The site has other anatomical radiology tutorials as well, but the wrist came up lately, and seemed like a good time for a refresher.


Check it out!


References: radiology masterclass site (w/pictures).