drk1980
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In a suspect case of osteomyelitis when the Xray is negative, the next best step in evaluation would include:
A)MRI
B)Technetium Bone Scan
[Differences seen again in UW and Kaplan!!!]
thanks
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| achilles
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good point dr1980.... i too had this confusion.
this is what i know and i hope others will add to this or correct this.
i'll go for MRI. bone scan and MRI, both, have equal sensitivity but the MRI is more specific. bone scan gives false positives because of inflammation. therefore if xray is -ve then do MRI and if xray is +ve then go for a bone biopsy and culture. the biopsy must be taken from the bone and not the sinus tract.
the limiting factor in real practice is that MRI might not be readily available.
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| an
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here's what i came across, from UW step 3...for suspected osteomyelitis of vertebral body and lower foot, MRI is the investigation of choice..for other sites, a 3-phase Tc bone scan is inv of choice.
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| achilles
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an, why is it that the bone scan is better than MRI in sites other than the vertebral bodies.
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| an
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i take back what i wrote before, achilles, what u said bfor was correct..that mri is better but not readily available...
if the qu says suspected OM of spine or diabetic foot...u have to go for mri, coz bone scan wont be reliable, why u have already explained nicely.
but suspected OM elsewhere..if the qu asks for next step in evaluation after having normal radiographs, bone scan is more appropriate, as its readily available, cheaper, and gives reliable results. Again, if the qu asked for the most appropriate/best investigation...then i would go for mri.
Edited by an on 06/20/06 - 09:44 AM
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| cyra
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Is it ok to use the fact that whether or not there is overlying inflammation as the pivot point? If there is inflammation and they ask for the "next step in evaluation"....would MRI be it?or does it have to be site specific like you pointed out an?Maybe i am misunderstading it a bit here....could you please clairfy this?
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| achilles
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thanks for the info an.
so if there OM of spine or diabetic foot, next step would also be MRI. and elsewhere next step would be bone scan and most apt Ix would be MRI. i am writing this just to make sure that i have understood everything right.
thanks again an. as always you just make things more clear.
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| an
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the decision is site-specific...diabetic foot/spine..go for MRI as next step in evaluation
elsewhere, a 3-phase bone scan(3-phase bone scan can differentiate inflammation from cellulitis from osteomyelitis)..
check this out, scroll down to imaging studies..
http://www.emedicine.com/orthoped/topic429.htm
oops sorry achilles...my post is a repitition of what u posted(i think we posted at same time)..i was addressing cyra.
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| drk1980
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thanks for the discussion u both,
BTW, this Q is pertaining to pediatric osteomyelitis.
Its really confusing, coz Cvetnic (lectures) insists MRI is the diagnostic method of choice, since it also proves useful for aspiration as well as evaluation before surgery if needed.
UW, on the other hand, reserves MRI for vertebral OM. And advises to go straight for bone scan after an unremarkable xray.
achilles, adding to ur point on FPs in bone scan, FN is seen during active bone infection.
so is this wht we conclude?...
'next appropriate step in management' - bone scan
'next best step in evaluation' - MRI
'best method of choice for diagnosing' - bone aspirate culture
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| cyra
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Awesome!
Thanks a million an!
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| achilles
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yes drk1980, the best Ix of all would be biopsy and culture. thanks for initiating this wonderful discussion.
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| drk1980
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oops, sorry. I must hv idled too long wth my last post, hadnt seen all those missed conversations before mine!
went thru ur link, an. good stuff. prompted me to checkup pediatrics discussion on the same. Since osteomyelitis in peds is mainly from hematogenous spread focused mostly to long bones....instead of contiguous from diabetic foot.
Imaging Studies:
Radiography
-Plain radiographs usually only show soft tissue swelling and loss of normally visible tissue planes, but radiographs can be useful in detecting bone tumors, fractures, and healing fractures. Osteopenia, lytic lesions, and periosteal changes are late radiographic signs, but their absence does not exclude a diagnosis of acute osteomyelitis.
Three-phase technetium radionuclide bone scanning
-This procedure, through enhanced uptake of the radioisotope, demonstrates increased osteoblastic activity of the infected bone and distinguishes osteomyelitis from deep cellulitis.
-Technetium bone scan has a false-negative rate of as much as 20%, particularly in the first few days of illness.
-Fractures, bone tumors, and surgery also cause enhanced technetium uptake. (False Postive)
Magnetic resonance imaging (MRI)
-This test is increasingly used to define bone involvement in patients with a negative bone scan.
for more..... http://www.emedicine.com/ped/topic1677.htm
Better hurry up and submit this, before i miss out on any more conversations!!
great input from each one of u, thanks!
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