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Magnetic Resonance Imaging for Diagnosing Foot Osteomyelitis: A Meta-analysis. Arch Intern Med. 2007 Jan 22;167(2):125-32
Kapoor A, Page S, Lavalley M, Gale DR, Felson DT
Quote:
BACKGROUND: Uncertainty exists regarding the optimal workup of patients with suspected osteomyelitis of the foot, many of whom have diabetes mellitus. We conducted a meta-analysis to determine the diagnostic test performance of magnetic resonance imaging (MRI) for osteomyelitis of the foot and compared this performance with that of technetium Tc 99m bone scanning, plain radiography, and white blood cell studies.
METHODS: We searched MEDLINE (from 1966 to week 3 of June 2006) and EMBASE (from 1980 to week 3 of June 2006) for English-language studies in which adults suspected of having osteomyelitis of the foot or ankle were evaluated by MRI. We then extracted data using a standard form derived from the Cochrane Methods Group. To summarize the performance of diagnostic tests, we used the summary receiver operating characteristic curve analysis, which relies on the calculation of the diagnostic odds ratio (DOR). We also examined subsets of studies defined by the presence or absence of particular design flaws or populations.
RESULTS: Sixteen studies met inclusion criteria. In all studies combined, the DOR for MRI was 42.1 (95% confidence interval, 14.8-119.9), and the specificity at a 90% sensitivity cut point was 82.5%. The DOR did not vary greatly among subsets of studies. In studies in which a direct comparison could be made with other technologies, the DOR for MRI was consistently better than that for bone scanning (7 studies-149.9 vs 3.6), plain radiography (9 studies-81.5 vs 3.3), and white blood cell studies (3 studies-120.3 vs 3.4).
CONCLUSIONS: We found that MRI performs well in the diagnosis of osteomyelitis of the foot and ankle and can be used to rule in or rule out the diagnosis. Magnetic resonance imaging performance was markedly superior to that of technetium Tc 99m bone scanning, plain radiography, and white blood cell studies.
Re: Magnetic Resonance Imaging for Diagnosing Foot Osteomyelitis
This is great - but have you tried getting access to an mri? I work in a public hospital and inpatients have been discharged simply to access mri's as the current system pays more for outpatient access. In addition there is quite a waiting period to access the machine. There needs to be some way of being able to increase speed of access to patients with suspected osteomyelitis so that diagnosis can occur quickly and treatment implemented in a timely manner. Any ideas?
Re: Magnetic Resonance Imaging for Diagnosing Foot Osteomyelitis
Role of magnetic resonance imaging in the evaluation of diabetic foot with suspected osteomyelitis.
Rozzanigo U, Tagliani A, Vittorini E, Pacchioni R, Brivio LR, Caudana R. Radiol Med. 2008 Oct 25. [Epub ahead of print]
Quote:
PURPOSE: This study evaluated Magnetic Resonance Imaging (MRI) in infected diabetic foot ulcers.
MATERIALS AND METHODS: Sixteen diabetic patients underwent foot MRI between January 2006 and September 2007 for suspected unilateral osteomyelitis. Three of 16 patients showed radiographic changes due to Charcot neuropathic osteoarthropathy. Twelve of 16 patients also underwent MR angiography of the lower limbs for the purpose of planning surgical or endovascular treatment. The musculoskeletal and vascular MRI studies were retrospectively reviewed by three radiologists.
RESULTS: The final diagnosis, based on clinical, imaging, microbiological and histological findings, was osteomyelitis in 13/16 cases. Foot MRI allowed a correct diagnosis in 15/16 patients, with 1 false positive result demonstrated by computed tomography (CT)-guided bone biopsy. MR angiography of the lower limbs was considered nondiagnostic in 5/12 patients in the infrapopliteal region owing to venous contamination.
CONCLUSIONS: MRI has high sensitivity for the detection of osteomyelitis in the diabetic foot but lower specificity related to Charcot neuropathic osteoarthropathy. If diagnostic uncertainty persists, a bone biopsy is indicated. The inflammatory hyperaemia caused by the ulcer deteriorates the diagnostic quality of 40%-50% of MR angiography studies in the infrapopliteal region. In these cases, selective arteriography is appropriate, as it can be performed in the same session as angioplasty.
Re: Magnetic Resonance Imaging for Diagnosing Foot Osteomyelitis
Interesting and relavant thread.
I recently encountered a 35 yr old client , with diabetes,who was admitted to hospital 8 weeks ago and given i.v. antibiotics for an wound beneath the 1st ip joint.
Unclear weather she was discharged with oral cover, certainly currently is not on any.
. X rays have been taken twice and not demonstrated signs of osteomyelitis.
I debrided the wound recently it had some hypergranulation tissue, modest exudate and nil odour. The toe is swollen apprx 2x normal size and the client denies any symptoms of systemic illness. The foot has good circulation and the HbA1c is over 12.
In discussion with the visiting Dr ,he declined to prescribe any antibiotics but review the case in a couple of weeks. Logic being that as the wound had been reported as improving (therefore antibiotics were not nessecary) then if it was not progressing on next review an mri was nessecary before surgical debridement of the bone could be undertaken.
As rjna points out the issues in accessing mri in a timely manner are significant, and perhaps there is a case for management on the basis of "clinical suspicion"
Furthermore i feel the Dr's course of management is inappropriate or is it just me?
Re: Magnetic Resonance Imaging for Diagnosing Foot Osteomyelitis
"This is great - but have you tried getting access to an mri?"
hmmmmmmmmmmm
I wish EVERYONE on the US of A could read this post. especially those who THINK they WANT National Health Care!!!
Even in my smallish town of 100,000 we have several MRI centers having to MARKET themselves for utilization. In fact, if you so much as twist your knee you'll end up with an MRI.
Steve
__________________
DrSArbes
Fellow American College of Foot & Ankle Surgeons
Board Certified Foot & Ankle Surgery, ABPS
Green Bay, Wisconsin, USA
Re: Magnetic Resonance Imaging for Diagnosing Foot Osteomyelitis
Hi Greg,
any further details on this case? Is the patient neuropathic? How longstanding is this ulceration? When were the x-rays taken? Other than her IV antibiotics, what other care has she received for this problem? Has there been input from any other departments? Has the patient had any recent blood tests?
With a HbA1c of 12, I am not surprised this patient is still requiring care. Is her diabetes normally this poorly controlled? This needs to be sorted out ASAP.
Where I work, we are quite lucky with the resources available to us but if we are caring for a patient on an inpatient basis, we routinely run CRP, FBC and take regular swabs. Relying on wound inspection and x-rays doesn't really provide enough information for me. We do not routinely request MR scans for cases suspicious of osteomyelitis (the orthopods on the other hand tend to request them all the time).
I would be suspicious of osteomyelitis in this case you have described. Whether the Dr's management is inappropriate would depend on the bigger picture but I think your "clinical suspicion" counts for an awful lot!
Look forward to hearing a few more details about this case,
Regards,
Ryan
The Following User Says Thank You to Ryan McCallum For This Useful Post:
Re: Magnetic Resonance Imaging for Diagnosing Foot Osteomyelitis
Hi Ryan
No the patient is not neuropathic.
Her diabetes is generally poorly controlled as she is not reliable about taking her medication.
Im not sure how old the ulcer is as she first presented 8 weeks ago ( not to me) and at that stage the notes record that she was systemically unwell and maggots were present in the wound. It's probably 1.5-2 cm diameter and I cannot probe to bone.
The x rays were close to the time of admission and 1 month later.
The patient comes from a remote area that has resident nursing staff available and a visiting Dr about once a week it is some 6hrs drive to the nearest small town hospital.
Im now wondering if she would be better managed in hospital as her bsl could be stabilised which I think would assist with wound management, although I guess that the admission criteria may require her to be more unwell.
Magnetic Resonance Imaging for Diagnosing Foot Osteomyelitis
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