Suspected discitis, vertebral osteomyelitis or epidural abscess

IDSA native vertebral osteomyelitis guideline (2015)

Contrast-enhanced MRI, with a whole-spine survey rather than a single level, because non-contiguous involvement is characteristic and because the finding that changes management fastest — an epidural abscess — is defined by enhancement.

Back pain with fever, raised inflammatory markers, positive blood cultures, recent instrumentation, intravenous drug use or haemodialysis, with or without a neurological deficit.

Referenced decision support — confirm against your local protocol.

Decision support, not a directive. Protocols and timings shown are typical published ones — your local protocol takes precedence, and the vetting radiologist decides.

The request in front of you

Everything is optional. Leave a field alone and the answer assumes nothing — the verdict updates as you go.

Study requested

What the referrer actually asked for. It is evidence of intent, not a constraint on the right answer.

Contrast as written

What the request form says, not what it should say.

Age

Pick a band, or type an exact age if it matters.

years

Pregnancy status

Focal neurological deficit

Fever or sepsis

Renal risk factors

The question a vetter can actually answer from the request. An explicit “none known” is a real answer, and it removes checks rather than deferring them.

Previous contrast reaction

The pathway — tap anything already done

Marking a study complete moves the answer on. A patient arrives partway through a pathway far more often than at the start of one.

Accept as requested

MRI Spine — suspected infection / discitis

MRI Whole Spine

What we'd amend, and why

Marrow oedema either side of a disc, with loss of the normal endplate definition, appears on MRI weeks before any bony change is visible on radiographs or CT — which is the entire reason MRI is first rather than confirmatory. Contrast then does the work that changes management: it distinguishes an enhancing phlegmon from a rim-enhancing collection needing drainage, and it defines the epidural extension that determines whether this is an antibiotic problem or a surgical one. Whole-spine sagittal coverage is included because non-contiguous involvement is common and a targeted study finds one level of a multilevel disease.

Nothing needs resolving before this goes ahead. Routine checks below are owned downstream.

How was this decided?

pathwayadult — Adults
rulerule-mr-device-screening — MR safety screening for implants and foreign bodies; checked by Radiographer at the scanner
rulerule-contrast-reaction-premed — Prior contrast reaction and elective premedication; checked by Nurse before the scan
rulerule-gadolinium-renal — Kidney function and gadolinium-based contrast; checked by Radiographer at the scanner
rulerule-pregnancy-gadolinium — Gadolinium in known or possible pregnancy; checked by Radiographer at the scanner
rulerule-iv-access — Intravenous access adequate for the planned injection; checked by Radiographer at the scanner

Decision support only. Local protocol takes precedence.

Handled at the scanner(2)nothing for you to do

Settled and owned downstream. Each returns to a radiologist only on the stated trigger.

MR safety screening for implants and foreign bodies
Complete the MR safety questionnaire, verify implant labelling and its stated conditions of use against this scanner and this protocol, and ensure no ferromagnetic object enters Zone IV.
Radiographer at the scannerBefore the scan
Flags back if: An implant or retained foreign body that is MR Unsafe, unlabelled, or cannot be identified; or an MR Conditional device whose stated conditions this scanner or the requested protocol cannot satisfy; or a credible unexcluded intraocular metallic foreign body history.
Intravenous access adequate for the planned injection
Site and test a cannula that supports the protocol flow rate, preferring an antecubital or large forearm vein, and observe the injection for extravasation. A 20-gauge or larger cannula is preferred for flow rates of 3 mL/s or more.
Radiographer at the scannerAt the scanner
Flags back if: No cannula can be sited that supports the protocol flow rate — for example only a 22-gauge hand or foot cannula for a CT angiogram needing 4–5 mL/s; or the only available access is a central line or port that is not labelled power-injectable; or an extravasation occurs.

Pathways

Big forks are separate pathways; the first whose conditions match is the one used.

Sepsis or a neurological deficit — emergency rather than urgent

Role	Study & protocol	Why this answers the question
First line	MRI Whole Spine MRI Spine — suspected infection / discitis usually appropriate	An epidural abscess compressing the cord behaves like any other compressive lesion, so a deficit converts this from a study booked for tomorrow into one done tonight, and the neurological state at decompression is what the patient keeps. Sepsis does the same for a different reason: the spine may be the source that has to be drained for the patient to improve, and blood cultures taken before antibiotics are worth more than any sequence here. The protocol is unchanged and its two features carry more weight than ever — gadolinium, because the drainable collection is defined by its enhancing rim rather than by the marrow oedema, and whole-spine sagittal coverage, because non-contiguous involvement is characteristic and the level that needs draining is regularly not the level that hurts. Do not defer the study for a creatinine; an unenhanced study started now, reported as unable to exclude an epidural collection, is more useful than an enhanced one tomorrow.
Second line	Bone scintigraphy Bone scintigraphy — whole body (± three phase)	A fallback only where MRI is genuinely contraindicated, and a poor one for this patient specifically: it localises increased bone turnover across the skeleton and says nothing about the epidural space, which is the compartment the deficit is coming from. If MRI cannot be delivered locally tonight in a patient with a deficit, transfer is the answer rather than substitution.

Adults

Matches your inputsDefault

Role	Study & protocol	Why this answers the question
First line	MRI Whole Spine MRI Spine — suspected infection / discitis usually appropriate	Marrow oedema either side of a disc, with loss of the normal endplate definition, appears on MRI weeks before any bony change is visible on radiographs or CT — which is the entire reason MRI is first rather than confirmatory. Contrast then does the work that changes management: it distinguishes an enhancing phlegmon from a rim-enhancing collection needing drainage, and it defines the epidural extension that determines whether this is an antibiotic problem or a surgical one. Whole-spine sagittal coverage is included because non-contiguous involvement is common and a targeted study finds one level of a multilevel disease.
Second line	Bone scintigraphy Bone scintigraphy — whole body (± three phase)	A fallback where MRI is contraindicated. It is sensitive to increased bone turnover and can localise disease across the whole skeleton in one study, but it is non-specific — degenerative change, fracture and tumour all take up tracer — and it says nothing about the epidural space, which is the compartment that determines urgency.

Pitfalls

Omitting gadolinium and reporting no abscess. The epidural collection is defined by enhancement, and its absence on an unenhanced study is not evidence of absence.
Imaging only the symptomatic level and missing non-contiguous involvement, which is characteristic in tuberculous disease.
Confusing Modic type 1 degenerative endplate change with infection. Disc signal, endplate cortical integrity and the paravertebral soft tissues are what separate them.
Underestimating the paravertebral component, particularly a psoas collection, which is often the drainable target.
Treating a normal early radiograph as reassuring; bony change lags the disease by weeks.

Priors — what to pull first

Recent CT performed for another reason often already shows endplate erosion and can be reviewed while MRI is arranged.
In a patient with previous instrumentation, the pre-operative and immediate post-operative studies distinguish expected post-surgical marrow change from infection.

What makes a good request

The IDSA guideline places MRI as the first imaging test where feasible, with reported sensitivity and specificity in the mid-nineties for native vertebral osteomyelitis.
Gadolinium is what separates a phlegmon from a drainable collection and defines the epidural component. Without it the study can confirm the diagnosis and still miss the finding that requires surgery tonight.
A neurological deficit in this context converts the request from urgent to emergency, because an epidural abscess compressing the cord behaves like any other compressive lesion.
Skip lesions are common, particularly in tuberculous spondylitis, which is why a sagittal whole-spine survey precedes the targeted sequences.

Scoring this once it is done

The classification and risk tools this question ends in.

SINS (Spinal Instability Neoplastic Score)

How these studies are acquired

Contrast, phases and timing for every study on the pathways above.

MRI Spine — suspected infection / discitis Bone scintigraphy — whole body (± three phase)

Confirm locally

MRI Spine — suspected infection / discitis: timings are typical — confirm against local protocol.
Timings, contrast volumes and rates above are typical published values. Your department's protocol, scanner and patient population decide the actual numbers.
Safety thresholds and premedication policy follow local policy where it differs from the cited guidance.

References

Implemented from the cited published sources. Educational and workflow support only; confirm against current guidelines and local policy before clinical use.