Elsevier

Clinical Radiology

Volume 72, Issue 7, July 2017, Pages 613.e7-613.e11
Clinical Radiology

Can the pattern of vertebral marrow oedema differentiate intervertebral disc infection from degenerative changes?

https://doi.org/10.1016/j.crad.2017.01.010Get rights and content

Highlights

  • Imaging of degenerative spine changes and infective discitis often overlap.

  • Patterns of marrow edema were hypothesized to assist in discriminating between these etiologies.

  • Unfortunately, none of marrow edema patterns evaluated was specific nor sensitive enough.

Aim

To evaluate whether various patterns of bone marrow oedema could be used to discriminate between infection and degenerative change.

Materials and methods

Seventy patients with imaging features suspicious for discitis and available clinical follow-up were blindly reviewed for vertebral marrow oedema on sagittal short-tau inversion recovery (STIR) images according to the following patterns: I, vertebra oedema is adjacent to the intervertebral space and sharply-marginated; II, vertebral oedema is adjacent to the intervertebral space but not sharply marginated from normal marrow or involves the entire vertebral body; and III, vertebral oedema is distant from the endplate with intervening hypointense marrow signal.

Results

Of 45 patients with a clinical diagnosis of discitis, pattern II was the most common oedema pattern (64%). Approximately 20% and 9% of discitis patients showed patterns I and III, respectively. In patients with degenerative changes, 44% patients showed pattern I, 32% showed pattern II, and 24% showed pattern III. Pattern II had a sensitivity, specificity, and positive predictive value of 0.64, 0.68, and 0.78 for diagnosing spine infection, respectively.

Conclusions

Although bone marrow oedema in infective discitis most often extends from the disc space and has indistinct margins, the oedema may also have sharp margins or be remote from the involved intervertebral space. Bone marrow oedema patterns of infective discitis overlap with those of degenerative disease and are not sufficiently reliable to exclude infection in cases with magnetic resonance imaging findings suggestive of discitis.

Introduction

Intervertebral disc degeneration is characterised by gradual dehydration of disc material and is manifested on magnetic resonance imaging (MRI) as loss of normal nucleus pulposus T2 hyperintensity and subsequent loss of disc height. Nevertheless, a severely degenerated disc occasionally demonstrates T2 hyperintense signal.1 In such cases, a degenerated disc level may be difficult to differentiate from pyogenic spondylodiscitis (“discitis”).1 Additionally, various bone marrow (BM) signal changes have been reported in vertebral endplates adjacent to degenerated discs.2 The degenerative Modic type I endplate changes (manifested as MRI T1 hypointensity and T2 hyperintensity) can also appear similar to endplate BM oedema seen with discitis.1, 2 These similarities are clinically problematic in that clinical management between degenerative disc changes and infective discitis is very different.

The objective of the present study was to evaluate if various patterns of BM oedema adjacent to a suspicious T2 hyperintense disc can be used to discriminate between infection and degenerative change. Specifically, as degenerative changes typically develop gradually, the border between BM oedema and adjacent normal marrow may be more sharply marginated as opposed to that associated with an infective process, which tends to progress quicker.3

In addition, when degenerative Modic type III endplate changes (T1 and T2 hypointensity likely representing relative absence of marrow in areas of endplate sclerosis) occur in combination with Modic I changes, the marrow T2 hyperintensity is often distant from the diseased intervertebral disc space due to the intervening endplate sclerosis. It was proposed that in the context of disc T2 hyperintensity, BM T2 hyperintensity separated from the disc by T2 hypointensity (sclerosis) is more suggestive of a degenerative process rather than disc infection.

Section snippets

Study design

An institutional review board-approved retrospective observational study was conducted by reviewing clinical data and initial spine MRI of patients with an imaging diagnosis that was suspicious of “intervertebral discitis”. Evaluation of BM oedema distribution and margination in adjacent endplates was evaluated by a radiologist blinded to the clinical records.

Population

A radiology information system (RIS)/picture archiving and communication system (PACS) search for the word “discitis” was performed with

Study population

A total of 119 patients had findings suspicious for intervertebral discitis based on imaging reports. Of these, 70 patients were included in the study based upon the inclusion and exclusion criteria (34 patients had multilevel disease; nine patients had markedly technically degraded MRI or MRI was performed without STIR sequence; six patients had no available clinical records). Of the present cohort, 36 were men and mean age was 59±14 years. The most common region for discitis or suspected

Discussion

Endplate BM oedema is commonly seen in both infective and degenerative intervertebral disc disease. None of the patterns of BM oedema evaluated in the present study showed sufficient diagnostic value in discriminating either pathology (i.e., there is significant overlap between degenerative and infective endplate changes regarding patterns of BM signal within adjacent vertebral marrow oedema). The majority of patients with a clinical diagnosis of discitis (29/45) showed indistinctly marginated

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There are more references available in the full text version of this article.

Part of this study was presented in ASNR 2016.

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