Can the pattern of vertebral marrow oedema differentiate intervertebral disc infection from degenerative changes?☆
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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Cited by (6)
Spinal disorders mimicking infection
2021, Insights into Imaging
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Part of this study was presented in ASNR 2016.