HIZ’s relation to axial load and low back pain: investigated with axial loaded MRI and pressure controlled discography

Abstract

Purpose The aims were to investigate if the detection of high-intensity zones (HIZ) is affected by axial load, and to study the correlation between HIZ and discogenic pain provoked with pressure controlled discography (PCD). Methods 41 consecutive patients with chronic low back pain, referred for discography, were included. Each patient underwent PCD, CT, MRI, and axial loaded MRI (alMRI) within 24 h. 35 patients completed all MRI sequences (140 discs). The detection of HIZ was compared between conventional MRI and alMRI. PCD was performed in 119 of the discs examined at MRI. Provoked pain at PCD was classified into four categories (none/unfamiliar/similar/ exact), with the patients' daily pain as reference, and correlated with presence of HIZ. Results AlMRI did not affect the detection of HIZ compared with conventional MRI. No significant correlation between HIZ and the 4-graded pain response at discography was found (p = 0.34), neither when combining similarly/exactly reproduced pain (p = 0.08). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of HIZ in detecting discs with exactly reproduced pain were 49, 69, 39 and 76 %. When combining similarly/exactly reproduced pain, PPV was higher but still only 70 %. Conclusions The detection of HIZ was not influenced by axial load. With strict PCD, discogenic pain can neither be confirmed when having HIZ (PPV 39 %) nor ruled out in discs without HIZ (NPV 76 %). Larger PCD studies including quantification of HIZ at conventional and alMRI are needed, before any dynamic component affected by axial load can be ruled out completely.

Guideline summary review: an evidence-based clinical guideline for the diagnosis and treatment of low back pain

“…There is insufficient evidence to make a recommendation for or against the use of axial loaded MRI for the diagnosis of low back pain [272].…”

Differences in IVD characteristics between low back pain patients and controls associated with HIZ as revealed with quantitative MRI

“…Several studies promote HIZ as a promising marker for discogenic pain [8, 20] as HIZ lesions contain antigenic NP material trapped between torn lamellae structures in AF that induce inflammation and ingrowth of vascularized granulation tissue deep into the IVD [8, 21]. However, a high prevalence of HIZ IVDs among asymptomatic individuals [22, 23] (33.3% in this study), and a wide range of reported sensitivity for HIZs and concordant pain during discography [7, 24, 25], questions the reliability and limits the use of HIZs in the diagnosis of LBP. Thus, it is plausible that the source for painful IVDs somehow is connected to HIZ, but other changes within the disc may be equally or more important.…”

Comparison between pain at discography and morphological disc changes at axial loaded MRI in patients with low back pain

“…In spite of the fact that discogenic pain is induced or aggravated by positions with increased load such as sitting and flexion, recumbent unloaded MRI is traditionally used for imaging the painful spine. Numerous studies without consensus, however, have tried to find morphological MRI parameters that can predict painful discs [26][27][28][29][30][31][32]. alMRI has been shown to add certain information about spinal morphology compared with unloaded MRI [17,18,20,[33][34][35].…”