Is the Transport of a Gadolinium-Based Contrast Agent Decreased in a Degenerated or Aged Disc? A Post Contrast MRI Study

Marta Tibiletti,Fabio Galbusera,Marco Brayda-Bruno,Cristina Ciavarro,Jeroen Hendrikse

doi:10.1371/journal.pone.0076697

Abstract

A post contrast magnetic resonance imaging study has been performed in a wide population of low back pain patients to investigate which radiological and phenotypic characteristics influence the penetration of the contrast agent in lumbar discs in vivo. 37 patients affected by different pathologies (disc herniation, spondylolisthesis, foraminal stenosis, central canal stenosis) were enrolled in the study. The selected population included 26 male and 11 female subjects, with a mean age of 42.4±9.3 years (range 18–60). Magnetic resonance images of the lumbar spine were obtained with a 1.5 T scanner (Avanto, Siemens, Erlangen, Germany) with a phased-array back coil. A paramagnetic non–ionic contrast agent was injected with a dose of 0.4 ml/kg. T1-weighted magnetic resonance images were subsequently acquired at 5 time points, 5 and 10 minutes, 2, 4 and 6 hours after injection. Endplates presented clear enhancement already 5 minutes after injection, and showed an increase in the next 2 hours followed by a decrease. At 5 and 10 minutes, virtually no contrast medium was present inside the intervertebral disc; afterwards, enhancement significantly increased. Highly degenerated discs showed higher enhancement in comparison with low and medium degenerated discs. Discs classified as Pfirrmann 5 showed a statistically significant higher enhancement than Pfirrmann 1, 2 and 3 at all time points but the first one, possibly due to vascularization. Disc height collapse and Modic changes significantly increased enhancement. Presence of endplate defects did not show any significant influence on post contrast enhancement, but the lack of a clear classification of endplate defects as seen on magnetic resonance scans may be shadowing some effects. In conclusion, disc height, high level of degeneration and presence of Modic changes are factors which increase post contrast enhancement in the intervertebral disc. The effect of age could not be demonstrated.

Highlights

The intervertebral disc (IVD) is the largest avascular structure in the human body
Lactic acid produced by cell anaerobic metabolism diffuses out of the disc, since its accumulation would consequence in a pH decrease and reduced cell viability [6]
Modic changes (MCs) were present on 46 upper endplates (UEPs) (15 MC I, 27 MC II, 4 MC I/II) and 45 lower endplates (LEPs) (12 MC I, 29 MC II, 4 MC I/II). 36 levels present MCs at both endplates, 19 only at one

Summary

Introduction

The intervertebral disc (IVD) is the largest avascular structure in the human body. A sparse population of cells produces and maintains the extracellular matrix, which confers to the healthy IVD the ability to withstand the compressive loads, and to allow spine bending and twisting [1]. Disc cells require an adequate nutrient exchange to survive and be viable [2], mostly from the capillaries of the subchondral plate of the vertebral body, across the layer of hyaline cartilage that constitutes the endplate [3]. Lactic acid produced by cell anaerobic metabolism diffuses out of the disc, since its accumulation would consequence in a pH decrease and reduced cell viability [6]. An alteration of this nutrient pathway is considered as one of the possible causes of IVD degeneration [2]. A recent works by Rodriguez et al [10] reported that total endplate permeability and porosity increase with ageing and degeneration

Methods

Results

Conclusion