Ultrashort time-to-echo MRI of the cartilaginous endplate and relationship to disc degeneration and Schmorl's nodes, andretrospective study of paediatric spines and the neurocentralsynchondrosis

Abstract

Background: An association between cartilaginous endplate (CEP) defects and

intervertebral disc (IVD) degeneration has been previously suggested in animal and

cadaveric studies. CEP defects may also be involved in Schmorl’s nodes (SN). There

have been no previous reports in the literature that describe the use of ultrashort

time-to-echo (UTE) MRI to assess the CEP in humans in vivo. In chapter 5 of this

thesis, a retrospective study of paediatric spines and the neurocentral synchondrosis

(NCS) was singled out to report the incidence of NCS and to raise the hypothesis of

NCS as a precursor of SN.

Purpose: To assess the feasibility of detecting CEP defects in live humans using UTE

MRI, and to assess their relationship with IVD degeneration and SN.

Subjects and Methods: A total number of 22 subjects underwent T2-weighted (T2W)

and UTE MRI to assess for the presence and severity of IVD degeneration, the

presence of SN and for the presence of CEP defects. SN and IVD degeneration were

confirmed by assessing T2W images and IVD degeneration was graded according to

the Schneiderman classification. CEP defects were defined as discontinuity of high

signal over 4 consecutive images and were independently assessed by two raters.

Results: Analyses of CEP defects between IVD degeneration and SN were performed

separately. For the study of CEP defects and IVD degeneration, subjects with SN

were excluded. 37 out of 108 (34.3%) CEPs had defects, which mainly occurred at

T12/L1, L1/L2 and L4/L5 (p=0.008). Inter-rater reliability was substantial (Kappa

statistic= 0.67, p<0.001). Multivariate logistic regression revealed that lower BMI

(p=0.009) and younger (p=0.034) individuals had a decreased likelihood of having

CEP defects. A statistically significant association was found to exist between the

presence of cartilaginous endplate defects and intervertebral disc degeneration

(p=0.036). Degenerated discs with CEP defects were found in L4/5 and L5/S1, while

degenerated discs with no CEP defects were found throughout the whole lumbar

region. Mean degeneration scores of L4/5 and L5/S1 levels with CEP defects were

higher than that of L4/5 and L5/S1 levels without. For the study of CEP defects and

SN, with all 22 subjects assessed, 125 out of 264 (47.3%) CEPs had defects. 40 SN

were found, and among those, 35 SN had CEP defects (87.5%). 125 CEPs had the

presence of CEP defects; among them, a large number of CEP defects did not have

SN underneath (92 out of 125, 73.2%).

Conclusion: The studies demonstrate the feasibility of using UTE MRI in live humans

to assess the integrity of the CEP. Longitudinal studies may reveal the diagnosis of

CEP defects to be clinically beneficial for assessment of IVD degeneration and SN.