Original article
Diffusion tensor imaging of the maturing paediatric cervical spinal cord: From the neonate to the young adultImagerie du tenseur de diffusion de la maturation de la moelle cervicale chez l’enfant : de la période néonatale à l’âge adulte

https://doi.org/10.1016/j.neurad.2011.05.002Get rights and content

Summary

Objective

Normative apparent diffusion coefficient (ADC) and fractional anisotropy (FA) metrics of the brain have been published previously. However, no larger studies evaluated the normal evolution of ADC/FA metrics of the maturing paediatric spinal cord. Goal of this study is to evaluate the age-dependent evolution of the ADC/FA values of the developing/maturing normal cervical spinal cord (CSC).

Patients and methods

Forty-one subjects, aged less than 18 years with a negative spinal MRI study and no systemic central nervous disease, underwent diffusion tensor imaging (DTI) of the CSC. DTI metrics were measured in the centre of the CSC. Regression and ANCOVA analyses were performed to evaluate the association between ADC/FA values and age and its potential modification by sex.

Results

A linear model emerged as the best fit for our data. ADC showed a continuous decrease with age; FA showed a continuous increase with age.

Conclusion

The simultaneous age-related ADC decrease and FA increase likely reflect progressive maturation, myelination and fibre packing within the CSC similar to that observed in the brain. Collection of age-dependent normative DTI metrics may be helpful in the early identification and quantification of altered water diffusion in a variety of pathologies affecting the developing paediatric spinal cord.

Introduction

Multiple techniques have been developed to study brain maturation both qualitatively and quantitatively. While conventional T1- and T2-weighted magnetic resonance imaging (MRI) plays a central role in the qualitative evaluation of normal [1] and abnormal brain development, functional sequences such as diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), and 1H-MR spectroscopy (MRS) allow a quantitative analysis of brain maturation [2], [3], [4], [5], [6], [7], [8].

DTI is a recently developed non-invasive functional MRI technique that exploits the three-dimensional diffusion characteristics of water within the central nervous system (CNS). Various DTI scalars including the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) can be calculated to quantify the integrity and architecture of the maturing brain in vivo [9], [10], [11]. ADC values are markers of overall diffusion within the brain while FA-measurements quantify the degree of anisotropic diffusion [12]. Previous studies have shown, that with ongoing brain maturation, ADC values progressively decrease while FA values increase [2], [3], [4], [5], [6], [7], [8]. Comparison of measured ADC/FA data with normative, age-related data allows for the quantification of brain injury and abnormal or delayed brain maturation non-invasively [2], [3], [4], [5], [6], [7], [8].

Several recent studies have demonstrated the clinical utility of DTI in the characterization of spinal cord pathologies [12], [13], [14], [15], [16], [17], [18], [19], [20], [21].

Currently no studies have summarized or evaluated the age-related evolution of the ADC/FA metrics of the maturing paediatric spinal cord. Similar to the brain, collection of age-correlated normative spinal cord DTI metrics may be helpful in the early identification and quantification of spinal cord pathology.

Consequently, the goal of our study was to evaluate the age-dependent evolution of the ADC/FA-values of the “healthy” cervical spinal cord (CSC) from the neonate through young adults.

Section snippets

Patients

All patients who had received a MRI study of the brain and cervical spinal cord between June 2009 and March 2010 were retrospectively evaluated. Inclusion criteria for enrolment in this study were: age less than 18 years, and; receiving a simultaneous MRI and DTI study of the brain and spinal cord. Exclusion criteria were:

  • clinically confirmed CNS/CSC disease/pathology;

  • focal or systemic CNS/CSC pathology identified on the MRI/DTI examination;

  • non-diagnostic image quality;

  • incomplete MRI/DTI data

Results

One hundred and five children between 0 and 18 years received a clinically indicated MRI of the cervical spine during the 10-month study period. Forty-one children who met the enrolment criteria were included for further analyses. There were 20 males and 21 females in this study group, ranging in age from 0.3 to 16 years, with a mean age of 6.2 (SD = 4.67) years. The demographic characteristics of our patient population as well as the mean and standard deviation of the measured FA and ADC scalars

Discussion

Our study demonstrates that DTI of the CSC is feasible at any age and can be used to quantitatively characterize the progressive maturation and development of the CSC in vivo. As expected, our data analysis showed that with increasing age (from the neonatal period to adolescence), the ADC values decrease while the FA values increase within the CSC. Age-related evolution of DTI scalars has previously been reported for the normal development of the brain [1], [2], [3], [4], [5], [6], [7], [8].

Conclusion

Our study demonstrates that DTI of the paediatric cervical spinal cord is feasible and can be used to quantitatively study the progressive maturation of the normal paediatric cervical spinal cord. The simultaneous age-related decrease in ADC and increase in FA metrics likely reflect progressive maturation, myelination and fibre packing within the spinal cord similar to that observed in the brain. The normative dataset derived from our study describes the normal maturation of the paediatric

Disclosure of interest

Wesley D. Gilson, is employed by Siemens Inc, Erlangen, Germany. All other authors have no conflict of interest.

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