Diffusion properties of asymptomatic lumbar intervertebral discs in a pediatric cohort: a preliminary study of apparent diffusion coefficient

Abstract

Purpose: To explore the apparent diffusion coefficients of intervertebral discs in an asymptomatic pediatric cohort.

Methods: We conducted a prospective MRI study of the lumbar spine from below the thoracolumbar junction to the lumbosacral junction on 12 subjects (mean age 13 y.o.) with no spinal pathology or spinal posture disorder. MRI was carried out using a 1.5 T machine with acquisitions realized both in sagittal and coronal planes. First, disc hydration was determined, and then, diffusion-weighted images were obtained using an SE single-shot echo-planar sequence. Apparent diffusion coefficients (ADC) of anterior annulus fibrosus (AAF), nucleus pulposus (NP) and posterior annulus fibrosus (PAF) were measured in the sagittal plane.

Results: Averaged hydration of 0.27 SD 0.03 confirmed the asymptomatic nature of discs. Average scaled values of ADC were 0.46 SD 0.01, 0.22 SD 0.09 and 0.18 SD 0.03 for NP, AAF and PAF, respectively. ADC of NP were almost constant along the spine; PAF values show a slight increase in the thorax-sacrum direction, while AAF values showed a pronounced decrease. Locally, ADC of AAF was higher compared to ADC PAF values below the thoracolumbar junction and it reversed for subjacent discs.

Conclusions: In our knowledge, our study provided the first diffusive properties of asymptomatic intervertebral discs in an adolescent cohort. ADC of NP was slightly higher than adults'. ADC evolutions of AAF were correlated with lordosis concavity which pointed out the role of compressive strain on fluid transport properties. This study could furnish information about segment homeostasis for exploration of pediatric spinal pathologies.

Keywords: ADC; Children; Intervertebral disc; MRI; Pediatrics.