Abstract
BackgroundEarly stages of scoliosis and spondylolisthesis entail changes in the intervertebral disc (IVD) structure and biochemistry. The current clinical use of MR T2-weighted images is limited to visual inspection. Our hypothesis is that the distribution of the MRI signal intensity within the IVD in T2-weighted images depends on the spinal pathology and on its severity. Therefore, this study aims to develop the AMRSID (analysis of MR signal intensity distribution) method to analyze the 3D distribution of the MR signal intensity within the IVD and to evaluate their sensitivity to scoliosis and spondylolisthesis and their severities.MethodsThis study was realized on 79 adolescents who underwent a MRI acquisition (sagittal T2-weighted images) before their orthopedic or surgical treatment. Five groups were considered: low severity scoliosis (Cobb angle ≤50°), high severity scoliosis (Cobb angles >50°), low severity spondylolisthesis (Meyerding grades I and II), high severity spondylolisthesis (Meyerding grades III, IV and V) and control. The distribution of the MRI signal intensity within the IVD was analyzed using the descriptive statistics of histograms normalized by either cerebrospinal fluid or bone signal intensity, weighted centers and volume ratios. Differences between pathology and severity groups were assessed using one- and two-way ANOVAs.ResultsThere were significant (p < 0.05) variations of indices between scoliosis, spondylolithesis and control groups and between low and high severity groups. The cerebrospinal fluid normalization was able to detect differences between healthy and pathologic IVDs whereas the bone normalization, which reflects both bone and IVD health, detected more differences between the severities of these pathologies.ConclusionsThis study proves for the first time that changes in the intervertebral disc, non visible to the naked eye on sagittal T2-weighted MR images of the spine, can be detected from specific indices describing the distribution of the MR signal intensity. Moreover, these indices are able to discriminate between scoliosis and spondylolisthesis and their severities, and provide essential information on the composition and structure of the discs whatever the pathology considered. The AMRSID method may have the potential to complement the current diagnostic tools available in clinics to improve the diagnostic with earlier biomarkers, the prognosis of evolution and the treatment options of scoliosis and spondylolisthesis.
Highlights
Stages of scoliosis and spondylolisthesis entail changes in the intervertebral disc (IVD) structure and biochemistry
Our hypothesis is that the distribution of the Magnetic resonance imaging (MRI) signal intensity within the IVD in T2-weighted images depends on the spinal pathology and on its severity, and has the potential to provide essential information on spine pathologies that could not be appreciated by direct visual observation as currently performed in clinics [37]
Bone normalized histograms of the IVD In the annulus fibrosus (AF), significant differences were found in the standard deviation, standard error, maximal voxel count in an intensity interval, median, 75th percentile and Kolmogorov-Smirnov distance between the control and the groups with spinal deformity (Table 2)
Summary
Stages of scoliosis and spondylolisthesis entail changes in the intervertebral disc (IVD) structure and biochemistry. This study aims to develop the AMRSID (analysis of MR signal intensity distribution) method to analyze the 3D distribution of the MR signal intensity within the IVD and to evaluate their sensitivity to scoliosis and spondylolisthesis and their severities. Spinal deformities such as scoliosis and spondylolisthesis affect both the structural and the biochemical composition of the intervertebral disc (IVD) [1,2] and lead to its degeneration. Analysis of T2weighted images can help to detect early signs of disc degeneration [4,32] but the current clinical use of T2weighted images is for the detection of late stages of the spine pathologies [30]
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