Leverage of applying diffusion tensor imaging (DTI) indices in assessment of cervical spondylotic myelopathy

Abstract

Abstract Background Cervical spondylotic myelopathy (CSM) is the most prevalent form of dysfunction in the cervical cord. For best results, CSM must be identified and treated quickly, before spinal cord injury develops. We aimed at determining the diagnostic value of quantitative and qualitative diffusion tensor imaging (DTI) indices in the assessment of CSM. Thirty patients were included in this prospective study with clinically suspected CSM of both sexes. This study aimed at determining the diagnostic value of quantitative and qualitative DTI indices in early assessment of CSM and subsequently early and proper management decision rendering better clinical outcome. Results This prospective study included 30 patients: with clinically suspected CSM with a mean age of 51.88 ± 10.28 years. Patients with CSM were graded to 3 grades, mild (No. = 17), moderate (No. = 13) and severe (No. = 0) according to the modified Japanese orthopedic association (mJOA) grading system. Correlation test was performed between mJOA grades of severity with fractional anisotropy (FA), apparent diffusion coefficient (ADC) and T2 cord signal. We found a negative correlation between ADC and FA with Spearman’s rho value of − 0.612 and “P value 0.000” (P value < 0.05), a positive correlation between FA with mJOA clinical score with Spearman’s rho value of − 0.504 & “P value 0.036” (P value < 0.05) and a negative correlation between ADC and mJOA clinical score with Spearman’s rho value of 0.385 and P value 0.005 (P value < 0.05), and no significant correlation was found between mJOA clinical score and T2 hyperintense signal with Spearman’s rho value of − 0.304 and “P value 0.102” (P value < 0.05). Qualitative maps grading by 3D tractography images were done, and 18 patients in the study (60%) showed homogenous intact fiber tracts (grade I), 9 patients (30%) showed reduction or alteration of anisotropy or mixed colors intensity (grade II), and 3 patients (10%) showed fiber tract disruption or displaced cord (grade III). Three DTI parameters (other than FA and ADC) were measured, and two of them show significant difference between their measures in the stenotic and non-stenotic portions of the spinal cord—RA (P value = 0.00) and RD (P value = 0.00). Conclusions We concluded that DTI is a crucial tool for early diagnosis and grading of CSM (cervical spondylosis myelopathy)—quantitatively and qualitatively—hence, it should be routinely integrated with conventional cervical spine MRI in case of clinically or radiologically suspected cervical cord compression, as the FA parameter together with the clinical assessment formulates the management plan decision for the CSM whether surgical or non-surgical and depicts the need for early surgical decision rendering better clinical outcome compared to that based on T2 hyperintense cord signal.

Keywords

• Diffusion tensor imaging
• Myelopathy
• Cervical spondylotic myelopathy
• CSM
• DTI