Quantitative Assessment Of Cervical Alignment In Hirayama Disease Using Magnetic Resonance Imaging

Purpose: We describe the radiographic characteristics of Hirayama disease using MRI in neural position.To evaluate the cervical alignment,We use the Borden method and introduce cervical sagittal parameters to quantify the cervical deformities.We try to reveal the correlation between the radiographic characteristics and the underlying mechanism.Materials and methods: 21 healthy teenagers and 21 patients with hirayama disease were recruited into the control group and patient group.MR imaging of the cervical spine was performed in neutral position for all subjects,with the following parameters measured: cervical sagittal parameters(thoracic inlet angle(TIA)、neck tilt(NT)、T1 slope(T1S)),Arc chord distance、disc-facet orientation;Results:(1)Loss Of Attachment(LOA)is the significant predictor of Hirayama disease,with the specificity of 86,36%,sensitivity of 90%,positive predictive value of 85.70%,negative predictive value of 90.50%;The high signal intensity in T2 WI MRI images also has significance in the diagnosis of Hirayama disease.Sensitivity,specificity,positive predictive value,negative predictive value,were 80.95%,95.24%,94.44%,83.33%,respectively.(2)The disc-facet angle of the hirayama disease group are greater than that of the control group.(p<0.05)The ROC curve of the disc-facet angle is obtained and AUC of C4、C5、C6、C7 disc-facet angle is 0.62,0.88、0.79,0.96,respectively.We calculate the Youden index and the cut-off value of C4,C5,C6,C7 disc-facet orientation is 126.86°、128.26°、121.63°、119.15°,respectively.(3)The arc chord distance in the patient group is about 1.96±2.83 cm,compared to that of control group,8.52±1.91.(4)TIA,NT,T1 S in the patient group is 35.79【32.45,43.56】、15.66【12.89,20.74】、48.64【46.90,56.13】,in the control group,TIA、NT、T1S is 43.96【39.24,54.90】、24.04【21.48,25.33】、62.77【59.08,73.72】,respectively.TIA,NT,T1 S is less than that in the control group.Conclusion: Among the MR imaging finding in neutral position,the decrement of T1 S,NT,TIA indicates the disappearance of cervical lordosis.The increment of the disc-facet orientation in Hirayama group relates to the insability of the facet joint,which may contribute to the change of the cervical alignment.