| Part Ⅰ Application value of quantitative evaluation of dynamic magnetic resonance imaging in the diagnosis of Hirayama disease.Objective: To explore the value of quantitative assessment of dynamic magnetic resonance imaging in the diagnosis of Hirayama disease.Methods: The clinical and imaging data of patients diagnosed with Hirayama disease(HD)(patient group)in Tongji Hospital of Wuhan from 2012 to 2019 were compared and analyzed,and the cervical MRI data of flexion and neutral position of young men around 20 years old(control group)were also compared and analyzed.We used independent sample t test(normal distribution)or Mann-Whitney rank sum test(non-normal distribution)to compare the age and measured values of d、LDS、D、AP、TR、d/D、LDS/D and AP/TR between the patient group and the control group.The differences between the measured values of d,D,AP,TR,d/D and AP/TR of the neutral position between the patient group and the control group were also compared.Paired sample t test(normal distribution)or Wilcoxon signed ranks test(non-normal distribution)were used to compare the measured values of d,D,AP,TR,d/D and AP/TR between the flexed and neutral positions of the patient group.Differences in d,D,AP,TR,d/D,and AP/TR between the flexed and neutral positions of the control group were also compared using the same way.Gender differences between the two groups were compared using Fisher’s exact probability method.The ROC curve was drawn to evaluate the diagnostic efficacy of measured values of d,d/D,LDS,LDS/D,AP,AP/TR in flexional position for Hirayama disease.The consistency of the two physicians’ measurements was evaluated by intraclass correlation coefficient(ICC).ICCI(29)0.75 indicated good consistency.Results: 1.35 patients in the patient group showed anterior displacement of the posterior wall of the dural sac in flexion position,compared with 77.8%(21/27)in the control group.The flexion MRI showed that d,LDS,LDS/D,d/D,and TR were larger in the patient group than that in the control group(P(27)0.05);The AP and AP/TR in the patient group were smaller than those in the control group(P(27)0.05);No significant difference was observed in gender,age,and D between the patient groups and control group(P(29)0.05).2.Neutral MRI showed that no significant anterior displacement of the posterior wall of the dural sac was observed in the patient group and the control group;The AP and AP/TR in the patient group were smaller than those in the control group(P(27)0.05);No significant difference was observed in d,D,d/D,and TR between the patient group and the control group(P(29)0.05).3.Compared with the patient group in the neutral position,the d,d/D increased,and the AP/TR decreased in the flexional position(P(27)0.05).On the control group,the d and d/D increased(P(27)0.05),but AP/TR did not decrease significantly(P(29)0.05).4.The ROC curve was drawn with d,d/D,LDS,LDS/D,AP,AP/TR as diagnostic indicators.AP,AP/TR have better sensitivity,and LDS,LDS/D have better specificity.Conclusions: 1.Anterior displacement of the posterior wall of the dural sac is not a specific sign of HD,but the laminodural space(LDS),degree(LDS/D)of anterior displacement of the posterior dural sac,the posterior edge of the spinal cord to the spinal canal(d)and degree(d/D)of flexional cervical spine in HD patients are more significant than normal people.And patients have atrophy(AP)and flattening(AP/TR)of the lower cervical spinal cord.2.Cervical spine MRI in the neutral position cannot show the posterior wall displacement of the dural sac in HD patients.Spinal cord atrophy and flattening of spinal cord in HD patients are more obvious than in normal people.3.HD patients changed from the neutral position to the flexion position,the distance and extent of posterior edge of spinal cord to spinal canal were significantly increased compared with normal people,and the spinal cord was compressed and flattened.There was no obvious spinal cord compression and flattening in this process in the control group.4.Cervical spine flexion MRI observation of spinal cord atrophy and flattening has a good sensitivity for the diagnosis of HD,and the distance and degree of anterior displacement of the posterior wall of the dural sac have good specificity for the diagnosis of HD.Combined anterior shifting of posterior dural sac and compression of the spinal cord are more adequate for the diagnosis of HD.Part Ⅱ Quantitative study of the effects of cervical spine magnetic resonance at different flexion angles on signs of Hirayama diseaseObjective: To study the influence of cervical spine magnetic resonance at different flexion angles on the characteristic signs of Hirayama disease(HD)in a quantitative manner.Methods: Retrospectively analyzed the neutral and flexional cervical spine imaging data of patients diagnosed with Hirayama disease from 2012 to 2019.The cervical spine flexion MRI was divided into a small angle group and a large angle group with a 20 ° flexion angle as the boundary.Use independent sample t test(normal distribution)or Mann-Whitney rank sum test(non-normal distribution)to compare the age and measured values of d,D,AP,TR,d/D and AP/TR in neutral position between the large and small angle group.The same methods compare the differences in d,LDS,D,AP,TR,d/D,LDS/D and AP/TR in flexion position between the large and small angle group.Paired sample t test(normal distribution)or Wilcoxon signed ranks test(non-normal distribution)were used to compare the measured values of d,D,AP,TR,d/D,AP/TR,LDS and LDS/D between the neutral and flexion position of the large and small angle group,respectively.Gender difference between large and small angle group was compared using Fisher’s exact probability method.The consistency of the two diagnosticians’ measurements was evaluated by intraclass correlation coefficient(ICC).Results: The two doctors had good consistency in measuring d,LDS,D,AP,and TR,and the ICC values were all larger than 0.75(P(27)0.05).In the large and small angle group,no obvious anterior displacement of the posterior wall of the dural sac was observed,and the LDS count was zero.There were no significant differences in gender,age,d,D,AP,TR,d/D,AP/TR between the two groups(P>0.05).In the flexion position,LDS,LDS/D,and d/D in the large angle group were larger than those in the small angle group(P(27)0.05).No significant difference was seen in d,D,AP,TR,AP/TR in flexion position between the large and small angle group(P> 0.05).Compared with the neutral position,the d,LDS,d/D,and LDS/D in the large angle group were significantly higher than the flexional position(P(27)0.05).No significant difference was seen in D,AP,TR,AP/TR between different positions of the large angle group(P>0.05).Compared with the neutral position,the d,LDS,d/D,and LDS/D in the small angle group were higher than the flexional position(P(27)0.05).No significant difference was observed in D,AP,TR,AP/TR between different positions in the small angle group(P> 0.05).The increase of d,LDS,d/D,and LDS/D in the different positions of the large angle group was higher than that of the small angle group.Conclusion: The flexion angle of cervical spine in patients with Hirayama disease has an influence on the observation of characteristic signs.The flexion angle of cervical spine in patients with Hirayama disease should be standardized.The 20 ° ～ 30 ° flexion angle is more conducive to the diagnosis of Hirayama disease. |
