| Objective To investigate the size of spinal cord buffer space on MRI of patients with ossification of the ligamentum flavum of the thoracic spine by measuring the MRI spinal cord morphology(sagittal diameter,transverse diameter),spinal cord area,and spinal canal area in thoracic ligamentum flavum patients and normal subjects.And the correlation between spinal canal encroachment rate,spinal cord morphology change rate with spinal cord area change rate and preoperative JOA score,respectively,and postoperative improvement rate to discuss the correlation between MRI image measurement indicators and clinical evaluation.Methods A retrospective study of 40 patients were diagnosed with ossification of the thoracic ligamentum flavum in the General Hospital of NingXia Medical University from January 2014 to February 2018 as a case group,including 22 males and 18 females,age range27-77 years old,the average age is 58.45±11.47 years old.General clinical data,clinical signs and symptoms,affected segments,preoperative and postoperative JOA scores were recorded.Randomized collection of 40 patients with no thoracic spinal stenosis in the image database of the General Hospital of NingXia Medical University as a control group,including 22 males and 18 females,aged range 29-74 years old,with an average age of 52.95±13.17 years old.The PACS imaging software of our hospital was used to measure the sagittal diameter,transverse diameter,spinal cord area,spinal canal area and ossification area of the ligamentum flavum in each cross section of the T1-T12 intervertebral disc level on the MRI of the case group and the control group.The differences in the size of the spinal cord buffer space at the corresponding segment of the case group and the control group were comparedand analyzed.The case group was divided into a mild group(9-11 points)and a moderate-to-severity group(0-8 points)according to the preoperative JOA score.The values of spinal canal encroachment rate,spinal cord morphology change rate and spinal cord area change rate were calculated,and the differences in spinal canal encroachment rate,spinal cord morphology change rate and spinal cord area change rate,respectively,were compared between the mild group and the moderately-to-severe group.The correlations between spinal canal encroachment rate,spinal cord morphology change rate with spinal cord area change rate index were compared and preoperative JOA score,respectively,and postoperative improvement rate.Results 1.The size of the spinal cord buffer space in the corresponding horizontal segment of the case group and the control group was 159.78mm±14.24 mm and158.68mm±12.12 mm,respectively.There is no statistically significant difference between the two groups(t=0.922,P= 0.357).In the case group,the size of the spinal cord buffer space in the lesion and the corresponding horizontal segmental spinal cord cushioning space in the control group were 62.77 mm±40.72 mm and 169.41 mm±18.30 mm,respectively.The spinal cord buffer space of the case group is significantly smaller than that of the normal group.There is significant difference between the two groups(t=24.719,P=0.00).2.The preoperative JOA score range of the case group was 3-10 points,with an average of 6.33±2.07 points.There are 8 patients in the mild group and 32 patients in the moderate-to-severe group.The mean values of spinal canal encroachment rate of the two group are 31.25%±11.71% and73.75%±18.63%,respectively.The rate of spinal canal encroachment in the mild group was significantly lower than that in the moderate-to-severe group.There is significant difference between the two groups(t =-4.117,P=0.00).The mean values of spinal cord morphological changes rate of the two group are 4.50%±0.10% and 12.94%±12.78%,respectively.The morphological change rate of the spinal cord in the mild group was significantly lower than that in the moderate-to-severe group.There is a statistically significant difference between thetwo groups(t=-2.063,P=0.039).The mean values of the spinal cord area change rate of the two group are 5.25%±13.43.%,13.63%±22.00%,respectively.The rate of spinal cord area change in the mild group is significantly lower than that in the moderate-to-severe group,and there is a statistically significant difference between the two groups(t=-2.435,P=0.015).The range and mean of spinal canal encroachment rate in the case group is: 16%-109%,66.85%±25.01%,respectively,which is negatively correlated with preoperative JOA score(R=-0.893,P=0.00);the range and mean of spinal cord morphological change rate is-36%-29%,11.25%±12.60%,respectively.And there is no correlation with preoperative JOA score(R=-0.184,P=0.255);the range and mean of spinal cord area change rate is-22%-66%,9.85%±21.81%,respectively.which is negatively correlated with preoperative JOA score(R=-0.673,P=0.00).The average postoperative JOA score in the case group was 8.64±2.28,and the postoperative recovery rate is 77.27%(17/22).There is a negative correlation between spinal canal encroachment rate and postoperative recovery rate in the case group(R=-0.707,P=0.00).There is no correlation between spinal cord morphological change rate and postoperative recovery rate(R=0.130,P=0.565);spinal cord area change rate is inversely correlated with the rate of recovery(R =-0.432,P = 0.045).Conclusion 1.The rate of spinal canal encroachment and spinal cord area change are negatively correlated with the preoperative JOA score,which could reflect the severity of clinical symptoms and signs.There is no correlation between the rate of spinal cord morphological changes and the preoperative JOA score,which can not reflect the severity of clinical symptoms.2.The rate of spinal canal encroachment and spinal cord area change is negatively correlated with the postoperative recovery rate,wich can judge the prognosis of patients.The rate of morphological changes in the spinal cord is not correlated with the postoperative recovery rate,and the prognosis could not be judged. |
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