MR T₂* Mapping Technique For The Quantitative Evaluation Of Lumbar Facet Joint Degeneration

The first research: The correlation between MRI radiographic grading and T₂*values of lumbar facet joints degeneration.Objective: We aimed to explore the feasibility and value of MR T₂*mapping in quantitatively analyzing the early degeneration of lumbar facet joints.Methods: Fifty-one patients with chronic lumbago and 17 healthy volunteers were involved in the study.3.0T MRI was used to acquire the axial T₂ WI and T₂*mapping images of the L1^S1 facet joints.The axial T₂ WI images used for grading the lumbar facet joints based on Weishaupt criterion.And the T₂*mapping images were to measure the T₂*values of lumbar facet joints' cartilage.The datas were for statistical analysis finally.Results:There was no significant difference in the T₂*values of the lumbar facet joint cartilage between patients and healthy volunteers?P>0.05?.The results of one-way analysis of variance?one-way ANOVA?of the mean T₂*values of facet cartilage graded by Weishaupt in patients showed that there were statistical significance between grade 1 and grade 2?P=0.001?,grade 1 and grade 3?P=0.001?,but there were no significant differences?P>0.05?between grade 1 and grade 4,grade 2 and grade 3,grade 2 and grade 4,and grade 3 and grade 4.Conclusion: The MR T₂*mapping has implicative value in quantitatively evaluating the early degeneration of lumbar facet joints.The second research: The correlation between CT combined with MRI radiographic grading,pathological grading and T₂*values of lumbar facet joints degeneration.Objective: We aimed to explore the relationship between radiographic criteria,pathological criteria,and T₂*alues to assess the feasibility and value of T₂*mapping for quantitatively assessing early LFJD in the current study.Methods: Seventy facet joints from 67 patients diagnosed with lumbar spinal stenosis or lumbar disc herniation or acute lumbar vertebral fractures requiring posterior lumbar surgery were included.All patients underwent computed tomography?CT?and magnetic resonance imaging?MRI?before surgery.The axial CT images,T₂-weighted images?WIs?,and T₂*mapping images of the L1^S1 facet joints were obtained.The axial CT and T₂ WI images were used for grading the LFJs by using Weishaupt's criteria.The T₂*values of the LFJ cartilage were measured from the T₂* maps.The LFJs pathological sections which obtained after decalcification and HE staining were used for grading the LFJs by using Gries criteria.Results: Moderate consistency was noted between the pathological and radiographic grades of LFJD?weighted kappa coefficient 0.578?.Both pathological and radiographic grade showed a trend of increased mean T₂* values of the LFJ cartilage from grade 1 to grade 3?Gries?was noted;the values decreased at grade 4.The results of one-way ANOVA among T₂* values in different radiographic grades demonstrated that there were no significant differences between grades 1 and 2?P=0.666?,grades 1 and 4?P=0.074?.But there were statistically significant differences between grades 1 and 3?P=0.043?,grades 2 and 3?P=0.023?,grades 2 and 4?P=0.020?,and grades 3 and 4?P=0.001?.The results of one-way ANOVA among T₂* values in different pathological grades demonstrated that there were no significant differences between grades 1 and 4?P=1.000?,2 and 4?P=0.878?,and 3 and 4?P=0.279?.However,there were statistically significant differences between grades 1 and 2?P<0.001?,1 and 3?P<0.001?,and 2 and 3?P=0.042?.Conclusions: T₂* mapping is a potentially feasible and utility technique for quantitatively evaluating the early and medium degeneration of LFJ cartilage.