| Objective1. To analyse the correlation of intervertebral disc degeneration with the blood perfusion of its superior border and inferior border of vertebral body by dynamic contrast-enhanced MRI.2. The purpose of this study is to evaluate the distribution of endplate edema in different types of Modic change especially in mixed type and to analyze the presence of endplate sclerosis in various types of Modic change.Materials and methods1.3.0 T-MR examinations were performed in 28 patients (90 disks). Intervertebral disks from L1 to L5 were classified to normal group and degeneration group based on the Pfirrmann grading system. The DCE-MRI pharmaeokinetic parameters of the ROI(region of interest):Ktransvolume transfer constant), BV(blood volume), BF(blood flow) were obtained. Independent sample t test was used between normal group and degeneration group.2.276 patients with low back pain were scanned with 1.5T MRI.3 radiologists assessed the MR images by T1-weighted, T2-weighted and fat-saturation T2-weighted sequences and classified them according to the Modic changes. Pure edematous endplate signal changes were classified as Modic type Ⅰ, pure fatty endplate changes as Modic type Ⅱ, and pure sclerotic endplate changes as Modic type III. A mixed feature of both type Ⅰ and Ⅱ with predominant edematous signal change is classified as Modic Ⅰ-Ⅱ, and a mixture of type Ⅰ and Ⅱ with predominant fatty change is classified as Modic Ⅱ-Ⅰ. Thus, the mixed types can be furtherly subdivided into 7 subtypes, type Ⅰ-Ⅱ, type Ⅱ-Ⅰ, type Ⅰ-Ⅲ, type Ⅲ-Ⅰ, type Ⅱ-Ⅲ, type Ⅲ-Ⅱ and type Ⅰ-Ⅱ-Ⅲ. During the same period,52 of 276 patients who underwent CT and MRI were retrospectively reviewed to determine endplate sclerosis.Results1. The mean Ktrans, BV and BF of the superior border of vertebral body in normal group (n=41)were (0.0371±0.0102) min-1, (4.89±1.14) ml/100ml, (5.93±1.28) ml/min/100ml, the mean Ktrans, BV and BF of the inferior border of vertebral body in normal group (n=41)were (0.0402±0.0116) min-1, (5.21±0.98) ml/100ml, (6.12±1.24) ml/min/100ml. The mean Ktrans, BVand BFof the superior border of vertebral body in degeneration group (n=49) were (0.0313±0.0107) min-1, (4.12±1.28)ml/100ml, (4.91±1.55)ml/min/100ml, the mean Ktrans, BVand BF of the superior border of vertebral body in degeneration group (n=49) were (0.0327±0.0129)min-1,(4.04±1.19)ml/100ml,(4.89±1.32)ml/min/100ml. (1) There were no significant differences between superior border and inferior border of vertebral body in Ktrans, BV and BF in normal group(t=-2.52、-1.36、0.68 separately, P>0.05). (2) There were no significant differences between superior border and inferior border of vertebral body in Ktrans, BV and BF in degeneration group(t=-0.59、0.32、0.069 separately, P>0.05). (3) There were significant differences between normal group and degeneration group in Ktrans, BV and BF. (t=3.79、3.80、3.83 separately, P<0.05).2. (1) Endplate edema:Of the 2760 endplates (276 patients) examined 302 endplates showed Modic changes of which 82endplates showed mixed Modic changes.The mixed Modic changes contained 92.7% of edematous changes. The mixed types especially type Ⅰ-Ⅱ and type Ⅱ-Ⅰ made the majority of endplate edematous changes.(2) Endplate sclerosis:52 patients of 276 patients were examined by both MRI and CT. Of 520 endplates 93 showed Modic changes, of which 34 endplates have shown sclerotic changes in CT images.11.8% of 34 endplates have shown Modic type Ⅰ,20.6% of 34 endplates had shown Modic type Ⅱ,2.9% of 34 endplates have shown Modic type Ⅲ, and 64.7% of 34 endplates have shown mixed Modic type.Conclusion1. The bone marrow perfusion in degeneration group was decreased compared to normal group with dynamic contrast-enhanced MRI. Intervertebral disc degeneration correlates with the loss of its blood supply.2. Endplate edema makes up the majority of mixed types especially type Ⅰ-Ⅱ and type Ⅱ-Ⅰ. The endplate sclerosis on CT images may not just mean Modic type Ⅲ but do exist in all types of Modic changes, especially in mixed Modic types, and may reflect the vertebral body mineralization rather than the change in the bone marrow. |
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