Abstract:
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Purpose: Uniform filling of bone cements within the vertebral bodies without leakage is ideal on percutaneous vertebroplasty. In this study, we correlated the distribution patterns of injected PMMA cements with MR findings, and also evaluated the way to predict the leakage of cements on vertebroplasty.
Methods and Materials: We treated 30 vertebral bodies in 20 patients. The causes of fractures were osteoporosis (28 vertebral bodies in 18 patients) and metastasis (2 in 2). The distribution of injected cements were classified into 3 patterns based on CT and plain films; trabecular (when cements spread in the fine bony trabeculae), solid (when cements form a mass ) and mixed (when trabecular and solid patterns mix). The vertebral lesions were also classified into 4 patterns based on MR findings. 1. Acute changes (edema or inflammation); low signal on T1-weighted images with contrast enhancement. 2. Chronic changes (sclerosis or necrosis); low signal on T1- and T2-weighted images without contrast enhancement. 3. Cleft; oval or tear-drop shaped region showing high signal on T2-weighted images. 4. Metastatic tumors; masses with contrast enhancement. We examined the relationship between the distribution patterns of cements and the leakage of cement into the disks or veins, or outside the vertebral bodies, and also correlated them with MR findings.
Results: All vertebral bodies showed acute changes on MR imaging but often mixed with chronic changes and/ or clefts. The cement distribution with primarily trabecular pattern was noted in 14 vertebral bodies, and injected cement was uniformly filled in the area of contrast enhancement. Primarily solid pattern was seen in 3 vertebral bodies; 2 in metastatic lesions and one is osteoporonic lesion. Mixed pattern was noted in 13 vertebral bodies. In these lesions, cement was mainly distributed in the area of contrast enhancement, but solid distribution was noted in the parts of chronic changes or in the cleft. When cleft or chronic changes were present, cements often tended to fill them first, and then extend into the areas of contrast enhancement, making a mixed pattern. Cement leakage into the disks, veins and paravertebral structures was observed in 10 vertebral bodies, 2 with trabecular pattern and 8 with mixed pattern. Such leakage was mainly observed in the vertebral bodies with the chronic changes and clefts.
Conclusion: Distribution of cements during vertebroplasty may be predicted from MR findings; thus we can accomplish better cement filling on vertebroplasty and reduce the risk of cement leakage.
Oka MD, M,
Cement Distribution Patterns on Percutaneous Vertebroplasty; Correlation with MR Findings. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3106202.html
