Objective To study the mechanism and the nomenclature of the lumbar disk herniation associated with posterior bony edge separation of the vertebral body, based on its CT findings in transverse and sagittal planes. Methods 18 patients with lumbar disk herniation were evaluated with the CT scan and sagittal reconstruction. Results There were 19 lumbar herniated disks associated with separated posterior bony edge of the vertebral body which protruded into the spinal canal. There was bony defect filled with disk material. In the sagittal plane, the bony separation and the posterior edge of the vertebral body formed the “V” type defect at 15 levels, and 4 were irregular or triangular. 15 cases of the disc herniation had bony separations and 4 had bone connection with the vertebral body. There were bony defect and sclerosis on the vertebral body edge. Conclusion The main mechanism was the separation compression of the herniated disk on the posterior vertebral body. The bony separation was the secondary change. So the authors suggest that such anatomical pathologic changes be named as intervertebral disk herniation associated with posterior bony separation of the lumbar vertebrae.

Objective To analyze the radiological findings of dedifferentiated chondrosarcoma, and to explore the imaging features of dedifferentiated tissue. Methods The X-ray and CT findings of 13 cases with dedifferentiated chondrosarcoma of bone were analyzed retrospectively, and studied with clinic and corresponding histological changes. Results The dedifferentiated chondrosarcoma not only had the radiological findings of typical chondrosarcoma but also had the imaging features of dedifferentiated tissues. In 13 patients, periosteal reactions were found in 11 cases, ossifications in 8 cases, soft tissue masses in 12 cases, calcifications in 10 cases, and the site of calcifications in 8 cases was in the center of the focus. Conclusion The dedifferentiated chondrosarcoma showed special imaging features, which includes ossification, calcification, periosteal reaction, and soft tissue mass. These features were not found in typical chondrosarcoma. Recognizing these specific features is helpful to the diagnosis of dedifferentiated chondrosarcoma.

Objective To retrospectively analyze the MRI findings of epithelioid angiomyolipoma (EAML) of the liver.Methods The MR findings in a series of 8 patients with pathologically proven liver EAML were retrospectively analyzed. Distribution of lesions, signal intensity characteristics, tumor vascularity,feeding arteries and draining veins, fat, hemorrhage, cystic necrosis and pseudocapsule formation were evaluated and correlated with pathology.Results A single lesion was found in each of the 8 patients.All eight lesions showed long T1,long T2 inhomogeneous signal,and high DWI signal. There was only 1 lesion presented with fat,3 lesions presented with hemorrhage. On the dynamic contrastenhanced MRI scan,all 8 lesions manifested as hypervascular with tortuous vasculature in 7 patients.Dilated feeding arteries and draining veins were seen in 5 patients. Conclusion Liver EAML has unique MR imaging features,exhibiting hyperwascular lesions with dialated,tortuous feeding arteries,and draining veins on DCE MRI,which could be helpful in the differential diagnosis of liver EAML.