imaging features of myositis ossificans have some characteristics. Misdiaguosis could be avoided when the disease was evaluated with the course.

Objective To observe the imaging features of intraosseous ganglion of the wrist. Methods The radiographs (6 cases), CT (4 cases), and MR (1 case) in 6 cases (7 lesions) of surgically confirmed intraosseous ganglion were retrospectively reviewed. Results Typical intraosseous ganglion was seen as sharp margined and cystic lesion with the size of approximately 0.5 cm in diameter. All but one lesion showed no communication with joint. No degenerative changes were seen in the joints nearby. CT was able to depict the lesions better than radiographs in 4 cases. Intraosseous ganglion was seen as slight low signal on T 1WI and slight high signal on T 2WI MR images. Conclusion Intraosseous ganglion was typically seen as sharp-margined and cystic lesion on radiographs, and it could be better demonstrated with CT and MR. With typical imaging appearance, a suggestion to the diagnosis of intraosseous ganglion could be made.

Objective To evaluate the diagnostic value of CT myelography (CTM) in brachial plexus injury. Methods Twenty-seven patients with brachial plexus injury were examined by using cervical CTM with spiral scan and bone reconstruction algorithm. CT images were reviewed by the senior radiologists, who determined if the nerve root avulsion was presented. The criteria of diagnosing nerve root avulsion were loss of normal nerve root appearance in the Isovist filled thecal sac in consecutive CTM slices plus companion signs. The sensitivity, specificity, and accuracy of CTM in diagnosing nerve root injuries were calculated with operation findings and follow-up results as gold standard. Results Direct sign of nerve root avulsion was the loss of normal nerve root defect seen in the Isovist filled thecal sac in consecutive CTM slices. Indirect signs included: (1) Pseudomeningocele bulge: The leak of Isovist into nerve root sheath, and extended into foramina; (2) Arachnoid cyst: displacement of spinal cord; (3) Dissymmetry of subarachnoid cavity: deformity of thecal sac, partially lack of Isovist into arachnoid space; (4) Non-integrity of dural capsule wall: one side of capsule cavity was obstructed. Part of the surface of spinal cord was exposed. Brachial plexus injury could be diagnosed by direct sign with one of the indirect signs. Of the 27 patients (128 nerve roots), 91 nerve root avulsions were found on CTM, and 37 was found normal. Compared with operation findings, 84 were true positive, 7 false positive, 34 true negative, and 3 false negative. Based on these results, the sensitivity, specificity, and accuracy were 96.6%, 82.9%, and 92.2%, respectively. Conclusion CTM is accurate in detecting nerve root avulsion of brachial plexus.

Objective To study the Gadolinium-enhanced MRI and diffusion weighted imaging (DWI) characteristics of the chondroid matrix-forming sarcomas.Methods Contrast-enhanced MRI and DWI were performed in 14 eases of chondroid matrix-forming sarcomas (10 chondrosarcomas,4 chondroblastic esteosarcomas) and 13 cases of other types of osteosarcomas.DWI was obtained with a single-shot echo-planar imaging (EPI) sequence using a 1.5 T MR imager with two different b values of 0 and 700 s/mm2.The apparent diffusion coefficient (ADC) values were obtained in GE Functiontool software.The contrast-enhancement pattern was evaluated and the ADC values of ehondroid matrix-forming sarcomas was compared with that of other types of asteosarcoma.Independent sample t-test was performed to evaluate the difference of ADC values between the group of chondroid matrix-forming sarcoma and the group of other types of osteosarcoma.In addition, nonparametrie test was used to assess the difference of ADC values between the chondrosareoma and the chondroblastic osteosarcoma.P value less than 0.05 was considered to represent a statistical significance.Results For 14 eases of ehondroid matrix-forming sarcomas, peripheral enhancement was found in all cases, septonodular enhancement was identified in 12 cases.While 13 eases of other types of osteosarcowas demonstrated heterogeneous enhancement.The mean ADC value of chondroid matrix-forming sarcomas [(2.56 ±0.35) × 10 -3 mm2/s] was significantly higher than that of other types of osteosarcoma [( 1.16±0.20) × 10-3 mm2/s] (t = 12.704,P <0.O1 ).There was no significant difference in the ADC value between the chondrosarcoma and the chondroblastie osteesarcama(Z =0.507 ,P =0.959).Conclusion Contrast-enhanced MRI and DWI can improve differentiation between chondroid matrix-forming sarcomas and other types of osteosarcomas.

Objective: Our purpose was to study the relationship between the Fas antigen expression and neuron apoptosis after cerebral ischemia. Methods: We detected the Fas antigen expression and neuron apoptosis dynamically in the animal models with cerebral ischemia by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method. Results: Fas antigen was positive after 30 minutes of ischemia and reached peak at 60 minutes. At the 24th hour, it began to decrease, and negative on the 3th day. While the positive cell for TUNEL method appeared after 60 minutes of ischemia, reached peak on 3 day, and decreased on 7 day. Conclusion: Neuron apoptosis after cerebral ischemia is closely related to the over-expression of Fas antigen.

ObjectiveTo evaluate the relationship between the proliferation of parathyroid cell in rabbit with primary hyperparathyroidism (PHPT) and the bone mineral density (BMD). MethodsEighty adult Chinese rabbits were randomly and equally divided into two groups. The contrast group was fed with normal diet ( Ca ∶ P, 1.0 ∶ 0. 7 ) and the experimental group was fed with high phosphate diet ( Ca ∶ P,1.0∶7.0) to establish the animal model of PHPT. At 3, 4, 5, and 6 months after the diet, bone mineral density of the rabbits was measured by the quantity CT (QCT). Then, the parathyroid and bone of the rabbits were removed for pathological examination. The number of parathyroid cell in PHPT was calculated.Proliferation was determined by immunohistochemistry of proliferation cell nuclear antigen ( PCNA ) and Bcl-2. The t test and Logistic regression was used to analyze the difference of data of two groups. ResultThe number of parathyroid cell in PHPT group was 1.61 times than that in the contrast group[ (673 ± 151 ) HP,(418 ± 25 ) HP,P ＜0. 01]. The rate of PCNA positive-cell was significantly increased in PHPT group than that in contrast group [(50.52 ± 11.62)％o, (26.70 ± 2. 78 )％, P ＜ 0.01], and so was Bcl-2[ (460. 37 ± 190. 05 )‰, (67. 02 ±:4. 38 )％‰,P ＜0. 05]. The value of BMD was significantly decreased in PHPT group than that in contrast group [ ( 152. 5 ± 34. 3 ), ( 188.6 ± 12. 2 ) g/cm3, P ＜ 0. 05]. There was a negative correlation between BMD and PCNA (r ＝ -0. 749, P ＜ 0. 05 ) and between BMD and Bcl-2 (r ＝-0.800, P ＜ 0. 05 ) in PHPT group. ConclusionThe BMD of PHPT is related to the parathyroid cells proliferation which provide a reliable method for early diagnosis of PHPT.

Objective To explore the findings of diaphysial osteosarcoma in long bone on X-ray,CT and MRI, and discuss their clinical features and manifestations for differential diagnosis. Methods Twenty-eight cases with diaphysial osteosarcoma in long bone proved by surgery and pathology were reviewed retrospectively. Eighteen tumors were located in the femur, 4 in fibula, 4 in humerus and 2 in tibia. All of the patients were examined by X-ray, CT and MRI. The imaging manifestations on X-ray, CT and MRI were analyzed, and the relationship of the imaging features with the pathological types was also observed. The imaging signs were correlated with the pathologic findings with a double blind method. Results Of the 28 cases, there were 16 cases with large bone destruction, 22 cases with periosteal reaction on X-ray and CT. On X-ray, 18 cases showed soft tissue mass and 12 cases with neoplastic bone and tumor calcification.While on CT, 22 cases showed soft tissue mass on plain scan and 2 more cases displayed soft tissue mass after the injection of contrast mediun. Sixteen cases showed neoplastic bone and tumor calcification on CT.On MRI, there were 10 cases with bone destruction and periosteal reaction with iso- and hypo-intense on T1WI and iso- signals on T2WI. Twenty-six cases showed soft tissue edema and bone marrow on MRI. The soft mass were iso-signals on T1 WI and iso-hyperintense signals on T2 WI or STIR. The soft tissue edema was found hyperintense signals on T2WI or STIR. The lesions had heterogeneous enhancement especially in bone marrow with edema and adjcent soft tissue. Conclusion The X-ray, CT and MRI can reflect the pathological changes of diaphysial osteosarcoma in long bone from different aspects. Lower incidence, large bone destruction and no pathological fracture were the features of diaphysial osteosarcoma. The osteogenic type is diagnosed easily, but the osteolytic lesion should be differentiated from Ewing sarcoma, malignant giant cell tumor of bone and so on.

Objective To investigate the relationship between the sensitivity of gastric cancer cells to arsenic trioxide（As2O3）and the level of reactive oxygen species（ROS）production.Methods The viability of gastric cancer cell lines MGC803,BGC823 and SGC7901 treated with As2O3 was determined by MTT assay.ROS levels of the gastric cancer cells before and after the treatment of As2O3 were detected by flow cytometry.Results Cell growth was significantly inhibited by As2O3 in time-and dose-dependent manner in three gastric cancer cell lines.The IC50（72 h）of As2O3 for MGC803,BGC823 and SGC7901 was about 2.8,3.1 and 10.2 μmol/L,respectively.IC50（72 h）of MGC803 and BGC823 was lower than that of SGC7901（P 0.01）,gastric cancer cell line SGC7901 was less sensitive than the others.The inherent ROS level of MGC803,BGC823 and SGC7901 was 20.3±2.0,64.2±3.3 and 57.7±2.0.After treatment with As2O3 5 μmol/L for 24 h,the peak level of ROS in MGC803 and BGC823 cells increased to 100.8±3.8 and 103.5±2.3,compared with inherent ROS level,the difference had statistical significance（P 0.001,P 0.01）,but the inherent ROS level in SGC7901 cells was 56.5±2.4（P 0.05）.Conclusion The sensitivity of gastric cancer cells to arsenic trioxide is associated with the increase of reactive oxygen species level.

Objective To evaluate the early appearance of SARS on chest CT scan and its role in the early diagnosis Methods Forty cases of SARS in keeping with the criteria of the Ministry of Health had chest CT scans within 7 days of onset of symptoms, and CR chest X-ray films were available as well These chest X-rays and CT images were retrospectively reviewed to determine if there were any abnormalities on the images The lesions on the chest CT images were then further analyzed in terms of the number, location, size, and density Results Positive abnormalities on chest CT scans were revealed in all 40 SARS cases Positive findings on CR chest films were showed in only 25 cases, equivocal in 6, and normal in 9 cases The main abnormalities seen on CT and X-rays were pulmonary infiltrations varied markedly in severity 70% cases had 1 or 2 lesions on chest CT scan, 30% cases had 3 or more lesions The lesions seen on chest CT scan tended to be ground-glass opacification, sometimes with consolidation which was very faint and inhomogeneous, easily missed on chest X-rays Typically the lesions were located in the periphery of the lung, or both central and peripheral lung, but very rare in a pure central location They were commonly in the shape of patch or ball Conclusions Chest CT scan is much more sensitive in detecting the lesions of the lung in SARS The early appearance of SARS on chest CT scan is characteristic but non-specific, indicating that chest CT scan plays a very important role in the early diagnosis and differential diagnosis of SARS

Objective To evaluate the appearances of osteochondral fracture of the knee on X-ray and MR imaging. Methods Twelve patients with knee acute injury were examined with X-ray and MRI. The findings of MRI and X-ray were analyzed and reviewed, and the results of each patient were confirmed by arthroscopy and operation. Results Thirteen areas of osteochondral fracture including 9 loose bodies in 12 patients were diagnosed by MRI. Seven locations were found by MRI in the distal lateral femoral condyle, and 6 in patellar. MRI could clearly show the location, the size, and the depth of each osteochondral fracture, and MRI could also differentiate the articular cartilage and the subchondral of the loose body. T 2WI, STIR, and FFE-T 2WI were the best sequences to demonstrate the osteochondral fracture. X-ray showed 5 loose bodies in the knee joint, but could not detect where they came from. Conclusion MRI can accurately reveal and diagnose the osteochondral fracture of knee after trauma, which improves the diagnostic certainty and is very helpful for arthroscopy and operation. X-ray is still the initial modality in detecting the osteochondral fracture of knee and should be combined with MRI to confirm the diagnosis.