MRI diagnosis of intraspinal primary melanocytic neoplasms / 中华放射学杂志

Objective To analyze and summarize the MR findings of intraspinal primary melanocytie neoplasms.Methods Five cases of intraspinal primary melanocytic neoplasms were retrospectively analyzed with emphasis on the location,growth pattern and MR signal intensity features of the tumors.Results A total of six tumors were found in five cases (one case had two tumors).The tumors were located in the cercival spine (2),thoracic spine (2),thoracolumbar junction (2) respectively.One tumor was located in the intramedullary space and 5 tumors in the extrumedullary-intradural space.Growth of the tumors were limited in the intradural space without evidence of extradural extension.The intramedullary tumor exhibited hyperintensity on both T2WI and T1 WI.The intradural tumors showed hyperintensity on T1WI and hypointensity or isointensity on T2WI of various degree.Three of these tumors were predominantly hyperintense on T1 WI and homogeneously hypointense on T2WI.Conclusion The intraspinal primary melanocytic neoplasms could be diagnosed pre-operatively due to their unique signal intensity features on imaging.

Correlation of MR imaging and histopathology after partial resection of normal rabbit brain / 中华医学杂志(英文版)

<p><b>OBJECTIVES</b>To investigate the findings of magnetic resonance (MR) imaging and histopathology in early postoperative normal brain, and to define the correlation between MR images and histopathology.</p><p><b>METHODS</b>Thirty-six New Zealand rabbits weighing 2.0 to 3.0 kg were divided into 10 groups according to different postoperative days: 1 to 10 days. A partial resection of the parietooccipital region was performed under usual aseptic conditions after the animals were anesthetized intravenously with 3% pentobarbital (30 mg/kg). MR imaging procedures consisted of pre- and postcontrast scanning and were carried out on postoperative days 1 to 10. Brain tissue samples were prepared for examination immediately after MR scanning. Histopathological examination was done under light both and electron microscopes. The findings of MR imaging were compared with histopathologic findings.</p><p><b>RESULTS</b>Surgical margin contrast enhancement on MR images could be seen 24 hours after surgery. The degree of contrast enhancement increased gradually up to 5 days postoperation, and no remarkable changes were present from days 5 to 10. Disruption of the blood brain barrier (BBB) was the main cause of contrast enhancement during the first 3 postoperative days. After that period, the mechanism responsible for contrast enhancement was the formation of neovascularity and a broken BBB. An increase in the amount of neovascularity played a predominant role in contrast enhancement in normal postoperative brain tissue.</p><p><b>CONCLUSIONS</b>The features of enhanced MR images present at the surgical margin followed a typical time course during the early postoperative period. The role of neovascularity and BBB disruption in the formation of contrast enhancement at the surgical margin varies with time. Knowledge of the features of contrast enhancement in postoperative MR images of normal brain can help in differentiating benign changes from residual malignant glioma.</p>

Correlation of MRI and histopathology after partial resection of normal brain: an experimental study in rabbits / 中华放射学杂志

Objective To investigate the manifestations of MR imaging and histopathology of early postoperative normal brain, and to define the correlation between MRI and histopathology. Methods Thirty six New Zealand rabbits weighing 2.0 to 3.0 kg were divided into 10 groups according to the different postoperative days: 1 to 10 day. Six animals were in groups 3, 5, 7, 10, and 2 were in the other groups. A partial resection of the parietooccipital region was performed under the usual aseptic conditions after the animals were anesthetized intravenously with 3% pentobarbital (30 mg/kg). MR imaging procedures consisted of pre and postcontrast scanning were carried out on postoperative 1 to 10 day respectively. Brain tissue samples were obtained to be prepared for examinations immediately after MR scanning. Histopathological study was made under microscope and electron microscope. The findings of MRI were compared with pathology findings. Results (1) Surgical margin contrast enhancement on MR images could be seen 24 hours after surgery. (2) The degree of contrast enhancement increased gradually before 5 days postoperatively, and no remarkable changes were present from 5 to 10 days. (3) The disruption of blood brain barrier(BBB) is the main cause of contrast enhancement during the postoperative 3 days. After that period, mechanism responsible for contrast enhancement is the formation of neovascularity and broken BBB, an increase in the number of neovascularity play a predominant role in the contrast enhancement in normal postoperative brain tissue. Conclusion The characteristics of enhanced MRI present at the surgical margin followed a typical time course during the early postoperative period. The role of neovascularity and BBB disruption in the formation of contrast enhancement at surgical margin vary with time. Knowledge of the characteristics on postoperative MR images of the normal brain can help in differentiating benign changes from malignant gliomas residual.

MR imaging of intramedullary subependymoma / 中华放射学杂志

Objective To delineate the MR imaging features of intramedullary subependymoma. Methods The MR imaging features of 4 cases of pathologically proved intramedullary subependymomas were analyzed retrospectively and correlated with operative reports, and the differential diagnosis was discussed. Results MR appearances of intramedullary subependymoma were as follows: (1) Intramedullary subependymoma often involved the cervical region or the extensive portions of the cervical and thoracic cord in 3 out of 4 cases, mainly affected adults, and was eccentric within the spinal cord. The tumor was in the thoracic-lumbar cord in 1 case. (2) They were heterogeneously hypointense relative to the normal spinal cord on T 1-weighted images and hyperintense on T 2-weighted images, occasionally with hemorrhagic foci (2 cases). (3) No enhancement or minimal enhancement was revealed on T 1-weighted images following Gd-DTPA administration (3 out of 4). Conclusion Intramedullary subependymoma are best delineated by MR imaging. The diagnosis of intramedullary subependymoma should be considered when above findings are confronted.

MR Imaging Features of Pyocephalus / 实用放射学杂志

Objective To analyze the MR imaging features of pyocephalus. Methods MR imaging features!of pyocephalus in 5 cases with clinically proved were analyzed retrospectively. All patients were undergone no-contrast MR imaging. 3 patients received diffusion weighted-imaging(DWI). Results In all five patients,the debris and pus with pus-fluid level were shown inside the lateral ventricle.The debris or pus was slightly hyperintense on T1WI, slightly hypointense on T2WI relative to cerebrospinal fulid(CSF). On DWI, the debris was hyperintense in 1 case and isointense in 2 cases.Conclusion The features of MR imaging of pyocephalus is specific. MR imaging is valuable in the diagnosis of pyocephalus.