A new study on diffusion tensor imaging of the whole visual pathway fiber bundle and clinical application / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>With conventional imaging methods only the morphous of the visual nerve fiber bundles can be demonstrated, while the earlier period functional changes can not be demonstrated. We hypothesized that diffusion tensor imaging (DTI) would demonstrated the whole optic never fiber bundle and visual pathway and the earlier period functional changes. The purpose of the present study was to evaluate the application of DTI technique in the demonstration of the whole optic never fiber bundle and visual pathway, and the influence of orbital tumors on them.</p><p><b>METHODS</b>GE 1.5 T signa HD MR System, and the software package DTV2 were adopted. The total 45 subjects were enrolled, including 15 volunteers and 30 patients. All patients had ocular proptosis from minor to major. Seven patients had visual acuity decrescence.</p><p><b>RESULTS</b>The nerve fiber bundles, e.g. optic chiasma, optic tract and optic radiation in posterior visual pathway were well demonstrated in all cases. Wherein, the intact whole visual pathway fiber bundles were clearly revealed in 10 volunteers and 17 patients, and optic nerve was not wholly revealed in the rest of the subjects. Shift of optic nerve caused by compression and partial deformation were seen in 7 patients with orbital tumor. In 6 of 7 patients, DTI displayed significant abscise and deformation of visual nerve. Chi-square test indicated significant correlation between visual acuity decrescence and DTI visual nerve non-display.</p><p><b>CONCLUSIONS</b>Visual nerve fiber bundles and the whole visual pathway were visualized in most of patients with DTI. It might be an effective method of providing imaging evidence for visual nerve fiber earlier period functional changes, and laid a foundation for the study in other cranial nerves.</p>

Value of fast dynamic contrast enhanced MRI in the diagnosis of orbital lesions / 眼科

Objective To study the value of fast dynamic contrast enhanced MRI in the diagnosis of orbital occupying lesions. Design Retrospective ease series.Participants 21 patients with orbital occupying lesions.Methods All the 21 patients were performed on fast dynamic contrast enhanced MRI and were verified by pathology.The raw datum were processed by the software of GE Functool. Parameters such as time-intensity curve(TIC),time to peak(Tpeak),1 minute enhancement ratio(ERlmin)and maximum enhancement ratio(ERmax)were analyzed to study the characteristics of orbital diseases on fast dynamic contrast-enhanced MRI.Main Outcome Measures TIC,ERlmin,and ERmax.Results The characteristics of TIC between benign diseases and malignant tumors were different. Of the 16 cases of benign lesions,12 demonstrated as continuous increasing type,and of 5 cases of malignant lesions,3 cases of lym- phoma were all platform type.The ER1min of the malignant tumors(150.47?42.18)was higher than that of the benign lesions (101.37?43.02)(P=0.021).Cavernous hemangiomas had special progressing enhancing model.Conclusions Fast dynamic contrast enhanced MRI is valuable to distinguish malignant tumors from benign occupying lesions.(Ophthalmol CHN,2007,16:305-308)