3T MR3D-FIESTA Demonstrating Cranial Nerves In Cisternal Segment And Their Relationship With Adjacent Lesions’

ObjectiveMR imaging has high tissue resolution and could display the nerves in posterior and middle fossa and their adjacent lesions. It plays an important role in the diagnosis of the relationship between nerves and lesions and has become an ideal tool in examining and diagnosing. To investigate the usefulness of3T MR3D-FIESTA in displaying the relationship between the nerves in posterior and middle fossa and their adjacent lesions.Method34patients (18males and16females,23-81years old, mean age46years) in the Shandong Medical Imaging Research Institute were included in the study form march of2010to December of2011. Their medical history was showed from3months to2years, and mostly manifested as repeated headaches、persistent dizziness with facial numbness、tinnitus and hearing obstacles.23patients were underwent surgery in all34cases.22lesions were confirmed benign tumours:9acoustic neuromas,6cholesteatomas,4meningiomas,1craniopharyngioma,1pituitary tumor,1arachnoid cyst, and1was malignant peripheral nerve sheath tumor.11cases untreated:7peripheral vascular compression,1neurofibromatosis Ⅱ(NF-Ⅱ),1metastases,1multiple meningioma,1glomus jugulare tumor.All examinations were performed on GE3.0MRI scanner with8-channel array coil. The MR scanning sequences included routine sequences and3D-FIESTA sequence. T1-weighted fluid-attenuated inversion recovery sequence (TR2580ms, TE23ms, TI860ms), fast SE T2-weighted sequence (TR4600ms, TE110ms); FOV240mm×240mm, section thickness4.0mm, intersection gap0.5mm, carrying out in the axial and coronal planes. The following parameters were used in3D-FIESTA sequence:TR4.9ms, Effective echo time (TEeff)1.5ms, anti-angle55°,ROI18cm×18cm～20cm×20cm, imaging matrix512×320, an axial plane and no intersection gap, section thickness1.0mm.After scaning, imagings were under multiplanar reconstruction at AW sdc4.3workstation. Tracking and locating the cranial nerves in cisternal segment must began from surface of brain until they travelling outside of skull. Two experienced radiologists diagnosed and evaluate the images of all patients together observing the nerves in posterior and middle fossa, among them CN Ⅳ-Ⅵ、Ⅺ were statistic independently. CNⅦ and Ⅷ were closed, CNIX-XI were thin and form neural complex, so they were all statistic together. According to the relationships between nerves and adjacent lesions showed in the3D-FIESTA sequence MR imagings, the relationships were grouped. We distinguished different types of nerves and lesions’, including nerves were involved、embedded、pushed by lesions or they were adjacent to. All of cases were contrast FSE T2WI to3D-FIESTA imagings. The relationships of cases with surgical treatments were confirmed at surgery.ResultDifferent types of tumors in posterior and middle fossa have their characteristics in3T MR imaging.34cases having48lesions mainly showed iso-or hypo-intensity on T1FLAIR, iso-or hyper-intensity on T2WI, and the solid part of lesions showed hypo-intensity, cystic part of lesions showing hyper-intensity on3D-FIESTA except malignant peripheral nerve sheath tumor and glomus jugulare tumor were high-low mixed signs in all sequences. Responsibility vascular in all7peripheral vascular compression showed hyper-intensity on3D-FIESTA for inflow enhancement effect and vascular wall were hypo-intensity. The cranial nerves in cisternal segment were characterized by linear low-signal on T1WI、T2WI and3D-FIESTA.306cranial nerves were displayed on3D-FIESTA in all patients.25nerves were involved by its adjacent lesions;9cranial nerves were embedded;51were pushed; lesions were adjacent to10nerves. The accuracy of T2WI imagings in demonstrating cranial nerves were10、0、5、1.23patients(24lesions) were underwent surgery in all34cases. The number of nerves being involved, embedded, pushed, adjacent to in surgery were13、6、28、3. Compared with surgical result, the accuracy of3D-FIESTA imagings in demonstrating relationship between cranial nerves with adjacent lesions were12/13、5/6、26/28、3/3.4lesions weren’t shown in3D-FIESTA due to their big size. However, The accuracy of T2WI were only76.9%、0%、7.1%、0%(10、0、2、0,)Conclusion 3T MR3D-FIESTA imaging could depict the relationship between the nerves in cisternal segment and its adjacent lesions correctly, and it is useful in preoperative evaluation and treatment of intracranial lesions.