Imaging Cross-Sectional Anatomy And CT, MRI Application Study On Meckel Cave

Meckel cave(MC) is a dural recess in the posterior of the middle fossa, depth in location, complex in structures, and adjacent to many important nerves and blood vessel. As the developing of modern imaging and the skull-base microsurgery, it is necessary to study the MC in detail about the contents and the adjacent structures. The study focused on the cross-sectional, comparative imaging, the normal appearance of CT and MRI, and the diagnosis and differential diagnosis of the MC disease.Part Ⅰ: Imaging Cross-Sectional Anatomy Study on the Meckel CavePurpose: To study the location, shape, the structures within MC(Meckel cave) and their relationship, and to provide the anatomic foundation for imaging diagnosis and microsurgery.Materials and methods: Forty-four MC specimens from 22 cadaver's heads were cross-sectioned in coronal (32MC) and axial plane (12MC) using collodion embedding process. The shape, location, structures within MC and their relationship were studied, the diameters of the MC, the distance between both sides MC and the thick of trigeminal ganglion were measured on typical sections in coronal and axial plane respectively.Results: 1. MC was a extradural recess in the posterior of the middle fossa, it contained subdural space, arachnoid, subarachnoid space, trigeminal ganglion, neural fibers and cerebrospinal fluid ,et al; 2. Walls of MC were formulated by dural, lateral wall was formulated by double durals, the other walls were formulated by single dural; 3. The trigeminal ganglion adhered anterior one third of medial and lateral wall, half of inferior wall and whole anterior wall, there was extensive venous plexus around the trigeminal ganglion and the proximal branches of ophthalmic nerve (V1), maxillary nerve (V2) and mandibular nerve (V3), which direct communication to cavernous sinus; 4. The location of the Ⅳ and Ⅵ were stable to MC; 5. The coronal and axial plane specimens were necessary to combing togther in observing the shape of the MC and the structures within MC.Part Ⅱ: Comparative Imaging Study on the MC: CT and MRI sequencesPurpose: To compare CT and MRI sequences in detection of normal MC anatomy and artifacts, and inquire into an appropriated methods and sequences.Materials and methods: Sixty patients with normal MC were divided into three groups each with twenty patients. The first group were simultaneously performed SE T1WI, GRE T1WI, and FSE T2WI; The second group were performed SE T1WI-C+, FR FSE T2WI, and 3D FSE T2WI; And the third group were performed CT and CT-C+examination. Then the efficacy of the 8 methods in the detection of normal anatomy and artifacts were evaluated and compared with each other.Results: 1. Dural walls: (1) GRE T1WL 3D FSE T2WI, and CT were inferior to other 5 methods in the detection of lateral wall (P < 0.05 ); (2) SE T1WI, FSE T2WI, FR FSE T2WI, and SE T1WI-C+were superior to other methods in the detection of medial wall, superior wall, inferior wall, anterior wall, and posterior wall(P < 0.05 );2. SE T1WI, FSE T2WI, FR FSE T2WI, and SE T1WI-C+ were superior to other methods in detection of trigeminal ganglion (P < 0.05 ); 3. FSE T2WI and FR FSE T2WI were superior to other 6 methods in detection of fibers (P < 0.05 ); 4. SE T1WI, FSE T2WI, FR FSE T2WI, and SE T1WI-C+ were superior to other 4 methods in detection of trigeminal cistern (P < 0.05); 5. Magnetic susceptibility artifact in GRE T1WI and 3D FSE T2WI were more than that of other methods (P < 0.05); 6. There was bone artifact on the CT examination; 7. There were no difference between tooth artifact and moving artifact on CT and MRI examination.Part Ⅲ: CT and MRI Study on the normal MCPurpose: According to the cross-sectional anatomy, to study the appearances of the walls and the structures within MC on CT and MRI.Materials and methods: Forty patients with normal MC included 22 males and 18 females. The mean age was 45.57 years old(±15.83years). Twenty of patients were simultaneously performed both coronal and axial SE T1WI, FSE T2WI, and SE T1WI-C+ examination. Another 20 patients were simultaneously performed both coronal and axial CT and CT-C+. To analyze the rate of showing of the walls and the structures within MC on CT and MRI.Results: (1) The rate of showing lateral wall was high both on CT and MRI; the rate of showing medial wall, anterior wall, posterior wall, and superior wall were higher on MRI than CT, they demonstrated iso-density on pre-contrast CT and iso-intensity on FSE T2WI, and enhanced obviously on CT-C+ and SE T1WI-C+; inferior wall can't be identified on CT and MRI itself; (2) Trigeminal ganglion was within the inferolateral aspect of Meckel cave on coronal section, the rate of showing on pre-contrast CT and MRI were 35% and 90% respectively, it appeared high density/intensity on post-contrast images, the rate of showing were 40% and 95% respectively; (3) Perineural venous plexus was not appeared on pre-contrast CT and MRI; it demonstrated high density/signal intensity on CT-C+ / SE T1WI-C+;(4)Trigeminal cistern demonstrated low density/long T1 and long T2 signal on CT/ MRI;(5)Fibers only demonstrated on FSE T2WI;(6)Trigeminal porus was not demonstrated on the sections;(7)Both coronal and axial section were necessary to combing tighter in observing MC.Part Ⅳ: CT and MRI Study of the MC DiseasesPurpose: According to study the MC diseases on CT and MRI, and to discuss their imaging features, and which value in the diagnosis and differential diagnosis.Materials and methods: 33 cases MC diseases, pre-contrast examination were scanned in 4 cases with CT and 22 cases with MRI, post-contrast, pre- and post -examinations were scanned in 7 and 4 cases with MRI respectively.Results: The MC diseases were included 18 secondary tumors(54.6%), 11...