748 High-Resolution CT of the Normal and Abnormal Fallopian Canal Anton Valavanis ,1 Stefan Kubik,2 and Othmar Schubiger3 A two-part anatomic and clinical high-resolution computed of the cadaver heads and the temporal bone specimens, respec­ tomographic (HRCT) study of the fallopian canal was conducted. tively, with the help of the laser beam. All the temporal bones were From the correlation of HRCT images of eight specimen temporal th en sectioned with the microtome at th e marked levels. bones with their corresponding anatomic sectional images, it was evident that the full length of the fallopian canal can be accurately visualized. An axial section demonstrates the labyrin­ Clinical Studies thine segment, geniculate ganglion fossa, and proximal part of A seri es of 55 patients was examined by HRCT for demonstration t he tympanic segment, whereas a Stenver projection is used for of the fall opian canal. the tympanic segment, second knee, and mastoid segment. In Twenty-eight patients presented with acute facial nerve palsy. clinical studies axial sections simultaneously visualized the prox­ On the basis of the clinical and laboratory examinations a diagnosis imal parts of the fallopian canal in 82% of 28 cases, whereas of idiopathic (Bell) palsy or Ramsey-Hunt syndrome was made. Stenver projections simultaneously visualized the distal parts in Th ese patients were investigated by HRCT either for exclusion of a 75% of 16 cases of acute facial nerve palsy. Twenty-one patients tumor involving the fallopian canal or for measurement of the meatal with intratemporal facial nerve palsy and six patients with con­ foramen of the fallopian canal, which represents th e site of stran­ genital atresia of the external auditory canal were also examined. gulation of the facial nerve in 94% of cases with Bell palsy [8, 9]. HRCT was highly accurate in detecting and defining neoplastic, The results of these measurements will be reported at a later date, inflammatory, and congenital lesions of the fallopian canal. A since the study has not been completed . HRCT images on these lower rate of detection was recorded for traumatic lesions. patients were obtained in axial and coronal planes. In 16 patients additional images were obtain ed in the Stenver projection. These After the introduction of high-resolution computed tomography images formed the basis for the study of the normal fallopian canal. Sixteen pati ents presented with progressive peripheral facial (HRCT) in clinical radiologic practi ce and its application to the study nerve palsy. Five patients presented with complete (two cases) or of the temporal bone, preliminary reports emphasized its high incomplete (three cases) posttraumatic peripheral facial nerve accuracy in visualizing normal intratemporal anatomy [1 - 5] and in palsy. Six pati ents without facial nerve palsy were examined by detecting various intratemporal lesions [1 , 2, 6]. However, the HRCT because of congenital atresia of the external auditory canal. fallopian or facial nerve canal received little attention, although its Both the anatomic and clinical HRCT examinations were per­ anatomy and pathology are partly covered in more general reports form ed with 2 mm collimati on overlapping at 1 mm . Pati ents with on HRCT of the temporal bone [4 , 5, 7]. We present briefly the progressive peripheral facial nerve palsy were studied after prescan normal appearance of the fallopian canal on HRCT and analyze the bolus injecti on and interscan infusion of meglumine ioxithalamate value of HR CT in detecting and further defining the various types of 30% (Telebrix 30R) with a total iodine content of 60 g. lesions involving the fallopian canal. Materials, Subjects, and Methods Results Anatomic Studies Norm al Fallopian Canal on HR CT The temporal bones in five cadaver heads and three exarticulated From the HRCT-anatomic correlative study it was evident that for temporal bone specimens were scanned in various planes: (1) axial adeq uate visuali zati on of individual segments of the fallopian canal, sections parall el to the infraorbitomeatal line (Reid base line), (2) sections must be obtained in vari ous pl anes. However, the full axial sections parall el to the orbitomeatal line, (3) axial sections length of the canal can be demonstrated with only two sections: An parallel to a line from the glabell a to the superi or border of the axial section at the level of the glabella and parallel to the superi or zygomatic arch (glabellozygomatic line) , (4) coronal secti ons per­ border of th e zygomati c arch visualizes the labyrinthine segment, pendicular to the infraorbitomeatal line, and (5) Stenver secti ons. genicu late ganglion fossa, and proximal part of the tympanic seg­ The scanning planes for each section were marked on the surfaces ment (fig. 1). A Stenver projecti on at the level of a line from the 'Department of Diagnostic Radiology, University Hospital, 8091 Zurich, Switzerland. Address reprin t requests to A. Valavanis. ' Departm ent of Anatomy, Unive rsity of Zurich, Zurich, Switzerl and . 3Departm ent of Di ag nostic Radiology, Kantonsspital, 5001 Aarau, Switze rland. AJNR 4 :748 -751 , May / June 198 3 0 195- 6 108/ 8 3 / 0403-0748 $ 00.00 © Am erican Roentgen Ra y Society AJNR:4, May/June 1983 HEAD, NECK, AND ORBITS 749 Fig. 1 .-HRCT of left temporal bone specimen. Fig. 2.-A, HRCT of left temporal bone specimen. Stenver projection parallel to line from outer Axial section parall el to glabell ozygomati c line. Si­ margin of contralateral orbit to ipsilateral mastoid process. Sim ultaneous visualizati on of tympanic multaneous visualization of labyrinthine segment (1), segment (I) coursing below horizontal semicircular canal; second knee (k); and descendin g mastoid geniculate ganglion fossa (2), and tympanic seg­ segment (m) in their full length . S, Anatomic section corresponding to A . Genic ulate ganglion fossa (1), ment (3) in their full length. tympanic segment (2), oval window (3), horizontal semic irc ular canal (4), second knee of fall opian canal (5), mastoid segment (6), tympanic promontory (P), and carotid canal (CC). 3 4 5 Fig. 3 .-HRCT of right temporal bone in pati ent with normal fallopian inferior cortical outline (arrow). canal. Geniculate ganglion fossa (double arrow) in cross section. Fig. 5.-Glomus tumor of left temporal bone in volvin g tympani c segment Fig. 4. -lntrinsic tumor (hemangioma) of fall opian canal at level of genic­ of fallopian canal. Coronal secti on. Erosion of cortical outli ne of jugular fossa ulate ganglion fossa. Left side, coronal section. Significant enlargement of (arrowhead), tumor mass in middle ear (white arrow), and in volvement of genicul ate ganglion fossa (arrowheads ) and circ umscribed erosion of its tympani c seg ment (black arrow) by tumor. outer margin of the contralateral orbit to the ipsilateral mastoid segment of th e canal. This was demonstrated in three cong enital process visualizes the tympanic segment, the second (or inner) cholesteatomas involving th e labyrinthine segment and geniculate knee, and the mastoid segment (fig. 2). ganglion fossa, fi ve glom us tumors involving either th e tympanic A coronal section at the cochlear level visualizes the geniculate (fig. 5) or mastoid segment, two middle ear carc in omas involvin g ganglion fossa in cross section (fig. 3). Consecutive coronal slices the tympanic segment, and one metastasis from a breast carcinoma, posterior to the cochlear level visualize the tympanic segment in involving the geniculate gangli on fossa. cross secti on. The frequency of HRCT visualization of each segment Inflammatory lesions. Three of the 16 patien ts with progressive of the fallopian canal in various planes in the clinical study is peripheral fac ial nerve palsy had inflammatory lesions of the fall o­ summarized in table 1 . pian canal on HRCT. HRCT demonstrated erosion of the proxim al tympanic segment of the canal in two cases with secondary choles­ teatoma. In one case of mali gnant extern al otitis, osteolyti c destruc­ Abnormal Fallopian Canal on HRCT tion of the distal part of the mastoid segment was evident. Tum ors. Of th e 16 patients who presented with progressive Traumatic lesions. Of five patients with traum ati call y induced peripheral facial nerve palsy, 13 had fallopian canal tumors dem­ peripheral facial nerve palsy, HRCT demonstrated th e site of in­ onstrated by HRCT. Tumors originating in the fallopian canal caused volvement of th e fall opian canal by the fracture line in three. In two enlargement and erosion of the involved segment. This was dem­ patients longitudinal fractures of the temporal bone were found. In onstrated in a facial nerve neuroma and a cavern ous hemangioma, these cases the fall opian canal lesion was at the level of the both occurring at the level of the geniculate ganglion fossa (fig. 4). geniculate gangli on (fig. 6). In one patient a transverse fracture was Tumors involving the fallopian canal secondarily were located ec­ demonstrated in the internal auditory canal near the fu ndus. centric to the involved segment, either in the supralabyrinthine area, Congenital ea r malformations. Of six patients with congenital the middle ear cavity, or the mastoid part of the temporal bone. atresia of the extern al auditory canal who underwent HR CT for They caused erosion or complete destruction of the corresponding middle ear evaluation, an abberant course of the fall opian canal 750 HEAD, NECK, AND ORBITS AJNR:4, May/June 1983 was found in two, whereas the canal appeared normal in the other patients. A Stenver projection parallel to a line from the outer margin four patients. In the two abnormal cases the tympanic segment was of the contralateral orbit to the ipsilateral mastoid process visualizes significantly shortened, the mastoid segment was situated anteriorly the tympanic segment, second knee, and mastoid segment simul­ and coursed in a lateral direction, and the exit foramen of the canal taneously (fig .