3D curved multiplanar cone beam CT reconstruction for intracochlear position assessment of straight electrodes array. A temporal bone and clinical study.

A retrospective review of post-op cone beam CT (CBCT) of 8 adult patients and 14 fresh temporal bones that underwent cochlear implantation with straight flexible electrodes array was performed to determine if the position of a long and flexible electrodes array within the cochlear scalae could be reliably assessed with CBCT. An oto-radiologist and two otologists examined the images and assessed the electrodes position. The temporal bone specimens underwent histological analysis for confirm the exact position. The position of the electrodes was rated as scala tympani, scala vestibule, or intermediate position for the electrodes at 180°, 360° and for the apical electrode. In the patient group, for the electrodes at 180° all observers agreed for scala tympani position except for 1 evaluation, while a discrepancy in 3 patients both for the 360° and for the apical electrode assessment were found. In five temporal bones the evaluations were in discrepancy for the 180° electrode, while at 360° a disagreement between raters on the scalar positioning was seen in six temporal bones. A higher discrepancy between was found in assessment of the scalar position of the apical electrode (average pairwise agreement 45.4%, Fleiss k = 0.13). A good concordance was found between the histological results and the consensus between raters for the electrodes in the basal turn, while low agreement (Cohen's k 0.31, pairwise agreement 50%) was found in the identification of the apical electrode position confirming the difficulty to correct identify the electrode position in the second cochlear turn in temporal bones. In conclusion, CBCT is a reliable radiologic exam to correctly evaluate the position of a lateral wall flexible array in implanted patients using the proposed imaging reconstruction method, while some artefacts impede exact evaluation of the position of the apical electrode in temporal bone and other radiological techniques should be preferred in ex vivo studies.

[Mandibular reconstruction with fibula free flap. Experience of virtual reconstruction using Osirix®, a free and open source software for medical imagery]. / Reconstruction mandibulaire par lambeau microanastomosé de fibula. Modélisation radiologique préopératoire par le logiciel Osirix(®).

The techniques of free tissue transfers are mainly used for mandibular reconstruction by specialized surgical teams. This type of reconstruction is mostly realized in matters of head and neck cancers affecting mandibular bone and requiring a wide surgical resection and interruption of the mandible. To decrease the duration of the operation, surgical procedure involves generally two teams, one devoted to cancer resection and the other one to raise the fibular flap and making the reconstruction. For a better preparation of this surgical procedure, we propose here the use of a medical imaging software enabling mandibular reconstructions in three dimensions using the CT-scan done during the initial disease-staging checkup. The software used is Osirix®, developed since 2004 by a team of radiologists from Geneva and UCLA, working on Apple® computers and downloadable free of charge in its basic version. We report here our experience of this software in 17 patients, with a preoperative modelling in three dimensions of the mandible, of the segment of mandible to be removed. It also forecasts the numbers of fragments of fibula needed and the location of osteotomies.

[Choanal stenosis: a rare complication of radiotherapy for nasopharyngeal carcinoma]. / Sténose choanale post-radique: une complication rare de la radiothérapie des carcinomes nasopharyngés.

Choanal stenosis is usually a congenital anomaly in children. Acquired choanal stenosis after radiotherapy for nasopharyngeal carcinoma is a very rare pathology; only two publications report seven cases in the literature. We describe the clinical history, preoperative evaluation, surgical treatment and outcome of a case of acquired choanal stenosis after radiotherapy. The patient, a 56-year-old woman, presented with a history of nasopharyngeal carcinoma (T2- NO-MO) one year before that had been successful treated with radiotherapy (68 Gy). At the end of radiotherapy, she complained of complete nasal obstruction, anosmia and hearing loss due to a bilateral serous otitis media. Bilateral complete choanal stenosis was confirmed by endoscopy and CT scan. Functional endoscopic surgery was performed, and nasal stents were left in place for 3 weeks. One year after, the patient have good airflow, and a patent nasopharynx without choanal stenosis. In conclusion, choanal stenosis is an unusual complication of radiotherapy that can be successfully treated with transnasal endoscopic resection.

The vomeronasal cavity in adult humans.

We observed the surface of the anterior part of the nasal septum of living subjects using an endoscope. In approximately 13% of 1842 patients without pathology of the septum, the vomeronasal pit was clearly observed on each side of the septum, and in 26% it was observed only on one side. The remaining observations indicated either the presence of putative pits or no visible evidence of a pit. However, repetitive observations on 764 subjects depicted changes over time, from nothing visible to well-defined pits and vice versa. Based on 130 subjects observed at least four times, we estimate that approximately 73% of the population exhibits at least one clearly defined pit on some days. By computer tomography, the vomeronasal cavities were located at the base of the most anterior part of the nasal septum. Histological studies indicated that the vomeronasal cavities consisted of a pit generally connected to a duct extending in a posterior direction under the nasal mucosa. Many glands were present around the duct, which contained mucus. There was no sign of the pumping elements found in other mammalian species. Most cells in the vomeronasal epithelium expressed keratin, a protein not expressed by olfactory neurons. Vomeronasal epithelial cells were not stained by an antibody against the olfactory marker protein, a protein expressed in vomeronasal receptor neurons of other mammals. Moreover, an antibody against protein S100, expressed in Schwann cells, failed to reveal the existence of vomeronasal nerve bundles that would indicate a neural connection with the brain. Positive staining was obtained with the same antibodies on specimens of human olfactory epithelium. The lack of neurons and vomeronasal nerve bundles, together with the results of other studies, suggests that the vomeronasal epithelium, unlike in other mammals, is not a sensory organ in adult humans.

[Value of MRI and computerized tomography scanner in oro-buccopharyngeal cancers with bone invasion]. / Apport de l'IRM et du scanner dans les cancers oro-buccopharyngés avec envahissement osseux.

The purpose of this prospective study was to assess the impact of Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) in the surgical management of carcinomas with mandibular bone invasion. Thirty-five patients with squamous cell carcinoma of oral cavity or oropharynx, with mandibular spread, were studied with both imaging methods before surgical treatment. We compared the radiographic findings with histologic examination. Sensitivity of CTScan and MRI was respectively 25% and 80% to identify bone invasion. CTScan was found less effective in the assessment of bone invasion before mandibular resection and was considered more radiologist dependent. MRI is becoming the imaging method of choice for these cancers, despite inherent disadvantages including limited availability and increased cost over CTScan. MRI is accurate in large oropharyngeal tumors with extension of base of tongue and pterygoid muscle, and to study bone invasion before surgery in oral cavity tumors.

[Imaging of the inner ear]. / Bildgebung des Innenohrs.

New computed tomography (CT) and magnetic resonance (MR) techniques allow more detailed anatomic studies of the inner ear. CT is still the best technique to study patients with fractures, congenital malformations and otodystrophies involving the inner ear. During recent years MR imaging has emerged as an excellent method to detect pathology in the internal auditory canal, membranous labyrinth and bony labyrinth and to characterize petrous apex lesions. MR has even proved its value in patients with fractures and congenital malformations making the diagnosis of, for instance, labyrinthine concussion and absence of the vestibulocochlear nerve possible. The diagnosis of acute/chronic labyrinthitis and intralabyrinthine tumors has also became possible. However, MR and CT are often complementary, as is the case in patients with mixed hearing loss, congenital malformations and petrous apex lesions.

Traumatic luxation of the stapes evidenced by high-resolution CT.

We encountered a case of acquired perilymphatic fistula in which the origin of the disease, namely, the stapes begin medially displaced into the vestibule, was shown by thin-section CT. Accordingly, we recommend that every patient with suspected perilymphatic fistula of traumatic origin undergo high-resolution CT of the petrous bone.

Radiological studies in trigeminal nerve pathology.

The authors have used CT scans and MRI to study pathology in anatomical and radiological correlations of brain slices. The CT scan was particularly useful for studying structures at the skull base, although at the level of the posterior fossa such scans could visualize only those tumors that were larger than 8 mm. even after injection. The CT scan was found to be the most useful examination before surgery for facial neuralgia. In contrast MRI gave a precise cisternal course of the trigeminal nerve and its relations with vascular structures.

[5 cases of epidermoid cyst (or primary cholesteatoma) of the petrous pyramid. Clinical, radiologic, pathogenic and therapeutic aspects. Value of nuclear magnetic resonance in the diagnosis and postoperative monitoring]. / Cinq cas de kyste épidermoïde (ou cholestéatome primitif) de la pyramide pétreuse.Aspects clinique, radiologique, pathogénique et thérapeutique. Intérêt de la RMN dans la diagnostic et la surveillance post-operatoire.

Five cases of epidermoid cyst (or primary cholesteatoma) of petrous bone are described and the criteria necessary to consider these tumors as truly primary outlined. The most plausible theories appear to be either congenital: embryonic inclusions or, to a lesser degree, acquired: papillary proliferation. Emphasis is placed on facial signs, even minimal, associated with progressive perception or mixed unilateral deafness. Advantages and indications for different surgical approaches are discussed and the value of NMR imaging emphasized, both for diagnosis and postoperative follow up review, especially when a closed technique had been selected.

[Minor abnormalities of the internal ear. Radioclinical correlations]. / Malformations mineures de l'oreille interne. Corrélations radio-cliniques.

Moderately severe cochleovestibular disorders of often late onset may arise from minor dysplasias of the internal ear. Diagnosis of these bone dysplasias is radiologic. The problem that arises is that of the indications for radiotomography of the internal ear, insofar as on the one hand no certain radioclinical equivalence exists, and on the other hand this radiologic examination is of greater diagnostic than therapeutic value.

[Comparative efficacy of multidirectional and computed tomography in the diagnosis of tumors of the pontocerebellar angle (author's transl)]. / Comparaison de l'efficacité des tomographies pluridirectionnelles et de la tomodensitométrie dans le diagnostic des tumeurs de l'angle ponto-cérébelleux.

Extensive investigation of 41 patients highly suspected of having pontocerebellar angle tumors led to the detection of 21 surgically confirmed tumors. Precise criteria, involving numerical rating of sensitivity and specificity, were applied to compare the diagnostic reliability of multidirectional and computed tomography. An analysis of the diagnostic value of internal auditory canal anomalies demonstrated the obvious superiority of 3 mm as against 6 to 9 mm scanner sections, and the good correlation between the anomalies detected by these thin scanner sections and those obtained by tomography. Above all, however, the efficacy of thin scanner sections appears to be markedly superior to that of tomography, as 80 p.cent of tumors were visualized without false positives even when the internal auditory canal was normal. The number of cisternography examinations was thus considerably reduced. This efficacy of thin scanner sections varied as a function of the tumor size : all those of 2 cm diameter or more were detected by the scanner, 50 p.cent of those between 1 and 2 cm by both the scanner and tomography, the latter being more effective for detecting tumors less than 1 cm in diameter. The availability of the 4th generation scanner will markedly increase its effectiveness.