Jean Pierre Lassau

High-resolution computed tomography of the canals of the temporal bone: anatomic correlations

The aim of this study was to define precisely the imaging of the canals of the temporal bone by means of high-resolution computed tomography (HR CT). Based on 24 temporal bones removed from embalmed cadavers and investigated with HR CT, several canals were studied: the canal of the chorda tympani (CdT), the canal of the auricular branch of the vagus nerve (ABV), the canal of the tympanic nerve, the canal of the carotico-tympanic nerve and that of the lesser petrosal nerve. Anatomic correlations for six temporal bones were made to confirm the validity of our radiologic hypotheses. In CT, in axial sections OM 0°, the posterior canal of the CdT was visualized in 71% of cases, the ABV canal in 4%, the inferior tympanic canal in 12.5%, the carotico-tympanic canal in no cases and the canal of the lesser petrosal nerve in 50% (and in 75% with an incidence of OM+10°). In coronal incidence, the posterior canal of the CdT was seen in 20% of cases, the ABV canal in 25%, the inferior tympanic canal in 85%, the carotico-tympanic canal in 65% and that of the lesser petrosal nerve in 15%. The six anatomic comparisons confirmed the radiologic hypotheses in every case. These different structures are easy to identify in HR CT and are important to define so that any lesion (tumoral or vascular) developing in their vicinity may not be overlooked.

Anatomic approach to the parametrium: value of computed tomographic in vitro study compared to dissection.

The aim of this study is to describe the morphology of the normal parametrium by correlating the slices obtained with computed tomography of 12 female cadavers studied after intravascular injection of latex with the dissection findings in 6 of these patients. The upper limit, represented by the isthmus, was defined by the uterine a. and/or a superficial uterine v. and/or the coronary v. (Charpy). The lower limit corresponded to the insertion of the levator ani mm. at the junction of the middle and inferior thirds of the vagina. The paracervical and paravaginal tissues above the levator ani m. and medial to the pelvic fascia covering these muscles were perfectly visualized. The posterior limit, formed by the lateral ligament of the rectum and/or the sacrouterine ligaments, and the anterior limit determined by the umbilico-vesical fascia were more difficult to demonstrate. In this study the parametrium appeared as a highly vascular and essentially venous connective structure with a variable morphology dependent on the uterine position.

Serial anatomy of the larynx in MRI: MRI-histologic correlations.

The larynx is an organ with a complex anatomic structure. MRI allows the performance of sections in the three planes of space, so that this study of the soft parts of the larynx yields results superior to those of other imaging techniques. Together with laryngoscopy, MRI is most often used in assessing the extension of malignant laryngeal tumors. This assessment is fundamental in choosing the indications for surgery, but the published reports of MRI of the larynx are sometimes discordant. The visualization of certain important anatomic structures such as the conus elasticus is uncertain. Our aim was to study the MRI radio-anatomy of the larynx based on correlations between MRI and histologic sections. Eight anatomic specimens were studied four in the transverse plane, two in the sagittal plane, and two in the frontal plane. The MRI and histologic sections made at the same levels were compared. These comparisons allowed a description of the sectional radio-anatomy of the larynx and an assessment of the reliability and limitations of MRI. All the major anatomic structures could be identified. It was possible to demonstrate the conus elasticus. We were able to visualize the vocal process of the arytenoid cartilage, which has not to our knowledge been previously described in the literature.

Correlation between computed tomography and gross anatomy of the suspensory ligament of the ovary.

To assess the morphology of the suspensory ligament of the ovary on CT scan examination, an anatomic study of the suspensory ligament of the ovary was performed to demonstrate its morphology on CT and to facilitate the visualization of the ovaries. Twelve female cadavers were studied after intravascular injection of latex (venous 2, arterial 6, arterio-venous 4). We first observed all the pelvises after their transection. Six dissections were then made to obtain optimal anatomic correlations on the content and relations of the infundibulo-pelvic ligament. The arterial opacifications were poor compared with to the good quality of the venous or arterio-venous opacifications. An upright correlation between CT slices and the anatomic study was made. This radio-anatomic study emphazises the importance of the veins, which really support the suspensory ligament of the ovary, as opposed to the involution of the arteries. This study points out the link between the infundibulo-pelvic ligament above and the utero-ovarian below, then with the superficial uterine vv. All these structures were well analyzed on CT and during the anatomic studies. A very well developed periovarian venous plexus which frequently concealed the ovaries was demonstrated. Some anatomic variations which were invisible on the CT scan examinations were displayed. The visualization of the suspensory ligament of the ovary should facilitate the visualization of the ovaries and could optimize the search for lymphadenopathies originating from ovarian cancers.

High-resolution computed tomographic study of the retrotympanum

Summary: The aim of this study was to define the imaging of the retrotympanum precisely by means of high-resolution CT. Based on 66 scans of petrous bones performed in 49 patients observed in an otologic department, several retrotympanic structures were studied: the pyramidal eminence, ponticulus, subiculum, chordal ridge, tympanic sinus of Proctor, sinus tympani and recess of the facial n. The variations in morphology and depth were noted as well as the relationship between the pyramid and the facial canal. In a second phase the same anatomic structures were studied in 24 temporal bones removed from embalmed cadavers and investigated with the same radiologic technique. Anatomic correlations were made for six temporal bones to confirm the general applicability of our radiologic hypotheses. In CT the pyramidal eminence was visualised in 100% of cases, the chordal ridge in 52%, the ponticulus in 63% and the subiculum in 57%. As regards the different recesses, the sinus tympani was visualised in 95% of cases, the posterior tympanic sinus of Proctor in 38%, the fossula of Grivot in 47% and the facial recess in 80%. The mean depth of the sinus tympani was 2.7 mm and that of the tympanic sinus of Proctor was 1.65 mm; the fossula of Grivot was assessed as 2.1 mm and the facial recess as 2.2 mm. A better knowledge of these sinuses and their variations will aid the surgeon, particularly in a posterior tympanotomy or a retro-facial approach.