Petrous bone extension of middle-ear acquired cholesteatoma.

PURPOSE: To describe CT and MR features of extension to the petrous bone, which is a rare complication of acquired cholesteatoma (AC). MATERIAL AND METHODS: Postcontrast CT was performed in 4 patients, in axial (n=4) and coronal planes (n=2). The section thickness was 1.2 or 2.5 mm. MR was performed in 3 cases, using T1- and T2-weighted images (n=3) and postcontrast T1-weighted images (n=2). RESULTS: CT demonstrated a well-outlined lesion involving the petrous bone (n=4). Density could be assessed in 3 cases, showing a hypodense unenhanced mass. Lateral (n=1), superior (n=2), and posterior (n=2) semicircular canals were affected in 3 patients. AC extended to the vestibula, cochlea, and internal acoustic meatus (IAM) in 3 patients. Two ACs extended to the level of IAM, whereas 2 extended further, to the petrous apex. In one case the sphenoid sinus was affected. On MR imaging the lesion was hypointense relative to brain on T1-weighted images and hyperintense on T2-weighted images. MR imaging helped to delineate the lesion and to distinguish it from other cystic lesions of the petrous bone. CONCLUSION: CT and MR offer accurate preoperative assessment of the extension of cholesteatoma, which helps to choose the surgical approach.

[Spiral scanners: the key to imaging of kidney injuries]. / Le scanner spiralé: la clé de l'imagerie des traumatismes du rein.

Whatever the mechanism or extent of other lesions, ultrasonography is essential in evaluating damage to the kidney after abdominal trauma in order to identify renal devascularization, fracture or fragment separation, to recognize the different blood or urine components in perirenal collections, to search for associated or prior lesions, and to obtain a baseline measurement for future follow-up. Progression introduced with spiral scans now provides 3-D images for then entire organ at different times during contrast product diffusion. The corticovascular time is used to analyse the renal pedicle and cortical vascularization; the tubular time is ideal for analysing fractures and dislocations; the calicial or excretory time, together with urography films give information on extravasation of contrast product, the upper tract and the bladder. 3-D images allow reconstructions in all three plans for the different structures, faciliting interpretation. Spiral scan should be available in all emergency centers to guarantee quality management or renal trauma.

[Factors of image quality in spiral x-ray computed tomography]. / Facteurs de qualité de l'image en scanner spiralé.

In helical CT, there are 4 mains factors of quality: The in-plane spatial resolution that is the same in conventional CT; The spatial resolution on the Z axis, which is the slice thickness. The increase factor of the slice thickness between a conventional and a helical CT depends on the pitch and the reconstruction algorithm. The value of the increase factor can be easily calculated; The signal to noise ratio which depends on the collimation, the mA, the KV and the reconstruction algorithm. The signal to noise ratio is not depending on the table speed; The reconstruction interval which can be less than the slice thickness. Then the contrast of small lesion is improved and stair-step artifacts are reduced in 3D reformations.

Ultrasound assessment of ovarian stroma hypertrophy in hyperandrogenism and ovulation disorders: visual analysis versus computerized quantification.

OBJECTIVE: To extend our previous findings on the diagnostic validity of ovarian stroma hypertrophy in women with hyperandrogenic and/or menstrual disorders. DESIGN: Transvaginal ultrasonography was performed in 69 patients complaining of hyperandrogenism and/or menstrual disorders and in 48 normal ovulatory women in early follicular phase. To check the validity of stroma assessment by visual analysis, we used computer-assisted analysis, which allowed selective measurement of the stromal area on a longitudinal ovarian cut. Sensitivity and specificity of each method were estimated by using the normative data from the control group. RESULTS: Stromal area was considered to be increased using visual analysis and computer-assisted analysis in 74% and 61% patients, respectively. Specificity of this sign was 84% and 96% by visual analysis and computer-assisted analysis, respectively. In patients, the increase in stromal area correlated very significantly with the one of total ovarian area, whose upper normal limit was 5.5 cm2 per ovary. CONCLUSION: Visual assessment of stroma may be misleading in some cases, with the risk of overestimating its hypertrophy. An increased total ovarian area > 5.5 cm2 (which can easily be detected by carefully shaping a strict longitudinal ovarian cut) has the same diagnostic value as an increased stromal area by computerized measurement.

Serial anatomy of the auditory tube: correlation to CT and MR imaging.

Serial anatomy of the auditory tube (AT), was studied in nine anatomical specimens, according to transverse, coronal and specific oblique planes and was correlated to computed tomography and magnetic resonance imaging. In order to assess the orientation of the oblique plane, parallel to the AT, 30 AT specimens were catheterized: the mean angle between the AT and the Virchow plane or the bony palate was 34 degrees. The bony portion is better explored with CT, whereas the cartilaginous portion is better studied with MR. The cartilage, posterior and medial, is closed anteriorly and inferiorly by a fibrous membrane (lamina membranacea), which is not seen on CT or MR images. The AT is closely related to the tensor veli palatini muscle (TVPM) anterolaterally, and the levator veli palatini muscle inferiorly (LVPM); both are well imaged on the oblique plane. They are bounded by fascias: the submucosal fascia (tela submucosa) is medial, the pharyngobasilar fascia runs between the TVPM and the LVPM and the auditory tube; the fascia of Weber-Liel is lateral to the TVPM. Fascias are difficult to distinguish from the surrounding fatty tissue and the adjacent muscles. The auditory tube and its muscles, forming the lateral wall of the nasopharynx, are well studied by CT and MR imaging, using the transverse or, preferably oblique plane, together with coronal plane.

[Anatomy of the auditory tube: CT scan and MRI aspect]. / Anatomie de la trompe auditive: aspect tomodensitométrique et IRM.

The auditory tube is a bony and cartilaginous canal which connects the middle ear to the nasopharynx. The bony portion (protympanum), explored by computed tomography, is cone shaped, with a posterior base. The main relations are: the intrapetrous carotid, the tensor tympani muscle, the middle cerebral fossa and temporo-mandibular joint. The fibrocartilaginous portion is explored by computed tomography and mainly by magnetic resonance. The fibrocartilaginous tube is posteromedial; its upper margin is curled outward to form the roof of the cartilaginous tube. Anterioly and Laterally, the auditory tube is closed by a fibrous membrane extending along the inferior surface of the auditory tube to form its floor. The auditory tube is in contact with two main muscle: the tensor veli palatini anterolateral and the levator veli palatini posterolateral and inferior. They are bounded by fascia: the intrapharyngeal fascia is medial, the pharyngo basilar fascia (salpingopharyngeal fascia of Trölstch, is between the tensor and levator veli palatini muscles; the fascia of Weber Liel is lateral to the tensor veli palatini. The auditory tube and its muscles form the lateral wall of the rhinopharynx and prevent the extension of a pathologic process to the para pharyngeal and infratemporal spaces.