Mucosal detail at CT virtual reality: surface versus volume rendering.

PURPOSE: To evaluate computed tomographic virtual reality with volumetric versus surface rendering. MATERIALS AND METHODS: Virtual reality images were reconstructed for 27 normal or pathologic colonic, gastric, or bronchial structures in four ways: the transition zone (a) reconstructed separately from the wall by using volume rendering; (b) with attenuation equal to air; (c) with attenuation equal to wall (soft tissue); (d) with attenuation halfway between air and wall. The four reconstructed images were randomized. Four experienced imagers blinded to the reconstruction graded them from best to worst with predetermined criteria. RESULTS: All readers rated images with the transition zone as a separate structure as overwhelmingly superior (P <.001): Nineteen cases had complete concurrence among all readers. The best of the surface-rendering reconstructions had the transition zone attenuation equal to the wall attenuation (P <.001). The third best reconstruction had the transition zone attenuation equal to the air attenuation, and the worst had the transition zone attenuation halfway between the air and wall attenuation. CONCLUSION: Virtual reality is best with volume rendering, with the transition zone (mucosa) between the wall and air reconstructed as a separate structure.

The feasibility of surgical site tagging with CT virtual reality of the paranasal sinuses.

PURPOSE: The purpose of this work was to evaluate the feasibility of tagging (highlighting) surgical sites using volumetric CT virtual reality of the paranasal sinuses in the planning for endoscopic sinus surgery. METHOD: Twenty-five patients with significant paranasal sinus disease had a planned surgical site marked on 2D coronal images. This planned surgical site was then tagged and included on CT volumetric virtual reality imaging. Each case was evaluated as to the ability of the CT virtual reality to demonstrate the planned surgical site and its orientation with respect to adjacent superficial anatomy. RESULTS: For all 25 planned surgeries, the virtual images showed the entire surgical site marked on the 2D coronal images. In all 25 cases, the orientation of the planned surgical site to adjacent normal anatomy was well demonstrated. For surgery into the maxillary sinuses, tagging and electronic removal of the middle turbinates and uncinate processes mimicked the actual surgery and allowed complete visualization of the infundibulum and the planned surgical site. CONCLUSION: Planned endoscopic paranasal sinus surgical sites can be easily and reliably highlighted using CT virtual reality techniques with respect to the patient's normal endoscopic anatomy.

[An angiographic study of spinal vascularization at the thoracic-lumbar level]. / Etude angiographique de la vascularisation médullaire à l'étage dorso-lombaire.

In this retrospective work based on a series of spinal angiograms performed in the Neuroradiology Department of the Salpêtrière Hospital, Paris, we studied the number of examinations that showed one or several anterior radiculospinal arteries at the thoracolumbar level, as well as their origin at different levels from T6 to L3. Analysis of the whole group of 552 patients showed some deviation from the previously published radio-anatomical papers. This was confirmed and illustrated more clearly by the analysis of a series of 174 cases selected among these 552 patients. This second series was particular in that it featured bilateral catheterization of every artery likely to give off a radiculospinal artery at all levels from T6 to L3, thus providing more reliable statistical data. We found that 48% of the patients had their thoracolumbar blood supply based on two anterior radiculospinal arteries the lowest of which was located at, or lower than, T12, and the second and higher one between T6 and T10. Only 45% of the studies showed a blood supply relying on a single anterior radiculospinal artery which most frequently had its origin at T9. In 7% of the cases the thoracolumbar spinal cord was supplied by 3 anterior radiculospinal arteries. Our results demonstrate the presence of at least two different patterns of spinal cord blood supply at the thoracolumbar level, with a variation in the origin of the anterior radiculospinal arteries. These recent findings may increase the reliability and improve the technique of spinal angiography, especially in difficult cases.

[Echography of the parotid gland]. / L'échographie de la parotide.

Ultrasound is the first choice imaging modality for the evaluation of parotid lesions because of its simplicity and its sensitivity which is as high as that of a CT scan. It can differentiate between benign and malignant tumors. However MRI is necessary for the exploration of the deep lobe, regional spread and a better histopathologic differentiation.

[Lipoma of the parotid gland. Apropos of a case]. / Lipome de la parotide. A propos d'un cas.

Lipoma of the parotid gland is a rather rare tumor (2-3% of all tumors of the gland). Comparative imaging of a case of parotid lipoma by computed tomography, sonography and magnetic resonance is presented.

[Benign pathology of the facial bones]. / Pathologie bénigne du massif facial.

Benign pathology of the facial bones is divided into three groups: congenital, infectious and neoplastic. The knowledge of segmentation of the face into meridians is important for understanding malformations. Panoramic X-rays remain their diagnostic value. CT is able to define the exact location and contents of the tumor. Nowadays, MRI, sometimes gives information concerning the exact contents of tumors. The face is divided into meridians numbered from 0 to 7 and from 8 to 14 counting from the middle part to the external auditory neatus. Infection from dental caries may spread to the maxilla and the mandible and sometimes into masticator spaces. It can be responsible for maxillary fungal sinusitis in tumor. The main problem is not exact diagnosis but the exact location and extent of the disease in order to allow large surgical removal.

Mandibular nerve: MR versus CT about 10 proved unusual tumors.

10 patients with symptoms of mandibular neuralgia formed the basis of this study. They were studied by both enhanced CT and MRI. MRI, better than CT, easily permits distinction between intrinsic and extrinsic lesions and detects involvement of the cavernous sinus and meninges. Moreover, because of its multiplanar imaging capability, and ability to portray exquisite anatomic details and characteristic tissue signal intensity, MRI is helpful in the evaluation of tumor involvement for biopsy and preoperative planning for these deep tumours.