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Several studies have served to underline the interest of MRI in the diagnosis and assessment of epidural abscess and malignant extradural spinal tumors. In our work, one of the quantitatively greatest published to this day, 64 patients presenting epidural pathology were evaluated by means of MRI. All the explorations were brought about through weighted multiplaned sequences T1, T2 and gadolinium injection. The pathological spectrum encountered is comprised of: metastatic extradural spinal tumors (58%), primary extradural spinal tumors (7%), epidural localizations of hematological diseases (9%), epidural abscess (25%), and one case of epidural hematoma. Assessment was brought to bear upon behavior in relation to type of sequence, spread of disease, medullary effects, type of enhancement following gadolinium injection. Degree of correlation with clinical data and surgical findings was also appraised. As concerns tumourous epidural pathology, positive diagnosis due to a lesion hinges upon the T1 and T2 sequences. Gadolinium's contribution is restricted to analysis of perivertebral and vertebral spreading; it also facilitates recognition of the spinal cord in circumferential epiduritis. So much said, gadolinium appears to be essential in frequently less compressive forms of infectious epiduritis; it plays a pronounced role in both follow-up of their evolution and recognition of acute epidural hematoma.

Adamantinoma of the long bones in a very rare tumor that mainly affects the tibia. Its diagnosis is difficult both radiologically, as the lesion appears as a poorly specific metaphyseal lacuna with or without periosteal reaction, and histologically. Its prognosis used to be guarded because of recurrence and of possible metastatic diffusion, but it has been considerably improved by wide resection with reconstruction. On the occasion of a new case, the authors describe the appearance observed with MRI and the merits of this examination for the preoperative assessment.

As leiomyosarcomas of the inferior vena cava are extremely infrequent, the preoperative diagnosis of such tumors is rarely established. We report two cases in which the diagnosis was suggested by modern imaging prior to surgery. Three examination techniques allo contemplating this diagnosis. Ultrasound and cavography show either an intraluminal, multilobulated, roughly hyperechogenic lacuna on one of the segments of the vena cava, without any remote thrombosis image, or a complete obstruction of the vena cava with collateral circulation and a hyperechogenic right paraaortic mass. Computed tomography demonstrates the extraluminal extension. It reveals the presence of a right lateroaortic tumor with heterogeneous tissue density, in which the vena cava is concealed. The association of an intraluminal lacuna and of a tumoral syndrome on CT is highly suggestive. These three techniques are equally essential for the assessment of this tumor, which is primarily based on vascular findings. Exeresis is always difficult and the prognosis very poor.

378 tomodensitometric investigations were performed in cases of acute pancreatitis. The evolution of inflammatory lesions were analyzed with special attention to tissue aggressive inflammation in order to recognize early signs of gravity on CAT scans. Pancreatic lesions less than 15 mm in diameter called "hypodense islets-1" are compatible with oedematous lesions while lesions greater than 15 mm in diameter ("hypodense islets-2") are characteristic of developing necrosis. Tissue aggressive inflammatory lesions were classified in five grades retrospectively and showed that the incidence of abcesses was greater in grade II (76.5%) than in grade I lesions (11.75%).

Chronic rhinosinusitis endoscopic surgery needs an accurate evaluation of diseases and paranasal sinus anatomic variations. High resolution CT by thin section (2 mm) allow this pre-operative assessment. An anatomical study of the ethmoid air cell system is always possible in axial plane. The bidimensional CT exploration (axial and coronal plane) displays the anatomic variations of ostiomeatal unit, that have been reported to predispose sinusitis. They are nasal septal deviation, pneumatization and paradoxical curvature of the middle turbinate, pneumatization of unciform process, Haller's cells, prominent agger nasi cell and ethmoid bulla. The endoscopic endonasal surgery landmarks, the individual morphologic variations, the topographic relations to the orbit and to the brain are also well shown by CT.

The advance of endoscopic endonasal surgery allows limited surgical resection in chronic rhinosinusitis. An accurate topographic evaluation of diseases and individual morphologic variation are necessary for this functional surgery. The preoperative radiological investigations require a precise knowledge of ethmoid and osteo-meatal unit anatomy. Thin sections by high resolution CT were performed in coronal plane. The anatomical land marks and the ethmoidal bony roots, which allow a study of the osteo-meatal unit and ethmoid air cells system, are showed. Like endoscopic view, coronal slices better display the different grooves for paranasal sinus draining and their relations with the ethmoid.

A case of chondrosarcoma arising from the 7th left rib in a patient with multiple exostosis disease is reported. The initial CT scan feature is a purely intrathoracic mass with a parietal and pericardial junction and calcifications within the tumor. A review of the literature about the costal chondrosarcoma and their CT scan features is done and shows the uncommon initial aspect of this case.

Computed tomography is currently the most effective method for investigating the pancreas. Though far from superseding ultrasonography, which should always precede it, possible insufficiences of this examination can be corrected and doubtful images clarified. Its greatest usefulness is in acute pancreatitis, as the size of the lesion can be defined as well as subsequent therapeutic measures. It also appears to be the most reliable examination for chronic pancreatitis or cancer of the pancreas at the present time, but their differential diagnosis can raise problems when certain localized hypertrophic lesions exist. However, diagnosis of a pancreatic lesion is only possible when it deforms the gland or modifies its density, and it is illusory to expect early detection of lesions less than 2 or 3 cm in diameter, particularly in cancer cases.

Three methods are currently employed for the diagnosis of sciatica due to disc lesions: radiculography, spinal phlebography, and computed tomography. Though their indications vary according to the author, it seemed worthwhile to compare radiation delivered by each of them, because of the often young age of the patients. Dosimetric studies using a Rando Phantom enabled calculation of doses to the skin, spinal cord, and gonads. Results indicated that low doses were delivered by the scanner, relatively high doses by spinal phlebography, and intermediate doses by radiculography. These findings suggest that the initial examination preoperatively in cases of simple sciatica due to herniated disc should be a CT scan whenever possible. Phlebography, on the contrary, and particularly in young women, should be used only exceptionally, as a result of the high doses delivered to the ovaries even during technically simple explorations.

An original aspect of a case of atheromatous aneurysm of an aberrant right subclavian artery was the evaluation of the complementary diagnostic value of CT scan and intravenous digital subtraction angiography imaging. The vascular anomaly was clearly identified, the CT scan visualizing the aneurysm sac more effectively and the angiography providing a vascular cartography. These two non-invasive exploratory examinations provide complementary data for the preoperative diagnosis and investigation of the aberrant right subclavian artery aneurysm.

Findings in a series of 53 examinations performed in patients with extrahepatic cholestasis demonstrated the value of computed tomography exploration to determine mechanisms and etiology of biliary tract affections. Sensitivity of the CT scan for detection of biliary tract dilatations was equivalent to that obtained by ultrasound, and was even higher for certain types of patient (obese, distended, etc.). Results of this study combined with data in the literature enables precise diagnostic criteria to be established when determining etiology of these dilatations, which require investigation by a CT scan when ultrasound imaging proves unsatisfactory.

The primitive thoracic seminoma is a rare tumor. Given their low frequency, these tumour have rarely been the object of C.T. exploration. It determines the compressive effect on neighbouring organs, the volume and extensive character of the tumor. C.T. exploration allows proper surveillance after therapeutic.

One case of esophageal duplication cyst in adult. Hydric hypodensity of the posterior mediastinum from the apex to the dome of the diaphragm without connection with descending aorta.

Epithelioid hemangioendothelioma is a rare, ubiquitous, vascular tumor, difficult to diagnosis but sometimes identified after detection of metastases, and with a prognosis intermediary between angioma and angiosarcoma. The tumors have been described as developing in the large venous trunks and recently lesions have been reported in liver. Little documented data exist with respect to radiologic appearances. A case is reported with a histologically confirmed hepatic localization in association with a lesion in superior vena cava.

The authors report about the observation of a subperitoneal pelvic cystic lymphangioma in an adult patient: ultrasound and CT dat had yet never been described for the rare pelvic form, and are the same as with the other locations of cystic lymphangioma in adults.

Correlation of radiological and pathological findings in 155 cases of operated herniated discs emphasizes the value of a CT scan in the diagnosis of these lesions. Imaging by the scanner is a safe and relatively low-cost procedure and its reliability is identical to that of other conventional exploratory methods. It should, therefore, become the initial examination conducted during investigation of sciatica thought to be of discal origin. Reliability of results has varied between 85 and 90 p. 100, according to the author, for this essentially simple and atraumatic method. Confirmation of the presence of a hernia requires the observance of clear signs: material of discal density amputating the spinal canal and spreading over the dural sheath. False negatives or positives usually occur in borderline cases or in previously operated patients. Differences in clinical and computed tomography findings, with undoubted absence of signs on the scan image, require further investigation by radiculography.

A case of massive digestive bleeding due to an arterial abnormality of the jejunal wall is reported. Its interest is twofold: a) After a complete endoscopic and operative examination of the GI tract proved negative, an emergency superior mesenteric angiography was the only investigation which allowed to recognize the site and mechanism of the bleeding; b) from a nosologic point of view, the clinico-pathological picture was entirely similar to that of "Dieulafoy's erosion", a syndrome which has been only described, up to now, in the gastric mucosa.

A case of aneurysm of the arch of the greater azygos vein is reported. This extremely rare congenital anomaly appears as a large rounded opacity in the anterosuperior mediastinum. Though diagnosis may be suspected by the variations in size according to the period of observation and the position of the patient, if can only be confirmed by angiography, to eliminate an aneurysm of the superior vena cava or one of azygos vein from obstruction of the inferior vena cava.

The appearance observed with CT during and following eclampsia seem to be related to edema, hemorrhagic lesions and ischemic lesions. The authors report on a reversible appearance of hypodense central grey nuclei and of the calcarine cortex fitting into this new context.

The sudden development of an abdominal mass following umbilical artery catheterization during neonatal reanimation in a 1-month-old infant of an alcoholic mother was found to be due to an aneurysm of the abdominal aorta. Diagnosis was established by computed tomography and confirmed by arteriography. In the absence of any pathological examination, surgical treatment having been temporarily delayed, a mycotic origin for the aneurysm was suggested by the conditions of onset. A review of the 13 cases of primary mycotic aneurysms of the abdominal aorta in infants reported in the literature emphasizes the rare but serious nature of these lesions at this age.

This report based on a series of 8 cases deals with the appearance of cerebral venous angiomas with computed tomography (CT), arteriography and magnetic resonance imaging (MRI). The CT data are not conclusive, and venous involvement is demonstrated by arteriography, as well as the site of involvement. Magnetic resonance imaging seems to be useful owing to the morphological information and data on flow phenomena it provides.