[Magnetic resonance angiography: fields of exploration, main indications and limitations]. / L'angiographie par résonance magnétique: domaines d'exploration, principales indications et limites.

Magnetic resonance angiography (MRA) has become a widely accepted technique with regards to the other available noninvasive techniques in the diagnosis of vascular disease. This paper proposes a review of the different indications of this technique in arterial and venous diseases. Among several MRA pulse sequences, the most frequently used until today consisted of a time-of-flight technique which provided angiograms without any injection of intravascular contrast medium. It required to be performed in a plane perpendicular to the main axis of the vessel to be optimal. New techniques, such as contrast medium bolus-enhanced acquisitions allow examination of vascular segments in a plane parallel to their course (coronal for the aorta and lower limb arteries). An increasing number of clinical applications has raised since the implementation of MRA techniques on MR devices; some of them are widely accepted, whereas some others remain under the scope of extensive validation. With a high level of accuracy in grading carotid artery stenosis, MRA is now routinely used in cerebral arterial occlusive diseases and has in part replaced contrast angiography. MRA of the venous system of the brain plays a major role in the diagnosis and follow up of dural venous thrombosis. Other vascular brain diseases, such as vascular malformations, yet have limited uses. Carotid artery dissections are fairly demonstrated with MRA, which can be used for diagnosis as well as for follow-up. The accuracy of MRA in the diagnosis of venous thrombosis of the cervical/mediastinal veins has been reported as high as 100%. Moreover, MRA allows a precise assessment of collateral vessels in case of complete cervical/mediastinal venous thrombosis.

Detection of Mycobacterium paratuberculosis by polymerase chain reaction in children with Crohn's disease.

Mycobacterium paratuberculosis, the causative agent of Johne's disease (a chronic enteritis in ruminants), has been suspected to be involved in Crohn's disease. In this study, polymerase chain reaction was used to detect the presence of IS900 DNA sequences specific to M. paratuberculosis genomes in biopsies and surgical resections from 53 children with various gastrointestinal diseases and disorders. IS900 sequences were found in 13 of 18 samples from patients with Crohn's disease (72%; P < .01 vs. samples from patients without Crohn's disease), in 1 of 5 with ulcerative colitis, in 2 of 6 with severe unclassified colitis, and in 7 of 24 with other gastrointestinal illnesses. These results appear to support the hypothesis that M. paratuberculosis is involved in the pathogenesis of Crohn's disease.

Cerebral venous thrombosis in Behçet's disease: clinical study and long-term follow-up of 25 cases.

Among 250 patients with Behcet's disease, we describe 25 cases of angiographically proven cerebral venous thrombosis. Intracranial hypertension was the most frequent manifestation. Two initially untreated patients relapsed. Treatment of cerebral venous thrombosis consisted of combined heparin and steroids in 19 patients, steroids alone in three, and heparin alone in three others. Neurologic symptoms improved rapidly in all. Nineteen patients received long-term anticoagulation, and two received aspirin. Relapse of cerebral venous thrombosis or development of optic atrophy did not occur in treated patients. Partial or total recanalization of the occluded sinus was frequent. After more than 3 years of follow-up, the prognosis of dural sinus thrombosis is satisfactory.