[Imaging of subarachnoid hemorrhage]. / Imagerie de l'hémorragie sous-arachnoïdienne.

Even if acute subarachnoid hemorrhage (SAH) accounts for only 5% of strokes, its diagnosis is very important because its clinical consequences can be tragic. Recent technological advances in medical imaging have improved diagnostic and therapeutic management of patients with SAH. Nonenhanced CT of the head is the initial imaging modality in suspected SAH for the detection of ruptured intracranial aneurysms. Digital subtraction angiography (DSA) remains the reference exam. Multidetector row CT angiography may potentially replace DSA in the emergency setting, as it provides image data that allows evaluating aneurysmal morphology, the neck size or the visualization of vessels in the vicinity of the aneurysm. For SAH unrelated to aneurysm rupture (15% of cases), MRI and MRA can be added to the diagnostic work-up in order to exclude other differential diagnoses such as venous thrombosis or angiitis. Finally, transcranial color-coded duplex sonography, CT, or MRI are used in clinical practice in order to detect aggravating factors of SAH like hydrocephalus or vasospasm.

MR imaging features of idiopathic thoracic spinal cord herniations using combined 3D-fiesta and 2D-PC Cine techniques.

Idiopathic thoracic spinal cord herniation (TISCH) is a rare cause of surgically treatable progressive myelopathy. The authors report 3 cases of TISCH diagnosed based on conventional T1- and T2-weighted Spin-Echo (SE) MR images in one case, and T1- and T2-weighted SE images combined with 3D-FIESTA (Fast Imaging Employing Steady state Acquisition) and 2D-Phase-Contrast Cine MR imaging in 2 cases. Conventional MRI findings usually provided the diagnosis. 3D-FIESTA images confirmed it, showing the herniated cord in the ventral epidural space. Moreover, in combination with 2D-Phase Contrast cine technique, it was a sensitive method to for the detection of associated pre- or postoperative cerebrospinal fluid spaces abnormalities.

MR imaging features of spinal schwannomas and meningiomas.

Spinal schwannomas and meningiomas are mostly benign, intra-dural extramedullary tumours. We retrospectively reviewed the Magnetic Resonance Imaging (MRI) examinations of 52 spinal schwannomas and meningiomas operated on at our institution since 1998. The series included 28 schwannomas and 24 meningiomas. We compared MRI features of schwannomas and meningiomas and evaluated statistical features that would allow differentiation. Tumours with extraspinal extension were excluded. Concerning the cranio-caudal distribution, half of the cervical tumours were schwannomas, 72% of thoracic lesions were meningiomas and all lumbar tumours were schwannomas. Meningiomas were significantly located at the upper and mid thoracic levels and schwannomas in the lumbar area. On T1-weighted images, MRI signal intensity and heterogeneity were not statistically different between meningiomas and schwannomas. On T2-weighted images, the signal intensity appeared significantly hyperintense and heterogeneous for schwannomas. After Gd-DTPA, we observed a significant difference between meningiomas and schwannomas, the enhancement being intense and heterogeneous in cases of schwannomas, and moderate and homogeneous in cases of meningiomas. The last significant qualitative item was the "dural tail sign", a dural enhancement or thickening near the tumour. It was found in only 16 cases of meningiomas. A simple diagnostic test was built for schwannomas by processing a multiple agreement analysis with the 6 significant items: cranio-caudal location, T2 signal intensity, T2 signal heterogeneity, Gd-DTPA enhancement intensity and heterogeneity, and the "dural tail sign". This test allowed diagnosis of schwannomas with a sensitivity of 96.4%, a specificity of 83.3%, a positive predictive value of 87.1%, and a negative predictive value of 95.7%. In conclusion, we consider that a diagnosis of schwannoma should be made when a spinal intradural extramedullary tumour shows hyperintensity on T2W images or intense enhancement without dural tail sign; otherwise meningioma is more probable.

Superparamagnetic iron oxide: clinical time-response study.

Superparamagnetic iron oxide (AMI 25) is a promising new contrast agent for imaging the reticuloendothelial-system. Iron oxide crystals possess a large magnetic susceptibility and enhance proton relaxation rates, especially transverse relaxation (T2). In order to guide the clinical utilization of this contrast media we analyzed 4 patients with malignant lesions of the liver before and after slow intravenous administration (20 mumol Fe/kg) of AMI 25. We performed two magnetic resonance (MR) sequences at different times using a 0.35 T magnet. MR signal-to-noise ratio (SNR) of the reticuloendothelial system (particularly the liver SNR) decrease promptly. The maximum decrease in SNR (67-72% for the liver, 46-65% for the spleen, 23-41% for the bone marrow) is observed 3 h after injection (P less than 0.01). However, except the peak of contrast enhancement in T1-weighted sequences of splenic tissue, the curve describes a plateau within 30 min and 6 h, allowing a delay between injection and imaging. T2-weighted sequences give a greater contrast-to-noise ratio (CNR) by adding the spontaneous tumor contrast to the effect yielded by AMI 25. These results suggest that images must be acquired between 1 and 6 h after intravenous administration of superparamagnetic iron oxide.

Magnetic resonance imaging in acute cerebral ischaemia.

The frequency of cerebral vascular accidents justifies a rapid evaluation of the patients to distinguish between ischaemia and haematoma. In acute cerebral ischaemia, data from the literature show that magnetic resonance imaging is sensitive early (4th to 6th hours) and anatomically efficient (posterior fossa, brain stem) although it lacks specificity, being based on water movements alone. The most difficult differential diagnosis in the acute phase is bleeding, and in that phase early computerized tomography images are easier to interpret.

[Diabetes insipidus caused by metastasis to the hypothalamo-hypophyseal axis. Apropos of 4 cases]. / Diabète insipide par métastase de l'axe hypothalamo-hypophysaire. A propos de 4 cas.

This study concerns the cases of 4 patients with polyuria and polydipsia syndrome as part of a known evolutive neoplasia. MRI demonstrated an intra- and supersellar tumoral process developed from the pituitary stalk and the posterior pituitary lobe suggesting metastasis.

[The role of 3-dimensional reconstructions in the angiographic evaluation of cerebral vascular malformations: 3D morphometry]. / Place des reconstructions tri-dimensionnelles dans le bilan angiographique des malformations vasculaires cérébrales: le morphomètre 3D.

The need for medical images which can directly contribute to therapeutic decision making has led to the development of 3D visualization techniques. With this objective, a procedure capable of producing 3D volume reconstructions using isotropic voxels from digitalized 2D films obtained by rotation around the object has been developed: 3D morphometry. The technique has been assessed from 1993 through 1996 for vascular malformations in the brain, particularly aneurysms. Recognition of collateral vessels originating at the malformation was helpful in better identifying the lesions and evaluating possible therapeutic difficulties. The morphometric sequence thus is a possibility for the future assessment of neurovascular arches.

Contribution of MRI to the diagnosis and post-therapeutic monitoring of brain stem tumours.

MRI has become indispensable to the positive diagnosis of brain stem tumours which develop preferentially in young people. The prognosis of these tumours, especially infiltrating gliomas, being relatively sombre, it is important to make a precise morphological diagnosis of the lesions (increase in size, signal abnormalities) which will help both neurosurgeons and radiotherapists. As regards post-therapeutic monitoring, MRI with gadolinium contrast injection is harmless and will make it possible to follow these patients regularly and to detect recurrences.

Apparently isolated, spontaneous haematomas of the brain stem. Seven cases explored by CT and MRI.

The authors present seven cases of apparently isolated spontaneous haematomas of the brain stem detected by computerized tomography (CT). Magnetic resonance imaging (MRI) was performed in all patients, and in three of these on two occasions at different stages of the lesion. Changes in MRI signal according to the moment this examination was carried out (acute, subacute or chronic stage) are described. In two of three patients operated upon the haematoma was found to be due to an occult vascular malformation.

Contribution of MRI to the diagnosis of ACTH-secreting pituitary adenomas. Exploration of 9 patients with Cushing's disease.

Between June 1987 and October 1989, nine patients with suspected Cushing's disease were explored by magnetic resonance imaging (MRI), using an 0.35 or 0.5 Tesla magnet. All these patients underwent transsphenoidal surgery and radio-surgical correlations could be established. MRI showed a lesion in 5 cases; it was negative in 2 cases and doubtful in 2 cases. Surgery was positive for pituitary adenoma in 7 cases and negative in 2 cases (including 1 patient with subsequently discovered paraneoplastic syndrome). Using sagittal and coronal planes and combined with gadolinium enhancement, MRI proved to be the most sensitive and specific of all exploratory methods for the diagnosis of ACTH-secreting pituitary adenomas.

[Parostal lipoma of the axilla. Apropos of a case and review of the literature]. / Lipome parostal du creux axillaire. A propos d'une observation et revue de la littérature.

The authors report a case of soft tissue tumor discovered fortuitously in a 52 year old woman. This lesion was in the axilla and on standard films was seen as a well-defined radiotransparent zone, accompanied by a typical spiculated bone reaction of the lateral edge of the scapula. CT and MRI confirmed the fatty and noninvasive nature of the lesion. Histopathological examination of the operative specimen showed it to be a parostal lipoma.

[Traps in hepatobiliary echotomography caused by technical artifacts and the method of evading them]. / Les pièges de l'échotomographie hépatobiliaire dus à des artéfacts techniques et la manière de les déjouer.

Errors encountered during evaluation of hepatobiliary ultrasonography explorations due to various artefacts are described. These are mainly due to the problem of the lateral resolution of ultrasonographic recordings leading to false negatives and positives during diagnosis of the pathological process, lithiasis and cholecystitis. These are also the cause of errors during ultrasound guiding of needle punctures and thus the precision of the explorations. The major problem of echogenetic resolution is raised as this is also a cause of numerous artefacts, though it is much more difficult to evaluate their importance. Suggestions are made concerning the use of equipment for conducting explorations with the minimum of error, and the techniques to be employed.

[Renal arteriovenous fistula associated with fibromuscular dysplasia of the renal arteries]. / Fistule artérioveineuse rénale associée a une dysplasie fibromusculaire des artères rénales.

Three to 5% of hypertensive diseases have a renovascular origin. Atherosclerosis and fibromuscular dysplasia are the two major causes of renovascular hypertension. Association of renal arteriovenous fistula and fibromuscular dysplasia is uncommon. The authors propose to illustrate the usefulness of Doppler ultrasonography and digital subtraction angiography in the diagnostic and therapeutic management of a renal arteriovenous fistula associated with fibromuscular dysplasia discovered after severe preeclampsia in a 30 year-old woman.

[Radiological and magnetic resonance aspects in cerebral venous angioma]. / Aspects radiologiques et en résonance magnétique des angiomes veineux cérébraux.

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.

[Radiologic aspects of a case of Waldmann's disease]. / Aspects radiologiques d'un cas de maladie de Waldmann.

The Waldmann's disease or intestinal lymphangiectasia is a rare disease. We observed a case which occurred in a 14 years old boy. The disease was discovered in the screening of an intermittent diarrhea. The diagnosis was suspected on biological signs of protein-losing enteropathy and the presence of lymphangiectasias seen during endoscopy. The lymphography was conclusive showing the abnormal opacification of the mesenteric region. The other examinations were also important to assert the idiopathic origin of the disease.

[Test of a teleradiology network based on ATM (asynchronous transfer mode)]. / Essai d'un réseau de téléradiologie basé sur ATM (asynchronous transfer mode).

The retain project (Radiological Examination Transfer on ATM Integrated Network) consisted in teleradiology trials focused on pediatric imaging between two university hospitals. Rennes (France) and Barcelona (Spain) using an integrated broadband communication network based on ATM (asynchronous transfer mode), as part of a European research program. The network used was a full 10 Mbits/s ATM network directly connected to local PACSs (medical imaging hospital networks). One important reason to explicitly consider ATM for medical imaging is that multimedia applications on such networks allow integration of digital data and person-to-person communication. The utility of broadband communication for teleradiology has been confirmed. High quality video and sound are important for both human communication and medical video transfer. The project led to guidelines regarding technical options still open to improvement.

[Spontaneous disappearance of a thoracic disc hernia]. / Disparition spontanée d'une hernie discale thoracique.

We report a case of a 55-year-old man who experienced spontaneous resolution of a large herniated disc at T8-9. Spontaneous resolution of disc herniation is well known at the lumbar level. This case is a rare example of a large thoracic disc herniation diagnosed by CT and MRI which completely regressed six months after a medical treatment with complete disappearance of symptoms. The mechanism of resolution of a disc herniation is unclear and we discuss theoretical considerations. We emphasize the interest of conservative therapy in patients with thoracic disc herniation without neurological deficit.

[The place of arteriography in the etiologic diagnosis of spontaneous intracerebral hematomas]. / Place de l'artériographie dans le diagnostic étiologique des hématomes intra-cérébraux spontanés.

456 cases of spontaneous cerebral hemorrhage have been referred at the Neurosurgical Department of the University of Rennes since the CT scan is available, i.e. from 1979 till 1984. Sixteen passed away at the time of admission itself. Among the remaining 440 cases a diagnosis of cerebro-vascular malformation was suspected in 189 according to some atypical features in clinical and/or scanographic presentation, but only 101 patients were actually submitted to an angiographic evaluation, 88 others presenting with a very deep comatose state leading to death in a few hours. We found 14 vascular anomalies (14 p. cent) amongst them eight arterial aneurysms, five arteriovenous malformations and one combining cerebellar AVM and arterial aneurysm of the basilar artery. We couldn't perform an autopsy in all lethal cases but the necropsy findings lead to discover eight additional cases (4 aneurysms and 4 AVM). Statistically it means that a gross vascular lesion is responsible of 5% of cases of cerebral hematomas (22 out of 440). We didn't take in account the cavernomas discovered at the pathological examination of the walls of several hematomas. We may conclude that a careful angiographic study is justified in following cases: young age of the patient (under 65); lack of risk factors, especially cardio-vascular or hematologic; relatively satisfactory clinical status of the patient; topographic criteria related to the CT scan (hematomas located in the fronto-basal area and near sylvian fissure).

[Why should vascular patients have a dietary assessment?]. / Pourquoi devons-nous évaluer l'alimentation des sujets à risque vasculaire ?

Vascular diseases are a major health problem in Western countries. Coronary heart disease (CHD), stroke, and peripheral arterial disease (PAD) share many common risk factors such as age, smoking, dyslipidemia, and diabetes. Although the dietary pattern is considered as a risk factor for CHD, the impact of dietary pattern on stroke and PAD is debated. However, new studies showed that dietary pattern could also be considered as a risk factor in stroke and PAD. Dietary pattern should be evaluated in vascular patients and new tools of dietary assessment must be developed for a better prevention of vascular disease.

Quality-evaluation scheme for cerebral time-resolved 3D contrast-enhanced MR angiography techniques.

BACKGROUND AND PURPOSE: No practical tool has been reported in the literature to evaluate the quality of cerebral TR-3D-CE-MRA techniques. Our study assessed a large list of parameters used to propose a quality-evaluation scheme for TR-3D-CE-MRA. MATERIALS AND METHODS: A large list of visual and quantitative parameters used to study the quality of images was collected from the literature and evaluated in 19 healthy patients and 11 patients with arteriovenous shunts who had undergone both CENTRA keyhole TR-3D-CE-MRA at 3T and CCA. Several observers evaluated the visual parameters, such as the diagnostic confidence index, artifacts, maximum vascular signal intensity, arterial-to-venous separation, and visibility of 17 arteries and 7 veins; and quantitative parameters, such as maximum arterial SI, arteriovenous transit time, arteriovenous contrast curve, and ADW. A statistical analysis was used to determine interobserver reproducibility of the visual parameters, to calculate the sensitivity of TR-3D-CE-MRA for detecting each vessel (with CCA as standard of reference), and to compare the results of the visual and quantitative evaluations. RESULTS: Diagnostic confidence index, artifacts, arterial-to-venous separation, and 4 vessels-the PICA, ophthalmic and occipital arteries, and the ISS-demonstrated high reproducibility and sensitivity. The ADW was the most reliable dynamic quantitative parameter and was correlated with arterial-to-venous separation. CONCLUSIONS: The image quality of TR-3D-CE-MRA can be effectively evaluated with a scheme of 1 quantitative and 7 visual parameters.