Diffusion weighted MR imaging on a low-field open magnet. Comparison with findings at 1.5T in 18 patients with cerebral ischemia.

Diffusion-weighted MR imaging (DWI) is particularly sensitive for the detection of acute stoke. Until recently, DWI was performed with EPI technology. We compared 18 patients with clinical suspicion of acute stroke on a standard 1.5T unit and an open low-field MR scanner. Eighteen patients with 20 lesions of acute stroke were studied retrospectively with DWI and ADC mapping on both systems. The technique used was a rotating fast-spin echo T2 at low-field and an EPI sequence at 1.5T. Both examinations were performed within 24 hours and analyzed by two neuroradiologists. We obtained the same results on DWI sequences on both systems, regarding high intensity lesions on DWI. Interpretation of the ADC maps proved to be difficult on low-field MR near the lateral ventricles (3/18). We experienced the same difficulty of interpretation at low and high field in the cerebellum, in the temporal fossa and in cortex situated near bone, due to susceptibility artifacts. Chronic lesions were better visualized at low than at high field. In our opinion, DWI on a low-field open MR scanner is a good technique to evaluate subacute stroke and was as reliable as when performed on a 1.5T MR system.

Preoperative silk suture embolization of cerebral and dural arteriovenous malformations.

OBJECT: The aim of this study was to evaluate the use of silk sutures as a medical implant when applied for the embolization of cerebral and dural arteriovenous malformations (AVMs). The facility of surgery and the clinical significance of complications related to preoperative silk suture embolization were evaluated immediately after surgery and at long-term follow up. METHODS: Thirty-four patients harboring 29 cerebral and five dural AVMs underwent embolization in which silk alone or in association with other agents was used. Medical and radiological records obtained in these 34 patients were reviewed retrospectively. The cerebral AVMs were classified according to the Spetzler-Martin grading system and the dural AVMs to the Djindjian grading system. The facility of the resection and the adverse outcomes, including new neurological deficits, hemorrhage, and fever, as well as histopathological evidence of vessel inflammatory changes, were determined in each case. In all 23 surgical cases, the AVM could be easily manipulated and excised. New temporary neurological deficits occurred in three patients. A high Spetzler-Martin grade was not associated with a higher incidence of new neurological deficits. One delayed-onset hemorrhage was detected after embolization. Fever was present in 24% of the patients. No sign of significant vasculitis or perivascular inflammation was found on radiological or histopathological examination. CONCLUSIONS: Silk sutures are safe embolic agents especially for proximal occlusion of AVM feeding vessels. New permanent neurological deficits were not encountered in this series. Fever was considered to be a minor, temporary side effect of silk suture embolization.

Termination of the inferior petrosal sinus: an anatomical variant.

Unusual caudal terminations of the inferior petrosal sinus (IPS) characterized by an extracranial extension joining the internal jugular vein up to 40 mm below the external skull base are reported. This variation was observed bilaterally on an anatomical specimen and unilaterally on four patients during diagnostic cerebral angiography. It may be considered an accessory internal jugular vein and, if present, may allow for an alternate endovascular access to the IPS.

Magnetic resonance imaging of facial vascular anomalies.

In 36 patients, facial vascular anomalies were studied with 46 magnetic resonance (MR) examinations, 9 angiograms, and 5 computed tomographic scans. All lesions were categorized into classic pathologic groups on the basis of radiologic and pathologic studies, clinical examination, and behavior. Overall, 2 juvenile hemangiomas, 3 capillary malformations (port-wine stains), 18 venous malformations, 9 lymphatic malformations, and 4 arteriovenous malformations were found. MR imaging was superior to computed tomography and angiography for demonstrating the precise anatomic extent of the facial vascular anomalies and their relationship to the adjacent soft tissues but was inferior to computed tomography for demonstrating radiopaque structures such as trophic bone changes and phleboliths. MR imaging was also inferior to angiography in determining the nidus and the exact nature of collateral vascular structures in arteriovenous malformations. MR studies confirmed the clinically suspected diagnosis of facial vascular anomalies and demonstrated typical characteristics for each type of lesion. MR imaging is an ideal initial technique to triage patients with facial vascular anomalies for appropriate management, including observation, endovascular therapy, or surgical excision.