Multishell Diffusion MRI-Based Tractography of the Facial Nerve in Vestibular Schwannoma.

BACKGROUND AND PURPOSE: Tractography of the facial nerve based on single-shell diffusion MR imaging is thought to be helpful before surgery for resection of vestibular schwannoma. However, this paradigm can be vitiated by the isotropic diffusion of the CSF, the convoluted path of the facial nerve, and its crossing with other bundles. Here we propose a multishell diffusion MR imaging acquisition scheme combined with probabilistic tractography that has the potential to provide a presurgical facial nerve reconstruction uncontaminated by such effects. MATERIALS AND METHODS: Five patients scheduled for vestibular schwannoma resection underwent multishell diffusion MR imaging (b-values = 0, 300, 1000, 2000 s/mm2). Facial nerve tractography was performed with a probabilistic algorithm and anatomic seeds located in the brain stem, cerebellopontine cistern, and internal auditory canal. A single-shell diffusion MR imaging (b-value = 0, 1000 s/mm2) subset was extrapolated from the multishell diffusion MR imaging data. The quality of the facial nerve reconstruction based on both multishell diffusion MR imaging and single-shell diffusion MR imaging sequences was assessed against intraoperative videos recorded during the operation. RESULTS: Single-shell diffusion MR imaging-based tractography was characterized by failures in facial nerve tracking (2/5 cases) and inaccurate facial nerve reconstructions displaying false-positives and partial volume effects. In contrast, multishell diffusion MR imaging-based tractography provided accurate facial nerve reconstructions (4/5 cases), even in the presence of ostensibly complex patterns. CONCLUSIONS: In comparison with single-shell diffusion MR imaging, the combination of multishell diffusion MR imaging-based tractography and probabilistic algorithms is a more valuable aid for surgeons before vestibular schwannoma resection, providing more accurate facial nerve reconstructions, which may ultimately improve the postsurgical patient's outcome.

Acute endovascular treatment (< 48 hours) of uncoilable ruptured aneurysms at non-branching sites using silk flow-diverting devices.

A blood blister-like (BBL) or dissecting aneurysm should be carefully considered if located at a non-branching site of the supra-clinoid internal carotid artery (ICA). Several surgical and endovascular treatment methods have been proposed but they all carry a relatively high risk of morbidity and mortality. This study evaluated the effectiveness of a novel Silk flow-diverting device (SFD) placed in the early acute stage. Three patients presenting with acute subarachnoid haemorrhage caused by small blister-like aneurysms of the carotid siphon were treated within 48 hours after admission by placement of SFDs. More than one device was placed to cover the lesion. None of the patients were premedicated and started anti-platelet therapy during the procedure. All aneurysms were successfully occluded. A good outcome was observed in two out of three treated patients. No thromboembolic or haemorrhagic event occurred during or after the procedures, or during follow-up (6-14 months). SFD prevented rebleeding and the use of these devices could be proposed as an option to treat fragile uncoilable BBL aneurysms, even in the early acute phase without anti-platelet premedication. Larger studies and long-terms results are necessary.

Progressive multiple sclerosis is not associated with chronic cerebrospinal venous insufficiency.

OBJECTIVE: Chronic cerebrospinal venous insufficiency (CCSVI) had been suggested to play a major pathogenetic role in multiple sclerosis (MS), but recent data on early stages of MS have not confirmed this theory. Nonetheless, CCSVI could represent a late phenomenon of MS or be associated with progression of disability. Thus, we studied CCSVI prevalence in primary progressive (PP) and secondary progressive (SP) MS, to clarify whether CCSVI characterizes the progressive forms of this disease. METHODS: A total of 35 patients with SPMS, 25 patients with PPMS, and 60 age- and gender-matched normal controls (NC) were enrolled into a cross-sectional study. Extracranial and transcranial high-resolution venous echo color Doppler sonography (ECDS-TCDS) was performed in all patients and NC. Those patients having any abnormal ultrasound finding were asked to undergo selective venography (VGF). RESULTS: Patients with PPMS (11 women, 14 men; mean age 47 ± 11 years) had a disease duration of 11 ± 7 years and Expanded Disability Status Scale (EDSS) score of 6.0 ± 0.5. Patients with SPMS (22 women, 13 men; mean age 45 ± 14.5 years) had a disease duration of 18 ± 14 years and EDSS score of 6.0 ± 0.8. TCDS was normal in all patients. ECDS showed one or more abnormal findings in 9/60 (15.0%) patients (7/35 [20.0%] SPMS, 2/25 [8.0%] PPMS) and in 14/60 (23.3%) NC (p not significant for all comparisons). CCSVI criteria were fulfilled in 0 NC and 4 (6.7%) patients with MS: 3 SPMS and 1 PPMS. VGF, performed in 6/9 patients, was abnormal only in one case who had bilateral internal jugular vein stenosis. CONCLUSION: Our findings indicate that CCSVI is not a late secondary phenomenon of MS and is not associated with disability.

CT-3D rotational angiography automatic registration: a sensitivity analysis.

Preprocessing, binning and dataset subsampling are investigated with regard to simultaneous maximisation of the speed, accuracy and robustness of CT-3D rotational angiography (3DRA) registration. Clinical diagnosis and treatment can both take advantage of this integration, because 3DRA allows the shape of vessel structures to be evaluated three-dimensionally with respect to standard 2D projective angiography. The method for optimising preprocessing, binning and subsampling consisted of independent variation of the corresponding parameters to maximise robustness and speed while maintaining subvoxel accuracy; the latter was computed as the sum of the mean squared errors initially present in the registrations with the errors relative to both binning and subsampling. The results suggest the choice of 256 bins, steps between 14 mm (coarse optimisation) and 2.5 mm (fine optimisation) and bone segmentation by threshold, for binning, subsampling and preprocessing, respectively. The application of this parameter set-up to 50 CT-3DRA registrations resulted in a saving, on average, of 40% of the time with respect to the method previously used, while registration error was maintained within 2 mm (1.97 mm, 90% confidence interval) and robustness was increased, so that no manual initial realignment was needed in 48 registrations. Validation by the registration of images acquired for a head phantom showed subvoxel residual errors. In conclusion, the proposed procedure can be considered a satisfactory strategy to optimise CT-3DRA registration.

Carotid stenting with filter protection. Correlation of ACT values with angiographic and histopathologic findings.

BACKGROUND AND PURPOSE: Filter cerebral protection during carotid stenting has been proposed as a new tool to reduce brain embolism. Angiographic findings (filter patency), pathological analysis of the collected materials inside the filters and coagulation parameters were analyzed to identify potential down sides in the use of these protection devices. METHODS: 29 consecutive endovascular treatments with filter cerebral protection in 27 patients affected by symptomatic internal carotid stenosis>70% were considered. Angiographic findings, activated clotting times and histopathologic specimens were recorded and correlated. RESULTS: Satisfactory dilatation of the stenosis was always achieved with a complication rate of 3% (1 transient neurological deficit). During the procedure, 9 filters (31%) appeared occluded, with temporary flow impairment. Histopathologic examination demonstrated material inside the filters in 86% of cases but this material was fibrin alone in 38% and plaque debris in 48%. Significant statistical correlation (p=0.009) was found between low activated clotting time and occlusion of the filter. CONCLUSION: Distal protection filters can collect plaque fragments occurring during carotid stenting. Significant proportion of the debris found in the filters consisted of thrombotic material. Precise monitoring of heparin anticoagulation is recommended to prevent filter occlusion.

[Endovascular treatment of carotid stenosis]. / Trattamento endovascolare delle stenosi caratidee.

PURPOSE: To evaluate the efficacy and risks of endovascular treatment of carotid stenosis by percutaneous angioplasty and stenting, and to point out the potential indications of this technique compared to surgery. MATERIAL AND METHODS: From June 1996 to May 2000 we performed 84 endovascular treatments of epiaortic vessels in 79 patients with age ranging from 42 to 80. Sixty-eight symptomatic carotid stenosis greater than 70% were treated in 63 patients: 28 (41%) were post-surgical restenosis of the carotid bifurcation after carotid endarterectomy and 40 (59%) were primitive carotid stenosis. In 14 cases (20%) there was occlusion of the contralateral internal carotid artery. All the procedures were performed in the angiographic suite, with local groin anesthesia and with femoral arterial approach. Angioplasty alone was done in 9 cases (13%) while stents were positioned in 59 cases (87%). The stenoses were pre-dilated in 57% of the procedures, and post-dilated in 61%. In 8 patients (12%) the endovascular treatment was performed during distal cerebral protection. During the follow-up period patients underwent echo-Doppler studies after 24 hours, at 6 and 12 months. RESULTS AND DISCUSSION: The stenotic tracts were successfully dilated in all the patients, with a residual stenosis less than 30% in 94% of cases. We didn't observe any complication in the 30 days post-operative period. One permanent neurological deficit (1.5 %) and 1 transient neurological deficit (1.5%) were observed in 2 patients within 1 hour after treatment. Other 2 patients complained a transient ortostatic hypotension. Combined major stroke and death rates was of 1,5% after 30 days post-operative follow-up. The presence of associated occlusion of the contralateral internal carotid and the presence of cardiological failure or pulmonary insufficiency has not influenced the outcome. No new clinical complication has been reported during the follow-up while the restenosis rate after the endovascular procedure is 1.5%. Our results with the endovascular treatment of the carotid stenosis appear not significantly different from those reported by the main surgical publications and trails about the carotid endarterectomy. In particular in our experience the complication rate is similar to surgery, probably due to our patient selection and to the evolution of the materials for endovascular therapy. CONCLUSIONS: Our experience points out an improvement of the efficacy and safety of the endovascular technique. We confirm the indication of the angioplasty and stenting in post-surgical restenosis and in patients with high surgical risk. Moreover we think that the endovascular treatment can be performed also in primitive carotid stenosis with acceptable complication risk.

Interventional radiology in percutaneous management of bile duct obstruction: biliary drainage through a spontaneous common hepatic duct-duodenal fistula.

Bile duct injuries are a serious complication of biliary surgery. We report a case of benign obstruction of the common hepatic duct associated with common hepatic duct-duodenal spontaneous fistula following complex surgical intervention. We managed percutaneously the fistula with balloon dilatation and long-term stenting, as the fistula allowed biliary flow in the duodenum. We avoided reintervention preserving biliary flow, with good clinical results after a follow-up of a 3 years. We emphasize the role of a clinically focused approach to percutaneous management of complications following biliary surgery.