The new imaging modality offers an easier and more immediate interpretation of 3D data, while maintaining the same accuracy in target definition as that provided by the standard technique. Moreover, the new method has the advantage of using nonstereotactic 3D angiography, which can be performed at a different site and a different time with respect to the irradiation procedure.
In this paper a novel technique is proposed and validated for radiosurgery treatment planning of arteriovenous malformations (AVMs). The technique was developed for frameless radiosurgery by means of the CyberKnife, a nonisocentric, linac-based system which allows highly conformed isodose surfaces to be obtained, while also being valid for other treatment strategies. The technique is based on registration between computed tomography (CT) and three-dimensional rotational angiography (3DRA). Tests were initially performed on the effectiveness of the correction method for distortion offered by the angiographic system. These results determined the registration technique that was ultimately chosen. For CT-3DRA registration, a twelve-parameter affine transformation was selected, based on a mutual information maximization algorithm. The robustness of the algorithm was tested by attempting to register data sets increasingly distant from each other, both in translation and rotation. Registration accuracy was estimated by means of the "full circle consistency test." A registration quality index (expressed in millimeters) based on these results was also defined. A hybrid subtraction between CT and 3DRA is proposed in order to improve 3D reconstruction. Preprocessing improved the ability of the algorithm to find an acceptable solution to the registration process. The robustness tests showed that data sets must be manually prealigned within approximately 15 mm and 20 degrees with respect to all three directions simultaneously. Results of the consistency test showed agreement between the quality index and registration accuracy stated by visual inspection in 20 good and 10 artificially worsened registration processes. The quality index showed values smaller than the maximum voxel size (mean 0.8 mm compared to 2 mm) for all successful registrations, while it resulted in much greater values (mean 20 mm) for unsuccessful registrations. Once registered, the two data sets can be used for CyberKnife treatment planning. Target delineation is performed on 3DRA while dose calculation and DRR generation are performed on CT. In conclusion, a method was developed for using 3DRA images for AVM frameless radiosurgery treatment planning. The method proved to be feasible, robust, and accurate for clinical use. 3DRA can be performed at different times or locations compared to standard, frame based stereotactic angiography. Unlike two-dimensional angiography, 3DRA allows examination of the shape of the AVM and of the surrounding target from any arbitrary point of view during treatment planning. The method can be applied to any case of intermodality registration, is operator-independent, and allows estimation of registration quality. Further research is desirable to improve time resolution in order to distinguish between feeding and draining vessels.
A series of 10 surgically treated "spontaneous" spinal haematomas (7 cases with epidural, 3 with intramedullary location), is presented. Symptomatology was rarely acute. Clinical onset was mostly dominated by spinal or radicular pain, followed by severe motor deficit. Surgical outcome was satisfactory in the majority of cases. Age, duration of symptoms, haematoma site and size appeared to have no influence on final outcome. This was significantly correlated only with the preoperative neurological condition.
to evaluate the role of anticoagulation therapy in carotid stenting with filter devices, we compared the activated clotting times (aCt) to angiographic filter patency and to the materials found inside the filters.29 endovascular treatments with filter cerebral protection in 27 patients affected by symptomatic internal carotid stenosis > 70% were considered. angiographic findings, aCt and histopathologic specimens were recorded and statistically correlated.Satisfactory dilatation of the stenosis was always achieved with a complication rate of 3%. during the procedure nine filters caused 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. distal protection filters can collect plaque fragments occurring during carotid stenting. a significant proportion of the debris found in the filters consisted of thrombotic material. monitoring of heparin anticoagulation is recommended to prevent filter occlusion.
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