A medical software system for volumetric analysis of cerebral pathologies in magnetic resonance imaging (MRI) data.
ABSTRACT In this contribution, a medical software system for volumetric analysis of different cerebral pathologies in magnetic resonance imaging (MRI) data is presented. The software system is based on a semi-automatic segmentation algorithm and helps to overcome the time-consuming process of volume determination during monitoring of a patient. After imaging, the parameter settings-including a seed point-are set up in the system and an automatic segmentation is performed by a novel graph-based approach. Manually reviewing the result leads to reseeding, adding seed points or an automatic surface mesh generation. The mesh is saved for monitoring the patient and for comparisons with follow-up scans. Based on the mesh, the system performs a voxelization and volume calculation, which leads to diagnosis and therefore further treatment decisions. The overall system has been tested with different cerebral pathologies-glioblastoma multiforme, pituitary adenomas and cerebral aneurysms- and evaluated against manual expert segmentations using the Dice Similarity Coefficient (DSC). Additionally, intra-physician segmentations have been performed to provide a quality measure for the presented system.
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ABSTRACT: The simulation of pituitary gland surgery requires a precise classification of soft tissues, vessels and bones. Bone structures tend to be thin and have diffuse edges in CT data, and thus the common method of thresholding can produce incomplete segmentations. In this paper, we present a novel multi-scale sheet enhancement measure and apply it to paranasal sinus bone segmentation. The measure uses local shape information obtained from an eigenvalue decomposition of the Hessian matrix. It attains a maximum in the middle of a sheet, and also provides local estimates of its width and orientation. These estimates are used to create a vector field orthogonal to bone boundaries, so that a flux maximizing flow algorithm can be applied to recover them. Hence, the sheetness measure has the essential properties to be incorporated into the computation of anatomical models for the simulation of pituitary surgery, enabling it to better account for the presence of sinus bones. We validate the approach quantitatively on synthetic examples, and provide comparisons with existing segmentation techniques on paranasal sinus CT data.Computer Aided Surgery 10/2006; 11(5):247-55. · 0.78 Impact Factor
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ABSTRACT: To determine if there was a relationship between intrassellar pressure (ISP) and pituitary tumor volume. Between August 2002 and May 2004, 60 patients aged between 13 and 75 years old (39 males), having a pituitary adenoma were submitted to an endoscope transseptal approach. During the surgery and before tumor resection, 2 mm of the sellas floor were removed and a 1.5 mm dural opening made to place a transducer into the pituitary adenoma. The transducer was connected to a pressure monitor. The intrasellar pressure, ranged from 2-51 mmHg and was measured based on the classification of Hardy-Vezina. The most elevated was in the type II macro adenomas with 32.6 mmHg, sharply superior to the value of a normal intracranial pressure. These values showed that the macroadenomas confined to the sella, without destruction of the floor and integrity of the diaphragm, type II of Hardy-Vezina, presented a value of ISP much higher than intra-extrasellar macroadenoma's.Arquivos de Neuro-Psiquiatria 01/2007; 64(4):971-5. · 0.83 Impact Factor
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ABSTRACT: Endovascular detachable coil treatment is being increasingly used as an alternative to craniotomy and clipping for some ruptured intracranial aneurysms, although the relative benefits of these two approaches have yet to be established. We undertook a randomised, multicentre trial to compare the safety and efficacy of endovascular coiling with standard neurosurgical clipping for such aneurysms judged to be suitable for both treatments. We enrolled 2143 patients with ruptured intracranial aneurysms and randomly assigned them to neurosurgical clipping (n=1070) or endovascular treatment by detachable platinum coils (n=1073). Clinical outcomes were assessed at 2 months and at 1 year with interim ascertainment of rebleeds and death. The primary outcome was the proportion of patients with a modified Rankin scale score of 3-6 (dependency or death) at 1 year. Trial recruitment was stopped by the steering committee after a planned interim analysis. Analysis was per protocol. 190 of 801 (23.7%) patients allocated endovascular treatment were dependent or dead at 1 year compared with 243 of 793 (30.6%) allocated neurosurgical treatment (p=0.0019). The relative and absolute risk reductions in dependency or death after allocation to an endovascular versus neurosurgical treatment were 22.6% (95% CI 8.9-34.2) and 6.9% (2.5-11.3), respectively. The risk of rebleeding from the ruptured aneurysm after 1 year was two per 1276 and zero per 1081 patient-years for patients allocated endovascular and neurosurgical treatment, respectively. In patients with a ruptured intracranial aneurysm, for which endovascular coiling and neurosurgical clipping are therapeutic options, the outcome in terms of survival free of disability at 1 year is significantly better with endovascular coiling. The data available to date suggest that the long-term risks of further bleeding from the treated aneurysm are low with either therapy, although somewhat more frequent with endovascular coiling.The Lancet 11/2002; 360(9342):1267-74. · 39.06 Impact Factor