We present a generative approach for simultaneously registering a probabilistic atlas of a healthy population to brain magnetic resonance (MR) scans showing glioma and segmenting the scans into tumor as well as healthy tissue labels. The proposed method is based on the expectation maximization (EM) algorithm that incorporates a glioma growth model for atlas seeding, a process which modifies the original atlas into one with tumor and edema adapted to best match a given set of patient's images. The modified atlas is registered into the patient space and utilized for estimating the posterior probabilities of various tissue labels. EM iteratively refines the estimates of the posterior probabilities of tissue labels, the deformation field and the tumor growth model parameters. Hence, in addition to segmentation, the proposed method results in atlas registration and a low-dimensional description of the patient scans through estimation of tumor model parameters. We validate the method by automatically segmenting 10 MR scans and comparing the results to those produced by clinical experts and two state-of-the-art methods. The resulting segmentations of tumor and edema outperform the results of the reference methods, and achieve a similar accuracy from a second human rater. We additionally apply the method to 122 patients scans and report the estimated tumor model parameters and their relations with segmentation and registration results. Based on the results from this patient population, we construct a statistical atlas of the glioma by inverting the estimated deformation fields to warp the tumor segmentations of patients scans into a common space.

The Silk stent (Balt, Montmorency, France) is a retractable device designed to achieve curative reconstruction of the parent artery associated with an intracranial aneurysm. We present our initial experience with the Silk flow-diverting stent in the management and follow-up of 25 patients presenting with intracranial aneurysms. Twenty-five patients (age range, 34–81 years; 24 female) were treated with the Silk flow-diverting device. Aneurysms ranged in size from small (5), large (10) and giant (10) and included wide-necked aneurysms, multiple, nonsaccular, and recurrent intracranial aneurysms. Nine aneurysms were treated for headache, 14 for mass effect. None presented with haemorrhage. All patients were pretreated with dual antiplatelet medications for at least 72 hours before surgery and continued taking both agents for at least three months after treatment. A total of 25 Silk stents were used. Control MR angiography and/or CT angiography was typically performed prior to discharge and at one, three, six and 12 months post treatment. A follow-up digital subtraction angiogram was performed between six and 19 months post treatment. Complete angiographic occlusion or subtotal occlusion was achieved in 15 patients in a time frame from three days to 12 months. Three deaths and one major complication were encountered during the study period. Two patients, all with cavernous giant aneurysms, experienced transient exacerbations of preexisting cranial neuropathies and headache after the Silk treatment. Both were treated with corticosteroids, and symptoms resolved completely within a month. In our experience the Silk stent has proven to be a valuable tool in the endovascular treatment of intracranial giant partially thrombosed aneurysms and aneurysms of the internal carotid artery cavernous segment presenting with mass effect. The time of complete occlusion of the aneurysms and the risk of the bleeding is currently not predictable.

OBJECTIVE: Flow diversion has emerged as a viable treatment option for selected intracranial aneurysms and recently has been gaining traction. The aim of this study was to evaluate the safety and effectiveness of flow-diverter devices (FDDs) over a long-term follow-up period. METHODS: The authors retrospectively reviewed all cerebral aneurysm cases that had been admitted to the Division of Neurosurgery of the Università degli Studi di Napoli between November 2008 and November 2015 and treated with an FDD. The records of 60 patients (48 females and 12 males) harboring 69 cerebral aneurysms were analyzed. The study end points were angiographic evidence of complete aneurysm occlusion, recanalization rate, occlusion of the parent artery, and clinical and radiological evidence of brain ischemia. The occlusion rate was evaluated according to the O’Kelly-Marotta (OKM) Scale for flow diversion, based on the degree of filling (A, total filling; B, subtotal filling; C, entry remnant; D, no filling). Postprocedural, midterm, and long-term results were strictly analyzed. RESULTS: Complete occlusion (OKM D) was achieved in 63 (91%) of 69 aneurysms, partial occlusion (OKM C) in 4 (6%), occlusion of the parent artery in 2 (3%). Intraprocedural technical complications occurred in 3 patients (5%). Postprocedural complications occurred in 6 patients (10%), without neurological deficits. At the 12-month follow-up, 3 patients (5%) experienced asymptomatic cerebral infarction. No further complications were observed at later follow-up evaluations (> 24 months). There were no reports of any delayed aneurysm rupture, subarachnoid or intraparenchymal hemorrhage, ischemic complications, or procedure- or device-related deaths. CONCLUSIONS: Endovascular treatment with an FDD is a safe treatment for unruptured cerebral aneurysms, resulting in a high rate of occlusion. In the present study, the authors observed effective and stable aneurysm occlusion, even at the long-term follow-up. Data in this study also suggest that ischemic complications can occur at a later stage, particularly at 12–18 months. On the other hand, no other ischemic or hemorrhagic complications occurred beyond 24 months.