Daniel Ruefenacht

High-Profile Flow Diverter (Silk) Implantation in the Basilar Artery: Efficacy in the Treatment of Aneurysms and the Role of the Perforators

Background and Purpose— The introduction of flow diverters (FDs) has expanded the possibilities for reconstructive treatment of difficult intracranial aneurysms. Concern remains as to the long-term patency of the perforating arteries and side branches covered during stent placement. Our purpose was to evaluate the performance of and early effect on covered branches after implantation of the Silk FD in the treatment of basilar artery aneurysms. Methods— Twelve patients with an aneurysm of the basilar artery that was treated by implantation of the Silk FD were included in our retrospective study. Both unruptured and previously ruptured, formerly untreated, and recurrent aneurysms were treated. During follow-up, patients were monitored for clinical evolution, patency of the covered vessels, and aneurysmal obliteration. Results— Of the 2 ruptured aneurysms, 1 was initially treated by FD implantation. The FD covered the basilar bifurcation and the origin of a P1 segment of the posterior cerebral artery in 9 cases, the origin of the superior cerebellar artery in 9, and of the anterior inferior cerebellar artery in 3. There was 1 acute basilar artery occlusion a few hours after FD implantation. During a mean follow-up of 16 weeks, 3 patients experienced a symptomatic neurologic event. Conclusions— Implantation of the Silk FD in the basilar artery was feasible and well tolerated in most cases to date. However, late ischemic events affecting perforating arteries may occur after FD implantation, suggesting that the indication should be restricted to otherwise untreatable aneurysms in this location.

Angiographic Vasospasm Is Strongly Correlated With Cerebral Infarction After Subarachnoid Hemorrhage

Background and Purpose— The long-standing concept that delayed cerebral infarction after aneurysmal subarachnoid hemorrhage results exclusively from large artery vasospasm recently has been challenged. We used data from the CONSCIOUS-1 trial to determine the relationship between angiographic vasospasm and cerebral infarction after subarachnoid hemorrhage. Methods— We performed a post hoc exploratory analysis of the CONSCIOUS-1 data. All patients underwent catheter angiography before treatment and 9±2 days after subarachnoid hemorrhage. CT was performed before and after aneurysm treatment, and 6 weeks after subarachnoid hemorrhage. Angiograms and CT scans were assessed by centralized blinded review. Angiographic vasospasm was classified as none/mild (0%–33% decrease in arterial diameter), moderate (34%–66%), or severe (≥67%). Infarctions were categorized as secondary to angiographic vasospasm, other, or unknown causes. Logistic regression was conducted to determine factors associated with infarction. Results— Complete data were available for 381 of 413 patients (92%). Angiographic vasospasm was none/mild in 209 (55%) patients, moderate in 118 (31%), and severe in 54 (14%). Infarcts developed in 6 (3%) of 209 with no/mild, 12 (10%) of 118 patients with moderate, and 25 (46%) of 54 patients with severe vasospasm. Multivariate analysis found a strong association between angiographic vasospasm and cerebral infarction (OR, 9.3; 95% CI, 3.7–23.4). The significant association persisted after adjusting for admission neurological grade and aneurysm size. Method of aneurysm treatment was not associated with a significant difference in frequency of infarction. Conclusions— A strong association exists between angiographic vasospasm and cerebral infarction. Efforts directed at further reducing angiographic vasospasm are warranted.

Elevated levels of angiogenic cytokines in the plasma of cancer patients

Although in the normal healthy organism angiogenesis is a tightly regulated process, under a variety of circumstances it may contribute to disease states. These include the growth of solid tumors, the hematogenous spread of tumor cells and the growth of metastasis. Our aim was to measure the levels of 5 angiogenic cytokines in the plasma of patients with a variety of cancers, to establish a plasmatic angiogenic profile. We prospectively obtained blood samples in citrated tubes from 40 healthy individuals and 75 patients with a variety of solid tumors. Patients who had received any form of treatment in the preceeding 6 months were excluded from the study. Plasma levels of the following 5 cytokines were determined by ELISA: vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), basic fibroblast growth factor, transforming growth factor‐β and tumor necrosis factor‐α. In some cases, additional samples were taken 4 and 15 days after surgical removal of the tumor. Our findings demonstrate, that firstly, compared to the tumor group VEGF was almost always undetectable or present at very low levels in healthy individuals; secondly, a threshold value for HGF was found to exist between the 2 groups (healthy vs. tumor); and thirdly, there was a clear relationship between plasma levels of VEGF and HGF and extension of disease (i.e., without or with metastases). The timing of blood sampling in the post‐operative period was found to be critical, particularly with regard to VEGF and HGF. The existence of a systemic angiogenic profile in the plasma of cancer patients may be useful as a diagnostic and prognostic tool and may help in the future to monitor the responses of individual patients to anti‐tumor and, particularly, anti‐angiogenic therapy. Int. J. Cancer 85:40–45, 2000.

Intracranial aneurysm stenting: Follow‐up with MR angiography

Intracranial stenting is increasingly being used to treat intracranial aneurysms and stenoses. We wanted to assess the utility of magnetic resonance angiography (MRA) in the follow‐up of patients treated with various types of intracranial stents and to assess the utility of performing gadolinium‐enhanced MRA. A total of 19 patients having undergone intracranial stenting for aneurysms were imaged by MRI at 1.5T. A total of 20 stents were placed in 19 patients. In addition to conventional T2‐ and diffusion‐weighted MRI, 3D time‐of‐flight MRA was performed before and after contrast administration. In the case of metallic INX stents (N = 7), there was a signal drop at the level of the vessel. which did not allow to evaluating the parent vessel, whereas this was visible in Nitinol stents (N = 8). Additionally a stent with a wire had a small artifact (N = 3). Contrast administration also improved vessel lumen visualization. In the case of Nitinol stents, MRA can be used to reliably demonstrate the vessel lumen after intracranial stenting. The use of postcontrast 3D time‐of‐flight imaging helps improve the intraluminal definition. J. Magn. Reson. Imaging 2006.

Endovascular Treatment or Neurosurgical Clipping of Ruptured Intracranial Aneurysms. Effect on Angiographic Vasospasm, Delayed Ischemic Neurological Deficit, Cerebral Infarction, and Clinical Outcome

Background and Purpose— The effects of aneurysm treatment modality (clipping or coiling) on the incidence of cerebral vasospasm and infarction after subarachnoid hemorrhage have not been clearly defined. We hypothesized that there may be a difference in angiographic and clinical vasospasm, cerebral infarction, and clinical outcome between patients undergoing clipping compared to coiling. Methods— A retrospective, exploratory analysis of 413 patients randomized into the CONSCIOUS-1 trial was conducted. Patients underwent baseline and follow-up catheter angiography and computed tomography, as well as clinical assessments. Radiology end points were adjudicated by central blinded review, and angiographic vasospasm was quantified by measurements of arterial diameters on catheter angiography. The effect of method of aneurysm treatment (clipping [n=199] or coiling [n=214]) on angiographic vasospasm, delayed ischemic neurological deficit, cerebral infarction, and clinical outcome was analyzed using univariate and multivariate logistic regression. Propensity matching was used to adjust for differences in baseline risk factors between clipped and coiled patients. Results— In all patients and the propensity-matched subset, aneurysm coiling was associated with a significantly reduced risk of angiographic vasospasm and delayed ischemic neurological deficit compared to clipping. Cerebral infarction and clinical outcome were not associated with clipping or coiling. Conclusions— In this exploratory analysis, aneurysm coiling was associated with less angiographic vasospasm and delayed ischemic neurological deficit than surgical clipping, whereas no effect on cerebral infarction or clinical outcome was observed. Whether this is attributable to differences in baseline risk factors between clipped and coiled patients or a true difference cannot be proven here.

Three- to five-dimensional biomedical multisensor imaging for the assessment of neurological (dys)function

This report describes techniques and protocols implemented at the Geneva Canton University Hospitals (HUG) for the combination of various biomedical imaging modalities and sensors including electromagnetic tomography, to study, assess, and localize neurological (dys)function. The interest for this combination stems from the broad variety of information brought out by (functional) magnetic resonance imaging, magnetic resonance spectroscopy, computed tomography, single-photon emission tomography, positron emission tomography, and electromagnetic tomography. Combining these data allows morphology, metabolism, and function to be studied simultaneously, the complementary nature of the information from these modalities becoming evident when studying pathologies reflected by metabolic or electrophysiologic dysfunctions. Compared with other current multimodality approaches, the one at the HUG is totally compatible with both clinical and research protocols, and efficiently addresses the multidimensional registration and visualization issues. It also smoothly integrates electrophysiology and related data as fully featured modalities.

Percutaneous Vertebroplasty in Octogenarians: Results and Follow-Up

Objectives:  To determine pain relief, performance status, morbidity, and mortality associated with percutaneous vertebroplasty for spinal pain in patients aged 80 years and older.

Image quality of digital radiography using flat detector technology

One of the most demanding applications in dynamic X-Ray imaging is Digital Subtraction Angiography (DSA). As opposed to other applications such as Radiography or Fluoroscopy, there has been so far limited attempts to introduce DSA with flat detector (FD) technology: Up to now, only part of the very demanding requirements could be taken into account. In order to enable an introduction of FD technology also in this area, a complete understanding of all physical phenomena related to the use of this technology in DSA is necessary. This knowledge can be used for detector design and performance optimization. Areas of research include fast switching between several detector operating modes (e.g. switching between fluoroscopy and high dose exposure modes and vice versa) and non stability during the DSA run e.g. due to differences in gain between subsequent images. Furthermore, effects of local and global X-Ray overexposure (due to direct radiation), which can cause temporal artifacts such as ghosting, may have a negative impact on the image quality. Pixel shift operations and image subtraction enhance the visibility of any artifact. The use of a refresh light plays an important role in the optimization process. Both an 18x18 cm2 as well as a large area 30x40 cm2 flat panel detector are used for studying the various phenomena. Technical measurements were obtained using complex imaging sequences representing the most demanding application conditions. Studies on subtraction test objects were performed and vascular applications have been carried out in order to confirm earlier findings. The basis for comparison of DSA is, still, the existing and mature IITV technology. The results of this investigation show that the latest generation of dynamic flat detectors is capable of handling this kind of demanding application. Not only the risk areas and their solutions and points of attention will be addressed, but also the benefits of present FD technology with respect to state-of-the-art IITV technology regarding DSA will be discussed.

Assessment of neurological (dys)function through multidimensional and fully multisensor biomedical imaging

Various biomedical imaging sensors, including ElectroMagnetic Tomography, are being combined to study, assess, and localized neurological (dys)function. The interest for this combination stems from the broad variety and complementarity of information brought out by (functional-) Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Computed Tomodensitometry, Single Photon Emission Tomography, Positron Emission Tomography and ElectroMagnetic Tomography. Besides allowing morphology, metabolism and function to be studied simultaneously, this complementarity is also expected to show best when studying pathologies reflected by metabolic or electromagnetic dysfunctions. An example of clinical application for epilepsy assessment and surgery planning is presented, along with suggestions for further potential developments.