Faculty Bibliography

The aim of this review is to describe the acquisition and reformatting of state of the art high resolution cone beam CT (HR-CBCT) and demonstrate its role in multiple neurovascular conditions as a tool to improve the understanding of disease and guide therapeutic decisions. First, we will review the basic principle of CBCT acquisition, followed by the injection protocols and the reformatting paradigms. Next, multiple applications in different pathological conditions such as aneurysms, arteriovenous malformations, dural arteriovenous fistulas, and stroke will be described. HR-CBCT angiography, widely available, is uniquely useful in certain clinical scenarios to improve the understanding of disease and guide therapeutic decisions. It rapidly is becoming an essential tool for the contemporary neurointerventionalist.AChoAho.

BACKGROUND:The superficial temporal artery (STA)-to-middle cerebral artery (MCA) bypass requires precise preoperative planning, and 3-dimensional virtual reality (VR) models have recently been used to optimize planning of STA-MCA bypass. In the present report, we have described our experience with VR-based preoperative planning of STA-MCA bypass. METHODS:Patients from August 2020 to February 2022 were analyzed. For the VR group, using 3-dimensional models from the patients' preoperative computed tomography angiograms, VR was used to locate the donor vessels, potential recipient, and anastomosis sites and plan the craniotomy, which were referenced throughout surgery. Computed tomography angiograms or digital subtraction angiograms were used to plan the craniotomy for the control group. The procedure time, bypass patency, craniotomy size, and postoperative complication rates were assessed. RESULTS:The VR group included 17 patients (13 women; age, 49 ± 14 years) with Moyamoya disease (76.5%) and/or ischemic stroke (29.4%). The control group included 13 patients (8 women; age, 49 ± 12 years) with Moyamoya disease (92.3%) and/or ischemic stroke (7.3%). For all 30 patients, the preoperatively planned donor and recipient branches were effectively translated intraoperatively. No significant difference were found in the procedure time or craniotomy size between the 2 groups. Bypass patency was 94.1% for the VR group (16 of 17) and 84.6% for the control group (11 of 13). No permanent neurological deficits occurred in either group. CONCLUSIONS:Our early experience has shown that VR can serve as a useful, interactive preoperative planning tool by enhancing visualization of the spatial relationship between the STA and MCA without compromising the surgical results.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Stereotactic radiosurgery (SRS) of larger arteriovenous malformations (AVM) is associated with an elevated incidence of adverse radiation effects (ARE). To date, volume-response and dose-response models have been used to predict such effects. To understand radiological outcomes and their hemodynamic effects on the regional brain. METHODS:A retrospective analysis was conducted at our institution using a prospective registry of patients managed between 2014 and 2020. We included patients with AVM with a nidus larger than 5 cc who received either single-session or volume-staged Gamma Knife radiosurgery. AVM volume changes, volumes of parenchymal response, and obliteration were analyzed and correlated with transit times and diameters of feeding arteries and draining veins. RESULTS:Sixteen patients underwent single-session SRS, and 9 patients underwent volume-staged SRS. The average AVM volume was 12.6 cc (5.5-23). The AVM locations were predominantly lobar (80%) and 17 (68%) were in critical locations. The mean margin dose was 17.2 Gy (15-21), and the median V12Gy was 25.5 cc. Fourteen (56%) AVMs had a transit time shorter than 1 second. The median vein-artery ratio (sum diameter of the veins/sum diameter of feeding arteries) was 1.63 (range, 0.60-4.19). Asymptomatic parenchymal effects were detected in 13 (52%) patients and were symptomatic in 4 (16%) patients. The median time to ARE was 12 months (95% CI 7.6-16.4). On univariate analysis, significant predictors of ARE were lower vein-artery ratio (P = .024), longer transit time (P = .05), higher mean dose (P = .028), and higher D95 (P = .036). CONCLUSION/CONCLUSIONS:Transit times and vessel diameters are valuable predictors of the subsequent parenchymal response after SRS. A more quantitative understanding of blood flow is critical for predicting the effects on the regional brain after AVM radiosurgery.

Meaningful contributions to neurointerventional practice may be possible by considering the dynamic aspects of angiography in addition to fixed morphologic information. The functional approach to venous anatomy requires integration of the traditional static anatomic features of the system-deep, superficial, posterior fossa, medullary veins, venous sinuses, and outflow routes into an overall appreciation of how a classic model of drainage is altered, embryologically, or pathologically, depending on patterns of flow-visualization made possible by angiography. In this review, emphasis is placed on balance between alternative venous networks and their redundancy, and the problems which arise when these systems are lacking. The role of veins in major neurovascular diseases, such as dural arteriovenous fistulae, arteriovenous malformations, pulsatile tinnitus, and intracranial hypertension, is highlighted, and deficiencies in knowledge emphasized.

The persistent carotid-vertebrobasilar anastomoses are arterial communications between the anterior and posterior circulations due to the persistence of embryological connections. We here present an extremely rare instance of a transclival persistent carotid-vertebrobasilar anastomosis in a 10-month-old infant, which does not fit into any of the traditionally described categories, such as the trigeminal artery, hypoglossal artery, or proatlantal artery.

BACKGROUND:The pipeline embolization device (PED; Medtronic) has presented as a safe and efficacious treatment for small- and medium-sized intracranial aneurysms. Independently adjudicated long-term results of the device in treating these lesions are still indeterminate. We present 3-year results, with additional application of a flow diverter specific occlusion scale. METHODS:PREMIER (prospective study on embolization of intracranial aneurysms with pipeline embolization device) is a prospective, single-arm trial. Inclusion criteria were patients with unruptured wide-necked intracranial aneurysms ≤12 mm. Primary effectiveness (complete aneurysm occlusion) and safety (major neurologic event) endpoints were independently monitored and adjudicated. RESULTS:As per the protocol, of 141 patients treated with a PED, 25 (17.7%) required angiographic follow-up after the first year due to incomplete aneurysm occlusion. According to the Core Radiology Laboratory review, three (12%) of these patients progressed to complete occlusion, with an overall rate of complete aneurysm occlusion at 3 years of 83.3% (115/138). Further angiographic evaluation using the modified Cekirge-Saatci classification demonstrated that complete occlusion, neck residual, or aneurysm size reduction occurred in 97.1%. The overall combined safety endpoint at 3 years was 2.8% (4/141), with only one non-debilitating major event occurring after the first year. There was one case of aneurysm recurrence but no cases of delayed rupture in this series. CONCLUSIONS:The PED device presents as a safe and effective modality in treating small- and medium-sized intracranial aneurysms. The application of a flow diverter specific occlusion classification attested the long-term durability with higher rate of successful aneurysm occlusion and no documented aneurysm rupture. TRIAL REGISTRATION/BACKGROUND:NCT02186561.

There are multiple treatment alternatives for cavernous dAVFs, with transvenous routes being most common. Among these routes, occluded inferior petrosal sinus is well-described, and, apart from being imaginative and elegant, it is also safe and effective. Herein we describe the application of this method to reach the fistulous pouch of a cavernous dAVF via an occluded superior petrosal sinus.

BACKGROUND:Flow diverters have revolutionized the treatment of intracranial aneurysms. Nevertheless, some aneurysms fail to occlude with flow diversion. The Prospective Study on Embolization of Intracranial Aneurysms with the Pipeline Device (PREMIER) was a prospective, multicenter and single-arm trial of small and medium wide-necked unruptured aneurysms. In the current study, we evaluate the predictors of treatment failure in the PREMIER cohort. METHODS:We analyzed PREMIER patients who had incomplete occlusion (Raymond-Roy >1) at 1 year angiographic follow-up and compared them with those who achieved Raymond-Roy 1, aiming to identify predictors of treatment failure. RESULTS:25 aneurysms demonstrated incomplete occlusion at 1 year. There was a median reduction of 0.9 mm (IQR 0.41-2.43) in maximum diameter between pre-procedure and 1 year measurements, with no aneurysmal hemorrhage. Patients with incomplete occlusion were significantly older than those with complete occlusion (p=0.011). Smoking (p=0.045) and C6 segment location (p=0.005) were significantly associated with complete occlusion, while location at V4 (p=0.01) and C7 (p=0.007) and involvement of a side branch (p<0.001) were significantly associated with incomplete occlusion. In multivariable logistic regression, significant predictors of incomplete occlusion were non-smoker status (adjusted OR 4.49, 95% CI 1.11 to 18.09; p=0.03) and side branch involvement (adjusted OR 11.68, 95% CI 3.84 to 35.50; p<0.0001), while C6 location had reduced odds of incomplete occlusion (adjusted OR 0.29, 95% CI 0.10 to 0.84; p=0.02). CONCLUSIONS:The results of our study are consistent with previous retrospective series and warrant consideration for technique adaptations to achieve higher occlusion rates. Further follow-up is needed to assess progression of aneurysm occlusion and clinical behavior in these cases.

OBJECTIVE:Morphological and angioarchitectural features of cerebral arteriovenous malformations (AVMs) have been widely described and associated with outcomes; however, few studies have conducted a quantitative analysis of AVM flow. The authors examined brain AVM flow and transit time on angiograms using direct visual analysis and a computer-based method and correlated these factors with the obliteration response after Gamma Knife radiosurgery. METHODS:A retrospective analysis was conducted at a single institution using a prospective registry of patients managed from January 2013 to December 2019: 71 patients were analyzed using a visual method of flow determination and 38 were analyzed using a computer-based method. After comparison and validation of the two methods, obliteration response was correlated to flow analysis, demographic, angioarchitectural, and dosimetric data. RESULTS:The mean AVM volume was 3.84 cm3 (range 0.64-19.8 cm3), 32 AVMs (45%) were in critical functional locations, and the mean margin radiosurgical dose was 18.8 Gy (range 16-22 Gy). Twenty-seven AVMs (38%) were classified as high flow, 37 (52%) as moderate flow, and 7 (10%) as low flow. Complete obliteration was achieved in 44 patients (62%) at the time of the study; the mean time to obliteration was 28 months for low-flow, 34 months for moderate-flow, and 47 months for high-flow AVMs. Univariate and multivariate analyses of factors predicting obliteration included AVM nidus volume, age, and flow. Adverse radiation effects were identified in 5 patients (7%), and 67 patients (94%) remained free of any functional deterioration during follow-up. CONCLUSIONS:AVM flow analysis and categorization in terms of transit time are useful predictors of the probability of and the time to obliteration. The authors believe that a more quantitative understanding of flow can help to guide stereotactic radiosurgery treatment and set accurate outcome expectations.