Diagnostic performance of intraoperative cone beam computed tomography compared with postoperative magnetic resonance imaging for detecting hemorrhagic transformation after endovascular treatment following large vessel occlusion.

OBJECTIVES: Early detection of hemorrhagic transformation (HT) in patients with large vessel occlusion (LVO) after endovascular treatment is important for postoperative patient management. We investigated the diagnostic performance of intraoperative cone beam computed tomography (CBCT) with reference standard magnetic resonance imaging (MRI) for detecting HT. MATERIALS AND METHODS: Consecutive patients with LVO treated by endovascular treatment who underwent intraoperative CBCT and postoperative MRI were included. Two observers evaluated all images for the presence of HT. Sensitivity and specificity for detecting HT were calculated with MRI as reference standard. The observers classified HT according to the European Cooperative Acute Stroke Study (ECASS). Inter-method and inter-rater agreement for the detection of HT and for the ECASS classification were assessed using kappa or weighted Brennan-Prediger (wBP) statistics. RESULTS: Images of 106 procedures (94 for anterior circulation) were analyzed. The sensitivity and specificity for detecting HT on CBCT were 0.77 and 0.83, respectively, for all procedures and 0.83 and 0.8, respectively, for anterior circulation. The inter-method agreement for HT detection (κ = 0.63 overall, κ = 0.69 anterior circulation) and ECASS classification (wBP = 0.67 overall, wBP = 0.77 anterior circulation) were substantial. The inter-rater agreement for HT detection (κ = 0.87 overall, κ = 0.85 anterior circulation) and for ECASS classification (wBP = 0.95 overall, wBP = 0.92 anterior circulation) were almost perfect. CONCLUSIONS: The diagnostic performance of CBCT for the detection of HT in stroke patients treated for LVO was acceptable with excellent inter-rater agreement. Intraoperative CBCT may be useful to trigger early interventions if HT is detected, although detailed classifications of HT may be difficult.

4D Digital Subtraction Angiography for the Temporal Flow Visualization of Intracranial Aneurysms and Vascular Malformations.

PURPOSE: To assess the benefit and radiation dose of four-dimensional (4D) digital subtraction angiography (DSA) - a time resolved three-dimensional (3D) DSA application - to evaluate the flow and architecture of aneurysms and vascular malformations. METHODS: All patients with cerebrovascular disease were considered who underwent 4D-DSA at our institution between January 2015 and February 2016. For the aneurysm patients, we evaluated the image quality in terms of the visualization of contrast flow in the aneurysm on a 3-point scale (excellent, fair and poor). Interrater agreement between two raters was estimated using Cohen's Kappa statistics. For the shunt disease patients, the additional information obtained from the 4D-DSA was described for each disease. The median radiation dose and volume of contrast medium required for the acquisitions were estimated. RESULTS: A total of 173 patients underwent 4D-DSA; 126 intracranial aneurysms, 10 arteriovenous malformations (AVM), 15 dural arteriovenous fistula (dAVF) and 22 other diseases. For aneurysm patients, excellent and fair visualization of the intra-aneurysmal flow was observed in 27.7%, 72.3%, and excellent (κ = 0.9) agreement between the raters was found. For AVM and dAVF patients, 4D-DSA clarified the complex vasculature by viewing the discrete time phase of contrast filling. Median radiation dose for intracranial lesions was 79.6 mGy for 6s 4D-DSA, and 175 mGy for 12s 4D-DSA. The median amount of contrast medium used was 18.0 ml for 6s 4D-DSA and 21.0 ml for 12s 4D-DSA. CONCLUSIONS: 4D-DSA provided additional information regarding intra-aneurysmal flow and contributed to detect different component of nidus or shunt points.

Immunohistochemical Analysis of Debris Captured by Filter-Type Distal Embolic Protection Devices for Carotid Artery Stenting.

BACKGROUND: Little is known about the micro-debris captured in filter-type distal embolic protection devices (EPD) used for carotid stenting (CAS). This study aimed to determine the histological and immunohistochemical characteristics of such debris by using a new liquid-based cytology (LBC) technique. METHODS: Fifteen patients who underwent CAS using a filter-type distal EPD (FilterWire EZ; Boston Scientific, Marlborough, MA, USA) were included in the study. After gross inspection of each recovered filter device, micro-debris were collected using a new LBC technique (SurePath; TriPath Imaging, Inc., Burlington, NC). Histological and immunohistochemical analysis of the recovered debris was performed. The pre- and postoperative brain magnetic resonance imaging and neurological status of each patient were also reviewed. RESULTS: No patient developed ipsilateral symptomatic stroke due to a thromboembolic event. All 15 patients (100%) had microscopically identifiable debris in the filters, whereas gross inspection detected visible debris only in 5 patients (33.3%). Histological analysis revealed various types of structural components in an advanced atheromatous plaque, including fragments of fibrous cap, calcified plaque, smooth muscle cells, and necrotic tissue fragment infiltrated with monocytes and macrophages. CONCLUSIONS: Filter-type EPDs may contribute to reducing the risk of CAS-related embolic events by capturing micro-debris even when gross inspection of the recovered filter shows no visible debris in the device.

Clinical outcomes of procedures combining endovascular embolization with a direct surgical approach in a hybrid operating room for the treatment of refractory dural arteriovenous fistulas.

BACKGROUND: We reviewed the clinical outcomes of a procedure that combines endovascular embolization and a direct surgical approach in a hybrid operating room (OR) for the treatment of refractory dural arteriovenous fistulas (dAVFs). METHODS: All patients with intracranial dAVFs who underwent a procedure combining endovascular embolization and direct surgical approach with biplane angiography or a robotic C-arm system in a hybrid OR between February 2004 and June 2020 were considered. Borden grading, occlusion rate, pre-and post-operative modified Rankin Scale (mRS) scores, and complications were retrospectively investigated. The pre-and postoperative mRS scores were compared using the Wilcoxon signed-ranks test. RESULTS: We evaluated 14 arteriovenous fistulas (AVFs) in consecutive 13 patients. Of these, ten AVFs were previously treated with endovascular embolization, ten were located in the transverse-sigmoid sinus, and four in the cortical vein. The Borden grade was II in two AVFs and III in 12 AVFs. Immediate occlusion of the AVF was achieved in 13 AVFs, and gradual occlusion was observed in one case. The median preoperative mRS was 1 (0-3), whereas the median postoperative mRS was 0 (0-1) which indicated marked improvement (P = 0.006). Complications including postoperative transient visual disturbance and intraprocedural extravasation were observed in only two cases. CONCLUSION: The combination of endovascular embolization and direct surgical approach in a hybrid OR could achieve sufficient occlusion of refractory AVFs with acceptable complication rates and improved symptoms.

Visual complications after coil embolization of internal carotid artery aneurysms at the ophthalmic segment.

BACKGROUND: Coil embolization of aneurysms of the ophthalmic segment of the internal carotid artery (ICA-OphA ANs) has potential risks of visual complications. We analyzed this risk and focused on the relationship of the ophthalmic artery (OphA) origin with the aneurysm neck. METHODS: From January 2003 to April 2018, 179 unruptured ICA-OphA ANs were treated with endovascular surgery in our institution. Two ruptured and four aneurysms with missing data were excluded. Finally, 173 unruptured aneurysms were included in this study. The aneurysms were classified into three groups according to the location of the OphA origin: Separate, Shared, and Dome type. We retrospectively assessed visual complications based on the relationship between types of aneurysm and postoperative angiographic findings for the OphA. RESULTS: Visual deficits remained permanent in eleven cases (6.4%). In the Dome type, visual complications were significantly more frequent compared to the Separate type. Change in the OphA flow was significantly associated with a higher complication rate of 2.9%, but patients with changed OphA flow had a significant rate of 7.5% (p = 0.020). We found no significant difference in the incidence of visual complications concerning the use of perioperative antithrombotic therapy. CONCLUSIONS: The location of OphA origin regarding the aneurysmal neck and postoperative OphA flow were significantly correlated with the visual outcome after coil embolization for ICA-OphA ANs. Post-procedural flow in the OphA was an important factor affecting the rate of ischemic retinal complications. Retinal embolic events occurred with preserved flow in the OphA, albeit at a lower rate.

Flow Diverter Apposition in Patients with Large or Giant Intracranial Aneurysms Evaluated on Three-Dimensional Fusion Images Acquired by High-Resolution Cone-Beam Computed Tomography and Digital Subtraction Angiography.

OBJECTIVE: To investigate flow diverter (FD) apposition on fused images acquired by high-resolution cone-beam computed tomography (CBCT) and 3-dimensional (3D) digital subtraction angiography. METHODS: Patients with large or giant internal carotid artery aneurysms treated with Pipeline FDs who underwent CBCT imaging at our institution between October 2016 and May 2019 were included. Two neurosurgeons measured the maximum malapposition between FDs and vessel walls on 3D fusion images of high-resolution CBCT images displaying the FD and 3D digital subtraction angiography images displaying the vessels. Associations between the relative malapposition, FD diameter, vessel diameter, proximal and distal vessel diameter discrepancy, and siphon angle were evaluated by linear regression analysis. Inter-rater and intermethod (3D and 2D image) agreements of the malapposition measurements were assessed by Bland-Altman analysis and by interclass correlation coefficients. RESULTS: Images of 2 patients were excluded because of image artifacts or fusion errors, and 3D fusion images were acquired in the remaining 26 patients. Our results did not suggest that relative malapposition was associated with vessel diameter (P = 0.12), vessel diameter discrepancy (P = 0.60), or syphon angle (P = 0.34), but relative malapposition increased by an estimated 13% (95% confidence interval: 4%-23%, P = 0.006) for each 1 mm increase in FD diameter. Inter-rater and intermethod agreements for apposition measurements were excellent and good, respectively. CONCLUSIONS: Three-dimensional fusion images provided clear visualization of structures of both the stent and parent artery with excellent diagnostic reliability. Careful deployment may be needed for FDs with larger diameters, as they tended to have larger relative malapposition.

Comparison of Clinical Outcomes After Stent-Assisted Coiling with 3 Types of Self-Expanding Laser-Cut Stents in Patients with Wide-Necked Intracranial Aneurysms.

OBJECTIVE: We report the clinical outcomes of stent-assisted coiling for wide-necked intracranial aneurysms using 3 low-profile laser-cut stents and compare the results according to stent type. METHODS: All patients treated with stent-assisted coiling for their intracranial aneurysms at our hospital between July 2010 and September 2019 were reviewed. We selected patients with Enterprise, Neuroform EZ, or Neuroform Atlas stents who underwent imaging follow-up and investigated aneurysm and stent features, stent-related complications, recanalization, and retreatment rates. We compared the retreatment risk among the patients treated with the 3 stent types using Kaplan-Meier survival analysis and Cox regression analysis. RESULTS: We evaluated 364 consecutive cases (103 Enterprise, 105 Neuroform EZ, and 156 Neuroform Atlas stents). Neuroform Atlas was more frequently used in distal vessels: 8 (7.8%) Enterprise, 2 (1.9%) Neuroform EZ, and 41 (26.3%) Neuroform Atlas cases, respectively. The median follow-up durations were 6.49, 4.91, and 1.24 years for the Enterprise, Neuroform EZ, and Neuroform Atlas cases, respectively, and retreatment was performed in 11 (10.1%), 9 (8.6%), and 6 (3.8%) cases. In the first 2 years of follow-up, the estimated retreatment risk ratios for Neuroform EZ and Neuroform Atlas with Enterprise as reference were 0.63 (95% confidence interval, 0.24-1.65; P = 0.35) and 0.54 (95% confidence interval, 0.18-1.59; P = 0.26), respectively. CONCLUSIONS: Neuroform Atlas stents were more frequently deployed in small-caliber vessels compared with the other 2 types of stents. The complication rate and retreatment risk until at least 1 year after the aneurysm treatment appeared to be similar for the 3 stent types.

Evaluation of Balloon Test Occlusion Before Therapeutic Carotid Artery Occlusion: Flat Detector Computed Tomography Cerebral Blood Volume Imaging versus Single-Photon Emission Computed Tomography.

OBJECTIVE: We aimed to compare flat detector computed tomography cerebral blood volume (FD-CBV) imaging to single-photon emission computed tomography (SPECT) as an adjunctive technique during balloon test occlusion (BTO) in patients with intracranial aneurysms or tumors. METHODS: Twelve patients who underwent SPECT (99mTc-ethyl cysteinate dimer) and FD-CBV imaging during BTO were enrolled. Color-coded cerebral blood flow (CBF) images and color-coded FD-CBV images were generated and visually inspected whether there were asymmetries between the ipsilateral and contralateral cerebral hemispheres. Region of interest measurements were performed on the color-coded images at the same locations for both modalities. The mean interhemispheric region of interest ratios were calculated, and the ratio between these were estimated using linear regression models. RESULTS: Ten patients had no symptoms during BTO. Two patients developed subtle but inconclusive neurologic changes approximately 10 minutes after balloon inflation; their images showed asymmetric color-coded images with decreased CBF and FD-CBV in the ipsilateral hemisphere. The mean interhemispheric ratio of CBF was significantly smaller in patients with subtle changes than in those without (0.84 vs. 0.98; P < 0.001). Similarly, the mean interhemispheric ratio of FD-CBV was significantly smaller in patients with subtle changes than in those without (0.88 vs. 1.06; P = 0.01). No patient showed increased CBF or FD-CBV in the ipsilateral hemisphere. CONCLUSIONS: The patients with decreased CBF on SPECT also showed decreased FD-CBV in the ipsilateral hemisphere. FD-CBV imaging may be useful as an adjunctive technique for BTO before potential therapeutic carotid artery occlusion.

Visualization of stent apposition after stent-assisted coiling of intracranial aneurysms using high resolution 3D fusion images acquired by C-arm CT.

PURPOSE: We used an imaging technique based on 3-dimensional (3D) C-arm CT to assess the apposition of three types of stents after coiling of intracranial aneurysms. METHODS: All patients with intracranial aneurysms were considered who received stent-assisted coiling with Enterprise2, Neuroform EZ, or Neuroform Atlas stents confirmed by C-arm CT imaging at our institution between June 2015 and November 2017. A 3D digital subtraction angiography (DSA) scan for vessel imaging followed by a high-resolution cone beam CT (HR-CBCT) scan for coil and stent imaging was performed. The images were fused to obtain dual volume 3D fusion images. We investigated malapposition of the stent trunk (crescent sign) and of the stent edges (edge malapposition) and used the χ2 statistic to test for an association with stent types. Inter-rater agreement between two raters was estimated using Cohen's kappa statistics. RESULTS: We evaluated 75 consecutive cases. Enterprise2 stents were used in 22 cases, Neuroform EZ in 26, and Neuroform Atlas in 27 cases. By stent type, crescent sign was detected in 27% of Enterprise2, 8% of Neuroform EZ, and none of Neuroform Atlas stents (p=0.007), while edge malapposition was detected in 27% of Enterprise2, 58% of Neuroform EZ, and 30% of Neuroform Atlas stents (p=0.05). Excellent (κ=0.81) and good (κ=0.78) agreement between the raters was found for the detection of edge apposition and crescent sign, respectively. CONCLUSION: Stent malapposition was clearly visualized by dual volume 3D imaging. The Neuroform Atlas stents showed good apposition even in vessels with strong curvature.

Combination of high-resolution cone beam computed tomography and metal artefact reduction software: a new image fusion technique for evaluating intracranial stent apposition after aneurysm treatment.

We introduce a new imaging technique to improve visualisation of stent apposition after endovascular treatment of brain aneurysms employing high-resolution cone beam CT and three-dimensional digital subtraction angiography. After performing a stent-assisted coil embolisation of brain aneurysm, the image datasets were processed with a metal artefact reduction software followed by the automated image fusion programmes. Two patients who underwent aneurysm coiling using a Neuroform stent were evaluated. The reconstructed 3D images showed a detailed structure of the stent struts and identified malappositions of the deployed stents. Case 1 showed good apposition on the outer curvature side of the carotid siphon, while the inner curvature side showed prominent malapposition. Case 2, with multiple aneurysms, showed good apposition on both outer and inner curvature sides, although inward prolapse of the struts was observed. This new imaging technique may help evaluate stent apposition after the endovascular aneurysm treatment.

Time-resolved magnetic resonance angiography (TR-MRA) for the evaluation of post coiling aneurysms; A quantitative analysis of the residual aneurysm using full-width at half-maximum (FWHM) value.

Magnetic resonance image (MRI) is now widely used for imaging follow-up for post coiling brain aneurysms. However, the accuracy on the estimation of residual aneurysm, which is crucial for the retreatment planning, remains to be controversial. The purpose of this study is to evaluate a new post-processing technique that provides improved estimation of the residual aneurysm after coil embolization. One hundred aneurysms on 93 patients who underwent coil embolization for brain aneurysm were evaluated using the 1.5 Tesla time-resolved magnetic resonance angiography (TR-MRA) one year after the treatment. To minimize the inter-observer variability caused by the window level adjustment, an automatic post processing protocol using the full-width at half-maximum (FWHM) value was utilized. The result was then compared with that from the conventional cerebral angiography. Of the 97 aneurysms that underwent both TR-MRA and DSA, 23 (23.7%) showed residual neck / dome during follow-up. After window level adjustment, the size of the parent artery in the TR-MRA was consistent with that in the DSA. The reconstructed Volume Rendering images provided clear contours of the residual aneurysms and contributed to the understanding the configuration of residual aneurysm. The largest and the smallest diameter of the residual aneurysms was larger in the TR-MRA than in the DSA (8.05 vs. 7.72 mm, p = 0.0004; 4.99 vs. 4.19 mm, p = 0.007 respectively). The sensitivity, specificity, and positive and negative predictive values of TR-MRA compared to DSA were 100%, 97%, 73%, and 100%, respectively. Using the FWHM value to optimize the window level adjustment, the size of the residual component observed in the TR-MRA was larger compared to that in the DSA whereas the size of neck and the parent artery showed consistency between the two modalities. This image processing technique can be used as an effective screening tool for evaluating residual component in post-coiling brain aneurysms.