Shougo Kaku

Drainage Pathway of the Superior Petrosal Vein Evaluated by CT Venography in Petroclival Meningioma Surgery.

Objectives This study aimed to clarify the drainage location of the superior petrosal vein (SPV) in relation to Meckels cave and the internal acoustic meatus (IAM) and to discuss its significance in petroclival meningioma surgery. Design Prospective clinical study. Setting Hospital-based. Participants Five patients with petroclival meningioma and 50 patients (primarily unruptured supratentorial aneurysm patients, with a few hemifacial spasm patients) with no posterior fossa lesions. Main Outcome Measures On computed tomography venography (CTV), the drainage site was classified into three patterns based on its relationship to Meckels cave and the IAM: Meckels cave type, Intermediate type, and Meatal type. Results In all patients, the SPV was patent and emptied into the superior petrosal sinus (SPS). In patients without posterior fossa lesions, 35% had Meckels cave type, 54% had Intermediate type, and 11% had Meatal type. Of the five patients with petroclival meningioma, three had Intermediate type, and two had Meckels cave type. Conclusion The SPV is a significant vein that should be preserved to prevent venous complications. Preoperative knowledge of the SPV drainage site is helpful for planning the approach and preserving the SPV in petroclival meningioma surgery.

Determining the Presence of Thin-Walled Regions at High-Pressure Areas in Unruptured Cerebral Aneurysms by Using Computational Fluid Dynamics.

BACKGROUND Thin-walled regions (TWRs) of cerebral aneurysms are at high risk of rupture, and careful attention should be paid during surgical procedures. Despite this, an optimal imaging technique to estimate TWRs has not been established. Previously, pressure elevation at TWRs was reported with computational fluid dynamics (CFD) but not fully evaluated. OBJECTIVE To investigate the possibility of predicting aneurysmal TWRs at high-pressure areas with CFD. METHODS Fifty unruptured middle cerebral artery aneurysms were analyzed. Spatial and temporal maximum pressure (Pmax) areas were determined with a fluid-flow formula under pulsatile blood flow conditions. Intraoperatively, TWRs of aneurysm domes were identified as reddish areas relative to the healthy normal middle cerebral arteries; 5 neurosurgeons evaluated and divided these regions according to Pmax area and TWR correspondence. Pressure difference (PD) was defined as the degree of pressure elevation on the aneurysmal wall at Pmax and was calculated by subtracting the average pressure from the Pmax and dividing by the dynamic pressure at the aneurysm inlet side for normalization. RESULTS In 41 of the 50 cases (82.0%), the Pmax areas and TWRs corresponded. PD values were significantly higher in the correspondence group than in the noncorrespondence group (P = .008). A receiver-operating characteristic curve demonstrated that PD accurately predicted TWRs at Pmax areas (area under the curve, 0.764; 95% confidence interval, 0.574-0.955; cutoff value, 0.607; sensitivity, 66.7%; specificity, 82.9%). CONCLUSION A high PD may be a key parameter for predicting TWRs in unruptured cerebral aneurysms. ABBREVIATIONS CFD, computational fluid dynamicsMCA, middle cerebral arteryPave, average pressurePD, pressure differencePmax, maximum pressureTWR, thin-walled regionWSS, wall shear stress.

O-019 4d digital subtraction angiography: the advantages and limitations in the evaluation of brain arteriovenous malformation and brain aneurysms

Purpose To evaluate the potential advantages and limitations of 4D-DSA image acquisition, the acquired images on the patients with arteriovenous malformations (AVMs) and aneurysms were reviewed and analyzed. Methods Brain arteriovenous malformation (AVM) and brain aneurysm patients who underwent 4D-DSA during the pre and post assessment for the endovascular / surgical treatment were included. The obtained source image information of the 4D-DSA was transferred to a dedicated workstation and reconstructed using a software, “Syngo Dyna4D©”. The results were reviewed and interpretation of each image finding was evaluated. The radiation dose required for each examination was calculated, and compared with that required for conventional 5-second 3D-DSA acquisitions. Results 10 aneurysm patients and 4 AVM patients underwent 4D-DSA. One patient had both an intracranial aneurysm and an AVM. 6 aneurysm patients underwent 6-second acquisition protocol. 12-second acquisition was used for all AVM patients as well as 4 aneurysm patients. For aneurysm evaluation, with a temporal sampling of 28.7-volumes/sec and a region of interest (ROI) of 42 cm x× 42 cm, the quality of the image was not sufficient to evaluate contrast flow patterns in the aneurysm although the sizes of all aneurysms were less than 10 mm in the largest diameter. With 12-second acquisition, anatomical information of both arteries and veins were simultaneously obtained in one scan, which was useful for the pre-operative evaluation of surgical clipping. For AVMs, temporal change in the appearance of each feeding artery clearly differentiated the different feeding patterns of each artery to the nidus component. Detailed anatomical structures, e.g. a stenosis in the main drainer which was not detected in the 2D-DSA and difficult to see in the conventional 3D angiogram, were better depicted in the 4D-DSA images. Average surface dose of the radiation was 115 mGy in the 6-second acquisition, 225 mGy in the 12-second acquisition and 105 mGy in the conventional 3D angiogram. Conclusions 4D-DSA provides useful information for the treatment planning of AVM patients by depicting the temporal change in the 3D-DSA. Current temporal resolution was not sufficient for the evaluation of contrast flow patterns in the small aneurysms. The 12-second acquisition which covers the entire arterial phase to the venous phase required approximately double the radiation dose of the conventional 5-second 3D-DSA. However, the dose required for the 6-second acquisition, which mainly covers the arterial phase, was similar to the conventional 3D-DSA.Abstract O-019 Figure 1 Temporal change in the 3D DSA images of an AVM Disclosures I. Yuki: 1; C; Siemens Grant. T. Ishibashi: None. A. Ikemura: 1; C; Siemens Grant. Y. Kambayashi: None. I. Kan: None. Y. Abe: None. C. Dahmani: 5; C; Siemens K. K.. S. Kaku: None. K. Nishimura: None. Y. Murayama: 1; C; Siemens Grant.

E-032 Combination of High Resolution Cone-beam CT and 3D DSA for the Evaluation of Intracranial Stents used for Aneurysm Treatment

Purpose Incomplete stent apposition after the treatment of brain aneurysm can increase the risk of thromboembolic complications and remains to be the major concern during the procedure. Utilizing the high resolution cone-beam CT (HR-CBCT) and metal artifact reduction software (MAR), the metal artifact produced by the coil mass is reduced and the visualization of the deployed stent is optimized. After combining with the 3D digital subtraction angiography (3D-DSA), the resulting image is used for the evaluation of the stent apposition in the artery. Initial clinical experience of this novel imaging method is reported. Methods A total of 24 aneurysm patients who underwent the stent assisted coil embolization was selected for this study. All patients were treated using either Neuroform® stent or Enterprise® stent system. Artis PURE® Platform (Siemens) was used in this study. Acquisition protocols are follows. A HR-CBCT acquisition was performed to obtain the image of stent and coil mass. The dataset was then reconstructed using MAR. A 3 D DSA acquisition was performed for the visualization of the vasculature. The two datasets were combined using a dedicated software. A 3D volume rendering (VR) image was created and the stent apposition of each treated patient was evaluated. Results All 24 patients underwent the image acquisition successfully. Relationship between the deployed stent and the wall of the parent artery was well visualized in every patient although partial image defect of the stent due to the metal artifact was observed in the relatively large aneurysms. The incomplete stent apposition was frequently seen near the carotid siphon, especially at the inner curve of the target vessel. Conclusion Combination of high resolution cone-beam CT and 3D DSA for the evaluation of intracranial stents provided sufficient visualization of the deployed stent and parent artery. This imaging method can be used for the evaluation of stent apposition during/after the treatment of brain aneurysms.Abstract E-032 Figure 1 Disclosures I. Yuki: 1; C; Siemens Grant. S. Hataoka: None. T. Ishibashi: 1; C; Siemens Grant. C. Dahmani: 5; C; Employee of Siemens Healthcare. A. Ikemura: None. Y. Kambayashi: None. I. Kan: None. Y. Abe: None. S. kaku: None. K. Nishimura: None. T. Kodama: None. Y. Sasaki: None. Y. Murayama: 1; C; Siemens Grant.

O3-E-20. Intraoperative cochlear nerve mapping by cochlear nerve action potential

Methods for intraoperative mapping of the cochlear nerve (CN) in surgery for acoustic neurinoma (AN) have not yet been established. We attempted intraoperative mapping of the cochlear nerve by cochlear nerve action potential (CNAP) with a new recording probe. The subjects were 10 patients who had undergone surgery for AN using a retrosigmoid approach. Three of the 10 patients had severe hearing impairment so that CNAP data could not be obtained. In six of seven patients with useful hearing acuity, CN could be identified during surgery. However, CNAP was obtained in the nerves adjacent to CN. We could identify CN by the difference in waveforms between CN and the adjacent nerves. The recording probe was appropriate for mapping, but was inappropriate for functional monitoring. In contrast, conventional electrodes were more suitable for functional monitoring, but were not suitable for mapping. The combination of these electrode types would greatly improve the accuracy of monitoring. We performed CNAP by monopolar and bipolar recording. In bipolar recordings, the signal to noise ratio was higher than that in the monopolar recordings. The combination of monopolar and bipolar recordings would also improve the accuracy of monitoring.