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Background: The caudate lobe is located deep in the dorsal portion of the liver. Complete resection is an extremely demanding surgery due to the limited surgical field, especially in cases with severe intra-abdominal complications. A major concern of isolated caudate lobectomy is the difficulty associated with securing the contralateral visual field during parenchymal transection. To overcome this issue, we present a new technique for isolated caudate lobectomy that uses a modified hanging maneuver., Methods: We performed an anatomical isolated caudate lobectomy via the high dorsal resection technique using our new modified hanging maneuver in two patients with HCC in November and December 2019., Results: Patient 1 was severely obese, so the upper abdominal cavity was occupied by a large amount of great omental fat, and fibrous adhesions were observed around the spleen. Patient 2 had undergone six preoperative treatments, and a high degree of adhesion was observed in the abdominal cavity around the liver. It was difficult to secure the surgical field due to severe abdominal complications in both cases. The total operation times in these two cases were 617 and 763 min, respectively, while the liver parenchymal dissection times of the caudate lobe were 96 and 108 min, respectively. The resection margin was negative in both patients (R0). Neither patient had any complications after surgery; both were discharged on postoperative day 14., Conclusion: Our modified hanging maneuver is useful, particularly in cases with a narrow surgical field due to severe adhesions, bulky tumors, and/or hypertrophy of the Spiegel lobe.

Purpose: Arteriovenous fistulas (AVFs) located in the cavernous sinus (CS), clivus, and condyle can be osseous shunts in nature. Here, we reviewed the angioarchitecture, clinical characteristics, and treatment results of AVFs in these lesions., Methods: Twenty-five patients with 27 lesions who underwent rotational angiography in our department between May 2013 and December 2019 were reviewed. We examined 20 CS AVFs, 2 clival AVFs, and 5 condylar AVFs. We divided the anatomical shunted pouches into five locations: the dorsum sellae (posteromedial of the CS), posterolateral wall of the CS, lateral wall of the CS, clivus, and condyle. We divided the AVFs into three categories: intraosseous, transitional, and nonosseous shunts. We analyzed the characteristics and treatment results., Results: A total of 33 shunted pouches or points were identified in 27 lesions. The dorsum sellae (n = 16) was the most frequent location. Fourteen AVFs (88%) in the dorsum sellae were osseous (intraosseous or transitional) shunts. All AVFs in the clivus or condyle were also osseous shunts. Eleven lesions (92%) of intraosseous and all lesions of transitional shunts exhibited bilateral external carotid artery involvement as feeders. Ten lesions (83%) of intraosseous shunts were treated with selective transvenous embolization of the shunted pouch with or without additional partial embolization of the sinus. Eleven (92%) intraosseous shunts were completely occluded, and symptom resolution was achieved in all intraosseous shunts., Conclusion: Most of the CS AVFs with shunted pouches in the dorsum sellae and all of the AVFs in the clivus and condyle share similar characteristics.

Purpose: Endovascular therapy to the spinal dural arteriovenous fistula (SDAVF) with a common origin of the radiculomedullary artery and the feeder of the shunt has the risk of spinal cord infarction. This study aimed to retrospectively assess the detection rate of normal spinal arteries from the feeder of SDAVF., Methods: We retrospectively collected the angiographic and clinical data of SDAVFs. This study included 19 patients with 20 SDAVF lesions admitted to our department between January 2007 and December 2018. We assessed the detection rate of normal radiculomedullary artery branched from the feeder of SDAVF between the period using the image intensifier (II) and flat panel detector (FPD) and evaluated the treatment results., Results: The detection rates of the radiculomedullary artery branched from the feeder of SDAVF were 10% (1/10 lesions) during the II period and 30% (3/10 lesions) during the FPD period. During the FPD period, all normal radiculomedullary arteries branched from the feeder were only detected on slab maximum intensity projection (MIP) images of rotational angiography, and we could not detect them in 2D or 3D digital subtraction angiography. All lesions that had a common origin of a normal radiculomedullary artery and the feeder were completely obliterated without complications. There was no recurrence during the follow-up period., Conclusions: The flat panel detector and slab MIP images seem to show the common origin of the normal radiculomedullary arteries from the feeder more accurately. With detailed analyses, SDAVF can be safety treated.

Purpose: Intracranial hemorrhage following hyperperfusion syndrome (HPS) is a rare but potentially fatal complication after carotid artery stenting (CAS). Staged angioplasty (SAP) is a two-stage form of CAS that can prevent the abrupt increase of cerebral blood flow. In this study, we investigated the safety and efficacy of SAP., Methods: One hundred thirty-four patients who underwent CAS for high-grade carotid artery stenosis between January 2010 and December 2018 were enrolled. Patients who showed severe impairment of hemodynamic reserve in 123 I-IMP SPECT with acetazolamide received SAP (SAP group), while the others received regular CAS (RS group)., Results: Twenty-six (19.4%) patients at risk for HPS received SAP. HPS was not observed in either group. Diffusion-weighted image (DWI)-positive lesions on postoperative MRI were observed in 56 (52.3%) cases in the RS group and 16 (64.0%) cases in the SAP group. Symptomatic procedure-related complications occurred in 5 (4.6%) cases in the RS group and 1 (3.8%) case in the SAP group. These differences were not statistically significant. Modified Rankin Scale score had declined 30 days after discharge in 4 (3.0%) cases. Distal filter protection was significantly correlated to the occurrence of new DWI-positive lesions., Conclusions: For patients at high risk of HPS, SAP was a reasonable treatment strategy to prevent HPS. SAP did not increase the rate of DWI-positive lesions or procedure-related complications compared with regular CAS.

Purpose: The aim of the present study was to assess image quality improvement using a metal artifact reduction (MAR) algorithm in cases of medium or large cerebral aneurysms treated with stent-assisted coil embolization (SAC), and to analyze factors associated with the usefulness of the MAR algorithm., Methods: We retrospectively evaluated the cone-beam computed tomography (CBCT) data sets of 18 patients with cerebral aneurysms treated with SAC. For subjective analysis, images of all cases with and without MAR processing were evaluated by five neurosurgeons based on four criteria using a five-point scale. For objective analysis, the CT values of all cases with and without MAR processing were calculated. In addition, we assessed factors associated with the usefulness of the MAR by analyzing the nine cases in which the median score for criterion 1 improved by more than two points., Results: MAR processing improved the median scores for all four criteria in 17/18 cases (94.4%). Mean CT values of the region of interest at the site influenced by metal artifacts were significantly reduced after MAR processing. The maximum diameter of the coil mass (< 17 mm; odds ratio [OR], 4.0; 95% confidence interval [CI], 1.2-13.9; p = 0.02) and vessel length covered by metal artifacts (< 24 mm; OR, 2.3; 95% CI, 1.1-4.7; p = 0.03) was significantly associated with the usefulness of the MAR., Conclusions: This study suggests the feasibility of a MAR algorithm to improve the image quality of CBCT images in patients who have undergone SAC for medium or large aneurysms.

Introduction: Embolization of intracranial tumor is widely performed in Japan, mainly before neurosurgical resection. A retrospective, multicenter, observational study in Japan was conducted to clarify the nature, frequency, and risk factors of complications in intracranial tumor embolization., Methods: Patients were derived from the Japanese Registry of NeuroEndovascular Therapy 2 (JR-NET2). A total of 20,854 patients were enrolled in JR-NET2, of which 1,018 patients (4.88 %) with intracranial tumors underwent embolization. The primary end point was the proportion of patients with a modified Rankin scale (mRS) score of 0-2 (independency) at 30 days. The secondary end point was the occurrence of complications related to the procedures. The risk factors of the occurrence of complications were studied., Results: The proportion of patients with mRS scores ≤2 at 30 days after procedure was 91.3 %. Complications occurred in 15 of the 1,012 patients (1.48 %). Multivariate analysis showed that embolization for tumors other than meningioma (OR, 4.626; 95 % CI, 1.347-14.59; p = 0.0105) was significantly associated with the development of complications., Conclusion: The frequency of complications after intracranial tumor embolization was relatively low in this large Japanese cohort. Embolization for tumors other than meningioma was the only significant risk factor for the occurrence of complications.

Introduction: Although self-expanding carotid stents may dilate gradually, the degrees of residual stenosis have been quantified by the NASCET criteria, which is too simple to reflect the configuration of the stented artery. We measured the volumes of the stent lumens chronologically by 3D-CT in patients after carotid artery stenting (CAS), and analyzed the correlations between the volume change and medical factors., Methods: Fourteen patients with carotid artery stenosis were treated using self-expanding, open-cell stents. All patients underwent preoperative plaque MRI (magnetization-prepared rapid acquisition gradient-echo, MPRAGE) and chronological 3D-CT examinations of their stents immediately after their placement and 1 day, 1 week, and 1 month after the procedure. The volume of the stent lumen was measured using a 3D workstation. The correlations between stent volume and various factors including the presence of underlying diseases, plaque characteristics, and the results of the CAS procedure were analyzed., Results: Stent volume gradually increased in each case and had increased by 1.04-1.55 (mean, 1.25)-fold at 1 postoperative month. The presence of underlying medical diseases, plaque length, the degree of residual stenosis immediately after CAS, and plaque calcification did not have an impact on the change in stent volume. On the other hand, the stent volume increase was significantly larger in the patients with vulnerable plaques that demonstrated high MPRAGE signal intensity (P < 0.05)., Conclusions: A 3D-CT examination is useful for precisely measuring stent volume. Self-expanding stents in carotid arteries containing vulnerable plaques expand significantly more than those without such plaques in a follow-up period.

We report our results of endovascular treatment for elderly patients with ruptured aneurysm and discuss the indication for treatment. One hundred and thirty four consecutive patients with ruptured aneurysm treated in our institute during the last 4 years were retrospectively evaluated. Fifty eight patients were included in group A (over 70 years old), and 76 patients in group B (under 69 years old). In both groups, the outcome was strongly related to the preoperative Hunt & Kosnik grade. However, significant risk factors (i.e. pneumonia, rupture of extracranial aneurysm) which make prognosis poor were more common in group A. Group A showed poor outcome in grade III patients, although there were no outcome differences between the two groups in patients of other grades. Endovascular treatment for elderly patients with ruptured aneurysms seemed to be useful. Their outcome was strongly related to their preoperative condition. General risk factors should be evaluated before treatment, especially in elderly patients. Patients with low Hunt & Kosnik grade seem to be most suitable for endovascular treatment. On the other hand, outcome of patients with poor preoperative grade was worse despite the less invasive nature of endovascular treatment. An improvement of outcome in grade III patients is desirable.

Purpose: To evaluate contact between cerebral berry aneurysms and the perianeurysmal environment and to study the influence this contact has on aneurysm rupture., Materials and Methods: In a series of 76 consecutive patients, pre- and post-contrast CT images of 87 aneurysms were evaluated. Aneurysm locations were identified and aneurysms were divided into two different groups depending on whether they had ruptured or not. Contact between aneurysms and the perianeurysmal environment was studied when present, and considered to be balanced or unbalanced according to symmetry of contact and type of contact interface, i.e. with bone, dura, etc., Results: Rupture occurred in 47 aneurysms at an average maximum dome size of 7.4 mm. There was contact with elements of the perianeurysmal environment in 38 (81%) of ruptured cases and no evidence of contact in 7 (15%). The nature of contact was unclear in 2 (4%) ruptured aneurysms. In the aneurysms with contact, the nature of contact was unbalanced in 34 (72%) and balanced in 4 (9%). Unbalanced aneurysms ruptured at significantly smaller sizes (average: 7.7 mm) than balanced aneurysms (average: 11.4 mm). Seven aneurysms of small size (3.3-6.9 mm, average: 4.8 mm) were found to have ruptured, despite the fact that they were too small to exhibit contact with the perianeurysmal environment. In 40 unruptured aneurysms (average size: 6.3 mm), contact with the perianeurysmal environment was found in 15 aneurysms, for which balanced contact was found in 11 (27.5%) and unbalanced contact in 4 (10%), and no contact in 25 (62.5%). The average size of the aneurysms without contact (3.7 mm) was significantly smaller than that with balanced contact (10.3 mm) or with unbalanced contact (11.3 mm)., Conclusion: Aneurysms exhibit contact with their perianeurysmal environment as soon as they reach a size that exceeds their allowance given by the local subarachnoid space. The contact with the environment was found to be an additional determinant parameter in the evolution of cerebral berry aneurysms and their risk to rupture.