The impact of high-resolution cone-beam CT findings on decision-making for the treatment of unruptured middle cerebral artery aneurysms.

Even with the advent of endovascular treatment for intracranial aneurysms, microsurgical clipping continues to play a significant role in the treatment of middle cerebral artery (MCA) aneurysms. Securing perforators around unruptured intracranial aneurysms (UIAs) is essential for minimizing procedural risks in each treatment option. Therefore, we herein investigated whether the findings of high-resolution cone-beam computed tomography (HR-CBCT) have an impact on decision-making for the treatment of MCA UIAs. Patients with MCA UIAs between October 2017 and September 2021 were consecutively recruited for this study. All patients underwent HR-CBCT and 3D-DSA before treatment. The imaging quality of both modalities to visualize the microvasculature around aneurysms was evaluated. Specific findings on the microvasculature surrounding aneurysms on HR-CBCT were investigated to facilitate microsurgical clipping. Fifty-two MCA UIAs were treated, including 43 by microsurgical clipping and 9 by endovascular approaches. The overall imaging quality of HR-CBCT was superior to that of 3D-DSA. Regarding microsurgical insights, sensitivity and specificity for the visualization of small vessels around aneurysms were 79 and 100%, respectively, using HR-CBCT, and 57 and 93%, respectively, using 3D-DSA. The presence of a low-density band between adhesive vessels and aneurysm sacs was indicative of successful and safe microsurgical dissection between these structures. HR-CBCT enabled visualization of the intracranial microvasculature around MCA UIAs at the submillimeter level in vivo. In cases in which the tight adhesion of the microvasculature to the aneurysm sac is indicated by HR-CBCT, an endovascular approach may be considered in order to avoid the risks associated with securing perforators.

Impact of Cone-Beam Computed Tomography Angiography on Visualization of Sylvian Veins.

BACKGROUND: A detailed understanding of the anatomy of Sylvian veins preoperatively is needed for venous-preserving Sylvian dissection. Better visualization of the venous architecture will facilitate surgical strategies for Sylvian dissection. This study evaluated and compared the image quality of the Sylvian veins and their tributaries using high-resolution cone-beam computed tomography angiography (CBCT-A) and three-dimensional computed tomography angiography (3D-CTA). METHODS: Twenty-four patients who underwent 3D-CTA and CBCT-A as a preoperative simulation for clipping of unruptured intracranial aneurysms were retrospectively reviewed. In comparisons with intraoperative inspections, 3 raters evaluated the image quality of the Sylvian veins by 3D-CTA and CBCT-A with a 5-point scale. Visualization of the Sylvian veins and their tributaries by the 2 imaging modalities was compared using Wilcoxon signed rank test. RESULTS: CBCT-A showed superior image quality to 3D-CTA in evaluations of the discrimination of adjacent superficial Sylvian veins (2.8 ± 0.80 vs. 4.6 ± 0.37, P < 0.0001), adjacent Sylvian veins at the sphenoid wing (3.1 ± 0.71 vs. 4.1 ± 0.56, P = 0.0001), and visualization of the tributaries of the Sylvian veins (2.5 ± 0.70 vs. 4.4 ± 0.37, P < 0.0001). CONCLUSIONS: CBCT-A was superior to 3D-CTA for visualizing the Sylvian veins and their tributaries. CBCT-A will provide important information on the anatomy of the Sylvian veins preoperatively.

Changes in response properties of periodontal mechanoreceptors during tooth movement in rats.

Using an in vitro model, we investigated the chronological effects of orthodontic force on the response properties of periodontal mechanoreceptors (PMRs) in the rat mandibular first molar (M1). Experimental tooth movement was obtained by attaching a super-elastic titanium-nickel (Ti-Ni) alloy closed coil spring from the mandibular incisors to the right M1. On 1, 2, 3, 4, 7 and 14 days after the appliances were set, three right mandibular molars were extracted and direct stimulation with von Frey hairs was applied to the PMRs remaining in the tooth sockets of right M1. Single unit discharges were recorded from the inferior alveolar nerve. Following results were obtained; (1) in the 1-, 2- and 3-day groups, the mechanical thresholds were significantly lower than those in the control group. In the 4-day group, the mechanical threshold was significantly higher than that of the 3-day group. (2) In the 3-, 4-, 7- and 14-day groups, the conduction velocities of A(beta) units were lower than those in the control group. These results imply that orthodontic force applied to M1 induced functional changes in the PMRs within a few days, suggesting that the PMR seems to respond to orthodontic force at early stage of tooth movement.