This retrospective study included 81 outpatients who underwent non-contrast and post-contrast MRI at the Medical Satellite Yaesu Clinic between April 2010 and May 2015. The patients presented with headaches, dizziness, tinnitus, hearing loss, sensory disturbances, or focal seizures. The population consisted of 38 men and 43 women, aged 50.4 ± 15.8 years (mean ± standard deviation; range, 18–76 years). Patients with visual impairment were excluded from the study. Initial examinations using axial T1- and T2-weighted imaging, T2 gradient echo, fluid-attenuated inversion recovery, diffusion-weighted sequences, and MR angiography confirmed that none of the patients had any signs of pathological conditions in their orbits, optic pathways, cerebral hemispheres and ventricles, cerebral vessels, ophthalmic arteries, cavernous sinuses, and cranial dura maters. The patients then underwent volumetric imaging with intravenous gadolinium infusion (0.1 mmol/kg) in the axial, coronal, and sagittal planes, involving the entire orbits and cavernous sinuses. The following parameters were adopted: repetition time 4.1 ms; echo time 1.92 ms; slice thickness 1 mm; interslice gap 0 mm; matrix 320 × 320; field of view 250 mm; flip angle 13°; and scan duration 7 min 25 s. All imaging sequences were performed using a 3.0-T MRI scanner (Achieva R2.6; Philips Medical Systems, Best, The Netherlands). Imaging data were transferred to a workstation (Virtual Place Lexus 64, 64th edition; AZE, Tokyo, Japan) and independently analyzed by two of the authors (S.T. and H.I.). The CRAs and relevant neurovascular and muscular structures were assessed on serial axial and sagittal images. A linear, small vessel arising from the ophthalmic artery at the orbital apex and coursing forward along the lower optic sheath was considered the CRA. In addition, the distance between the CRA branching site from the ophthalmic artery and the posterior limit of the bulb was measured on these images (Figs. 2 and 3). Due to their low performance in depicting the CRA, as confirmed in preliminary observations, coronal images were not used in this study.
In this article, pictures of cadaveric CRAs and the relevant neurovascular structures are presented. Dissections were performed by one of the authors (S.T.) at the Department of Neurological Surgery, University of Florida, Gainesville, FL, USA.
The study was conducted in accordance with the guidelines of our institution and those of the Medical Satellite Yaesu Clinic for human research. Written informed consent was obtained from all patients prior to their participation in the study.