[Reproducibility and comparison study of two methods evaluating the optic nerve subarachnoid space sectional area using MRI].

Objective: To optimize the method of acquiring the ONSAS parameter and to access the repeatability of the new method comparing with the traditional one. Methods: This is a cross-sectional study. Standard operation procedure of an optimized method of acquiring the ONSAS sectional area was made against the defect of the traditional method. Ten healthy volunteers (20 eyes) in different ages were recruited from March 2016 to October. Two times of MRI scan were proceeded with the interval of one week. The optimized and traditional methods were both applied for each scanning. The images were analyzed by two ophthalmologists. The rate of high quality images between two groups was compared with matching chi-square test. The orbital subarachnoid space areas between groups at different locations were compared using analysis of variance of repeated measurement data. The ICC between different scans and different ophthalmologists was calculated. Results: The mean age of the volunteers was 43.8±13.1 years old. Male/Female was 1∶1. The rates of high quality images from the optimized method (100%, 83%, 78%) was higher than those of the traditional method(80%, 78%, 70%). The orbital subarachnoid space area at 3 mm, 9 mm and 15 mm behind the eye ball acquired from the new method(7.2±1.8, 6.1±1.8, 5.9±1.4 mm(2)) were bigger than those of the traditional method (9.0±2.9, 7.6±2.4, 7.1±1.6 mm(2)). Statistical significances were found at 9 mm(F=4.30, P=0.048) and 15 mm(F=5.67, P=0.026) behind the eye ball. The ICC between two different scans (0.879, 0.857, 0.857 vs 0.741, 0.762, 0.639) and two different ophthalmologists (0.864, 0.890, 0.894 vs 0.785, 0.609, 0.753) were higher in the new method group than in the traditional method group. Conclusions: The optimized method of acquiring the parameters of optic nerve subarachnoid space is easier to get the sectional cross area. The measuring reproducibility is better than the traditional one. (Chin J Ophthalmol, 2017, 53: 440-444).

Accuracy of vessel-encoded pseudocontinuous arterial spin-labeling in identification of feeding arteries in patients with intracranial arteriovenous malformations.

BACKGROUND AND PURPOSE: Identifying feeding arteries of intracranial AVMs is very important for preoperative evaluation. DSA remains the reference standard for diagnosis but is invasive. Our aim was to evaluate the diagnostic accuracy of vessel-encoded pseudocontinuous arterial spin-labeling in identifying feeding arteries of intracranial AVMs by using DSA as the criterion standard. MATERIALS AND METHODS: Eighteen patients with AVMs were examined with vessel-encoded pseudocontinuous arterial spin-labeling and DSA. Three postlabeling delays (postlabeling delay = 1, 1.3, and 1.6 seconds) were applied in 6 patients, and a single postlabeling delay (1 second) was applied in the remainder. Perfusion-weighted images were decoded into individual vascular territories with standard and relative tagging efficiencies, respectively. The supply fraction of each feeding artery to the AVM was calculated. The within-subject ANOVA was applied to compare supply fractions acquired across 3 postlabeling delays. Receiver operating characteristic analysis curves were calculated to evaluate the diagnostic accuracy of vessel-encoded pseudocontinuous arterial spin-labeling for identifying the feeding arteries of AVMs. RESULTS: There were no significant differences in supply fractions of the 3 major arteries to AVMs acquired with 3 postlabeling delays (P > .05). For vessel-encoded pseudocontinuous arterial spin-labeling with standard labeling efficiencies, the area under the receiver operating characteristic analysis curve was 0.942. The optimal cutoff of the supply fraction for identifying feeding arteries was 15.17%, and the resulting sensitivity and specificity were 84.62% and 93.33%, respectively. For vessel-encoded pseudocontinuous arterial spin-labeling with relative labeling efficiencies, the area under the receiver operating characteristic analysis curve was 0.957. The optimal cutoff of the supply fraction was 11.73%, which yielded an 89.74% sensitivity and 93.33% specificity. CONCLUSIONS: The contribution fraction of each feeding artery of the AVM can be reliably estimated by using vessel-encoded pseudocontinuous arterial spin-labeling. Vessel-encoded pseudocontinuous arterial spin-labeling with either standard or relative labeling efficiencies offers a high level of diagnostic accuracy compared with DSA for identifying feeding arteries.