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Purpose This study aimed to examine the inter-method reliability and volumetric differences between NeuroQuant (NQ) and Freesurfer (FS) using T1 volume imaging sequence with different slice thicknesses in patients with mild cognitive impairment (MCI). Materials and Methods This retrospective study enrolled 80 patients diagnosed with MCI at our memory clinic. NQ and FS were used for volumetric analysis of three-dimensional T1-weighted images with slice thickness of 1 and 1.2 mm. Inter-method reliability was measured with Pearson correlation coefficient (r), intraclass correlation coefficient (ICC), and effect size (ES). Results Overall, NQ volumes were larger than FS volumes in several locations: whole brain (0.78%), cortical gray matter (5.34%), and white matter (2.68%). Volume measures by NQ and FS showed good-to-excellent ICCs with both 1 and 1.2 mm slice thickness (ICC=0.75–0.97, ES=−1.0–0.73 vs. ICC=0.78–0.96, ES=−0.9–0.77, respectively), except for putamen, pallidum, thalamus, and total intracranial volumes. The ICCs in all locations, except the putamen and cerebellum, were slightly higher with a slice thickness of 1 mm compared to those of 1.2 mm. Conclusion Inter-method reliability between NQ and FS was good-to-excellent in most regions with improvement with a 1-mm slice thickness. This finding indicates that the potential effects of slice thickness should be considered when performing volumetric measurements for cognitive impairment.

Purpose: To demonstrate robust myelin water fraction (MWF) mapping using an artificial neural network (ANN) with multi-echo gradient-echo (GRE) signal. Methods: Multi-echo gradient-echo signals simulated with a three-pool exponential model were used to generate the training data set for the ANN, which was designed to yield the MWF. We investigated the performance of our proposed ANN for various conditions using both numerical simulations and in vivo data. Simulations were conducted with various SNRs to investigate the performance of the ANN. In vivo data with high spatial resolutions were applied in the analyses, and results were compared with MWFs derived by the nonlinear least-squares algorithm using a complex three-pool exponential model. Results: The network results for the simulations show high accuracies against noise compared with nonlinear least-squares MWFs: RMS-error value of 5.46 for the nonlinear least-squares MWF and 3.56 for the ANN MWF at an SNR of 150 (relative gain = 34.80%). These effects were also found in the in vivo data, with reduced SDs in the region-of-interest analyses. These effects of the ANN demonstrate the feasibility of acquiring high-resolution myelin water images. Conclusion: The simulation results and in vivo data suggest that the ANN facilitates more robust MWF mapping in multi-echo gradient-echo sequences compared with the conventional nonlinear least-squares method. K E Y W O R D S artificial neural network, multi-echo gradient echo, myelin water imaging, T * 2 distribution [Correction added after online publication 18 August, 2020. The authors have corrected the spelling of author name Won-Jin Moon.] | 381 JUNG et al. 1 | INTRODUCTION Myelin water fraction (MWF) as a method for measuring quantitative myelin signals has demonstrated potential to diagnose various demyelinating diseases such as multiple sclerosis, schizophrenia, and stroke. 1,2 Conventional myelin water imaging (MWI) uses multi-echo spin-echo acquisition and nonnegative least-squares estimation, 3,4 whereas more recently multi-echo gradient echo (mGRE) has been suggested. 5-9 These methods provide benefits such as faster acquisition time and lower specific absorption rates. Several studies have proposed methods to acquire high-quality MWI data using mGRE. Such studies suggest applying the nonlinear least-squares (NLLS) algorithm to the acquired signal using a defined model, such as the three-pool exponential model. 8,10 These methods are based on the assumption that the white-matter (WM) water can be reliably modeled by three-pool exponential components with individual frequency shifts. 5,6,8 These methods can be further improved by physiological noise compensation 11 and B 0 field inhomogeneity correction. 10,12,13 Despite these developments, there are still challenges in improving the accuracy and robustness of the MWF. The NLLS (used for estimating MWFs) has been reported to be inaccurate and unstable, especially at low-to-moderate SNRs. 14-16 This requires high SNR data acquisition for MWFs, limiting the scan...

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ObjectiveThe aim of this study was to examine the incidence of ischemia during protected carotid artery stenting (CAS) as well as to compare the protective efficacy of the balloon and filter devices on diffusion-weighted MR imaging (DWI).Materials and MethodsSeventy-one consecutive protected CAS procedures in 70 patients with a severe (> 70%) or symptomatic moderate (> 50%) carotid artery stenosis were examined. A balloon device (PercuSurge GuardWire) and a filter device (FilterWire EX/EZ, Emboshield) was used in 33 cases (CAS-B group) and 38 cases (CAS-F group) to prevent distal embolization, respectively. All the patients underwent DWI within seven days before and after the procedures. The number of new cerebral ischemic lesions on the post-procedural DWI were counted and divided into ipsilateral and contralateral lesions according to the relationship with the stenting side.ResultsNew cerebral ischemic lesions were detected in 13 (39.4%) out of the 33 CAS-Bs and in 15 (39.5%) out of the 38 CAS-Fs. The mean number of total, ipsilateral and contralateral new cerebral ischemic lesion was 2.39, 1.67 and 0.73 in the CAS-B group and 2.11, 1.32 and 0.79 in the CAS-F group, respectively. No statistical differences were found between the two groups (p = 0.96, 0.74 and 0.65, respectively). The embolic complications encountered included two retinal infarctions and one hemiparesis in the CAS-B group (9.09%), and one retinal infarction, one hemiparesis and one ataxia in the CAS-F group (7.89%). There was a similar incidence of embolic complications in the two groups (p = 1.00).ConclusionThe type of distal protection device used such as a balloon and filter does not affect the incidence of cerebral embolization after protected CAS.