Abstract Background Previous studies reported increased concentrations of metallic ions and imbalanced Na+ and K+ ions in patients with Alzheimer’s disease (AD) and the increased mobility of protons by microstructural disruptions in AD. The purposes of this study were: 1)to apply a high‐frequency conductivity (HFC) mapping technique using a clinical 3T MRI system and 2)to compare HFC values among participant groups. Method This prospective study included 74 participants (23 AD patients, 27 amnestic mild cognitive impairment (MCI) patients, and 24 cognitively normal (CN) elderly people) to explore the clinical application of HFC mapping in the brain. For the brain MREPT images, a multi‐echo turbo spin‐echo pulse sequence was used. A homemade software was used to map the HFC at the Larmor frequency of 128 MHz at 3T. We performed statistical analyses to 1) compare HFC maps between the three participant groups and 2) to evaluate the association of HFC maps with Mini‐Mental State Examination (MMSE) scores. Result The HFC value was higher in the AD group than in the CN and MCI groups. MMSE scores were negatively associated with HFC values, but age was positively associated with HFC values. The HFC value in the insula has a high area under the ROC curve (AUC) value to differentiate AD patients from the CN participants (Sensitivity (SE) = 82, Specificity (SP) = 97, AUC = 0.902, p < 0.0001), better than GMV in hippocampus (SE = 79, SP = 83, AUC = 0.880, p < 0.0001). Conclusion HFC values were significantly increased in the AD group compared to the CN group and increased with age and disease severity. HFC values of the insula along with the GMV of the hippocampus can be used as an imaging biomarker to improve the differentiation of AD from CN.

Abstract Background Developing an imaging technique to map myelin changes in the brain within a short scan time is needed due to the inability of Alzheimer’s disease (AD) patients to remain motionless during MRI scanning. Purpose To investigate myelin loss in both AD and mild cognitive impairment (MCI) patients with a new myelin water mapping technique within reasonable scan time and evaluate the clinical relevance of the apparent myelin water fraction (MWF) values by assessing the relationship between decreases in myelin water and the degree of memory decline or aging. Method In this prospective study from March 2019 to October 2021, the participants were allocated as follows: 29 individuals were assigned to the cognitively normal (CN) elderly group (mean ± SD, 73 ± 5 years, 16 females), 32 participants were assigned to the MCI group (74 ± 5 years, 21 females), and 31 patients were assigned to the AD group (74 ± 6 years, 26 females). A 3D visualization of the short transverse relaxation time component (ViSTa)‐gradient and spin‐echo (GraSE) sequence was developed to map apparent MWF. Then, the MWF values were compared between the three participant groups, and was evaluated the relationship with the degree of memory loss. Result A total of 92 participants were evaluated. The AD group showed a reduced apparent MWF compared to the CN and MCI groups. Moreover, the MWF was decreased with age and positively correlated with Mini‐Mental State Examination scores. The largest AUC value (0.799) was in the corpus callosum and used to classify the CN and AD groups using the apparent MWF. Conclusion The ViSTa‐GraSE sequence can be a useful tool to map the MWF in a reasonable scan time. Combining the MWF in the corpus callosum with the detection of atrophy in the hippocampus can be valuable for group classification. Funding The research was supported by the National Research Foundation of Korea (NRF) grant funded by Ministry of Science and ICT (No. 2020R1A2C1004749, GHJ), Republic of Korea.

Abstract Background Conventional MRI techniques cannot demonstrate microvascular alterations in mild and moderate Alzheimer’s disease (AD). Thus, the diagnosis of microvascular pathology commonly relies on postmortem. The purpose of this study was to evaluate alterations of microvascular structures in patients with AD using a 3T clinical MRI system with a commercially available contrast agent. Method Eleven patients with AD and 11 non‐AD controls were included in this cross‐sectional prospective study. R2 and R2* relaxation rate changes (∆R2 and ∆R2*) before and after a Gd‐based contrast agent injection were calculated from images obtained with a multi‐echo turbo spin‐echo sequence and multi‐echo gradient‐echo sequence to obtain microvascular index maps of blood volume fraction (BVf), mean vessel diameter (mVD), vessel size index (VSI), mean vessel density (Q), and microvessel‐weighted imaging (MvWI). Two‐sample t‐test was used to compare those values between the two groups. Correlation analysis was performed to evaluate the relationship between those values and the mini‐mental state examination (MMSE) score. Result Compared with the non‐AD group, BVf was significantly increased in the AD group at the parahippocampal gyrus (p = 0.033), gray matter area (p = 0.008), and white matter area (p = 0.010). MvWI was also significantly increased in the AD group at the hippocampus (p = 0.010), parahippocampal gyrus (p = 0.010), precuneus (p = 0.045), and globus pallidus (p = 0.008). Both mVD and VSI were only significantly decreased in the AD group at the white matter hyperintensity (WMHI) area (p = 0.045 with mVD; p = 0.033 with VSI). BVf and MvWI were significantly positively correlated with age at some areas. VSI was significantly positively correlated with MMSE at caudate (rho = 0.475/ p = 0.030) and corpus callosum (rho = 0.435/ p = 0.049). Conclusion Microvascular index was a useful non‐invasive method to evaluate microvascular morphology alteration. The microvascular morphology of AD was manifested as vessel constriction and increasing blood volume fraction. It was associated with MMSE score.

Our findings suggest that gwJTV could be a valuable imaging biomarker for monitoring brain and vascular health in T2DM patients, particularly those affected by carotid atherosclerosis.

Motivation: This study provides novel insights into the intricate relationships between brain electrical conductivity, diffusivity, and tissue volume in elderly individuals. Goal(s): To explore the relationships between electrical conductivity, diffusivity, and brain tissue volume in the aging brain. Approach: With 77 patients, brain MREPT and DTI were employed to calculate high-frequency conductivity (HFC) and separate it into extra-neurite (EC) and intra-neurite (IC) conductivities. Results: Multiple regression revealed a positive association of both HFC and EC with MD, RD, and axial diffusivity (AxD) in the hippocampus and insula. IC correlated positively with intra-neurite diffusivity (ID) in the amygdala, thalamus, and insula. Impact: This research underscores the importance of distinguishing between conductivity and diffusion changes when interpreting clinical MREPT data.

Motivation: Prior research has primarily focused on overall brain atrophy and white matter hyperintensities. Goal(s): To evaluate the gray-white matter junction tissue volume (gwJTV) damage in Type 2 diabetes mellitus (T2D) patients with and without carotid plaque and its association with several metabolism-related biomarkers. Approach: A cross-sectional study of 69 T2D patients with (36) or without (33) asymptomatic atherosclerosis was conducted by evaluating the metabolic biomarkers and the gwJTV . Results: gwJTV was particularly sensitive to changes in these biomarkers. Higher brain tissue volumes were found in participants without plaque compared to those with plaque. Impact: This study contributes to the field of diabetes and neuroimaging by introducing the concept of gwJTV as a new MRI measure for evaluating brain tissue integrity in T2D patients.

These findings suggest that increased conductivity is associated with altered diffusivity and reduced cognitive performance, suggesting the use of MREPT to differentiate between conductivity changes due to ion mobility versus proton density, and how this approach contributes to understanding the aging brain and neurodegeneration. MREPT-derived measurements primarily reflect ion mobility and caution that clinical interpretations should consider the direct relationships between conductivity and diffusion changes.

The objective of this study was to investigate high-frequency conductivity (HFC) obtained using magnetic resonance electrical property tomography (MREPT) in participants with Alzheimer’s disease (AD), amnestic mild cognitive impairment (MCI), and cognitively normal (CN) elderly controls. High-frequency conductivity (HFC) values in the brain are significantly increased in Alzheimer’s disease (AD) patients compared to cognitively normal (CN) elderly people, are negatively associated with Mini-Mental State Examination (MMSE) scores, and therefore can be used as an imaging biomarker to improve the differentiation of AD from CN.

Motivation: Alzheimer's disease (AD) presents typically gray matter atrophy and white matter abnormalities in neuroimaging. Goal(s): Exploring gray-white matter boundary Z-score (gwBZ) and its tissue volume (gwBTV) between patients with Alzheimer’s disease (AD), amnestic mild cognitive impairment (MCI), and cognitively normal (CN) elderly participants. Approach: Three-dimensional T1-weight images of a total of 227 participants were acquired to calculate gwBZ and gwBTV, prospectively. Results: Both gwBZ and gwBTV were reduced in AD, were positively correlated with cognitive function, and could accurately discriminate AD from CN . Impact: gwBZ and gwBTV could be a useful tool for monitoring AD progression and diagnosis.

Abstract Background Previous studies reported increased concentrations of metallic ions and imbalanced Na+ and K+ ions in patients with Alzheimer’s disease (AD) and the increased mobility of protons by microstructural disruptions in AD. The purposes of this study were: 1)to apply a high‐frequency conductivity (HFC) mapping technique using a clinical 3T MRI system and 2)to compare HFC values among participant groups. Method This prospective study included 74 participants (23 AD patients, 27 amnestic mild cognitive impairment (MCI) patients, and 24 cognitively normal (CN) elderly people) to explore the clinical application of HFC mapping in the brain. For the brain MREPT images, a multi‐echo turbo spin‐echo pulse sequence was used. A homemade software was used to map the HFC at the Larmor frequency of 128 MHz at 3T. We performed statistical analyses to 1) compare HFC maps between the three participant groups and 2) to evaluate the association of HFC maps with Mini‐Mental State Examination (MMSE) scores. Result The HFC value was higher in the AD group than in the CN and MCI groups. MMSE scores were negatively associated with HFC values, but age was positively associated with HFC values. The HFC value in the insula has a high area under the ROC curve (AUC) value to differentiate AD patients from the CN participants (Sensitivity (SE) = 82, Specificity (SP) = 97, AUC = 0.902, p < 0.0001), better than GMV in hippocampus (SE = 79, SP = 83, AUC = 0.880, p < 0.0001). Conclusion HFC values were significantly increased in the AD group compared to the CN group and increased with age and disease severity. HFC values of the insula along with the GMV of the hippocampus can be used as an imaging biomarker to improve the differentiation of AD from CN.

Abstract Background Developing an imaging technique to map myelin changes in the brain within a short scan time is needed due to the inability of Alzheimer’s disease (AD) patients to remain motionless during MRI scanning. Purpose To investigate myelin loss in both AD and mild cognitive impairment (MCI) patients with a new myelin water mapping technique within reasonable scan time and evaluate the clinical relevance of the apparent myelin water fraction (MWF) values by assessing the relationship between decreases in myelin water and the degree of memory decline or aging. Method In this prospective study from March 2019 to October 2021, the participants were allocated as follows: 29 individuals were assigned to the cognitively normal (CN) elderly group (mean ± SD, 73 ± 5 years, 16 females), 32 participants were assigned to the MCI group (74 ± 5 years, 21 females), and 31 patients were assigned to the AD group (74 ± 6 years, 26 females). A 3D visualization of the short transverse relaxation time component (ViSTa)‐gradient and spin‐echo (GraSE) sequence was developed to map apparent MWF. Then, the MWF values were compared between the three participant groups, and was evaluated the relationship with the degree of memory loss. Result A total of 92 participants were evaluated. The AD group showed a reduced apparent MWF compared to the CN and MCI groups. Moreover, the MWF was decreased with age and positively correlated with Mini‐Mental State Examination scores. The largest AUC value (0.799) was in the corpus callosum and used to classify the CN and AD groups using the apparent MWF. Conclusion The ViSTa‐GraSE sequence can be a useful tool to map the MWF in a reasonable scan time. Combining the MWF in the corpus callosum with the detection of atrophy in the hippocampus can be valuable for group classification. Funding The research was supported by the National Research Foundation of Korea (NRF) grant funded by Ministry of Science and ICT (No. 2020R1A2C1004749, GHJ), Republic of Korea.