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Purpose: Three‐dimensional (3D) multiplexed sensitivity encoding and reconstruction (3D‐MUSER) algorithm is proposed to reduce aliasing artifacts and signal corruption caused by inter‐shot 3D phase variations in 3D diffusion‐weighted echo planar imaging (DW‐EPI). Theory and Methods: 3D‐MUSER extends the original framework of multiplexed sensitivity encoding (MUSE) to a hybrid k‐space‐based reconstruction, thereby enabling the correction of inter‐shot 3D phase variations. A 3D single‐shot EPI navigator echo was used to measure inter‐shot 3D phase variations. The performance of 3D‐MUSER was evaluated by analyses of point‐spread function (PSF), signal‐to‐noise ratio (SNR), and artifact levels. The efficacy of phase correction using 3D‐MUSER for different slab thicknesses and b‐values were investigated. Results: Simulations showed that 3D‐MUSER could eliminate artifacts because of through‐slab phase variation and reduce noise amplification because of SENSE reconstruction. All aliasing artifacts and signal corruption in 3D interleaved DW‐EPI acquired with different slab thicknesses and b‐values were reduced by our new algorithm. A near‐whole brain single‐slab 3D DTI with 1.3‐mm isotropic voxel acquired at 1.5T was successfully demonstrated. Conclusion: 3D phase correction for 3D interleaved DW‐EPI data is made possible by 3D‐MUSER, thereby improving feasible slab thickness and maximum feasible b‐value. Magn Reson Med 79:2702–2712, 2018. © 2017 International Society for Magnetic Resonance in Medicine. [ABSTRACT FROM AUTHOR]

Co-infection of human immunodeficiency virus (HIV) and neurosyphilis (NS) has become a rising trend, but the extent of brain damage associated with the concomitant infections remains unknown. Proton magnetic resonance spectroscopy ((1)H-MRS) can evaluate metabolic changes underlying early brain infections. 25 syphilitic patients (7 HIV-positive with NS; 6 HIV-positive without NS; 5 HIV-negative with NS; 7 non-HIV, non-NS) and 17 healthy controls (HC) underwent single-voxel (1)H-MRS in the bilateral hippocampi. Absolute concentrations of major metabolites were measured using a 3T MRI scanner. No significant structural abnormality was detected in all patients. However, metabolic changes were found in the left hippocampus of both the HIV-positive and NS subgroups, showing significantly higher choline (Cho), creatine (Cr) and myo-inositol (mI) compared to HC. In the right hippocampus, HIV-positive subgroup showed significantly higher Cr and reduced NAA, while NS subgroup only showed significantly reduced NAA compared to HC. The non-HIV, non-NS syphilitic subgroup showed no significant difference compared to HC. Substantial metabolic changes occurred in bilateral hippocampi in HIV and NS co-infections. NAA reduction might represent early neuronal damage, while mI/Cho elevation reflects gliosis/inflammatory changes. (1)H-MRS could serve as a non-invasive tool to triage patients suspected of NS for lumbar puncture in non-HIV syphilitic patients.