Detecting perfusion deficit in Alzheimer's disease and mild cognitive impairment patients by resting‐state fMRI

Background Vascular factors contributing to cerebral hypoperfusion are implicated in the risk of developing Alzheimer's disease (AD). Purpose To investigate the time‐shift mapping created time‐shift value of the brain by resting‐state functional magnetic resonance imaging (rs‐fMRI), and to determine the differences in time‐shift value among AD, mild cognitive impairment (MCI), and normal control (NC) groups to better understand the disease. Study Type Prospective. Subjects Twenty‐four AD, 24 MCI, and 24 age‐matched NC participants. Field Strength/Sequence T 2 *‐weighted single‐shot echo‐planar imaging sequence was performed at 3T. In addition, a T 1 ‐weighted fast spoiled gradient‐echo sequence was acquired for coregistration. Assessment The brain time‐shift value was determined from rs‐fMRI‐based blood oxygenation level‐dependent (BOLD) signal in the three groups by time‐shift mapping. The perfusion patterns were also investigated in the NC group. Statistical Tests One‐way analysis of variance and chi‐squared tests were used to compare demographic information. The normalized time‐shift maps were analyzed in a second‐level test using SPM8. All analyses were evaluated with a significance level of P < 0.05 after false discovery rate (FDR) correction. Results The time‐shift maps obtained from rs‐fMRI are consistent with the cerebral blood supply atlas. Compared with NC, both MCI and AD groups had less early perfusion arrival areas among the whole brain. In the delayed time‐shift value for the AD group, the areas were located in the bilateral precuneus, the sensory‐motor cortex in the left hemisphere, and the bilateral calcarine sulcus, which were different from the MCI group (both P < 0.05, FDR corrected). Data Conclusion The time‐shift mapping method could detect perfusion deficits in AD and MCI noninvasively. The perfusion deficits detected by rs‐fMRI may provide new insight for understanding the mechanism of neurodegeneration. Level of Evidence 2 Technical Efficacy Stage 3 J. Magn. Reson. Imaging 2019;49:1099–1104.