DTI studies in patients with Alzheimer's disease, mild cognitive impairment, or normal cognition with evaluation of the intrinsic background gradients

IntroductionThe objective of the study was to explore the impact of the background gradients on diffusion tensor (DT) magnetic resonance imaging (DT-MRI) in patients with Alzheimer's disease (AD), mild cognitive impairment (MCI), or cognitively normal (CN) aging.MethodsTwo DT-MRI sets with positive and negative polarities of the diffusion-sensitizing gradients were obtained in 15 AD patients, 18 MCI patients, and 16 CN control subjects. The maps of mean diffusivity (MD) and fractional anisotropy (FA) were computed separately for positive (p: pMD and pFA) and negative (n: nMD and nFA) polarities, and we computed the geometric mean (gm) of the DT-MRI to obtain the gmFA and gmMD with reducing the background gradient effects. Regional variations were assessed across the groups using one-way analysis of variance.ResultsIncreased regional gmMD values in the AD subjects, as compared to the regional gmMD values in the MCI and CN subjects, were found primarily in the frontal, limbic, and temporal lobe regions. We also found increased nMD and pMD values in the AD subjects compared to those values in the MCI and CN subjects, including in the temporal lobe and the left limbic parahippocampal gyrus white matter. Results of comparisons among the three methods showed that the left limbic parahippocampal gyrus and right temporal gyrus were the increased MD in the AD patients for all three methods.ConclusionBackground gradients affect the DT-MRI measurements in AD patients. Geometric average diffusion measures can be useful to minimize the intrinsic local magnetic susceptibility variations in brain tissue

Acupuncture on GB34 activates the precentral gyrus and prefrontal cortex in Parkinson’s disease

Background: Acupuncture is increasingly used as an additional treatment for patients with Parkinson’s disease (PD). Methods: In this functional magnetic resonance imaging study, brain activation in response to acupuncture in a group of 12 patients with PD was compared with a group of 12 healthy participants. Acupuncture was conducted on a specific acupoint, the right GB 34 (Yanglingquan), which is a frequently used acupoint for motor function treatment in the oriental medical field. Results: Acupuncture stimulation on this acupoint activates the prefrontal cortex, precentral gyrus, and putamen in patients with PD; areas that are known to be impaired in patients with PD. Compared with healthy participants, patients with PD showed significantly higher brain activity in the prefrontal cortex and precentral gyrus, especially visible in the left hemisphere. Conclusions: The neuroimaging results of our study suggest that in future acupuncture research; the prefrontal cortex as well as the precentral gyrus should be treated for symptoms of Parkinson’s disease and that GB 34 seems to be a suitable acupoint. Moreover, acupuncture evoked different brain activations in patients with Parkinson’s disease than in healthy participants in our study, stressing the importance of conducting acupuncture studies on both healthy participants as well as patients within the same study, in order to detect acupuncture efficacy. Trial registration KCT0001122 at cris.nih.go.kr (registration date: 20140530) Electronic supplementary material The online version of this article (doi:10.1186/1472-6882-14-336) contains supplementary material, which is available to authorized users

Phantom Acupuncture Induces Placebo Credibility and Vicarious Sensations: A Parallel fMRI Study of Low Back Pain Patients

Although acupuncture is an effective therapeutic intervention for pain reduction, the exact difference between real and sham acupuncture has not been clearly understood because a somatosensory tactile component is commonly included in the existing sham acupuncture protocols. In an event-related fMRI experiment, we implemented a novel form of sham acupuncture, phantom acupuncture, that reproduces the acupuncture needling procedure without somatosensory tactile stimulation while maintaining the credibility of the acupuncture treatment context. Fifty-six non-specific low back pain patients received either real (REAL) or phantom (PHNT) acupuncture stimulation in a parallel group study. The REAL group exhibited greater activation in the posterior insula and anterior cingulate cortex, reflecting the needling-specific components of acupuncture. We demonstrated that PHNT could be delivered credibly. Interestingly, the PHNT-credible group exhibited bilateral activation in SI/SII and also reported vicarious acupuncture sensations without needling stimulation. The PHNT group showed greater activation in the bilateral dorsolateral/ventrolateral prefrontal cortex (dlPFC/vlPFC). Moreover, the PHNT group exhibited significant pain reduction, with a significant correlation between the subjective fMRI signal in the right dlPFC/vlPFC and a score assessing belief in acupuncture effectiveness. These results support an expectation-related placebo analgesic effect on subjective pain intensity ratings, possibly mediated by right prefrontal cortex activity

Influence of selecting EPI readout-encoding bandwidths on arterial spin labeling perfusion MRI

The objective of this study was to investigate effects of varying readout bandwidths on the arterial spin labeling (ASL)-perfusion MRI measurements at a high magnetic field MRI system. Brain perfusion studies were performed on nine volunteers (four males, five females) using flow sensitive alternating inversion recovery (FAIR) ASL single-shot echo-planar imaging (EPI)-MRI. To investigate EPI bandwidth effects on the time-series perfusion-weighted imaging (PWI) data, two regions-of-interest (ROI) were placed outside the brain to determine the level of noise and another ROI inside the brain to determine the level of signal. Coefficients of variations (CoV) were calculated for the time-series PWI data. One-way analysis of variance (ANOVA) was used to investigate voxel-wise differences in the time-series PWI data between two different bandwidth values. At the level of ROI, there was no significant effect of changing EPI bandwidths on the time-series PWI data in any of the volunteers (P > 0.031). In contrast, CoV values over the dynamic PWI data varied with depending on selecting EPI bandwidths and voxel-based tests showed that N2 ghosting, modulated by EPI bandwidth, can appear in some brain regions, especially in areas that overlap with the spatial distribution of N2 ghosting artifacts. Although N2 ghosting can be reduced by adjusting the bandwidth of EPI on the time-series of PWI data, the effects cannot be entirely eliminated. In particular, N2 ghosting can bias CBF quantification if EPI control scans to determine the equilibrium-state signal are confounded by N2 ghosting. Therefore, careful tuning of the bandwidth of EPI is necessary to avoid artifacts in the ASL signal from N2-ghosting

Influence of selecting EPI readout-encoding bandwidths on arterial spin labeling perfusion MRI

The objective of this study was to investigate effects of varying readout bandwidths on the arterial spin labeling (ASL)-perfusion MRI measurements at a high magnetic field MRI system. Brain perfusion studies were performed on nine volunteers (four males, five females) using flow sensitive alternating inversion recovery (FAIR) ASL single-shot echo-planar imaging (EPI)-MRI. To investigate EPI bandwidth effects on the time-series perfusion-weighted imaging (PWI) data, two regions-of-interest (ROI) were placed outside the brain to determine the level of noise and another ROI inside the brain to determine the level of signal. Coefficients of variations (CoV) were calculated for the time-series PWI data. One-way analysis of variance (ANOVA) was used to investigate voxel-wise differences in the time-series PWI data between two different bandwidth values. At the level of ROI, there was no significant effect of changing EPI bandwidths on the time-series PWI data in any of the volunteers (P > 0.031). In contrast, CoV values over the dynamic PWI data varied with depending on selecting EPI bandwidths and voxel-based tests showed that N2 ghosting, modulated by EPI bandwidth, can appear in some brain regions, especially in areas that overlap with the spatial distribution of N2 ghosting artifacts. Although N2 ghosting can be reduced by adjusting the bandwidth of EPI on the time-series of PWI data, the effects cannot be entirely eliminated. In particular, N2 ghosting can bias CBF quantification if EPI control scans to determine the equilibrium-state signal are confounded by N2 ghosting. Therefore, careful tuning of the bandwidth of EPI is necessary to avoid artifacts in the ASL signal from N2-ghosting

Mapping Exchangeable Protons to Monitor Protein Alterations in the Brain of an Alzheimer’s Disease Mouse Model by using MRI

To investigate exchangeable proton signals of Aβ proteins of the brains of Alzheimer's disease (AD) model mice by using a chemical exchange-sensitive spin-lock (CESL) MR imaging technique. Method: Eight non-transgenic (Tg) mice (5 young and 3 old) and twelve Tg-APPswe/PSdE9 mice (5 young and 7 old) were used in this study. CESL Z-spectra were obtained by using two saturation powers, which were ω1 = 25 Hz with TSL = 3.0 s and ω1 = 500 Hz with TSL = 150 ms, at 71 offsets with uneven intervals between the offset frequencies at Ω = ±7.0 ppm at a 9.4-T animal MRI system. For Z-spectrum analyses, regions of interest (ROIs) were drawn in the cortex, hippocampus, and thalamus of both hemispheres. Magnetization transfer ratio asymmetry (MTRasym) curves were obtained from the Z-spectra. The Mann-Whitney test was used to compare the MTRasym values between the Tg and non-Tg mice for each offset frequency and for each ROI. Results: The water saturation width of the full Z-spectrum was narrow with the 25-Hz saturation power, but relatively broad with the 500-Hz saturation power. With the 25-Hz CESL saturation power, most of the MTRasym values were negative for the 3.5-, 3.0-, 2.0-, and 0.9-ppm offset frequencies and the MTRasym values were significantly different between the control and Tg groups only in the left thalamus region at 3.5 ppm offset (p=0.0487). The MTRasym values were -6% to -7% for both 3.5 and 3.0 ppm, but less than -2% for both 2.0 and 0.9 ppm. With the 500-Hz CESL saturation power, all the MTRasym values were positive for the 3.5-, 3.0-, 2.0-, and 0.9-ppm offset frequencies and the MTRasym values were not significantly different between the control and Tg groups at all ROIs and at all offset frequencies. However, a trend towards a significant difference was observed between the control and Tg groups in the right cortex at 3.5 ppm (p=0.0578). The MTRasym values were 6% to 9% for 3.5, 3.0, and 2.0 ppm, but less than 2% for 0.9 ppm. Conclusion: In the in-vivo AD model experiment, MTRasym values increased with the high saturation power than with the low saturation power. The MTRasym values were not significantly different, except in the left thalamus region at 3.5 ppm offset. The CESL technique should be further developed to enable its application in the brain of patients with neurodegenerative diseases. © 2018 Bentham Science Publisher