Three-dimensional pseudocontinuous arterial spin labeling and susceptibility-weighted imaging associated with clinical progression in amnestic mild cognitive impairment and Alzheimer's disease

Effect of acupuncture on brain functional networks in patients with mild cognitive impairment: an activation likelihood estimation meta-analysis

BACKGROUND

Prior research has shown that acupuncture, a traditional Chinese medical therapy, may have a certain therapeutic effect in patients with mild cognitive impairment (MCI). Furthermore, some studies have explored the effects of acupuncture on the brain functional networks of MCI patients to investigate the mechanism of action. Different studies have analysed the brain regions involved in acupuncture-induced changes, but (to our knowledge) these have not been summarized by a systematic review.

METHODS

We searched PubMed, EMBASE, Cochrane Library, SinoMed, CNKI and other databases in Chinese and English to identify neuroimaging studies of acupuncture interventions in MCI patients. After two stages of literature screening, bias risk assessment and data extraction, brain regions with significant differences were input into GingerALE software. Based on the activation likelihood estimation algorithm, coordinate-based meta-analyses were conducted.

RESULTS

The changes in functional activation of 95 different areas in 8 trials, including 212 MCI patients, were analysed. The three most commonly used traditional acupuncture point locations in acupuncture interventions for MCI were KI3 (Taixi), LR3 (Taichong) and LI4 (Hegu). The results of the ALE data analysis showed that, after acupuncture intervention, the degree of activation in the anterior cingulate, inferior frontal gyrus, medial frontal gyrus and cerebellar tonsil of MCI patients increased significantly.

CONCLUSIONS

Acupuncture intervention for MCI appears to change the plasticity of brain function and improve the cognitive function of patients. Due to the small number and low quality of the included studies, the conclusion of this meta-analysis should be treated with caution.

REGISTRATION

PROSPERO reference CRD42022301056 (http://www.crd.york.ac.uk/PROSPERO).

Neuroimaging modalities in the detection of Alzheimer's disease-associated biomarkers

Alzheimer's disease (AD) is the most common cause of dementia. Neuropathological changes in AD patients occur up to 10-20 years before the emergence of clinical symptoms. Specific diagnosis and appropriate intervention strategies are crucial during the phase of mild cognitive impairment (MCI) and AD. The detection of biomarkers has emerged as a promising tool for tracking the efficacy of potential therapies, making an early disease diagnosis, and prejudging treatment prognosis. Specifically, multiple neuroimaging modalities, including magnetic resonance imaging (MRI), positron emission tomography, optical imaging, and single photon emission-computed tomography, have provided a few potential biomarkers for clinical application. The MRI modalities described in this review include structural MRI, functional MRI, diffusion tensor imaging, magnetic resonance spectroscopy, and arterial spin labelling. These techniques allow the detection of presymptomatic diagnostic biomarkers in the brains of cognitively normal elderly people and might also be used to monitor AD disease progression after the onset of clinical symptoms. This review highlights potential biomarkers, merits, and demerits of different neuroimaging modalities and their clinical value in MCI and AD patients. Further studies are necessary to explore more biomarkers and overcome the limitations of multiple neuroimaging modalities for inclusion in diagnostic criteria for AD.

The Utility of Arterial Spin Labeling MRI in Medial Temporal Lobe as a Vascular Biomarker in Alzheimer's Disease Spectrum: A Systematic Review and Meta-Analysis

We sought to systematically review and meta-analy the role of cerebral blood flow (CBF) in the medial temporal lobe (MTL) using arterial spin labeling magnetic resonance imaging (ASL-MRI) and compare this in patients with Alzheimer's disease (AD), individuals with mild cognitive impairment (MCI), and cognitively normal adults (CN). The prevalence of AD is increasing and leading to high healthcare costs. A potential biomarker that can identify people at risk of developing AD, whilst cognition is normal or only mildly affected, will enable risk-stratification and potential therapeutic interventions in the future. All studies investigated the role of CBF in the MTL and compared this among AD, MCI, and CN participants. A total of 26 studies were included in the systematic review and 11 in the meta-analysis. Three separate meta-analyses were conducted. Four studies compared CBF in the hippocampus of AD compared with the CN group and showed that AD participants had 2.8 mL/min/100 g lower perfusion compared with the CN group. Eight studies compared perfusion in the hippocampus of MCI vs. CN group, which showed no difference. Three studies compared perfusion in the MTL of MCI vs. CN participants and showed no statistically significant differences. CBF measured via ASL-MRI showed impairment in AD compared with the CN group in subregions of the MTL. CBF difference was significant in hippocampus between the AD and CN groups. However, MCI and CN group showed no significant difference in subregions of MTL.

Application of 3D-ASL in hemodynamic analysis and prognosis evaluation of vascular cognitive impairment

OBJECTIVE

To investigate the application of magnetic resonance 3D arterial spin labeling (3D-ASL) imaging in the hemodynamic analysis and prognostic assessment of vascular cognitive impairment (VCI).

METHODS

Using a retrospective research method, 108 patients with ischemic cerebrovascular disease diagnosed in the Department of Neurology of Lianyungang Hospital of Traditional Chinese Medicine from January 2021 to April 2022 were chose as the research subjects. The Montreal cognitive assessment (MoCA) was used to evaluate cognitive function. The patients were divided into a VCI group (n=54, 28 males and 26 females) and a normal cognitive function group (NCF group, n=54, 30 males and 24 females). The 3D-ASL cerebral perfusion imaging was performed on the two groups of patients using different post label delay (PLD) (1525 ms, 2525 ms). The cerebral blood flow (CBF) values of bilateral frontal lobe, temporal lobe, temporal parietal junction, parietal lobe, and hippocampus were analyzed under different PLDs in the two groups. The two sets of MoCA scale scores were compared. The receiver operating characteristic curve (ROC) of CBF of VCI patients was drawn, and the area under curve (AUC), specificity and sensitivity under different PLDs was compared.

RESULTS

There was no statistical significance between the two groups in terms of sex, average age, hypertension, diabetes, coronary heart disease, smoking history, and drinking history (P>0.05). CBF 1525 values and CBF 2525 values in the bilateral frontal lobes, temporal lobes, temporoparietal junction, parietal lobes, and hippocampus were significantly reduced in the VCI group under different PLD (all P<0.05). There was no significant difference in the CBF 1525 value and CBF 2525 value of the bilateral frontal lobe and temporal lobe in the VCI group (all P<0.05). The language, delayed memory, executive ability, attention and calculation ability, naming, abstract thinking, orientation, and total scores of the VCI group were significantly lower than those of the NCF group (all P<0.05). The ROC analysis revealed that the AUC, specificity, and sensitivity of CBF (bilateral frontal, temporal, temporoparietal junction, parietal, and hippocampus) at PLD 1525 ms were lower than those of CBF at PLD 2525 ms (P<0.05).

CONCLUSION

Non-invasive 3D-ASL technology can be used to detect cerebral hemodynamics and predict prognosis in VCI patients. PLD 1525 ms was more sensitive to detect cerebral hypoperfusion. PLD 2525 ms showed a more accurate hypoperfusion range. This guides and adjusts treatment methods.

Mild cognitive impairment with Lewy bodies: blood perfusion with arterial spin labelling

Objective

To use arterial spin labelling to investigate differences in perfusion in mild cognitive impairment with Lewy bodies (MCI-LB) compared to Alzheimer type MCI (MCI-AD) and healthy controls.

Methods

We obtained perfusion images on 32 MCI-LB, 30 MCI-AD and 28 healthy subjects of similar age. Perfusion relative to cerebellum was calculated, and we aimed to examine differences in relative perfusion between MCI-LB and the other groups. This included whole brain voxelwise comparisons, as well as using predefined region-of-interest ratios of medial occipital to medial temporal, and posterior cingulate to precuneus. Differences in occipital perfusion in eyes open vs eyes closed conditions were also examined.

Results

Compared to controls, the MCI-LB showed reduced perfusion in the precuneus, parietal, occipital and fusiform gyrus regions. In our predefined regions, the ratio of perfusion in occipital/medial temporal was significantly lower, and the posterior cingulate/precuneus ratio was significantly higher in MCI-LB compared to controls. Overall, the occipital perfusion was greater in the eyes open vs closed condition, but this did not differ between groups.

Conclusion

We found patterns of altered perfusion in MCI-LB which are similar to those seen in dementia with Lewy bodies, with reduction in posterior parietal and occipital regions, but relatively preserved posterior cingulate.

An update on magnetic resonance imaging markers in AD

The purpose of the present review is to provide an update of the available recent scientific literature on the use of magnetic resonance imaging (MRI) in Alzheimer's disease (AD). MRI is playing an increasingly important role in the characterization of the AD signatures, which can be useful in both the diagnostic process and monitoring of disease progression. Furthermore, this technique is unique in assessing brain structure and function and provides a deep understanding of in vivo evolution of cerebral pathology. In the reviewing process, we established a priori criteria and we thoroughly searched the very recent scientific literature (January 2018-March 2020) for relevant articles on this topic. In summary, we selected 73 articles out of 1654 publications retrieved from PubMed. Based on this selection, this review summarizes the recent application of MRI in clinical trials, defining the predementia stages of AD, the clinical utility of MRI, proposal of novel biomarkers and brain regions of interest, and assessing the relationship between MRI and cognitive features, risk and protective factors of AD. Finally, the value of a multiparametric approach in clinical and preclinical stages of AD is discussed.

Brain hemodynamic changes in amnestic mild cognitive impairment measured by pulsed arterial spin labeling

We used pulsed arterial spin labeling (PASL) to investigate differences in cerebral blood flow (CBF) between 26 patients with amnestic mild cognitive impairment (aMCI) and 27 controls with normal cognition (NC). Hypoperfusion was observed in the right temporal pole of the middle temporal gyrus and the right inferior temporal gyrus in the aMCI compared with NC group. Interestingly, hyperperfusion was observed in the left temporal pole of the middle temporal gyrus, left superior temporal gyrus, bilateral precuneus, postcentral gyrus, right inferior parietal lobule, and right angular gyrus in the aMCI group, which likely resulted from a compensatory mechanism to maintain advanced neural activities. We found that mean CBF in the right inferior temporal gyrus, precuneus, and postcentral gyrus was positively correlated with cognitive ability in the aMCI but not NC group. Collectively, our data indicate that PASL is a useful noninvasive technique for monitoring changes in CBF and predicting cognitive decline in aMCI.