PURPOSE: To evaluate the effect of IE on the marrow fat content and fat unsaturation levels in the proximal femur using 1 H-MRS.
STUDY TYPE: Prospective.
SUBJECTS: Twenty-three subjects were included in this study, seven control and 16 β-thalassemia subjects.
FIELD STRENGTH/SEQUENCE: 3.0T; stimulated echo acquisition Mode (STEAM); magnetic resonance spectroscopy (MRS) sequence.
ASSESSMENT: Multiecho MRS scans were performed in four regions of the proximal left femur of each subject, that is, diaphysis, femoral neck, femoral head, and greater trochanter. The examined regions were grouped into red (diaphysis and femoral neck) and yellow marrow regions (femoral head and greater trochanter).
STATISTICAL TESTS: The Jonckheere-Terpstra test was used to evaluate the impact of increasing disease severity on bone marrow fat fraction (BMFF), marrow conversion index, and fat unsaturation index (UI). Pairwise comparison analysis was performed when a significant trend (P
OBJECTIVE: This systematic review analyzed the available evidence on (1) neurochemical changes; and (2) the relations between brain metabolite and validated cerebrospinal fluid biomarkers, and/or APOE in AD.
METHODS: PubMed, Cochrane, Scopus, and gray literature were systematically screened for studies deemed fit for the purpose of the current systematic review.
RESULTS: Twenty four articles met the inclusion criteria. Decreased levels of N-acetyl aspartate (NAA), NAA/(creatine) Cr, and NAA/(myo-inositol) ml, and increased ml, ml/Cr, Cho (choline)/Cr, and ml/NAA were found in the posterior cingulate cortex/precuneus. Increased ml is associated with increased tau levels, reduced NAA/Cr is associated with increased tau. ml/Cr is negatively correlated with Aβ42, and ml/Cr is positively correlated with t-tau. NAA and glutathione levels are reduced in APOE ε4 carriers. APOE ε4 exerts no modulatory effect on NAA/Cr. There is interaction between APOE ε4, Aβ42, and ml/Cr.
CONCLUSION: NAA, ml, NAA/Cr, NAA/ml and ml/Cr may be potentially useful biomarkers that may highlight functional changes in the clinical stages of AD. The combinations of ml and tau, NAA/Cr and Aβ42, and NAA/Cr and tau may support the diagnostic process of differentiating MCI/AD from healthy individuals. Large, longitudinal studies are required to clarify the effect of APOE ε4 on brain metabolites.