Fondazione IRCCS La Nostra Famiglia, San Vito al Tagliamento, Italy.
Department of Pathophysiology and Transplantation, University of Milan, via F. Sforza 35, 20122 Milan, Italy.
J Affect Disord. 2021 Jul 1;290:65-73. doi: 10.1016/j.jad.2021.04.056. Epub 2021 May 2.
Major depressive disorder (MDD) is a severe and pervasive psychiatric condition with a lifetime prevalence of 15-25%. Numerous Magnetic Resonance Imaging (MRI) studies employing scans at field strengths of 1.5T or 3T have been carried out in the last decades, providing an unprecedented insight into the neural correlates of MDD. However, in recent years, MRI technology has largely progressed and the use of scans at ultra-high field (≥ 7T) has improved the sensitivity and the resolution of MR images. In this context, with this review we aim to summarize evidence of structural and functional brain mechanisms underlying MDD obtained with ultra-high field MRI.
We conducted a search on PubMed, Scopus and Web of Science of neuroimaging studies on MDD patients, which employed ultra-high field MRI. We detected six structural MRI studies, two Diffusion Tensor Imaging (DTI) studies and five functional MRI (fMRI) studies.
Overall, the MRI and DTI studies showed volumetric and structural connectivity alterations in the hippocampus and, to a lesser extent, in the amygdala. In contrast, more heterogeneous results were reported by fMRI studies, which, though, described functional abnormalities in the cingulate cortex, thalamus and several other brain areas.
The small sample size and the heterogeneity in patients' samples, processing and study design limit the conclusion of the present review.
Studies employing scans at ultra-high magnetic field may provide a useful contribution to the mixed body of literature on MDD. This preliminary but promising evidence confirms the importance of performing ultra-high field MRI investigations in order to detect and better characterize subtle brain abnormalities in MDD.
重度抑郁症（MDD）是一种严重且普遍的精神疾病，终生患病率为 15-25%。在过去的几十年中，已经进行了许多采用 1.5T 或 3T 场强进行的磁共振成像（MRI）研究，为 MDD 的神经相关性提供了前所未有的深入了解。然而，近年来，MRI 技术有了很大的发展，超高场（≥7T）扫描的应用提高了磁共振图像的灵敏度和分辨率。在这种情况下，我们旨在通过超高场 MRI 综述总结 MDD 的结构和功能脑机制的证据。
我们在 PubMed、Scopus 和 Web of Science 上对使用超高场 MRI 的 MDD 患者的神经影像学研究进行了搜索。我们发现了六项结构 MRI 研究、两项弥散张量成像（DTI）研究和五项功能磁共振成像（fMRI）研究。
总体而言，MRI 和 DTI 研究显示海马体的体积和结构连接改变，而杏仁核的改变则较小。相比之下，fMRI 研究报告了更多异质的结果，这些研究描述了扣带回皮质、丘脑和其他几个脑区的功能异常。
样本量小以及患者样本、处理和研究设计的异质性限制了本综述的结论。
采用超高磁场扫描的研究可能对 MDD 的混合文献提供有用的贡献。这一初步但有希望的证据证实了进行超高场 MRI 研究的重要性，以便检测和更好地描述 MDD 中的细微脑异常。
