Di Salle F, Esposito F, Elefante A, Scarabino T, Volpicelli A, Cirillo S, Elefante R, Seifritz E
Department of Neurological Sciences, University Federico II of Naples, via Pansini 5, 80131 Naples, Italy.
Eur J Radiol. 2003 Nov;48(2):138-45. doi: 10.1016/j.ejrad.2003.08.010.
Functional magnetic resonance imaging (fMRI) has become the most widely used approach for studying brain functions in humans. The rapid and widespread diffusion of fMRI has been favoured by the properties this technique presents, and particularly by its sensitivity in analysing brain functional phenomena and by the lack of biological invasiveness, resulting in an unprecedented and unparalleled flexibility of use. These properties of fMRI brought the functional examination of the brain within the reach of the whole neuroscience community and have appreciably stimulated the research on the functional processes of the living brain. Among the main features of fMRI, its spatial and temporal resolution represents clear advantages compared with the other methods of functional neuroimaging. In fact, the high spatial resolution of fMRI permits to produce more precise and better localised information, and its temporal resolution provides the potential of a better understanding of neural dynamics at the level of single functional areas and of the neural constituents of functional patterns. A fundamental possibility of improving spatial and temporal resolution without excessively degrading signal-to-noise ratio consists in the use of high magnetic field intensity fMRI units. Besides, high field units make the use of more demanding fMRI paradigms, like single trial event related studies, much more compatible with the need of a solid statistical evaluation. This has notably promoted the diffusion of high field MRI units for human studies throughout the world, with very high field MRI units, up to 8 T, working in a few research centres, and a larger number of MRI units with field intensity ranging between 3 and 5 T.
功能磁共振成像（fMRI）已成为研究人类大脑功能最广泛使用的方法。fMRI的迅速广泛传播得益于该技术所具有的特性，特别是其在分析脑功能现象方面的敏感性以及缺乏生物侵入性，从而带来了前所未有的、无与伦比的使用灵活性。fMRI的这些特性使整个神经科学界都能够对大脑进行功能检查，并显著促进了对活体大脑功能过程的研究。与其他功能性神经成像方法相比，fMRI的主要特征之一是其空间和时间分辨率具有明显优势。事实上，fMRI的高空间分辨率能够产生更精确、定位更准确的信息，其时间分辨率则提供了在单个功能区域层面以及功能模式的神经组成部分层面更好地理解神经动力学的潜力。在不过度降低信噪比的情况下提高空间和时间分辨率的一个基本可能性在于使用高磁场强度的fMRI设备。此外，高场设备使更具挑战性的fMRI范式（如单次试验事件相关研究）的使用与可靠统计评估的需求更加兼容。这显著推动了用于人体研究的高场MRI设备在全球的普及，少数研究中心使用高达8T的超高场MRI设备，还有大量场强在3T至5T之间的MRI设备。
