RESUMO
Neuroimaging using the 7-Tesla (7T) human magnetic resonance (MR) system is rapidly gaining popularity after being approved for clinical use in the European Union and the USA. This trend is the same for functional MR imaging (MRI). The primary advantages of 7T over lower magnetic fields are its higher signal-to-noise and contrast-to-noise ratios, which provide high-resolution acquisitions and better contrast, making it easier to detect lesions and structural changes in brain disorders. Another advantage is the capability to measure a greater number of neurochemicals by virtue of the increased spectral resolution. Many structural and functional studies using 7T have been conducted to visualize details in the white matter and layers of the cortex and hippocampus, the subnucleus or regions of the putamen, the globus pallidus, thalamus and substantia nigra, and in small structures, such as the subthalamic nucleus, habenula, perforating arteries, and the perivascular space, that are difficult to observe at lower magnetic field strengths. The target disorders for 7T neuroimaging range from tumoral diseases to vascular, neurodegenerative, and psychiatric disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, epilepsy, major depressive disorder, and schizophrenia. MR spectroscopy has also been used for research because of its increased chemical shift that separates overlapping peaks and resolves neurochemicals more effectively at 7T than a lower magnetic field. This paper presents a narrative review of these topics and an illustrative presentation of images obtained at 7T. We expect 7T neuroimaging to provide a new imaging biomarker of various brain disorders.
RESUMO
This article reviews the stereotactic targets in the posterior subthalamic area(PSA), fields H1/H2 of Forel(pallidothalamic tract), and the pedunculopontine nucleus(PPN)to complement the preceding articles on stereotactic and functional neurosurgery for movement disorders in the present issue of No Shinkei Geka. Two regions within the subthalamus, the PSA and fields H1/H2 of Forel, are the revisited stereotactic targets to treat movement disorders. Currently, the PSA is often utilized to treat essential tremor and various types of tremor. Fields H1/H2 of Forel are investigated as a target for magnetic resonance-guided focused ultrasound to treat motor symptoms and motor complications in patients with Parkinson's disease. For the past twenty years, the PPN has been investigated to treat refractory gait freezing and fall in patients with Parkinson's disease. These revisited and novel targets may be utilized as substitutes and complements for the present standard stereotactic targets.