Ultra-high field 7.0T MRI was utilized for hippocampal volumetry. A new delineating method for the hippocampus has been described, and the boundaries between the “head and body” and the “body and tail” have been defined. Accurate volumetric measurements, as well as clear contrast images obtained with 7.0T in 3D images, might be helpful for the accurate diagnosis of diseases involving the hippocampus.
Fig. 1. An example of Alzheimer's patient (at the right). This set of hippocampal images is the typical representative case of Alzheimer's (at the right) and normal contral (at the left).
It has been difficult to observe small volumetric changes and changes occurring within the substructure of the hippocampus because of the limited resolution of the images obtained with 1.5T or 3.0T MRI. Accurate 3D T2* imaging with 7.0T provide incredibly detailed 3D images that can be used for volumetric studies. Figure 2 shows hippocampal images from 1.5T and 7.0T MRI, while in Figure 3, a complete set of 3D images obtained with 7.0T MRI is seen.
In comparison with magnified coronal images, the vague borderline of hippocampus seen in 1.5T MRI was clearly distinguished in the 7.0T images. Surrounding structures and the undifferentiated structure of the hippocampus were revealed in the 7.0T image set with an extremely high resolution and SNR.
The curvature and anatomical structures of the hippocampus are clearly presented in the coronal and sagittal images obtained using 7.0T MRI, allowing the sections that are unattainable using low field MRI to be observed.
In Figures 3 (a) and (b), T2* weighted coronal and sagittal images obtained using 3D Gradient Echo in ultra-high field 7.0T MRI. As shown, various substructures are visualized in each section. Obvious applications of these advanced high resolution imaging in the in vivo visualization of the Alzheimer's as shown in Fig. 4. The reduced volume of the hippocampus in the presence of neurodegenerative diseases such as Alzheimer’s disease is clearly viisualized. Equally, other neural diseases such as depression, and schizophrenia can be identified by hippocampal atrophy in the sub-regions of the hippocampus as shown in Fig. 4.
Subtle changes of the hippocampus could be detected with the aid of these high resolution and contrast images. Non-invasive in vivo human brain imaging with a high resolution and high contrast using ultra-high field 7.0T MRI will certainly change the landscape of medical imaging for many neurological diseases, such as Alzheimer’s and Parkinson's diseases in near future.
- Zang-Hee Cho, Young-Bo Kim, Jae-Yong Han, Hoon-Ki Min, Kyoung-Nam Kim, Sang-Han Choi, Eugene Veklerov, Larry A. Shepp. “New Brain Atlas-Mapping the Human Brain In Vivo with 7.0T MRI and Comparison with Postmortem Histology : Will These Images Change Modern Medicine ? ” International Journal of Imaging Systems and Technology Vol.18,2-8 (2008).
-Zang-Hee Cho, Jae-Yong Han, Seok-Il Hwang, Dae-shik Kim, Kyoung-Nam Kim, Nam-Beom Kim, Seog-Ju Kim, Je-Geun Chi, Chan-Woong Park, Young-Bo Kim. Quantitative analysis of the hippocampus using images obtained from 7.0T MRI. Neuroimage 49(3):2134-40 (2010).
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