Computed tomography (CT), originally known as 3D roentgenography (X-ray), is a medical imaging method as computed axial tomography (CAT or CT scan) and body section employing tomography where digital geometry processing is used to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images
Main principles of the CT
Magnetic resonance imaging was developed from knowledge gained in the study of nuclear magnetic resonance.
MRI uses non-ionizing radio frequency (not X-ray!) signals to acquire its images and is best suited for non-calcified tissue
Both CT and MRI scanners can generate multiple two-dimensional cross-sections (slices) of tissue and three-dimensional reconstructions. Unlike CT, which uses only X-ray attenuation to generate image contrast, MRI has a long list of properties that may be used to generate image contrast. By variation of scanning parameters, tissue contrast can be altered and enhanced in various ways to detect different features.
MRI can generate cross-sectional images in any plane (including oblique planes). CT is limited to acquiring images in the axial (or near axial) plane. However, the development of multi-detector CT scanners with near-isotropic resolution produces data that can be retrospectively reconstructed in any plane with minimal loss of image quality.
Example: Retinotopic maps in cortex
Main principles of the CT
Magnetic resonance imaging was developed from knowledge gained in the study of nuclear magnetic resonance.
MRI uses non-ionizing radio frequency (not X-ray!) signals to acquire its images and is best suited for non-calcified tissue
Both CT and MRI scanners can generate multiple two-dimensional cross-sections (slices) of tissue and three-dimensional reconstructions. Unlike CT, which uses only X-ray attenuation to generate image contrast, MRI has a long list of properties that may be used to generate image contrast. By variation of scanning parameters, tissue contrast can be altered and enhanced in various ways to detect different features.
MRI can generate cross-sectional images in any plane (including oblique planes). CT is limited to acquiring images in the axial (or near axial) plane. However, the development of multi-detector CT scanners with near-isotropic resolution produces data that can be retrospectively reconstructed in any plane with minimal loss of image quality.
the three systems form the major components of an MRI scanner:
- a static magnetic field,
-an RF transmitter and receiver, - three orthogonal, controllable magnetic gradients.
2003
Nobel Prize Reflecting the fundamental importance and
applicability of MRI in the medical field, Paul Lauterbur and Sir Peter Mansfield of the University of Illinois, Urbana-Champaig
Example: Retinotopic maps in cortex
Dougherty,
R. F., Koch, V. M., Brewer, A. A., Fischer, B., Modersitzki, J., &
Wandell, B. A. (2003). Visual field representations and locations of visual areas V1/2/3 in human visual cortex