CT Scan Provides Virtual Cuts Through the Body
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Computerized tomography (CT) scans provide cross-sectional images of the body by using X-rays, while magnetic resonance imaging (MRI) uses magnetic fields and radio waves to produce detailed images of organs and tissue. CT scans depict bone structures more clearly than MRI, while MRI provides better soft tissue contrast and detection of certain abnormalities without radiation exposure. Positron emission tomography (PET) scans use radioactive tracers to detect metabolic activity throughout the body at a cellular level, offering highly sensitive functional imaging but with a higher cost and less spatial resolution than CT or MRI.
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CT Scan Provides Virtual Cuts Through the Body
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- 4. •Computer-assisted tomography (CAT or CT) provides virtual cuts through the body based on the signals created by an X-ray source that moves around the body in the plane.
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- 10. Tissue Appearance BONE WHITE CALCIFIED TISSUE WHITE CLOTTED BLOOD WHITE GRAY MATTER LIGHT GREY WHITE MATTER MEDIUM GREY CSF NEARLY BLACK WATER NEARLY BLACK AIR BLACK The only component of brain better seen on CT scan is calcification, which may be invisible on MRI.
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- 14. Nuclei of all atoms are thought to spin about an axis randomly oriented in space. Place in magnetic field, axis of all odd-numbered nuclei(mainly hydrogen) align with the magnetic field. When exposed to a pulse of radiofrequency waves- axis of nucleus deviates away from the magnetic field. When the pulse terminates, the axis of the spinning nucleus realigns itself with the magnetic field. During this realignment, it emits its own radiofrequency signal. MRI scanners collect the emissions of individual realigning nuclei and use computer analysis to generate a series of 2-D images that represent the brain.
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- 16. • • • APPEARENCE BONE WHITE WHITE MATTER LIGHT GREY GREY MATTER MEDIUM GREY WATER/CSF/AIR BLACK
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- 18. • • • APPERENCE GRAY MATTER MEDIUM GREY WHITE MATTER DARK GREY CSF/WATER WHITE
- 22. MRI Scan CT Scan Detailed pictures in soft tissues Less detailed compared to MRI scans Bony structures are less detailed as compared to CT Bony structures are more clear and detailed No known side effects on radiation and very few side effects on MRI contrast scans Little side effects. Frequent radiations and CT scans might rarely cause cancer Due to the structure and sound, Claustrophobia patients may need to take anaesthesia Procedure is very simple and does require anaesthesia Higher cost They are less expensive than MRI Duration of MRI scan is much longer CT scan procedure is quicker Pts. with metal or certain medical implants are not able to undergo MRI’s due to the magnetic field pulses Can be performed with no risk to medical implants or metal
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- 32. •It is based on the detection of the products of radioactive decay from radioactively labelled tracers
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- 41. Injected with radio labelled material Gamma rays emitted detected by scanner Translated into 2D image These images added together to get a 3D image
- 42. SPECT PET SINGLE PHOTON POSITRON 99MTC OR I123 11C OR 18F SHORT HALF LIFE LONGER HALF LIFE LESS SENSITIVE HIGHLY SENSITIVE(100 TIMES MORE THAN SPECT) LOW SPATIAL RESOLUTION SUPERIOR SPATIAL RESOLUTION CHEAPER AND EASILY AVAILABLE COSTLY, NOT EASILY AVAILABLE •SPECT is used in the early diagnosis of alzheimer’s disease
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