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For this discussion board, provide an overview of each of the following types of imaging/assessment measures:
1. Computerized Tomography (CT)
2. Magnetic Resonance Image (MRI)
3. Functional Magnetic Resonance Image (fMRI)
4. Positron Emission Tomography (PET)
5. Single Photon Emission Computed Tomography (SPECT)
6. Electroencephalogram (EEG)
Which imaging technique would you select if you suspected a brain tumor? Why?
The following article may be helpful in answering this discussion board:
Camprodon, J.A., & Stern, T.A. (2013). Selecting neuroimaging techniques: A review for the clinician. The Primary Care Companion for CNS Disorders, 15(4), 12f01490. doi: 10.4088/PCC.12f01490
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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3869600/
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Carlson and Birkett (2017) advance that that computerized tomography is usually referred to as a CT scan. The means of how this works is by placing the patient’s head in a doughnut-shaped ring which contains an X-ray tube on one side and an X-ray detector on the opposite side. The X-ray beam passes through the patients head with the detector measuring the amount of radioactivity that gets through it. The beam scans the head from all sides and the information garnered from the detector translates to an image of the skull and its parts. Camprodon and Stern (2013) advance that CT images are formulated via a rotating axial plane. Since the conceptualization is via X-rays, water, fat, bone, and other tissue types appear differently on the film or digital sensor.
An even more detailed image can be produced via a process called magnetic resonance imaging (MRI). Carlson and Birkett (2017) advance that the MRI scanner has similarity to the CT scanner, however, it does not use X-rays. The means of how the MRI functions, is via passing a very potent magnetic field through the persons head. According to Camprodon and Stern (2013), the magnetic properties of hydrogen ions in the body are utilized. When the patient’s head is placed in this strong magnetic field, the nuclei of the whirling hydrogen atoms align with it. Subsequently, a radio frequency is passed through the brain, causing the nuclei to flip and then flip back to its original position. This causes a release of energy, detected by a coil of wire. Since tissues have different amounts of hydrogen, they emit different amounts of energy. It is from these differences in energy that pictures are formed.
Presently, the brain imaging mechanism with the best spatial resolution is the functional MRI. Carlson and Birkett (2017) advance that modification has been made to existing MRI scanners permitting devices to acquire images that indicate metabolism in certain regions. The manner in which this is accomplished is because brain activity is measured indirectly through discovering levels of oxygen in the brains blood. If there is an increase in activity, it stimulates greater blood flow to that area (Camprodon & Stern, 2013). Carlson and Birkett (2017) elucidate that the formal name is referred to as BOLD, namely blood oxygen level-dependent signal.
Carlson and Birkett (2017) advance that the first functional image method was the positron emission tomography (PET). The means of how it works is that a person receives an injection of radioactive 2-DG, which is not deleterious. The patients head is placed in a machine that is similar to a CT scan and when the radioactive 2-DG decomposes, they emit positrons that meet nearby electrons. The particles crush each other emitting two photons that travel in opposite directions. The sensors around the patients head detect the photons and scanner plots where they came from, eventually producing a picture of the persons brain showing the activity level. Two disadvantages are that PET scans are expensive and have poor resolution quality.
The National Center for Biotechnology Information [NCBI] (n.d.) advances that the single-photon emission computed tomography (SPECT) is an imaging technique that is predicated on nuclear medicine imaging and tomographic reconstruction methods. The images show images about a patient that is similar to PET scans. The difference is in how it achieves these results, with the SPECT measuring gamma rays as opposed to positrons in the PET scan. The SPECT is a highly functional image that shows how organs work. A radiopharmaceutical is administered to the patient and taken up by different organs or tissues. Typically, a certain type of camera system is used that picks up the decaying gamma and formulates a picture. According to Camprodon and Stern (2013), the PET scan is the preferred device.
According to Carlson and Birkett (2017), macro-electrodes do not detect individual neurons, rather they survey many thousands or millions of cells. The activity of macro electrodes is displayed on a polygraph, which is displayed on a computer screen. When electrical activity from macro-electrodes are taken from different areas of the scalp, that record is called an electroencephalogram (EEG), which means writing of electricity from the head.
Carlson and Birkett (2017) advance that the CT scan slices through tissues of the body and can pick up tumors or bleeding. Additionally, the MRI can achieve the same results as the CT scan but does so through the use of a magnetic field instead of X-rays. According to Dr. Serafini (personal communication, January 19, 2020), the MRI may be less used due to cost, time, and invasiveness. The CT scan is the first choice for tumors and bleeding.
References
Camprodon, J. A., & Stern, T. A. (2013). Selecting neuroimaging techniques: a review for the clinician. The primary care companion for CNS disorders, 15(4).
Carlson, N. R., & Birkett, M. A. (2017). Physiology of Behavior, 12th Edition. Boston, Massachusetts: Pearson.
NCBI. (n.d.). Single photon computed tomography. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK232492/
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