A. Computed Tomography (CT) Computed Tomography (CT) is a biomedical imaging technique which produces cross-section images also called "slices" of anatomy of the human body. Radiographic beams are made incident on the human body. The reflected radio beams create a detailed computerized picture taken with a specialized X-ray machine. CT is more precise than a standard X-ray, and provides a clearer image. Fig.1 shows a CT scan of transverse view of the brain. The cross-sectional images are used for a variety of diagnostic and therapeutic purposes. The CT imaging system consists of a motorized table which moves the patient through a circular opening. While the patient is inside the opening, an X-ray source and a detector assembly within the system rotate around the patient. A single rotation typically takes a second or less. During rotation the X-ray source produces a narrow, fan-shaped beam of X-rays that passes through a section of the patient's body. Detectors in rows opposite the X-ray source register the X-rays that pass through the patient's body as a snapshot in the process of creating an image [3, 8]. Many different "snapshots" (at many angles through the patient) are collected during one complete rotation. For each rotation of the X-ray source and detector assembly, the image data are sent to a computer to reconstruct all of the individual "snapshots" into one or multiple cross-sectional images (slices) of the internal organs and tissues [19]. Fig.2 shows the CT images for multiple slices of the brain. The minimum and maximum number of CT slices range from 1 to 64 and 320 [18, 19]. Fig. 1 Transverse view - CT scan of Brain Fig.2 multiple slices of CT scan of Brain CT scan is one of the most commonly used imag... ... middle of paper ... ...gery. A dye (contrast agent) may also be used to observe certain tissues, which then stand out on the scan. Functional MRI gives detailed pictures of brain activity [69, 75, 76, and 77]. It is used to determine precisely which part of the brain is handling critical functions such as thought, speech, vision, movement and sensation. It can also show the effects of stroke, trauma or Alzheimer's on brain function [70, 71, and 73]. Functional MRI and DTI have risk factors similar to MRI. Fig. 10 indicates DTI images of the brain. Fig.10 in Diffusion tensor imaging (DTI), each color represents a different white matter pathway. Fig.11 a 3D reconstruction from fMRI and DTI images shows the vision and hand movement areas that lie close to the brain tumor (green area) Fig. 11 shows a 3D reconstruction from fMRI and DTI images. The 3D view gives a good view of the brain.
The brain has four major lobes. The frontal lobe, the parietal lobe, the occipital lobe, and temporal lobe are responsible for all of the activities of the body, from seeing, hearing, tasting, to touching, moving, and even memory. After many years of debating, scientist presents what they called the localization issue, Garret explains how Fritsch and Hitzig studied dog with conforming observations, but the cases of Phineas Gage’s accident in 1848 and Paul Broca’s autopsy of a man brain in 1861 really grabbed the attention of an enthusiastic scientific community (Garret 2015 p.6)
Magnetic Resonance Imaging (MRI) has been around since the 1930s. An MRI machine has a great purpose in the medical field. It is a radiology technique that uses magnetism, radio waves, and a computer to produce images of body structures, such as a patient’s head, chest, blood vessels, bones and joints, and much more. MRI machines help doctors figure out what is wrong with their patient's bodies. It allows doctors to take a closer look at a certain location and see things that other machines cannot see. By using this machine, it helps doctors figure out the problem faster and allows them to try and find a treatment or a cure.
Magnetic Resonance Imaging (MRI) is one of the medical imaging modality which provides excellent internal structures of the body using magnetic radiation (WHO, 2014). Better Health Channel (2011) suggested MRI is notably helpful visualizing contrasts of body organs and soft tissues, WHO pointed out MRI generates excellent images of the brain, spine, muscles, joints and other body structures. The images generated by the MRI machine is multiplanar, this means the image is obtained in multiple planes of the body without the patient changing its body position (WHO, 2014). MRI can also be viewed in 3D (Southern Radiology).
Functional MRI is a measurement technique based on ultrafast MR imaging sequences that are sensitive to the physiological changes of cerebral blood flow (CBF) and cerebral blood volume (CBV).These allow the researcher to measure changes in brain function typically via increases or decreases in blood oxygenation during the scanning(2).
Computed tomography (CT) offers the advantages of 3D imaging with volumetric and multi-planar reconstructions (21, 22). Given the relatively high radiation doses involved, CT should not be used in place of conventional radiography, and should be restricted to critically ill children who may need neurosurgical intervention (21). Iterative reconstruction and all appropriate dose reduction techniques should be used to reduce radiation exposure (22).
Neuroimaging is a multidiscipline science and experts from the field of psychology, statistics, physics and physiology all contribute to its further development (Poldrack et al., 2007). In the last 20 years the imaging techniques developed from single proton emission tomography (SPET) to positron emission tomography (PET) and finally to functional magnetic resonance imaging (fMRI) (Page, 2006). Their applications are numerous in experimental and cognitive psychology. However, at one level they can constitute another dependent variable (brain activity) as a response to an independent variable (stimulus manipulation) and at the other level, understanding the structure and processes of the brain can shed light on ‘normal’ cognitive functioning (Kaye, 2010). Therefore, this essay will argue that imaging techniques not only tell us about the brain structure but also try to explain its cognitive functions. Two non-invasive imaging techniques will be put forward, namely, electroencephalogram (EEG) that measures electrical activity and gives excellent temporal resolution and fMRI that is based on changes in blood supply and provides excellent spatial resolution. The claim will be evaluated in the light of their basic assumptions, methodology and contribution to examining the brain function. Relevant evidence of studies with healthy adults will be provided. Finally, technologies that can only show the brain structure will be introduced.
CT scans and DWI are important testing techniques used in determining initiating causes of neurological changes in individuals. However, currently the best testing method available in identifying CPM is by a magnetic resonance imaging (MRI) scan. With the use of strong magnetic fields and radiowaves in MRIs accurate body images are produced. MRI scans are highly sensitive and offer better visualizations of grey and white matter contrast in the brain. MRIs are the optimal choice for testing of diseases and/or disorders in the central nervous system. The most optimal time to perform an MRI is the most critical time to perform the scan as well, when patients develop neurological symptoms. Diagnosed is generally confirmed by autopsy results (Gheorghita et. al 2010).
Brain scans -These tests can identify strokes, tumors, and other problems that can cause dementia. Scans also identify changes in the 19 brain’s structure and function. The most common scans are computed tomographic (CT) scans and magnetic resonance imaging (MRI). CT scans use X-rays to produce images of the brain and other organs. MRI scans use a computer, magnetic fields, and radio waves to produce detailed images of body structures, including tissues, organs, bones, and nerves. Other types of scans let doctors watch the brain as it functions. Two of these tests are single photon-emission computed tomography, which can be used to measure blood flow to the brain, and positron emission tomography (PET), which uses radioactive isotopes to provide
CT scans are able to find the position, the boundaries, and the solidity of the brain tumor. One job that a CT scan does is that it differentiates soft tissues from the tumor. CT scans use ionizing radiation to give the image. However, a CT scan does not produce the same type of specific information as other forms of neuroimaging technology. In some cases, a CT shows no signs of a tumor, so a magnetic resonance imaging (MRI) scan is needed (Hill et al. 4-5). A CT scan does cost a lot less money, but if an MRI has to be taken anyway, a CT scan is not a necessary step in the diagnosis
According to Russell Poldrack’s article, what fMRI can tell us is often overrated despite its powerful impact on the study of the human brain. fMRI is a useful technique that allows us to image brain activities by measuring blood flow in the brain. It expanded our understanding of mental disorders from a biological perspective and helped us understand structures and functions of the brain. However, there are several limitations on what neuroimaging can tell us because it is difficult to determine how our brain works or how we can diagnose and treat mental disorders from them.
Since the brain is extremely fragile and difficult to access without risking further damage, imaging techniques are used frequently as a noninvasive method of visualizing the brain’s structure and activity. Today's technology provides many useful tools for studying the brain. But even with our highest technology out there we do not know everything definitely. We do have fallbacks at times and these fallbacks can lead to serious problems.
CTscans stands for “Computed Tomography”. It is a way of looking inside your body using a special camera. It is an advanced scanning x-ray and computer system that makes detailed pictures of horizontal cross-sections of the body, or the part of the body that is x-rayed. A CT scan is a diagnostic test that combines the use of x-ray with computer technology. A series of x-beams from many different angles are used to get these cross-sectional images of the patient’s body. In a computer, these pictures are assembled into a 3-dimentianal picture that can display organs, tissues, bones, and any such thing. It can even show ducts, blood vessels and tumors. One of the advantages of CT is that it clearly shows soft tissue structures (such as brain), as well as dense tissue structure (such as bone). The pictures of a Ctscanner are a lot more detailed than the pictures of a regular X-ray machine. It can make pictures of areas protected or surrounded by bones, which a regular X-ray machine can not. Because of this, a CT scanner is said to be 100 times as affective and clever as an ordinary X-ray, and can therefore diagnose some diseases a lot earlier and quicker. It is recent technology that has made it possible to accurately scan objects into a computer in three dimensions, even though the machines and ideas were developed in the 1970s. In the 70s doctors started to use this new type of machine that could give detailed pictures of organs that the older type of x-ray, machine could not give.
1 Detre, John A, and Thomas F Floyd. "Functional MRI and its applications to the clinical
For examining the Brainstem, three important devices that can be used include the EEG, fMRI, and the MEG. Electroencephalography (EEG) Machines are used in laboratories and hospitals. Its purpose is to measure electrical activity generated by cortical layers of the Brain. The electrical signals are from gray matter regions that include many pyramidal cells. Large groups of pyramidal cells generate electricity that soon gets recorded as EEG electrodes. The electrodes go past electric fields and record processes and also monitor different states of the Brain. Examples of states of the Brain are motivation, engagement, and drowsiness. The second machine is the Functional Magnetic Resonance Imaging (FRMI) and it measures brain function by detecting changes in blood flow that relate to neural activity. This is done on the hypothesis that active neurons need a greater amount of oxygen. This device uses a superconducting magnet and it rotates around a person lying down. It measures the magnetization difference in oxygen-rich and oxygen-poor blood, which shows the different levels of brain activity in the different regions. The last machine is the Magnetoencephalography (MEG) Machine which captures magnetic fields that’re generated from neural activity. Just like the FRMI the MEG requires the patient to lay still. It has to happen in a shielded
Images of human anatomy have been around for more than 500 years now. From the sketches created by Leonardo da Vinci, to the modern day Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scan, images have played a great role in medicine. Evolution in medical imaging brought together people from various disciplines such as Biology, Physics, Chemistry and Mathematics, a collaboration which has further contributed to healthcare as a whole. Modern day imaging improves medical workflows by facilitating a non-invasive insight into human body, accurate and timely diagnostics, and persistence of an analysis.