Term Paper on "Radiology the Diagnosis of Disease in Human"

Term Paper 8 pages (2401 words) Sources: 1+

[EXCERPT] . . . .

Radiology

The diagnosis of disease in human patients is performed by the physician through medical or clinical imaging when the affected body part is not visible, or it is arrived at through a research-based understanding of the body processes (Wikipedia 2004). The physician infers the cause from the evident or visible tissue effect, that is, inversely.

Radiology is a diagnostic specialty that uses x-rays, ultrasound, radiographs, computed tomography, magnetic resonance imaging and other new technology forms. In the past, the physician performed imaging by simply feeling the affected body area in visualizing the condition of the invisible internal organs involved. This method was traditionally used in diagnosing conditions aneurysm, fracture, and enlarged internal organs, but the diagnosis was based on subjective interpretation and needed further tests to confirm it (Wikipedia).

Radiographs or x-rays were introduced and provided that required confirmatory step. X-rays became widely used in evaluating the kind and extent of fractures and visualize the intestines through barium dyes (Wikipedia 2004), as in cases of colon cancer.

The Computer Axial Tomography scan or CT or CAT scan was invented and which, through x-rays, produces a two-dimensional reflection of the affected structures in a diagnosis. Magnetic resonance imaging or MRI then came into the medical scene: the technology uses powerful magnets to stimulate hydrogen nuclei in water molecules in a given human tissue in order to produce a signal that can be detected. It also produces a two-dimensional image of the particular body part or organ, like the CAT scan, but became a preferred device because it does not use radiation or x-rays (Wikipedia) as a CAT scan does. Medical ultrasound technology uses high-frequency sound waves between 3.5 and 7 megahertz whereby a two-dimensional image of the internal organ is flashed on a TV monitor. It is often used in visualizing fetuses of pregnant women and has a lower resolution that CT, MRI and radiographs (Wikipedia).

Recently, scans have been combined by computers to produce three-dimensional images in greater detail, making this invention a valuable procedure in the more accurate diagnosis and more effective treatment of many more diseases (Wikipedia 2004). Other and more sophisticated modalities proposed or recently developed include diffused optical tomography, elastography, electrical impedance tomography, fluoroscopy, nuclear medicine, opto-acoustic imaging, and positron emission tomography or PET.

The most popular brain imaging tools were the CT scan, the MRI and the PET until the emergence of an MRI variant, called functional MRI or fMRI, as an evolutionary brain-imaging device (Pennisi 1994). PET follows blood flow in the brain and detects changes in the relative proportion between oxygenated and deoxygenated red cells but fMRI does it faster and without need for a risky radioactive tracer. Stephen M. Rao of the Medical College of Wisconsin in Milwaukee described functional MRI as an "extremely easy-to-use technology in probing brain function and something that many hospitals and diagnostic centers equipped with MRI machines can use with the substitution of a special coil. This special coil produces a different pattern of magnetic pulses that yield blood flow information, similar to those obtain from PET scans. Experiments with fMRI have demonstrated how the brain conducts its activities, such as the detection of a whole range of brain activity from the deliberate tapping of fingers. Medical authorities assumed that repetitive taps activate the primary motor cortex and stimulated other areas (Pennisi).

In the meantime, the Laboratory of Fluorescence Dynamics at the University of Illinois in Chicago developed its own non-invasive diagnostic tool to view and study the changes on the surface of the brain (LFD 2004). It evolved from near-infrared spectroscopy, simpler to use and more economical than other methods, including fMRI and PET. It assumes that when a particular part of the brain is activated by directing a finger movement towards it, that part will use more oxygen. It is an optical technique that measures blood flow and oxygen use in the brain. The light produced by near-infrared laser diodes is brought by optical fibers into the brain, penetrating the skull and measuring the brain's oxygen level and blood volume. These optical fibers collect the scattered light, sending it to detectors and a computer for analysis (LFD). By determining the how far the light scatters and how much is absorbed, parts of the brain can be mapped out and information on brain activity can be secured. The scattering of light will also detect neural stimulation that indicates or suggests both blood profusion and neural activity (LFD).

LFD is a valuable diagnostic, prognostic and clinical technique in such cases as in locating hematoma, studying blood flow during sleep apnea and serving as a monitor to recovering stroke patients in short intervals of time (LFD 2004). Findings can be validated by determining oxygen concentrations in the brain simultaneously with a functional MRI and the results constitute what is called the current "gold standard" in brain studies (LFD). Both the fMRI and the optical technique can be used to stimulate the brain's motor cortex through repeated finger motions and rest. Experiments showed the congruence between the hemoglobin signal and the MRI signal in the motor cortex that produce or stimulate brain activity. When a person moves different fingers, perfusion in different parts of the brain increases and the changes registered by the scattering of light and fast neurons, perceived by the optical technique, coincide in exactly the same locations (LFD).

Neuro-imaging innovations and research findings have reached explosive levels in the last decade. These can scan abnormal metabolic activity, such as that of the orbital frontal cortex in alcoholism and other forms of addiction (Krotz 2001). Harvard psychologist Stephen M. Kosslyn suspected that, based on many functional MRI scan findings, the visual and perception in the primary visual cortex is stimulated with and by mental imagery, and that, therefore, much of what is seen is a mere product of brain activity

Developers of neuro-imaging techniques have experimented with schizophrenics as they memorize words and with geniuses as they solve equations; the brain's adaptation to disease and its reaction to sounds and cries. Kosslyn also figured that these innovations are only the equivalent of computers in the early 70s when work was done on punch cards and a typewriter. He also surmised that neuro-imaging would be central the genetic and psychosocial research and enable scientists to connect brain function and genetics to thoughts and feelings (Krotz).

By next year, a PET scan can determine how to best treat depression, as a newly released drug addresses this psychiatric disorder as the outcome of a malfunctioning basal ganglia (Krotz 2001). A particular prototypical laboratory works on millions of blips, hot spots and electrical charges in the brain in framing, merging and solving disorders, such as anxiety, alcoholism, depression and speech problems, in a common effort at pushing the capabilities of neuro-imaging as far as possible (Krotz 2001). An MR scan is predicted to turn into an atlas of the brain, which enables a particular case to be compared with others that would match it.

The establishment of such an atlas is the goal itself of the International Consortium for Brain Mapping, with funding from the National Institutes of Health (Krotz 2001). This is a collection of research laboratories that acquire and share high-resolution structural and functional images of 7,000 people in seven countries. These labs gather behavioral and demographic information on diets, people's education, their parental background and medical histories. The collection becomes a gigantic database of the human brain and human experience itself that can be subjected to manipulation and the production of snapshot extensive and reliable information on a person of any age, race and experience. Director. John C. Mazziota of the University of California, Los Angeles Brain Mapping Center called it the "human phenome project (Krotz)." Dr. Mazziota pointed out that both genes and the environment determine or shape physical characteristics and that the 10-year project output can be a very reliable and very handy source for clinicians' use in matching ambiguous scans with the project's awesome collection. Its wide base of statistics and conclusions derived from global sources and subjects would establish the norms among far-ranging variables.

In the meantime, Dr. David Van Essen of the Department of Anatomy and Neurobiology of the University of Washington has been conducting computer-aided investigations into the cerebral cortex (Krotz 2001) and paying particular attention to the different ways the cerebral cortex is lodged in individual skulls. He observed that it is how the cerebral cortex is folded, not the activation of certain parts, that appears to make a difference in the functional scans of two different persons. He, then, suggested that an approach to the situation is to gently inflate the cortex, smooth its features and flatten it. He drew pictures of monkeys' cortexes 20 years ago and, today, through a fat grant from the National Institute of Mental Health, he grafts fMRI information into structural MRI images and then renders these data into surface-based maps of the brain (Krotz). He assumed that individual cortical differences can be settled… READ MORE

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