General Diagnostic Imaging vs. MRI - Coursework Example

NAME : XXXXXXXXXX TUTOR : XXXXXXXXXX TITLE : XXXXXXXXXXX COURSE : XXXXXXXXXX INSTITUTION : XXXXXXXXXX @2009 Introduction Diagnostic imaging is the process by which radiologist visualize the internal organs and skeletal systems. To do this, they employ noninvasive techniques which include computed tomography (CT) scans, nuclear medicine, x-rays, magnetic resonance imaging, ultrasound and digital fluoroscopy. These imaging tools enable the doctor to visualize internal organs of the patient to get a clear picture of the bones, organs, muscles, tendons, nerves and cartilage to determine if there are any abnormalities. The technique the physician decides to use on a particular patient depends on the symptoms and the part of the body to be examined. Diagnostic imaging techniques assist in narrowing the causes of a damage or illness and guarantee that the diagnosis is correct. X-rays are the most widely and commonly used diagnostic imaging techniques, where as computer tomography (CT) is a more advanced imaging techniques that combines x-rays with computer technology to generate amore detailed, slice image of the body. It allows the doctor to visualize the size, shape and position of the structures that are deep inside the body, for example tumors, tissues or organs (Oppelt 2006). Magnetic resonance imaging (MRI) is a more advanced technology which is used in general diagnostic imaging to visualize the internal structure and functions of the body. Magnetic resonance therefore falls under general diagnostic imaging. MRI is a more advanced technology compared to the other techniques employed in general diagnostic imaging. It is mostly used in brain, cancer, cardiovascular and musculoskeletal imaging due to it ability to provider a much greater contrast between the different soft tissues of the body as compared to CT scans. MRI utilizes a powerful magnetic field to line up the nuclear magnetization of hydrogen atoms found in the water molecules in the body, where as CT uses ionizing radiation. To modify the arrangement of this magnetization, MRI utilizes Radio frequency (FR). The radio frequency cause the hydrogen nuclei to generate a spinning magnetic filed which can be sensed by the scanner. To create enough information to build an image of the body, extra magnetic fields can be used to manipulate this signal. MRI is an important technique used to differentiate pathological tissue such as brain tumor from normal tissue. MRI is mostly used as a scanning technique in imaging because it is believed to cause no harm to the patient. It employs strong magnetic fields and does not use ionizing radiation in the radio frequency array. Ionizing radiation used mostly in CT scans and traditional x-rays increases the risk of malignancy, particularly in a fetus (Filler 2009). Computer tomography guarantees a high-quality spatial resolution that is the capacity to differentiate two structures at a randomly short distance from each other as separate. MRI guarantees analogous resolution with much greater contrast that is the capacity to differentiate the differences between two arbitrarily similar but not identical tissues. The multifaceted records of beat sequences that the advanced medical MRI scanner poses makes it easier to provide such an enhanced contrast resolution. Each of this pulse sequences is optimized to produce image contrast founded on the chemical sensitivity of MRI. For instance, given the specific principles of the resonance time and the echo time, which forms the vital parameters for image attainment, a sequence will possess the property of T2- weighting. A T2-weighted scanner, water and fluid containing tissues and fat-containing tissues are brightly and darkly displayed respectively. Injured tissue have a tendency of developing edema, which makes a T2-weighted sequence responsive to pathology making it possible for it to differentiate pathological tissue from normal ones. A T2-weighted sequence can be transformed to a flair sequence by adding additional radio frequency pulse and manipulating the magnetic gradient furthermore. In this way, the free water look dark, however, the edematous tissues remain bright. This sequence is recently the most sensitive way to assess the brain for demyelinating illness such as multiple sclerosis. A classic MRI assessment involves 5-20 sequences, each of which is selected to provide a particular type of information regarding the subject tissues (Golder 2007). A computed tomography scanner employs x-rays, to obtain its pictures and therefore it is superior equipment for investigating tissue made up of components of an elevated atomic number than the tissue surrounding them, such as bone and calcifications within the body or of structure like bowel and vessels. On the other hand, MRI employs non-ionizing radio frequency signals to obtain its images and is best suitable for non-calcified tissue. However, MR images can be obtained from bones, teeth and fossils. CT can be improved by use of contrast agents containing components of an advanced atomic number, for example iodine or barium. MRI’s contrast agents contain paramagnetic properties such as gadolinium and manganese. Both CT and MRI scanners can create several two-dimensional slices of tissue and three-dimensional rebuilding. CT uses only x-ray reduction to create image contrast, where as MRI employs a variety of properties to create image contrast. Tissue contrast can be distorted and enhanced in different ways to detect various feature by employing a variety of scanning parameters. MRI can create a slice of images in any plane even in oblique planes (Rosen 2007). MRI is generally considered to be superior in spotting and detecting tumor in the brain, where as in the case of hard tumors of the stomach and chest, CT is frequently favored due to less movement artifact. Moreover, CT is normally widely available, faster, and less costly and sometimes may not require the patient to be anesthetized. MRI is most preferred in cases where the patient is to go through the test numerous times successfully in the short period. This is because it does not expose the patient to the hazards of ionizing radiation as the case with CT. MRI equipments are quite expensive (Oppelt 2006). MRI is not employed in patients with some metal implants, cochlear implants and cardiac pacemakers due to the impact of the strong magnetic field and great radio frequency pulses. MRI can be used to image any part of the body; however, it is especially useful for neurological conditions, assessing tumors, displaying anomalies in the heart and blood vessels and for disorders of the muscles and joints. CT is used for diagnosing defects of the brain, nasal passage, muscular-skeletal system, backbone, stomach, lung and mediastinum. Modern scanner Doppler capabilities permit the blood to flow in arteries and veins to be assessed. It is easy to perform ultrasound and is less costly. It cal also be taken to chronically ill patients in intensive care units, avoiding the risks involved when transferring the patients from the ICU to the radiology room (Golder 2007). General diagnostic imaging also uses ultrasound, which produces high-frequency sound waves, to envisage soft tissue arrangements in the body in actual time. Ultrasound does not involve use of ionizing radiation, however, the skill and experience of the person carrying out the test determines the quality of the image produced. One limitation of ultrasound is its failure to image through air that is lungs and bowel loops, and bone. Due to the fact that ultrasound does not use ionizing radiation like CT scans and nuclear medicine, makes it a safer technique and is therefore it plays a critical role in obstetrical imaging. Ultrasound is able to assess fetal anatomic development making it easier to diagnosis fetal abnormalities early enough to avert the situation. It’s also able to evaluate growth over time, which is imperative for patients suffering from chronic disease or gestation-induced sickness and in numerous gestations, for example twins, triplets etc. Ultrasound is also helpful in image-guided interventions like biopsies and drainages such as thoracentesis (Filler 2009). One disadvantage of using MRI is that the patient has to hold still for a long periods of time in a noisy, overcrowded room while the imaging is performed. Most patients undergoing an MRI scan have displayed severe claustrophobia which can lead to termination of the MRI test. Current development of magnetic design which include stronger magnetic field, shorter magnetic bores, shorter test times and more open magnetic designs has led to reduction in claustrophobia cases. Though, as expected in any magnetic field of equal strength, there is trade-off between the quality of image and open design in MRI scans. The most improved areas include functional imaging, cardiovascular MRI and MR image guided therapy (Rosen 2007). Nuclear medicine imaging in general diagnostic imaging involves prescribing radiopharmaceuticals to the patient. These radiopharmaceuticals contain substances with attraction to definite body tissues marked with a radioactive tracer. The most frequently used tracer techniques include Thallium-201, Iodine-123, Gallium-67, Technetium-99m and Iodine-131. The most commonly assessed conditions using these techniques include the heart, liver, gallbladder and lungs. Nuclear medicine is useful in showing physiological function. It can be able to measure the excretory function of the kidney, blood flow to heart muscle, iodine concentration ability of the thyroid among others (Oppelt 2006). Despite the fact that CT is useful in detecting and assessing the extent of the tumor, it is limited as regards to predicting histopathological characteristics. Neither the MRI nor the CT is superior in predicting histopathologolgy of tumor in the salivary glands. CT and MRI provide almost the same data for pre-surgical planning and diagnosis. CT is able to better visualize malignant tumor because it is characterized by erosion of adjoining bone (Rosen 2007). There are no long-term impacts of contact to strong static fields which have been observed since 1980 when MRI was first introduced. Therefore, one can be subjected to numerous scans which are not possible with x-ray and CT. However, there are well-established health dangers linked to tissue heating from exposure to the RF field and the existence of entrenched devices in the body, for example pace makers. These risks are sternly restricted as an element of the instrument’s design and the scanning procedures employed. CT and MRI are responsive to diverse tissue properties and therefore the appearance of the images acquired using the two techniques vary distinctly. To generate a picture in CT, the x-rays have to be blocked using some form of thick tissue. Hence, the quality of image when looking at soft tissue is usually poor. In MRI, whilst other nucleus with a net nuclear spin can be employed, the hydrogen atom’s proton is the most widely used nucleus, particularly in the clinical setting, since it is so omnipresent and has the ability to give great signal. Hydrogen atom, which exists in water molecules, permits outstanding soft-tissue contrast attainable with MRI (Golder 2007). The magnetic field strength present in MRI is a critical factor in determining image quality. Higher magnetic fields amplify the signal-to-noise ratio, allowing higher resolution or faster scanning. However, it is costly to purchase and maintain such higher magnetic field strengths, which have raised accessibility concerns. There are also a number of injuries and deaths which have been reported in MRI. Components of the scanning procedure and prescriptions can be used to ease MRI imaging. There are also a variety of ways the patient and the doctor can utilize to help reduce some of the risks associated with MRI scanning which include providing a full, correct and thorough medical history to the MRI provider (Filler 2009). In conclusion, of all the techniques used in general diagnostic imaging, magnetic resonance imagining is the most advanced and effective tool. MRI uses a powerful magnetic field and does not use ionizing radiation in the radio frequency array. Ionizing radiation which is used mostly in general diagnostic imaging increases the risk of malignancy, particularly in a fetus. However, MRI is quite expensive and most patients may not be in a position to afford it. The government should consider providing high magnetic field strength in hospitals to reduce the costs associated with such patient care. Work Cited Oppelt, Arnult. Imaging Systems for Clinical Diagnostics: Basics, Technological Solutions and Applications for Systems Using Ionizing Radiation, Nuclear Magnetic Resonance and Ultrasound. London: Cornell University Press Ltd, 2006 p. 566 Rosen Bergen. The Recent advances in magnetic resonance neurospectroscopy. Neurotherapeutics 2007, 27 (3): 330–45. Golder Wilson. Magnetic resonance spectroscopy in clinical oncology. Oncology 2007, 27 (3): 304–9. Filler, Arden. The account, growth, and effect of computed imaging in neurological diagnosis and neurosurgery: CT, MRI, and DTI. London: G. Allen and Uwin Ltd, 2009. Read More