- Jaclyn Kotora
Types of Imaging Technology
By: Jaclyn Kotora, Contributing Writer
Edited by: Olivia Storti, Editor; Elias Azizi, Editor in Chief
Imaging technology has become increasingly beneficial throughout history in diagnosing and treating different diseases. However, imaging can be costly and should be used to suit the individual needs of the patient. Imaging can help with the early detection of problems, accurate diagnosis, and ongoing monitoring and management of a medical condition. Each type of imaging technology has different risks and benefits and serves to examine and treat various conditions.
X-rays detect bone fractures, certain tumors, foreign objects in the body, dental problems, and more. During the x-ray, a safe level of radiation passes through your body and records an image on a specialized plate. X-ray procedures are typically very short, only taking a few minutes. They can be longer for more-involved tests, such as those using a contrast medium, a liquid swallowed or injected that helps outline a specific area of the body on the X-ray image (Mayo Clinic). If given a contrast medium, patients may experience side effects such as a feeling of warmth or flushing, a metallic taste, lightheadedness, nausea, itching, and in very rare, extreme cases, severe low blood pressure, anaphylactic shock, or cardiac arrest. Drinking lots of fluids can help rid the medium from the body post-x-ray. The benefits from this type of radiology generally outweigh the risks. It is a quick, non-invasive, and painless way to diagnose various diseases and injuries, including broken bones, cancers, and infections. Radiation exposure during the test is low, so there is only a slight increased risk of cancer.
Computed tomography (CT) or computerized axial tomography (CAT scan) provides more detailed information than x-rays and can visualize nearly every part of the body. The National Institute of Biomedical Imaging and Bioengineering (NIH) explains, “During a CT scan, the patient lies on a bed that slowly moves through the gantry while the x-ray tube rotates around the patient, shooting narrow beams of x-rays through the body.” Images, called 'slices', are created that can be digitally stacked together to form a three-dimensional image of a patient. This 3D image can help identify and locate abnormalities. Throughout the scan, the technologist will be in a separate room; however, patients can still communicate with them through an intercom. A person would get a CT scan for detecting possible tumors, heart abnormalities, injuries, clots, hemorrhages, excess fluid or pneumonia in the lungs, complex bone fractures, and other conditions. Like x-rays, CT scans are quick and painless and can help diagnose and guide treatment for a wider range of conditions than an X-ray would. The risks are generally the same as for x-rays; however, since it uses higher doses of radiation than x-rays, there is a small increase in your potential risk of cancer. Before the procedure, patients are asked to change into a hospital gown, and people should refrain from eating or drinking for a few hours before the scan.
Magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and magnetic resonance venography (MRV) are other types of imaging technology that are a non-invasive way to examine the brain, spinal cord, heart, blood vessels, breasts, bones, joints, and other internal organs. It uses powerful magnets and radio waves to produce high-resolution images of the inside of the body that help diagnose many different problems. MRIs focus on organs and tissues, while MRAs focus on arteries and MRVs focus on veins. Like CTs, patients undress and lie on a narrow table, which moves into the scanner. Small coils may be placed around the areas being studied, which help send and receive the radio waves, and improve the quality of the images (Medicine Plus). The benefits of MRIs are that they do not use the damaging radiation of x-rays and can help diagnose and guide treatment for various conditions. However, some disadvantages are that it can be a lengthy and noisy procedure, generally lasting 30-60 minutes, which may make people feel claustrophobic. Additionally, NIH notes that since the machine employs a strong magnetic field, “people with implants, particularly those containing iron, — pacemakers, vagus nerve stimulators, implantable cardioverter- defibrillators, loop recorders, insulin pumps, cochlear implants, deep brain stimulators, and capsules from capsule endoscopy should not enter an MRI machine.”
Diagnostic ultrasounds, another type of imaging technology, use high-frequency sound waves to produce moving images onto a screen that can capture images of internal organs within the body. They are not meant to capture images of bones or tissues that contain air, except in a fetus or a small baby. Ultrasounds can monitor the fetus during pregnancy, but they can also scan the heart, blood vessels, eyes, thyroid, brain, breast, abdominal organs, skin, and muscles (NIH). Additionally, Functional ultrasound applications can measure the speed and direction of blood flow and measure the stiffness of tissues, which helps differentiate tumors from healthy tissue. Most ultrasounds require no preparation, but for some scans, including gallbladder or pelvic scans, a doctor may require some preparation. Ultrasounds are generally non-invasive, safe, and relatively painless, requiring no ionizing radiation or contrast mediums. However, many factors can affect the image quality, and the results highly depend on the skill of the person executing and interpreting the scan. Additionally, sometimes, the use of a probe is required in ultrasounds.
Nuclear medicine imaging, including positron emission tomography (PET), involves injecting a radioactive 'tracer' into a vein, which is then used by a scanner to show images of bones and organs. The tracer needs to absorb into the body before imaging, which usually takes 1 hour. Unlike MRI and CT scans, PET scans show the structure and blood flow in areas to and from organs. The procedure involves lying still on a narrow table that moves into a large tunnel scanner. The duration of the test depends on the area of the body scanned. Prior to the test, patients may be asked not to eat for 4 - 6 hours. PET scans are mostly used for monitoring how far cancer has spread and checking how well the cancer is responding in a patient. “It may also check brain function, identify the source of epilepsy in the brain, show areas in which there is poor blood flow to the heart, and determine if a mass in a lung is cancerous,” MedlinePlus states. PET scans are usually painless and highlight how different body parts are working and can monitor cancer. Some risks involve exposure to gamma-rays, and the radioactive tracer can sometimes cause allergic reactions.
Additional types of imaging technology include mammograms. They are an x-ray imaging method used to examine the breasts for the early detection of cancer and other breast diseases in which the breasts are compressed between two firm surfaces to spread out the breast tissue and exposed to x-rays for imaging. Also, Fluoroscopy is a type of x-ray that shows organs, tissues, or other internal body systems moving in real-time, like a movie. Fluoroscopy may be used to check the function of a particular body system or for guidance in certain medical procedures. Fluoroscopy is not harmful to people besides those who are pregnant; the radiation can be harmful to unborn babies.
There is no type of imaging technology that is better than another. Each has different advantages and disadvantages and suits different situations. Before having an imaging test, patients should understand the risks and benefits of each imaging technology and talk with their health professional to figure out which is best for them.