Question (100 Pts): Make a comprehensive comparison between following bio-imagin
ID: 3518683 • Letter: Q
Question
Question (100 Pts): Make a comprehensive comparison between following bio-imaging modalities a. Ultrasound, b. X-Ray, c. CT-Scan, d. MRI Hints: You can make a table and compare the above modalities with various technical/clinical features. e.g., How it works?, Safety, Invasiveness, Use/Coverage, Resolution (spatial/temporal), Dynamic Information, Cost, How to read results? (e.g., in X-Rays, bone appears as white in the image), Dimensions (1D/2D/3D), Portability, Accessibility, Results time (how long it takes to get the results?), Scan time (how long it takes to perform the experiments?), Accuracy, Exposed to radiation, Advantage/Disadvantage, Contrast agents etc..Explanation / Answer
Ultrasound
Diagnostic ultrasound, also called sonography or diagnostic medical sonography, is an imaging method that uses high-frequency sound waves to produce images of structures within your body. The images can provide valuable information for diagnosing and treating a variety of diseases and conditions.
Most ultrasound examinations are done using an ultrasound device outside your body, though some involve placing a device inside your body.
Ultrasound is used for many reasons, including to:
Risks
Diagnostic ultrasound is a safe procedure that uses low-power sound waves. There are no known risks.
Ultrasound is a valuable tool, but it has limitations. Sound doesn't travel well through air or bone, so ultrasound isn't effective at imaging body parts that have gas in them or are hidden by bone, such as the lungs or head. To view these areas, your doctor may order other imaging tests, such as CT or MRI scans or X-rays.
How you prepare
Most ultrasound exams require no preparation. However, there are a few exceptions:
Clothing and personal items
Wear loose clothing to your ultrasound appointment. You may be asked to remove jewelry during your ultrasound, so it's a good idea to leave any valuables at home.
Before your ultrasound begins, you may be asked to do the following:
You'll be asked to lie on an examination table.
During the procedure
Gel is applied to your skin over the area being examined. It helps prevent air pockets, which can block the sound waves that create the images. This water-based gel is easy to remove from skin and, if needed, clothing.
A trained technician (sonographer) presses a small, hand-held device (transducer) against the area being studied and moves it as needed to capture the images. The transducer sends sound waves into your body, collects the ones that bounce back and sends them to a computer, which creates the images.
Sometimes, ultrasounds are done inside your body. In this case, the transducer is attached to a probe that's inserted into a natural opening in your body. Examples include:
Ultrasound is usually painless. However, you may experience mild discomfort as the sonographer guides the transducer over your body, especially if you're required to have a full bladder, or inserts it into your body.
A typical ultrasound exam takes from 30 minutes to an hour.
Results
When your exam is complete, a doctor trained to interpret imaging studies (radiologist) analyzes the images and sends a report to your doctor. Your doctor will share the results with you.
You should be able to return to normal activities immediately after an ultrasound.
X-ray
Overview
An X-ray is a quick, painless test that produces images of the structures inside your body — particularly your bones.
X-ray beams pass through your body, and they are absorbed in different amounts depending on the density of the material they pass through. Dense materials, such as bone and metal, show up as white on X-rays. The air in your lungs shows up as black. Fat and muscle appear as shades of gray.
For some types of X-ray tests, a contrast medium — such as iodine or barium — is introduced into your body to provide greater detail on the images.
Why it's done
X-ray technology is used to examine many parts of the body.
Bones and teeth
Chest
Abdomen
Risks
Radiation exposure
Some people worry that X-rays aren't safe because radiation exposure can cause cell mutations that may lead to cancer. The amount of radiation you're exposed to during an X-ray depends on the tissue or organ being examined. Sensitivity to the radiation depends on your age, with children being more sensitive than adults.
Generally, however, radiation exposure from an X-ray is low, and the benefits from these tests far outweigh the risks.
However, if you're pregnant or suspect that you may be pregnant, tell your doctor before having an X-ray. Though the risk of most diagnostic X-rays to an unborn baby is small, your doctor may consider another imaging test, such as ultrasound.
Contrast medium
In some people, the injection of a contrast medium can cause side effects such as:
Rarely, severe reactions to a contrast medium occur, including:
How you prepare
How you prepare depends on the type of X-ray you need. Ask your doctor or nurse to provide you with specific instructions.
What to wear
In general, you undress whatever part of your body needs examination. You may wear a gown during the exam, depending on which area is being X-rayed. You may also be asked to remove jewelry, eyeglasses and any metal objects because they can show up on an X-ray.
Contrast material
Before some types of X-rays, you're given a liquid called contrast medium. Contrast mediums, such as barium and iodine, help highlight a specific area of your body on the X-ray image. You may swallow the contrast medium or receive it as an injection or an enema.
What you can expect
During the X-ray
X-rays are performed at doctors' offices, dentists' offices, emergency rooms and hospitals — wherever an X-ray machine is available. The machine produces a safe level of radiation that passes through your body and records an image on a specialized plate. You can't feel an X-ray.
A technologist positions your body to obtain the necessary views. Pillows or sandbags may be used to help you hold the position. During the test, you must stay still (and sometimes hold your breath to avoid moving) to prevent blurry images.
An X-ray procedure may take from a few minutes for a bone X-ray to more than an hour for more-involved procedures, such as those using a contrast medium.
Your child's X-ray
Restraints or other techniques may be used to keep a young child still during an X-ray. These won't harm your child. They will prevent the need for a repeat procedure, which may be necessary if your child moves during the X-ray exposure.
You may be allowed to stay with your child during the test. If you do, you'll likely be asked to wear a lead apron to shield you from unnecessary exposure.
After the X-ray
After an X-ray, you generally can resume normal activities. Routine X-rays usually have no side effects. However, if you receive contrast medium before the test, drink plenty of fluids to help rid your body of it.
Call your doctor if you have pain, swelling or redness at the injection site. Ask your doctor about other signs and symptoms to watch for.
Results
X-rays are saved digitally on computers, which can be viewed on-screen within minutes. A radiologist typically views and interprets the results and sends a report to your doctor, who then explains the results to you. In an emergency, your X-ray results can be made available to your doctor in minutes.
CT scan
A computerized tomography (CT) scan combines a series of X-ray images taken from different angles and uses computer processing to create cross-sectional images, or slices, of the bones, blood vessels and soft tissues inside your body. CT scan images provide more detailed information than plain X-rays do.
A CT scan has many uses, but is particularly well-suited to quickly examine people who may have internal injuries from car accidents or other types of trauma. A CT scan can be used to visualize nearly all parts of the body and is used to diagnose disease or injury as well as to plan medical, surgical or radiation treatment.
a CT scan help:
Risks
Radiation exposure
During a CT scan, you're briefly exposed to ionizing radiation. The amount of radiation is greater than you would get during a plain X-ray because the CT scan gathers more detailed information. CT scans have not been shown to cause long-term harm, although there may be a very small potential to increase your risk of cancer.
CT scans have many benefits that outweigh this small potential risk. Doctors use the lowest dose of radiation possible to obtain the needed medical information. Also, newer, faster machines and techniques require less radiation than was previously used. Talk with your doctor about the benefits and risks of your CT scan.
Harm to unborn babies
Although the radiation from a CT scan is unlikely to injure your baby, your doctor may recommend another type of exam, such as ultrasound or MRI, to avoid exposing your baby to radiation.
Reactions to contrast material
In certain cases, you receive a special dye called a contrast material through a vein in your arm before your CT scan. Although rare, the contrast material can cause medical problems or allergic reactions.
Most reactions are mild and result in a rash or itchiness. In rare instances, an allergic reaction can be serious, even life-threatening.
How you prepare
Depending on which part of your body is being scanned, you may be asked to:
Contrast material
A special dye called a contrast material is needed for some CT scans, to help highlight the areas of your body being examined. The contrast material blocks X-rays and appears white on images, which can help emphasize blood vessels, intestines or other structures.
Contrast material might be given to you:
Preparing your child for a scan
If your infant or toddler is having a CT scan, the doctor may recommend a sedative to keep your child calm and still. Movement blurs the images and may lead to inaccurate results. Ask your doctor how to prepare your child.
What you can expect
You can have a CT scan done in a hospital or an outpatient facility. CT scans are painless and, with newer machines, take only a few minutes. The whole procedure typically takes about 30 minutes.
During the CT scan
CT scanners are shaped like a large doughnut standing on its side. You lie on a narrow, motorized table that slides through the opening into a tunnel. Straps and pillows may be used to help you stay in position. During a head scan, the table may be fitted with a special cradle that holds your head still.
While the table moves you into the scanner, detectors and the X-ray tube rotate around you. Each rotation yields several images of thin slices of your body. You may hear buzzing, clicking and whirring noises.
A technologist in a separate room can see and hear you. You will be able to communicate with the technologist via intercom. The technologist may ask you to hold your breath at certain points to avoid blurring the images.
After the CT scan
After the exam you can return to your normal routine. If you were given a contrast material, you may receive special instructions. In some cases, you may be asked to wait for a short time before leaving to ensure that you feel well after the exam. After the scan, you'll likely be told to drink lots of fluids to help your kidneys remove the contrast material from your body.
Results
CT images are stored as electronic data files and are usually reviewed on a computer screen. A radiologist interprets these images and sends a report to your doctor.
MRI
Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body.
Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily realigns hydrogen atoms in your body. Radio waves cause these aligned atoms to produce very faint signals, which are used to create cross-sectional MRI images — like slices in a loaf of bread.
The MRI machine can also be used to produce 3-D images that may be viewed from many different angles.
Why it's done
MRI is a noninvasive way for your doctor to examine your organs, tissues and skeletal system. It produces high-resolution images of the inside of the body that help diagnose a variety of problems.
MRI of the brain and spinal cord
MRI is the most frequently used imaging test of the brain and spinal cord. It's often performed to help diagnose:
A special type of MRI is the functional MRI of the brain (fMRI). It measures the metabolic changes that occur within the brain. It may be used to examine the brain's anatomy and determine which parts of the brain are handling critical functions. This helps identify important language and movement control areas in the brains of people being considered for brain surgery. Functional MRI may also be used to assess damage from a head injury or from disorders such as Alzheimer's disease.
MRI of the heart and blood vessels
MRI that focuses on the heart or blood vessels can assess:
MRI of other internal organs
MRI may be used to check for tumors or other abnormalities of many organs in the body, including the:
MRI of bones and joints
MRI may be used to help evaluate:
MRI of the breasts
MRI may be used in addition to mammography to detect breast cancer, particularly in women who have dense breast tissue or who may be at high risk of the disease.
Risks
Because MRI uses powerful magnets, the presence of metal in your body may be a safety hazard or affect a portion of the MRI image. Before having an MRI, tell the technologist if you have any metal or electronic devices in your body, such as:
If you have tattoos, ask your doctor whether they might affect your MRI. Some of the darker inks may contain metal.
Before you schedule an MRI, tell your doctor if you think you're pregnant. The effects of magnetic fields on fetuses aren't well-understood. Your doctor may recommend choosing an alternative exam or postponing the MRI.
It's also important to discuss any kidney or liver problems with your doctor and the technologist, because problems with these organs may limit the use of injected contrast agents during your scan.
How you prepare
Before an MRI exam, eat normally and continue to take your usual medications, unless otherwise instructed. You will typically be asked to change into a gown and to remove things that might affect the magnetic imaging:
During the test
The MRI machine looks like a long narrow tube that has both ends open. You lie down on a movable table that slides into the opening of the tube. A technologist monitors you from another room. You can talk with the person by microphone. If you have a fear of enclosed spaces (claustrophobia), you may be given a medicine to help you feel sleepy and less anxious. Most people get through the exam without difficulty.
The MRI machine creates a strong magnetic field around you, and radio waves are directed at your body. The procedure is painless. You don't feel the magnetic field or radio waves, and there are no moving parts around you.
During the MRI scan, the internal part of the magnet produces repetitive tapping, thumping and other noises. Earplugs or music may be provided to help block the noise.
In some cases, a contrast material, typically gadolinium, may be injected through an intravenous (IV) line into a vein in your hand or arm. The contrast material enhances the appearance of certain details. The contrast material used for MRIs is less likely to cause an allergic reaction than the contrast material used for CT scans.
An MRI can last anywhere from 15 minutes to more than an hour. You must hold very still because movement can blur the resulting images.
During a functional MRI, you may be asked to perform a number of small tasks — such as tapping your thumb against your fingers, rubbing a block of sandpaper or answering simple questions. This helps pinpoint the portions of your brain that control these actions.
After the test
If you haven't been sedated, you may resume your usual activities immediately after the scan.
Results
A doctor specially trained to interpret MRIs (radiologist) will analyze the images from your scan and report the findings to your doctor