Enjoy the latest in imaging techniques and technologies
Facilitate your medical care with our patient-specific imaging and physician-responsive clinical services that are renowned for their accuracy, efficiency, compassion, and professional integrity.
Magnetic Resonance Imaging, or MRI, is a method of obtaining detailed images of organs and tissues throughout the body without the use of x-rays.
Computer Tomography (CT), or a CAT scan, is a mthod of medical diagnostic imaging that acquires detailed graphical images of the internal organs and parts of the body.
Ultrasound imaging, or sonography, is a way of using high frequency sound waves to image the inside of the body.
An x-ray is a painless medical test that uses radiography to produce pictures of the inside of the body.
MRI stands for magnetic resonance imaging. MRI is a way of obtaining very detailed images of organs and tissues throughout the body without the need for x-rays. Instead, it uses a powerful magnetic field, radio waves, a rapidly changing magnetic field, and a computer to demonstrate whether or not there is an injury or some disease process present. The MRI aligns atomic particles called protons that are present in most of the body's tissues. Radio waves then cause these particles to produce signals that are picked up by a receiver within the scanner. The signals are specially characterized using the changing magnetic field, and computer-processed to create very sharp images of tissues as "slices" that can be viewed in any plane or from any direction. MRI is widely used for evaluating orthopedic, joint, and sports medicine related injuries, as well as disc disease and other conditions that affect the spine. Neurologic imaging and tumor evaluation are other uses of MRI.
MRA stands for magnetic resonance angiography. It is an MRI examination devoted to evaluation of the vascular system, whether it be arteries or veins. MRA examinations are typically of the vessels of the brain, the carotid arteries (the main arteries in the neck), the aorta, the renal arteries (the arteries feeding the kidneys) or vessels of the legs. The main reason for performing an MRA examination is to look for stenosis, or narrowing, of specific vessels.
What MRI/MRA services are provided by Advanced Imaging of San Marcos?
These include, but are not limited to MRI evaluation of the brain and spine, joints, abdominal organs, bile ducts, and arteries.
Do I need a doctor’s prescription for an MRI?
Yes. Be sure to bring it with you when you come in for your MRI if your doctor hasn’t already faxed it to our office.
Is the MRI covered under my insurance?
Usually yes. Our staff will contact your insurance company to verify your coverage and will let you know should a problem arise. We will also let you know how much you will owe at the time of the exam and how your insurance company will cover. Additionally, please let us know if you have any supplementary insurance.
What if I need to cancel my appointment?
As a courtesy, please notify Advanced Imaging of San Marcos as soon as you are aware you will need to cancel your exam. If you need to reschedule for another time we will be happy to accommodate you with another appointment time.
Is there radiation associated with an MRI?
Unlike most other radiology imaging procedures, there is no radiation associated with an MRI exam.
Can anybody have an MRI scan?
No. For some people, an MRI can be dangerous, even fatal. If you have a cardiac pacemaker, you should not have an MRI. It can be fatal. There may be certain parts in the pacemaker that may be adversely affected by the magnetic field of the MRI scanner, causing the apparatus to malfunction or cease operation.
Other Potential Dangers:
- Metal Implants
- Drug Infusion Devise/Pump
- Ear Implants
- Inferior Vena Cava Filter
- Metal Objects in Eyes
- Certain Penile Implants
- Vascular Coils and Filtera
- Brain Aneurysm Clips
- Heart Valves
If any of the above applies to you, it MAY BE DANGEROUS for you to have an MRI exam. Be sure to make the technologist and the radiologist aware. They will be able to tell you if it is safe for you to have the MRI exam. In most cases you will be able to have the scan, but please leave that decision to the professionals.
What is the difference between MRI and CT?
Both MRI and CT are diagnostic exams used to thoroughly image a selected area of the human body. Similarly, both MRI and CT require the use of a large machine, and each method relies upon computer technology to reconstruct a cross-sectional image of the body. Aside from these very fundamental similarities, there are many inherent differences between MRI and CT scans.
Magnetic Resonance Imaging (MRI) - Developed in the mid 1980’s, MRI technology utilizes radio frequency waves and very powerful magnets. After applying a very strong, localized electromagnetic field, the MRI scanner emits a series of radio pulses into the body, exciting the hydrogen protons found in the body’s soft tissue. Upon measuring the relaxation times of these hydrogen protons, the MRI scanner employs sophisticated computer technology to interpret the protons’ behavior and recreates a 3-dimensional image of the body. Since hydrogen is the most abundant element in the body, MRI technology is capable of producing amazingly clear images of organs and soft tissue. MRI is able to detect disease or injury in muscle structure along ligaments, and is used to assist in the visualization of tumors. The ability to visualize soft-tissue and the vascular system make MRI an outstanding tool for imaging brain and spinal cord abnormalities. MRI is non-invasive, although certain studies may require the use of an intravenous contrast agent. MRI does not involve any ionizing radiation, and aside from a persistent thumping noise, patients will experience no discomfort or side effects.
Computerized Tomography (CT or CAT scan) - Developed in the 1970’s CT technology utilizes a highly sensitive X-ray beam that is focused on a specific part of the body. Upon passing through the body, the beam hits a detector, which relays this information into a computer. The computer analyzes the information based upon tissue density, and feeds it into a cathode ray tube. Like MRI, a cross-sectional representation (like "slices" of bread) of the body is produced. Bone shows up white, gases and liquids black, and tissue as varying shades of gray, depending on density. Generally, CT provides much better visualization of bone detail than MRI. CT scans provide excellent information on anatomical features and tissue density (this allows for the detection of tumors, and sometimes the ability to distinguish between malignant and benign tumors). CT scans can also detect calcium deposits, cysts, and abscesses. They are often used in place of ultrasound for obese patients because fat deposits often hinder ultrasonic waves.
How long does an MRI exam take?
The length of the MRI exam varies depending on the study being performed. Most MRI exams are on the order of 30 minutes, with some being slightly shorter or longer. All of our exams are tailored to your specific history. At Advanced Imaging San Marcos, we pride ourselves on doing the most detailed examination possible. No corners are cut. Therefore, many examinations may appear longer than a similar study at other imaging center.
Do I have to lie very still during the exam?
Yes, as still as you can. It is important to minimize movement in order to achieve the best imaging results. If the scan has too much motion, the exam will not be diagnostic. The technologist will give you opportunities to move occasionally throughout the scan.
Is it safe to have an MRI if I’m pregnant?
If you are pregnant or think you might be pregnant, you must first consult with the physician before you have an MRI scan. You must also inform the staff at Advanced Imaging San Marcos. It has not been shown that MRI is harmful to unborn children. However, if you choose to have the MRI, you will be asked to sign a consent form.
Do I need contrast/dye when I receive my MRI?
Depending on the exam ordered by you physician and the questions your doctor has, you may be required to have contrast/dye administered by vein. This would be performed by the MRI technologist or radiologist.
Can I be allergic to the contrast/dye?
The contrast material used for an MRI is not the same as that used for a CT examination or diagnostic x-ray studies. You should not experience any symptoms from the contrast. It is extremely rare to have any type of allergic reaction to the contrast material (nearly one in a million). An allergy to CT contrast does not mean that you will be allergic to MRI contrast, and does not preclude you from having a contrast enhanced MRI examination.
What will happen during my examination?
If your test requires you to disrobe, you will be escorted to a dressing room where you can change into a gown and remove jewelry or other objects that may interfere with the exam. For the exam, you will be asked to lie down on a movable table. You will be positioned on the table by the MRI technologists so that the area being imaged is in the middle of the bore. During the procedure, the table may move over short distances. The technologist will be talking with you through an intercom and may ask you to hold your breath or keep still to prevent motion or blurring of the pictures. The MRI scanner does make noise. We provide earplugs or headphones for you to listen to music during the exam if you desire.
What if I am claustrophobic?
Most patients who are claustrophobic can still undergo a closed MRI exam. With the assistance of the MRI technologist, it is usually possible to complete the MRI study. Some patients may require mild sedation with oral medication or other medication prescribed by their physician to be taken prior to the exam. If you think you might need sedation, please inform the scheduler when the appointment is being made. You will need to arrive at least 30 minutes prior to your appointment time to be given the sedation. You will need someone to drive you home.
Can someone be in the scan room with me during my exam?
Yes, a family member or friend can join you in the scan room but only after they have been screened with all of the criteria on the MRI checklist.
What do I have to do to prepare myself for an MRI?
Preparing for an MRI is easy. Unless your doctor tells you otherwise, you may take your medications as usual. There are no food or drink restrictions.
Why is it so important to remove ALL metallic objects before I enter the MRI scanning room?
You will need to remove all metal objects for safety reasons and because they can cause artifacts to appear on the MRI image. All body piercings will need to be removed prior to the exam.
How do I obtain results of the MRI scan?
After you leave, your images are interpreted by a radiologist, a doctor who specializes in reading MRI. The written report is then faxed or called to your physician with the results of your study. Your physician will then contact you to discuss your results. Technologists are not qualified to interpret MRI exams, nor are they allowed to, so please don’t ask them for their opinions.
Computed Tomography (CT), more commonly known as a CAT scan, is a form of medical diagnostic imaging that acquires detailed graphical images of the internal organs and parts of the body.
Joining separate images into one 3-D graphical cross-section, CT scans show both body tissue and internal body organs, aiding the location of suspected cancer growth. Computed Tomography is so detailed that it can show, and distinguish between, bone tissue, soft tissue, internal organs, muscles and tumors, empowering physicians with a unique tool to diagnose medical conditions and aid their treatment.
Using X-rays beams that pass through the body to measure how different tissues absorb different amounts of radiation, CT scans build an anatomical picture of an area of the body under investigation.
Computed Tomography is used in various medical situations where highly specific information is required to diagnoses a medical condition, such as the size, density and location of a tumor or malformation. Computed Tomography is commonly used in Cancer diagnosis and treatment, where it is of great benefit in confirming the existence of a tumor, determining its size and location, and addressing the question of whether the cancer has spread.
Computed Tomography as a diagnostic imaging tool has huge potential due to its ability to provide painless, quick and detailed internal images of the body as well as being the only method that provides detailed images of bone, soft tissue, and blood vessels-allowing doctors to detect life-threatening conditions.
Frequently Asked CAT Scan Questions
Who is a good candidate for a CT scan?
CT scans are designed to help identify medical conditions, diseases or traumas. CT scans are useful, then, for patients who have signs or symptoms of a particular condition, or for patients who have undergone injuries and are suspected of having internal damage or trauma. With a CT scan, a doctor can determine if a disease, trauma or other medical condition is present, and can take the next appropriate measure. People with symptoms have a higher probability of having a disease or condition than the general population. As well, symptoms usually indicate a more advanced form of a particular condition, meaning that the condition will likely be readily and easily detectable on CT images.
On a related note, CT scans can also help rule out certain medical conditions, diseases or traumas. A patient may be exhibiting signs or symptoms of a particular condition, but a CT scan may reveal that the condition does not exist. The doctor can thus eliminate that disease as a potential root of a problem. For example, a doctor may suspect a brain tumor in a patient who reports persistent dizziness and/or headache. A CT scan might reveal that a tumor is not present. Thus, the patient’s doctor can eliminate “brain tumor” as a possible root cause for the dizziness and headache, and can take measures to explore other possible conditions.
Finally, CT can be useful in situations where a medical condition is known and where further medical action is required. Such situations include:
- Planning a surgery
- Guiding a needle to obtain a biopsy (tissue sample)
In individuals where there is a known medical condition, a CT scan is an excellent way in determining:
- The extent of the problem
- The location of the problem
- The effect any treatment is having on the problem
How does a CT Scan work?
Ct uses a computer and rotating x-ray device to create detailed, cross-sectional images, or slices, of organs and body parts.
A CT machine resembles a large, square doughnut. A flat “patient couch” is situated in the circular opening, which is about 24 to 28 inches in diameter. The patient lies on the couch, which can be moved up, down, forward, and backward to position the patient for imaging.
The CT scanner itself is a circular, rotating frame with an x-ray tube mounted on one side and a banana-shaped detector mounted on the other. A fan-shaped beam of x-rays is created as the rotating frame spins the x-ray tube detector around the patient. For each complete rotation, one cross-sectional slice of the body is acquired.
As the scanner rotates, the detector takes numerous snapshots called “profiles.” Typically, about 1,000 profiles are taken in one rotation. Each profile is analyzed by computer, and the full set of profiles from each rotation is compiled into to form the slice-a two-dimensional image.
How do I prepare for a conventional CT Scan?
In general, no special preparation is required for a CT scan. Comfortable, loose clothing should be worn, although in some cases a patient may be asked to change into a hospital gown for the examination. It is also important to remove any metal prior to the exam: jewelry, dentures, eyeglasses, belt buckles, and metal zippers and buttons can interfere with the images.
A patient may be asked to limit eating and drinking to clear liquids, such as water, black coffee and tea, and broth for several hours prior to the appointment for a CT scan. This request will be dependent upon the facility and the type of examination.
For many CT examinations, a contrast agent (a liquid that enhances imaging of certain organs or blood vessels) will be administered. Depending on the type of examination, the contrast may be given orally, intravenously, or as an enema. If certain types of contrast will be used during as examination, the patient may be required to fast for several hours. If you are receiving the intravenous iodine contrast and you are 50years of age or older, have diabetes, or have any kidney problems you will be asked to get blood drawn for BUN and creatinine levels. Once we have these values we will be able to proceed with the exam.
Do all CT Scans require the administration of a contrast agent?
Not all CT examinations require the use of a contrast agent. When a contrast agent is required, it is because the radiologist and referring physician determine that it is necessary for diagnosis. Contrast agents are considered to be safe and side effects are uncommon. The benefits associated with the improved imaging of particular organs generally outweigh the low risk of allergic reaction.
Intravenous contrast is used to highlight blood vessels and to enhance the structure of organs like the brain, spine, liver, and kidney. The contrast agent (usually an iodine compound) is clear, with a water-like consistency. Typically the contrast is contained in a special injector, which injects the contrast through a small needle taped in place during a specific period in the CT exam.
Once the contrast is injected into the bloodstream, it circulates throughout the body. The CT’s x-ray beam is weakened as it passes through the blood vessels and organs that have “taken up” the contrast. These structures are enhanced by this process and show up as white areas on the CT images. When the test is finished, the kidneys and liver quickly eliminate the contrast from the body.
Is Iodine a Safe Contrast Agent?
Iodine is considered to be a safe contrast agent. It has been used for many years without serious side effects. Because iodine contrast increases the visibility of target tissues on the images, the benefits are considered to outweigh the risks.
The most common side effect of iodine is a warm or “flushed” sensation during the actual injection of the iodine, followed sometimes by a metallic taste in the mouth that usually lasts for less than a minute. No treatment is necessary for this sensation, if experienced.
Another mild reaction is itching over various parts of the body. This reaction lasts from several minutes to a few hours after the injection. When this reaction occurs, medication is usually administered to counteract the itching.
More serious allergic reactions, while uncommon, include difficulty breathing and swelling of the throat or other parts of the body. These reactions, if experienced, are treated immediately.
Newer forms of contrast help to reduce the risk of an allergic reaction. If you have had an allergic reaction to iodine or a contrast agent in the past, the physician may recommend a steroid prep the day before the exam that will help prevent a reaction.
In some cases, CT can still provide valuable diagnostic information without the administration of a contrast agent, so the physician may decide this is the best course of action.
Oral CT Contrast
Oral contrast is used to highlight gastrointestinal (GI) organs in the abdomen and pelvis. If oral contrast will be used during an examination, the patient will be asked to fast for several hours before administration.
Gastrografin is a yellowish, water-based drink mixed with iodine, sometimes mixed with a variety of flavors also. It can have a bitter taste. This is the chosen oral contrast used at our site.
After the contrast is swallowed, it travels to the stomach and gastrointestinal tract. Like intravenous iodine, gastrografin weakens x-rays. On CT images, the organs that have “taken up” the contrast appear as highlighted white areas.
Is Oral Contrast Safe?
In general, gastrografin contrast is safe and will pass uneventfully through the gastrointestinal tract. Minor and temporary side effects, such as constipation, may occur.
Rectal CT Contrast
Rectal contrast is used when enhanced images of the large intestine and other lower GI organs are required. The same types of contrast used for oral contrast are used for rectal contrast, but in different concentrations.
Rectal CT contrast is usually administered by enema. When the contrast is administered, the patient may experience mild discomfort, coolness, and a sense of fullness. After the CT is complete, the contrast is drained and the patient may go to the bathroom.
The preparation for rectal contrast is similar to oral contrast, in that the patient should be fasting for several hours before the test.
Is Rectal Contrast Safe?
Rectal contrast is considered to be safe and passes through the gastrointestinal tract uneventfully. Minor and temporary side effects, such as constipation, can occur.
What Happens During The Procedure?
If an intravenous contrast agent will be used, the procedure will be explained and the patient will be asked to sign a consent form. The needle will then be placed and taped down.
The technologist settles the patient on the scanner’s “couch.” The technologist glides the couch into place within the opening of the gantry, using cross-hair positioning lights to put the “target” area (for example, the chest) in the path of the x-rays.
After the patient is in position, the technologist usually leaves the CT room. The scanner is generally controlled by a computer in an adjacent room, which has a window facing the machine and patient. During this time, the technologist and patient can easily communicate through an intercom.
When images are being acquired, the patient is usually asked to hold his/her breath and remain motionless. Image acquisition typically lasts 18-30 seconds. When the scanner and patient couch move, the patient may hear whirring or clicking noises-this is normal. In addition, the scanner may tilt forward or back to capture images from the best angle during an examination of the head, sinus, inner ear, and spine.
It is very important to lie completely still while images are being taken. Any movement can reduce the clarity of the images, and the radiologist may then have difficulty interpreting them.
Will the CT Imaging Examination Hurt?
No, CT imaging itself should cause no pain. CT imaging requires that the patient remain still during the examination. For some patients, keeping still for some time may be uncomfortable. The CT examination itself causes no bodily sensation. CT imaging examinations that require the patient to receive iodine contrast injection may cause slight, temporary discomfort while the intravenous needle is placed.
Is CT Imaging Safe?
Yes, CT imaging is considered a safe examination. In general, the diagnostic benefit of a CT scan usually outweighs the risk of x-ray radiation exposure or injections of imaging contrast. Patients should inform the radiologist or technologist if they have a history of allergies (especially to medications or previous iodine injections), diabetes, asthma, a heart condition, or kidney problems.
How Long Will the CT Examination Take?
Most CT departments or centers offer a wide array of computed tomography (CT) imaging examinations. Depending on the type of exam you will receive, the length of the actual procedure will typically be between 5-30 minutes.
Also, many CT exams require the patient to hold their breath several times. This helps to eliminate blurring from the images, which can be caused by breathing or other patient motion. Please discuss specific questions about the duration of your CT imaging examination with the technologist before your exam.
Do I need a Referral (Prescription) to Receive a CT Examination?
Yes, your doctor must give you a referral (prescription) in order for you to receive a computed tomography (CT) imaging examination. However, CT can often be performed on an outpatient basis without having to admit the patient to the hospital.
Can I Move While I am in the CT Scanner?
You should not move when you are on the CT table and the images are being acquired. It is important that you not move the body part being imaged, for example your head, until the entire CT exam is complete. CT exams of the chest and abdomen require the patient to hold their breath for a short period of time, for example, 10 to 30 seconds. This eliminates blurring in the image caused by breathing or other patient motion.
Can I Talk With Anyone During the CT Scan?
You may talk to the technologists or ask a question in between CT data acquisitions. You should not talk while the images are being acquired.
Can I Bring a Friend or a Relative into the CT Scan Room With Me?
No, CT uses x-ray and only the person being imaged should be in the CT scanner room during the examination.
If I am Nursing an Infant, Can I Breast Feed After an Injection of CT Contrast?
Typically, patients are instructed to wait for 24 hours after receiving the CT contrast injection before breast feeding again. Patients may wish to pump breast milk prior to the CT exam store it for use during this 24-hour period. Always check with the radiologist and the imaging center for their specific recommendations.
Can I Have a CT Imaging Exam if I am Pregnant?
Pregnant women should not have a CT exam or any x-ray examination, especially if the woman is in her first trimester (first 3 months of pregnancy). Depending on the condition, there may be other exams available, such as ultrasound, to help diagnose a medical condition. Pregnant women should always inform their imaging technologist or radiologist that they are pregnant, or may be pregnant.
What is the Difference between MRI and CT?
Both MRI and CT are diagnostic exams used to thoroughly image a selected area of the human body. Similarly, both MRI and CT require the use of a large machine, and each method relies upon computer technology to reconstruct a cross-sectional image of the body. Aside from these very fundamental similarities, there are many inherent differences between MRI and CT scans.
Magnetic Resonance Imaging (MRI) – Developed in the mid 1980’s, MRI technology utilizes radio frequency waves and very powerful magnets. After applying a very strong, localized electromagnetic field, the MRI scanner emits a series of radio pulses into the body, exciting the hydrogen protons found in the body’s soft tissue. Upon measuring the relaxation times of these hydrogen protons, the MRI scanner employs sophisticated computer technology to interpret the protons’ behavior and recreates a 3-dimensional image of the body. Since hydrogen is the most abundant element in the body, MRI technology is capable of producing amazingly clear images of organs and soft tissue. MRI is able to detect disease or injury in muscle structure along ligaments, and is used to assist in the visualization of tumors. The ability to visualize soft-tissue and the vascular system make MRI an outstanding tool for imaging brain and spinal cord abnormalities. MRI is non-invasive, although certain studies may require the use of an intravenous contrast agent. MRI does not involve any ionizing radiation, and aside from a persistent thumping noise, patients will experience no discomfort or side effects.
Computerized Tomography (CT or CAT scan) – Developed in the 1970’s CT technology utilizes a highly sensitive X-ray beam that is focused on a specific part of the body. Upon passing through the body, the beam hits a detector, which relays this information into a computer. The computer analyzes the information based upon tissue density, and feeds it into a cathode ray tube. Like MRI, a cross-sectional representation (like “slices” of bread) of the body is produced. Bone shows up white, gases black, and tissue as varying shades of gray, depending on density. Generally, CT provides much better visualization of bone detail than MRI. CT scans provide excellent information on anatomical features and tissue density (this allows for the detection of tumors, and sometimes the ability to distinguish between malignant and benign tumors). CT scans can also detect calcium deposits, cysts, and abscesses. They are often used in place of ultrasound for obese patients because fat deposits often hinder ultrasonic waves.
What is the Difference between Conventional X-rays and CT scans?
X-rays are rays of electromagnetic radiation used to diagnosis and treat trauma and disease. When x-ray beams pass through the body, 2-dimentional images are created based on shadows made by body structures in the area being photographed. The image depends on the body structure’s absorption of the x-rays.
CT scans, meanwhile, produce 3-dimensional cross-section images of a particular body part. These images, too, are measures of x-ray absorption; however, many slices of the body join together to form an image. Typically, bone turns up white; air turns up black, and tissues and mucous turn up in shades of gray.
CT is more powerful and more detailed than conventional x-rays.
Ultrasound imaging, sometimes called sonography is a method of obtaining images from inside the human body by using high frequency sound waves. As sound passes through the body, echoes are produces that identify how far away an object is, the size of the object, its shape and consistency (solid, fluid or mixed). Ultrasound can also measure the flow of blood using a specialized method called Doppler ultrasound. No radiation is used with ultrasound imaging. Ultrasound is a useful way of examining many of the body’s internal organs such as the liver, gallbladder, spleen, pancreas, kidneys, bladder, uterus, ovaries, thyroid and testicles as well as veins, arteries, and fetal anatomy.
Ultrasound has many benefits. It is noninvasive (does not use any needles or injections) and is usually painless. Ultrasound is easily available. It uses no ionizing radiation (x-ray), which makes it the preferred method to image pregnant women and their unborn children. Ultrasound can provide real-time imaging which makes it useful for guiding biopsy procedures. Ultrasound does not penetrate bone. For visualization of bone, other imaging modalities, such as MRI may be used. Ultrasound does not pass through air. Therefore, it is not useful in evaluating the organs that contain gas such as the stomach, small intestine or large intestine. Intestinal gas may also prevent visualization of deeper structures such as the pancreas and aorta. Patients suffering from obesity are more difficult to image because extra tissue weakens the sound waves as they pass deeper into the body. There are no known harmful effects on humans. Advanced Imaging also offers IVP & Echo Cardiograms as well.
When is ultrasound used?
Many expectant parents have first seen their unborn child with an ultrasound exam. Ultrasound is used extensively for evaluating pelvic and abdominal organs, blood vessels, and can help a physician determine the source of pain, swelling or infection in many parts of the body. Because ultrasound provides real-time images, it is also useful as a guide for needle biopsies. Ultrasound is also used to evaluate superficial structures such as the breast, thyroid and testicles. Doppler ultrasound is a special technique used to examine blood flow. Doppler images can help to determine blockages of blood flow (such as a blood clot) and buildup of plaque inside a blood vessel.
How do I prepare of my ultrasound examination?
The exam preparation will vary slightly based on which part of the body you are having imaged. The different preparations are detailed below:
Abdomen or aorta: If your exam is before noon, do not eat or drink anything after midnight the day before your exam. You may take your medications with a small amount of water. If your exam is after noon, you may eat a low fat breakfast before 8:00 a.m. (no milk, butter, cream, cheese, peanut butter), then do not eat or drink anything else prior to the exam. You may take your medications with a small amount of water.
Kidneys: drink 24 ounces of water from 90 to 60 minutes before your exam starts. Do not empty your bladder until after your examination. Without water in the bladder we cannot evaluate your bladder at the time of the procedure.
Pelvis or obstetrical: drink 32 ounces of water from 90 to 60 minutes before your exam starts. Your bladder must be full for the exam. Do not empty your bladder until after the examination.
Scrotal, testicular, breast and thyroid ultrasound: There is no prep for this procedure
Arteries or veins: no preparation needed.
Why do I need to fast for my abdominal ultrasound?
Ultrasound cannot penetrate bowel gas and bowel substance which food and drink will cause. Food and drink can also affect how the gall bladder looks and reacts. Therefore, it is important that you not have anything to eat or drink (including water) for 8 hours prior to the procedure. If you are on medication that you cannot go without, you may take it with a very small amount of water.
Why do I need to fill my bladder for my pelvic and OB ultrasounds?
A full bladder pushes the intestines (which contain air) out of the way of the pelvic organs. A full bladder also pushes the fundus of your uterus away from your intestines in order to be viewable. In cases of an OB ultrasound the filling of the bladder is important to evaluate the cervix. Cervical evaluation in an OB ultrasound is essential part of the exam. This makes the ultrasound picture clearer.
What are common uses of this procedure?
Obstetrical ultrasound is used to evaluate an embryo or fetus. This ultrasound can estimate the age of the pregnancy, diagnose congenital abnormalities, evaluate the fetal and placental location and determine if there are multiple pregnancies. Conventional ultrasound displays the images as thin sections (like looking at single slices of bread in a loaf.) Ultrasound can watch the heart beat and movement of the fetus like an ongoing movie.
What should I do to prepare for my OB ultrasound procedure?
You should wear a loose fitting two-piece outfit for the examination, which allows for easy access to the lower abdomen. You will need to have a full bladder for this examination. You should drink 4-6 glasses of water before your exam. In order for the water to have time to get to your bladder, you should be finished drinking one hour prior to your exam time. Do not empty your bladder before your exam.
What can I expect during the procedure?
If you are less than 14 weeks along: You will be asked to lie on your back on the exam table with your bladder full. The technologist will use gel and press a transducer against the pelvis. The transducer will be swept back and forth across the pelvis to image the areas of interest.
Most early OB ultrasounds require a transvaginal ultrasound. This is performed by inserting a probe into the vagina – similar to having a pelvic exam at your physician’s office. Before the vaginal ultrasound, you will be asked to empty your bladder completely. You will also need to change into a gown. You will then be asked to lie on your back with your feet up in stirrups. The transvaginal probe is inserted into the vagina and images of the fetus, uterus and ovaries are obtained. You may experience some discomfort while images are obtained with your bladder full. The transvaginal ultrasound should not be painful. It is usually more comfortable than a gynecological exam. The entire exam should take approximately 30 minutes.
If you are more than 14 weeks pregnant: You will be asked to lie on your back on the exam table with your bladder full. The technologist will use gel and press a transducer against the lower abdomen. The transducer will be swept back and for the across the pelvis to image the areas of interest. The technologist may have to push and angle the transducer in various positions to get accurate pictures of the fetus. The exam should take approximately 45 minutes. You will receive pictures of your baby to take home.
X-rays are basically the same thing as visible light rays. Both are wavelike forms of electromagnetic energy carried by particles called photons. The difference between X-rays and visible light rays is the energy level of the individual photons. This is also expressed as the wavelength of the rays.
Our eyes are sensitive to the particular wavelength of visible light, but not to the shorter wavelength of higher energy X-ray waves or the longer wavelength of the lower energy radio waves.
Visible light photons and X-ray photons are both produced by the movement of electrons in atoms. Electrons occupy different energy levels, or orbitals, around an atom's nucleus. When an electron drops to a lower orbital, it needs to release some energy -- it releases the extra energy in the form of a photon. The energy level of the photon depends on how far the electron dropped between orbitals.
When a photon collides with another atom, the atom may absorb the photon's energy by boosting an electron to a higher level. For this to happen, the energy level of the photon has to match the energy difference between the two electron positions. If not, the photon can't shift electrons between orbitals.
The atoms that make up your body tissue absorb visible light photons very well. The energy level of the photon fits with various energy differences between electron positions. Radio waves don't have enough energy to move electrons between orbitals in larger atoms, so they pass through most stuff. X-ray photons also pass through most things, but for the opposite reason: They have too much energy.
They can, however, knock an electron away from an atom altogether. Some of the energy from the X-ray photon works to separate the electron from the atom, and the rest sends the electron flying through space. A larger atom is more likely to absorb an X-ray photon in this way, because larger atoms have greater energy differences between orbitals - the energy level more closely matches the energy of the photon. Smaller atoms, where the electron orbitals are separated by relatively low jumps in energy, are less likely to absorb X-ray photons.
The soft tissue in your body is composed of smaller atoms, and so does not absorb X-ray photons particularly well. The calcium atoms that make up your bones are much larger, so they are better at absorbing X-ray photons.
Frequently Asked X-Ray Questions
What is an X-Ray?
An x-ray (radiograph) is a painless medical test that helps physicians diagnose and treat medical conditions. Radiography involves exposing a part of the body to a small dose of ionizing radiation to produce pictures of the inside of the body. X-rays are the oldest and most frequently used form of medical imaging.
How does the procedure work?
X-rays are pictures made by passing radiant beams through an object and capturing the image on the other side. Solid objects, like bones, allow less light to pass through and appear white on the picture. Less solid objects, like organs in the body, allow more light to pass through and appear grayer on a picture.
How should I prepare for the procedure?
Most x-rays require no special preparation.
What will I experience during and after the x-ray procedure?
You may experience discomfort from the cool temperature in the examination room. You may also find holding still in a particular position and lying on the hard examination table uncomfortable, especially if you are injured. The technologist will assist you in finding the most comfortable position possible that still ensures x-ray image quality.
Who interprets the results and how do I get them?
A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your primary care or referring physician, who will share the results with you.