In contrast to two-dimensional radiographs, CT produces more detailed pictures of the inner body.
The CT machine has an x-ray tube and a detector ring. The radiation beam penetrates the patient’s body from all sides. Afterwards, depending upon how thick or thin the soft tissues or bones are, the radiation beam hitting the opposite side of the detector is weaker or stronger. They measure the different signals, and using the computer further, the generated CT image has several different shades of gray. Dark gray shows tissue that is less thick, and that therefore has allowed many x-rays to pass through it, while light gray represents thick tissue which has allowed fewer x-ray beans to penetrate.
Versatile and quick
A CT is a widely-applicable radiology technique (It can be used to study the skeleton and skull, but is equally good for imaging the organs and blood vessels.) ¬it is often used to learn the size and shape of cancer. Changes in the heart, lungs and abdominal organs can be seen very well. By injecting a contrast agent, we can also see the blood vessels. Thus, CT can also be used to study coronary artery disease. If a tissue sample of a tumour must be obtained, CT can show the doctor where the lesion and how best to approach it. Because CT is very quick and produces pretty images, CT is often the first exam done in the trauma setting.
Please ask your doctor if you will need to have current bloodwork drawn for the CT exam. Diabetics, people over 65 years old, or those who have kidney disease will also need to have a creatinine level as part of their bloodwork. If you are pregnant or think that you could be, or if you have thyroid disease or an iodine allergy, please mention this when you make your appointment. By some CT exams, we will have to inject iodinated contrast agent. It is usually well-tolerated, but allergic reactions can occur.
Please read our information sheet about Computer Tomography. It is written in German, but also in English, French, Croatian, Serbian and Turkish information sheets.
A Computer Tomography lasts just a few minutes and is completely painless. Before the exam, you must remove any metal—jewelry, watch, piercings, glasses, etc- and eventually some of your clothing. If your bowel will be examined, you may be asked to drink some water so that your small bowel can be more easily seen.
For the CT exam, after entering the CT room, you will be asked to lie on the table of the CT scanner. The table will by pushed inside the CT tube. The CT is a relatively quiet exam and goes very quickly.
The report will be ready within a few days and automatically sent to the doctor who referred you for the test. Your doctor will discuss the findings with you and decide upon the appropriate treatment.
In the second part, contrast material is injected to identify any lesions in the coronary arteries, plan the treatment of these lesions, or to check on the vessels after a heart transplant has been performed.
The cardiac CT is not invasive like a coronary angiogram. It does not require puncture of a leg artery to place a catheter in the heart. However, a coronary angiogram will be necessary if you have risk factors for coronary artery disease or urgently, if you had an acute myocardial infarct.
Please speak with your doctor to find out whether or not you will need to have bloodwork done before the cardiac-CT. If you are diabetic, over age 65 years or have kidney disease, then you will need a creatinine level drawn.
If you are or could be pregnant, have thyroid gland disease or an iodine allergy, please let us know this when you make your appointment. It is important because by many CT exams, we have to inject contrast material that contains iodine. The contrast agent is usually well-tolerated, but allergic reactions can occur.
You must be fasting for the exam. Do not eat anything for at least 4 hours before the exam. If you are thirsty, you may drink tap water only.
A cardiac-CT lasts approximately 15 minutes and has few risks. The radiation dosage is so low that it in a few hours after the exam, it will be dissipated (gone).
In order to slow down your heart beat to obtain better pictures of the heart vessels, you will probably be given a beta-blocker, provided that you have no medical problems or other medications precluding this. The beta-blocker effect lasts only a short time. By the end of the exam, your heart beat should be back to its baseline.
Before the exam, you must remove any metal on your body, e.g., jewelry, watch, piercings, glasses, etc. You will have to remove some of your clothing, too.
To synchronize your heartbeat with the CT scanner, an EKG device will be placed over your anterior chest wall.
Once you enter the exam room, you will lay on the table for the CT scan. The table will be pushed into the CT tunnel. The test is quick and virtually silent.
In the first part of the exam, a CT image without contrast will be obtained in order to estimate how much calcium is within your coronary arteries. This is called calcium-scoring.
During the second part of the exam, the coronary CT angiography will be performed. Therefore contrast agent will be injected into a vein to show the coronary arteries.
The report will be ready within a few days of the exam and will automatically be sent to the physician who ordered the CT. Your doctor will speak with you about the results and decide if treatment is necessary or not.
With cross-sectional images, CT and MRI can visualize the blood vessels anywhere in the body without using injected contrast material.
However, contrast material can be used to study the veins. Depending upon which area of the body the vessels are being evaluated, contrast-enhanced images may have advantages or disadvantages compared to non contrast images, and vice versa. The correct examination will be ordered by your specialist, usually in consultation with the radiologist.
The major advantage of both MR Angiography and CT Angiography is that, compared with conventional angiography, the artery does not have to be punctured. Therefore, complications of the blood vessels can be avoided. However, should changes in the arteries be found, conventional angiography may be required to treat the lesion with balloon dilatation and/or stent placement.
Please see the CT or MRI section for further details about your preparation for the exam and what you should expect during the test.
Fluoroscopy produces dynamic images of the inner body, captured by the radiologist in real-time as (s)he observes the motion and function of the area in question on a monitor. This allows the radiologist to make a diagnosis or plan treatment of the affected area. This technique is very useful for studying the digestive tract, including the esophagus, stomach, small and large bowel, as well as the heart, lungs, and diaphragm.
Fluoroscopy is done using low-dose radiation which is received by a digital detector. As with conventional radiography, body parts with thicker tissues appear lighter than those with thinner tissues where more of the radiation beam passes through the tissues.
The fluoroscopy machine is flexible, allowing the study of various organs.
When you make your appointment, please let us know if you are or could be pregnant.
All metal objects on your person, including jewelry, watch, piercings, glasses, dentures, etc, and some of your clothing must be removed for the exam.
Depending upon which part of the body is being evaluated, the exam will be done in the lying, standing or sitting position. Again, depending upon the area of study, you may be asked to hold your breath or to swallow during the exam.
Reports will usually be available the next day and will automatically be sent tot he referring physician. You doctor will tell you the results of the exam and discuss the treatment options with you.
During an MRI, cross-sectional images (i.e., transverse slices) of the body part under investigation will be produced. Other names for MRI include MRT nuclear spin tomography. An MRI does not use radiation to produce these images. Instead, while you lie inside the tunnel of the machine, a strong magnetic field and radiowaves produce the images.
The principle is simple. Each person’s body is 80% water (H20) which means you are made up of hydrogen (H) atoms. These H atoms spin, producing their own weak magnetic field, The machine’s strong magnetic field realigns these H atoms. During the exam, short radio waves are continually being emitted that temporarily try to return the H atoms to their normal position. This is what causes the emission of an electrical signal that the computer develops into images of the body part under investigation.
Be aware that modern MRI tunnels are quite spacious nowadays. Therefore, claustrophobia is no longer common.
How much water is contained within the area under investigation depends upon the tissue itself. Bones have little water and therefore relatively few H atoms while soft tissues--like the heart, bone marrow, intervertebral discs, joints and tendons, vessels (veins), muscles and digestive tract organs--are ideal for MRI because they have more water. MRI can diagnose pathological changes in the soft tissues, such as infectious foci.
Depending upon the reason for your exam, contrast agent may be necessary. In such cases, the dye will be injected through a vein.
The MRI machine is very sensitive tot he smallest bits of metal. As make-up contains a high percentage of metallic microparticles, please avoid wearing any make-up to you exam.
If you have a pacemaker, a defibrillator (i.e., AICD) or an inner ear implant, please let us know when booking your appointment as these metal-containing devices may be damaged during the MRI. Also, if you are or could be pregnant, please let us know when making an appointment.
Please read our information sheet regarding MRI. It is provided in German, English, French, Croatian, Serbian and Turkish.
Before the exam you must remove all metal, including jewelry, watch, glasses, piercings, barrettes, dentures, hearing aids, etc. and wash off any make-up off on your face. In addition, you must remove all clothing except your underwear. We will give you a hospital gown to wear.
An MRI can last from a few minutes up to one hour. The exam is painless with few risks. However, claustrophobic patients should let the technicians know of their condition. Before entering the MRI suite, you will be given earplugs and headphones to reduce the thumping noise during the MRI.
You will lie on a table that will be pushed into the tunnel of the MRI machine. Please keep your eyes closed and lie as still as possible during the exam. In no case should you cross your arms or legs. Skin burns may occasionally occur where the two limbs come in contact.
The technician will be able to see you during the entire exam and can react immediately. Should you feel anxious or unwell, you can push the emergency button to alert the technician.
Please follow all of the directions of the technician exactly! It is especially important to hold your breath when prompted to do so.
The report will automatically be made available to the referring physician within a few days of your MRI. Your doctor will explain the results to you and decide what treatment is best.
During a mammogram radiation is used to evaluate the breast. Subtle changes in the soft tissues of the breast indicating the first signs of breast disease can be seen long before a palpable breast mass becomes apparent. This is why mammography has become the screening method for breast cancer. It is recommended every two years in women aged 45 to 69 years
Mammograms are performed using x-ray equipment that has been customized for the breast tissues. A low-dose low-range x-ray beam that is well-absorbed is used to produce high soft-tissue contrast. The strength of the radiation beam varies according to the patient’s breast density, The shade of gray of the breast tissues on the mammogram film also depends upon the thickness of the breast Masses appear light gray since they are thicker than normal breast tissue and let fewer x-rays pass through them.
In mammography, low-dose x-rays optimize the appearance of the breast tissue.
The General Hospital of Vienna has two low-dose, fully-digital mammography units. A gray-scale image of the breast is generated once the radiation dose is automatically selected by a selenium detector. A special shutter guarantees that the breast image will be optimal. Then, a radiologist reviews the mammogram on a high-resolution monitor. The films are digitally stored.
Specialized mammography: Tomosynthesis
In cases where there is a particular question regarding the breast, the General Hospital of Vienna will use an innovative diagnostic machine called a tomosynthesis. This will require breast compression for a little longer than done for conventional mammogram. During the tomosynthesis exam, the x-ray tube will move in an arc-like manner around the breast, taking 25 exposures. Using breast images from different angles, the radiologist will be able to identify whether a density is in the breast or just overlying the breast, improving the diagnosis of breast cancer.
When you make your appointment, please let us know if you are or could be pregnant. We recommend that you make your appointment the week after your menstruation has ended as the breast is least sensitive to compression at this time.
A mammogram last just a few minutes. Thanks tot he equipment, the radiation dose is so low that it will have left your body within hours of the exam.
All metal objects on the upper part of your body, including jewelry, watch, piercings, glasses, etc. must be removed for the mammogram.
Once you are in the exam room, the technologist will instruct you how to lay your breast on the machine. Then the breast will be fixed between two discs to prevent any motion while each breast is imaged from two sides. Some patients find this pressure unpleasant and even painful. Please tell the technologist if you experience too much discomfort.
In order to get quality images and use as low a radiation dose as possible, the breast must remain compressed between the two discs a few seconds. This should not cause severe pain, though it may be unpleasant.
Sometimes, a few extra images or an ultrasound will be necessary. The ultrasound, which is radiation-free, can give additional information about the structure of the breast. In women with dense breast tissue, ultrasound is routinely performed to improve diagnostic precision.
The report will be ready within a few days of the mammogram and will automatically be sent to the referring doctor. You doctor will tell you the results of the exam and discuss the treatment options with you.
PET is an abbreviation for positron emission tomography while CT stands for computerized tomography. PET/CT is a modern procedure that combines both technologies, especially in oncologic diseases.
PET is a type of nuclear medicine test. Therefore, the patient will be injected with a radioactive material that will be distributed by blood throughout the body. The PET scanner measures the distribution of the radiotracer in the body’s tissues, generating three-dimensional images of the whole body.
With PET/CT cancer foci can be detected and their grade (e.g., low-, intermediate- high-) determined. PET is well-accepted for patients with known lung, thyroid, neck, esophageal, brain, ovarian and/or prostate cancers or by suspected brain tumors, especially to identify cancerous (malignant) lymph nodes. PET is also suitable for treating certain cancers.
Aside from its role in cancer diagnosis, PET can be used for studying cardiac and nerve diseases, diagnosing dementia, and to exclude a cardiac scar following bypass surgery.
No solid food must be taken by mouth from at least six hours before the exam. Chewing gum is particularly prohibited. If you are thirsty, it is best to drink tap water. However, you may drink sugar-free or carbonated-free drinks.
If you are a diabetic please let us know when booking your exam. Likewise, if you are or could be pregnant or breastfeeding, please notify us. The radioactive material has few side effects, however it does enter breast milk.
A PET exam lasts circa 45 minutes, is painless. The radiation to the body is very little and will be gone within a few hours.
In preparation for the exam, the radioactive material will be injected into a vein. During the 90 minutes that the radiotracer is being distributed throughout your body, please lie as still as possible with your eyes closed and without speaking.
Shortly before the PET exam starts, you will be asked to go to the WC to empty your bladder.
As with all other radiology exams, you must remove any metal—jewelry, watch, piercings, glasses, dentures, etc.
A PET/CT machine looks similar to a CT tube, but also contains a PET camera. You will be placed on a table and pushed into the relatively wide tunnel of the machine. The table will move through the tunnel in small increments allowing simultaneous images of the body to be taken by both the PET camera and CT scanner.
The report will be ready within a few days oft he exam and will automatically be sent tot he referring physician. Your doctor will explain the findings to you and discuss the treatment options.
Radiography, or so-call x-rays, send radiation through the body to obtain an image on the opposite side of the body that reflects the relative thickness of the tissues through which it has passed. The computer measures these relative intensities and creates a digital two-dimensional grayscale image of the body part of interest.
Thick tissues like bones allow fewer radiation beams to pass through and will appear light gray compared to less thick tissues, such as organs, fat or muscles, which allow more radiation beams to penetrate them and therefore appear dark gray. Almost always at least two views are obtained in conventional radiography to facilitate image interpretation. The different projections allow separation of overlapping tissue so that the radiologist can localize where exactly the pathology lies. The bones and lungs are well seen with conventional x-rays, but a dye may be necessary to see some of the other organs, e.g., kidneys.
Digital Radiography uses relatively little radiation.
Prior to digital radiography, i.e., before the 20th century, a much higher radiation dose of was necessary to achieve the same images. Therefore, digital x-rays represent a significant improvement in modern radiography.
Please let us know before your exam if you are or could be pregnant.
Obtaining an x-ray last at most a few minutes and is completely painless. Digital radiography requires such a negligible radiation dose that it is out of the body within a few hours.
Before radiography, all metal objects, including jewelry, watch, piercings, glasses, etc,. must be removed, and eventually some of your clothing, too.
In the exam room, the technologist will explain what part of the body is to be imaged and the position(s) required for the technologist to acquire the radiographs.
The report will be ready within a few days of the radiograph and will automatically be sent to the referring doctor. Your doctor will tell you the results of the exam and discuss the treatment options with you.
Ultrasound, called sonography by imagers, is one of the most commonly used procedures. It emits no radiation. The ultrasound transducer sends soundwaves through the body which return to the transducer when they encounter organs and other tissues. Depending upon the relative strength of the soundwaves, the tissues on the images appear as dark or light gray.
Ultrasound waves are not perceptible to the human ear and are totally harmless. Therefore it can be performed during pregnancy, and also in children. Ultrasound has many applications. Diseases in various organs, soft tissues, such as fat, and muscle, and in blood vessels can be diagnosed and followed. However, due to their calcium content, bone diseases are not amenable to ultrasound evaluation. Ultrasound is also poor at assessing the lungs since air bubbles can not reflect soundwaves. In circumstances where ultrasound is limited, complementary CT or MRI may be required.
In summary, ultrasound is a painless technique that exclusively uses harmless soundwaves. It has many applications.
Spectrum of Ultrasound Procedures
Depending upon the type of ultrasound, vascular diseases, such as atherosclerosis or other entities that narrow the arteries, can be diagnosed. Doppler especially is good for detecting valvular heart disease- Using the Doppler Effect, you can separate a moving object from a stationary object by their different tone frequencies. Likewise, the differences in speed or direction of two sound waves can identify different tissues and /or disease states. Ultrasound is also one of the most important imaging modalities used in the perinatal period.
Color-coded Doppler sonography is used to study the vessels. Instead of various shades of gray, arterial and venous flow are depicted as red and blue, respectively, and the intensity of the colour reflects the degree of patency of the vessel.
Usually no preparation is necessary for ultrasound exams.
Ultrasound of the belly is an exception, requiring that you fast for at least 4 hours before the test. However, it’s good to drink plenty of water so that you will have a full bladder which helps to visualize pelvic bowel loops, the urinary tract, the bladder and the prostate gland.
An ultrasound exam will last a few minutes. The exam is painless and has no side effects.
You will be asked to remove or push aside your clothing in the area to be evaluated by sonography.
Usually the exam will be done with you lying on your back. But occasionally, the exam will be done with you standing or lying on your belly. Please be aware that the water-based gel coating the ultrasound transducer is often quite cold. It is necessary for good contact between the device and your skin. At the end of the exam, you will be given a paper towel to wipe off any residual gel. The doctor performing the ultrasound may ask you at various times to breath in and then hold your breath. This often improves visualization of an organ.