Ultrasound imaging uses high frequency sound waves, passed from a probe into the body. The probe picks up the sound waves as they bounce back of the tissue and a computer processes images based on the results. The ultrasound waves are painless, inaudible and do not require any anaesthetic or a drip to be placed. The probe can also measure the flow in blood vessels (Doppler)
Ultrasound allows the doctor to visualise the internal organs, blood vessels and the body wall. It is usually recommended to help diagnose
- Abdominal abnormalities such as tumours, infections, cysts (fluid-filled sac-like structures). In general, ultrasound scans of the bowel are less reliable, in adults.
- Gallstones in the gallbladder and bile ducts
- Liver disease and inflammation of the pancreas
- Problems of the pelvic organs
- Abdominal and groin hernia
- Ultrasound is also used to guide procedures such as biopsy and surgery.
You will be asked to remove clothing covering the area to be scanned. If you are undergoing an upper abdominal or gallbladder scan, you will be asked not to eat for a few hours before the test, so that bowel gas does not obscure the pictures.
Ultrasound is usually done by a radiology technologist.
- You will lie on a bed next to the technician.
- The ultrasound probe, which is the size of a paintbrush, is pressed onto the area of interest.
- You may be asked to breathe, hold your breath, cough or stand during the test.
- The entire procedure takes about 10 to 20 minutes.
Risks & Complications
Ultrasound scanning is very safe and can be performed at any time during pregnancy.
Computerized tomography (CT scan) or Computer Axial Tomography (CAT) scan is an imaging procedure that uses an X-ray machine connected to a computer. The scan creates cross-sectional images or slices of the internal structures of the body. Sometimes, a contrast material or dye may also be injected into your arm or any other part of your body for a better view of an area. The internal structures are easily visible on the CT scan with the help of the dye.
CT scan images allow the doctor to look at the inside of the body and is usually recommended to help diagnose various conditions including:
- Abdominal and intestinal abnormalities such as tumours, infections, cysts (fluid-filled sac-like structures), and bowel disease.
- Kidney and bladder stones, urinary tract blockage, or other urinary tract diseases.
- Liver diseases and inflammation of the pancreas
- Problems of the pelvic organs
- Enlarged adrenal glands
- CT scan is also used to guide procedures such as biopsy, radiation therapy and surgery.
You will be asked to remove any jewellery or metal fastenings that are in the area to be scanned. The scan may require a contrast dye or substance that improves the picture of certain tissues or blood vessels. This material may be swallowed, given as an enema or injected into the blood stream, depending on the part of your body that is to be scanned. If you are undergoing an abdominal scan, you will be asked not to eat for six hours before the test.
A CT Scan is usually done by a radiology technologist.
- You will lie on a table that is attached to the CT scanner.
- The table will slide into a large donut-shaped machine which takes images while moving around your body. Each rotation will yield several thin sliced images of your body.
- You may be asked to breathe or hold your breath during the chest and abdomen scanning. You should lie still during the procedure as this increases the clarity of the images.
- The CT scan technologist will watch you through a window during the procedure. You can communicate with the technologist through an intercom.
- You should inform the technologist if you experience any problems during the scan. The entire procedure takes about 30 to 60 minutes.
You can return to your normal routine after the procedure. If a contrast dye was used, you will be instructed to drink plenty of fluids to flush out the dye from the body. In some cases, you may have to wait for an hour to make sure you feel okay after the scan.
Nursing mothers should wait for 24 hours after a scan using a contrast dye before resuming breastfeeding.
Risks & Complications
As with any procedure, a CT scan involves minor risks and complications.
- Doctors do not generally recommend CT Scans without a good medical reason as there is far more X-ray exposure than is involved in ordinary X-rays. There must be a diagnostic benefit to performing a CT scan, for the risk of x-ray expose to be justified.
- Pregnant women should not have a CT scan as there is a small risk that X-rays may cause abnormality to the unborn child.
- The contrast dye used in CT Scans often contains iodine, which can cause allergic reaction in some patients.
- Also, the dye may cause some kidney damage to people who already have kidney problems.
MRI or magnetic resonance imaging scan is an imaging test that creates pictures of internal body structures (bones and soft tissues) with the help of magnetic fields and radio waves.
The MRI can also be combined with other imaging techniques to provide a more definitive diagnosis. The scan is often used to clarify findings from previous X-rays or CT scans.
MRI scans provide information on a variety of conditions and procedures and to assess function of the internal organs such as:
- Brain and spinal cord abnormalities
- Prostate, liver and breast abnormalities
- Function and structure of the heart
- Joint problems
- Blood flow through blood vessels
- Tumour detection and help in staging (tumour size, severity and spread)
Before the procedure, you will be asked to remove any metallic devices such as hearing aids, hairpins, removable dental work or other objects that may interfere with the procedure. You may be provided with ear plugs or music to block the strong noises from the MRI scan. You may be sedated if required.
The MRI machine consists of a large strong magnet and a table that moves into the opening of the scanner. During the procedure, you will be asked to lie on the table, which will be advanced into the scanner. The machine creates a magnetic field that creates loud noises. In some cases, a contrast dye may be injected through your arm to provide a clearer view of the scan. A radio wave antenna directs signals to the body and receives them back to create images by a computer attached to the scanner. You need to keep very still throughout the scan as movement may blur the resulting images. The entire procedure may take up to an hour to complete.
If you were not sedated, you may resume your usual activities immediately after the MRI. If you have been given a sedative, you will need to arrange for a relative or friend to take you home after the scan.
Advantages & Disadvantages
Advantages of MRI include:
- Does not use radiation
- Is non-invasive
- Can take images of any part of the body from almost any direction and orientation
- Produces better images of soft-tissue structures compared to other imaging techniques
- Can differentiate between tissues based on their biochemical properties such as water, fat, iron
- Can scan large regions of the body
Disadvantages of MRI Include:
- Certain patients who get nervous in small spaces (claustrophobic) may not be able to have an MRI.
- Elderly or ill patients may find it difficult to cooperate, which may result in blurred images.
- MRI cannot be done on patients with implanted medical devices such as aneurysm clips in the brain, heart pacemakers and cochlear (inner ear) implants
- MRI is an expensive procedure
Risks & Complications
Since an MRI scan is a non-invasive test, it is a very safe procedure. However, there is a very small risk of an allergic reaction to the contrast dye or sedation medicine if used. Any metal or electronic devices in your body are a safety threat and you should not undergo an MRI in those circumstances. Before your MRI test, make sure you notify your doctor and the MRI technologist if you:
- Have any health conditions, such as kidney or liver problems that may prevent you from having an MRI using contrast material
- Are pregnant as the effects of magnetic fields on the baby are not yet known
Positron emission tomography scan, also called PET scan or PET imaging, is a highly specialized nuclear imaging test that uses small amounts of radioactive substances to produce powerful images of the body’s biological function. PET scan is non-invasive and usually painless.
PET scan uses a special camera and a radioactive chemical tracer to view organs in the body. The radionuclides used in PET scans are chemical substances such as glucose, carbon, or oxygen used naturally by the organ or tissue during its metabolic process.
During the test, the tracer liquid is put into a drip (intravenous, or IV) in your arm. The tracer may also be swallowed or inhaled depending on what part is being imaged. The tracer moves through your body, where much of it collects in a specific organ or tissue. The tracer gives off tiny positively charged particles called positrons. The camera records the positrons and turns the recording into pictures on a computer.
PET scans may be performed to:
- Detect certain types of cancer
- Determine if cancer has spread to other parts of the body
- Assess the effectiveness of cancer treatments
Before the Procedure
- Notify the radiologist or technician of any medications you are taking and if you are allergic to or sensitive to contrast dye, iodine, or seafood.
- Fasting for a certain period prior to the procedure is required, usually for at least four hours.
- Notify your physician if you are pregnant or breastfeeding.
During the Procedure
You will be positioned on an examination table. An IV line will be inserted into your arm if needed. The radiotracer will then be injected into your vein, swallowed or inhaled depending on the imaging needed.
You may have to drink a contrast liquid that helps the radiologist interpret the imaging results. The radiotracer takes about 30 to 60 minutes to concentrate in the organs. During this time, you will be asked to lie still and not talk.
After 30-60 minutes, you will be moved into the scanner for imaging.
You will be instructed to drink plenty of fluids and empty your bladder frequently for 24 to 48 hours after the test to help flush the remaining radionuclide from your body.
If you notice any pain, redness, and/or swelling at the IV site, you should notify your physician.
Advantages & Disadvantages
- PET scans provide information about both structure and function of the tissues.
- It helps detect some cancers or areas of spread which have not been identified by other imaging studies such as a CT or MRI.
- Since it provides information on cellular activity, it helps in the early detection of disease.
Risks & complications
- The amount of the radionuclide used for the procedure is small enough that there is no need for precautions against radioactive exposure.
- The injection of the radionuclide may cause some slight discomfort.
- Allergic reactions to the radionuclide are rare, but may occur.