Radiology
The Department of Radiology at Changi General Hospital provides a comprehensive range of diagnostic imaging services.
Our department offers subspecialties in body imaging (gastrointestinal, hepatobiliary, genitourinary), head and neck imaging, breast imaging, interventional radiology, musculoskeletal radiology and uroradiology.
Imaging Services
Bone Mineral Density (BMD) or DXA
What is BMD?
BMD is a special type of X-ray examination, also known as DXA or “dual X-ray absorptiometry, measures the bone density of a person. BMD study measures the bone mineral densities of lumbar spine and left hip, in some cases, BMD of the forearm if necessary.
What is BMD used for?
BMD scan is used to diagnose reduced bone densities, a condition known as osteopenia or osteoporosis, and predict fracture risk. BMD can be used to monitor response in patients who are on treatment for such conditions.
BMD of the whole body (total body composition) may be requested to measure body composition (amount of bone, fat and muscle in the body), as part of clinical evaluation for patients who are obese or have muscle wastage.
Is BMD safe?
The examination involves low level of radiation and is much lower than the standard X-ray examinations. The radiation dose is almost equivalent to the natural background radiation that is received daily. BMD is not recommended for pregnant patients as the X-rays may cause harm to the unborn baby.
Preparation for BMD
No special preparations are required for BMD scan. However, patients who had undergone recent imaging study involving oral contrast are required to wait 2 weeks before going for the BMD examination. For patients with Nuclear medicine (NM) appointment, BMD examinations should be done prior to or at least one day after the NM examination.
Computed Tomography (CT)
What is CT?
CT scan uses X-rays to produce cross sectional images of your body with the aid of computer allowing radiologists to visualise internal structures of the body to make appropriate diagnosis of the medical condition. The X-rays that passes through the body will be captured and analysed by the computer which will then create clear and detailed images of internal organs and structures.
For certain types of scans, contrast (special dye) is injected into the body to allow major blood vessels as well as organs to be seen more clearly. As the scan time is shorter and uses a doughnut-like gantry, claustrophobic patients are generally able to tolerate CT scan well.
What is CT used for?
CT scans can produce detailed cross sectional and 3D images which are used to look for abnormalities and diagnose various conditions. Depending on the type of diseases or medical conditions, CT may be used in conjunction with other imaging techniques like ultrasound (US) and Magnetic Resonance Imaging (MRI) to help doctors to evaluate a medical condition.
Is CT safe?
Advances in technology allow the x-ray dose used to be kept as low as possible. The use of contrast injection is often not recommended for patients who are allergic to contrast media, iodine or have kidney problems. Pregnant patients are not advised to go for CT scans due to the radiation, which may be risky to the unborn baby. However, it will be recommended for life-threatening cases by the doctor where benefits outweigh the risks involved in the scan.
Preparation for CT
No preparation required if there is no contrast injection involved in the scan. CT scans with contrast injection, require patients to fast (no food) to go through the injection with greater ease without vomiting or nausea. For asthma or for drug allergies, medication would be prescribed to be taken prior to scan in order to reduce the risk of reaction during the contrast injection. Patients need to inform doctor of these medical conditions prior to arranging for a scan. At times water may be given before the scan to produce clearer images during the scan.
Fluoroscopy
What is Fluoroscopy?
Fluoroscopy is a dynamic study of human body function in which contrast is introduced to outline body structures and a continuous stream of X-rays is used to produce images through which the doctors will be able to see the body part and its motion in detail.
What is Fluoroscopy used for?
The use of contrast to outline body structures allows the doctors to see the movement of the internal body structures in real time as the contrast travels through thus providing dynamic and functional information which helps doctors in diagnoses and treatment of patients.
Is Fluoroscopy safe?
Advancement in technology allows fluoroscopy to minimize the dose given to patients. Due to radiation involved, pregnant patients must inform the doctor and the radiographer before any fluoroscopic examination to avoid risks to the unborn baby. However, fluoroscopic examination is only recommended for pregnant patients when their condition is life-threatening. If patients are allergic to the contrast dye used, they must notify the doctor to avoid allergic reaction to the dye.
Preparation for Fluoroscopy
Depending on the nature of examinations, some exams may require patients to fast before the procedure or in some circumstances, refrain from smoking before fluoroscopy.
Mammography
What is Mammography?
Mammography is an X-ray examination of the breast to screen for breast abnormalities. Low dose X-rays passes through the breast which will be detected by the detectors in the machine and converted signals to images of the breast. The use of digital mammography produces high resolution 3D images of the breast which is more sensitive than conventional film-screen mammography for early breast cancer detection.
What is Mammography used for?
Mammography produces sharp images of the breast tissue and is highly sensitive in picking up small abnormalities. Mammography is often used as a complementary when breast abnormality is detected in other imaging techniques like ultrasound and MRI (Magnetic resonance imaging), to allow doctors to make a more accurate diagnosis.
Is Mammography safe?
Although radiation is used in mammography, low doses of X-rays that remains within safe levels are used to produce the images. Doctors will only request for mammography for diagnosis and treatment when the benefits outweigh the risks of the examination. Since radiation is involved, pregnant patients are required to inform the radiographer before the mammogram as it poses some risks to the unborn baby. It is safe for female patients who are breast feeding to go for mammogram. They will be advised to express out milk prior to the scan in order to obtain better images.
Preparation for Mammography
Mammography examination must be scheduled at least one week after the start of the menstrual period when breasts are least tender. On the day of the examination, patients should not use powder, lotion or deodorant under arms or on breasts as this may mimic micro calcifications. Patients are advised to bring along their previous breast images on films/CDs/reports done outside CGH for the radiologist to make comparison.
Magnetic Resonance Imaging (MRI)
What is MRI?
MRI is a medical imaging technique that uses strong magnetic field and magnetic waves to produce detailed images in different planes of any part of the human body. This allows radiologists to visualise internal structures of the body to make an appropriate diagnosis of patients’ medical condition.
What is MRI used for?
MRI is very useful to diagnose diseases and assess internal damage to soft tissues in our body. It also monitors organ abnormalities such as lesions which reduces the need for biopsy or exploratory procedures that are more invasive.
Some MRI scans may require contrast (special dye) to be injected into the body to highlight certain structures. The use of contrast injection is often not recommended for patients with poor kidney function as the contrast could not be effectively excreted and may pose health problems.
Is MRI safe?
The strong magnetic field used in MRI will attract any ferromagnetic objects (objects that contain iron) and may cause them to move inside the body. As a safety precaution, detailed screening will be carried prior to MRI scan. The radiographer must be informed of the following:
- Cardiac pacemaker/ stents
- Brain aneurysm clips
- Cochlear (inner ear) implants
- Foreign body within or near the eye
- Metallic implants / prostheses / devices
- Claustrophobia (fear of confined space)
Though no radiation is involved and no known risk for pregnant patients, they are still required to inform the doctor and the radiographer before the MRI Scan. MRI is only recommended by doctors if the benefits outweigh the risks or if patient’s condition is life-threatening.
Patients with claustrophobia (fear of being in a confined space), should discuss with their doctor if they require sedation during the MRI scan so that the doctor can make the necessary arrangements before the MRI scan.
Preparation for MRI
If MRI scans require fasting, patients are required to fast for 4 hours before your scan time. For MRI cardiac perfusion scan, patients are advised to avoid caffeine 24 hours before the scan time. Patients with dentures and hearing aids are required to remove them prior to the scan as these devices are attracted to the MRI magnet which is dangerous in the scan room
Ultrasound
What is Ultrasound?
An ultrasound scan uses high frequency sound waves to examine various structures in the body in including large organs and blood vessels. High frequency sound waves is transmitted into the body when a scanning probe is placed on the skin which enables the ultrasound machine to produce live or real-time images of your internal organs.
What is Ultrasound used for?
Ultrasound is commonly used to scan the organs and blood vessels in the body to detect abnormalities which aids the doctors to monitor and diagnose various conditions. Ultrasound scan can also assess the abnormalities in the muscles, tendons and ligaments. Ultrasound breast is often used as an initial or early diagnostic tool to assess the size and shape of breast lumps and to determine whether they are potentially tissue growths or fluid-filled cysts.
Is Ultrasound safe?
Ultrasound is one of the safest imaging techniques as it does not involve radiation. It is always the first imaging technique to be considered for pregnant women.
Preparation for Ultrasound
Some ultrasound scans require patients to fast or to fill up the urinary bladder before the scan. No preparation is required for breast ultrasound.
Nuclear Medicine (NM)
What is NM?
NM is a medical imaging procedure that involves injecting small amounts of radioactive materials (radiotracers) to examine bodily functions, diagnose or treat diseases. Radiotracer is a chemical attached to a radioactive label that is administered into the body via injection, inhalation or swallowing. It accumulates in specific areas in the body and emits radiation that will be detected by a scanner (gamma camera).
What is NM used for?
Nuclear Medicine imaging helps clinicians to diagnose and treat a variety of diseases within the body. Physicians use this form of imaging to visualize the structure and function of an organ, tissue, bone or system within the body. Some of the common procedures are bone scan, myocardial perfusion (cardiac) scan, lungs scan, renal scan and other systems scans.
Is NM safe?
NM procedures generally do not cause any side effects. The dose of radiation that your body receives is very small. The radiotracer will lose its radioactivity in the body over time. Patient is required to drink plenty of fluids to eliminate the radiotracer through urine. Special precautions have to be taken such as flushing the toilet twice and washing the hands thoroughly for 24 hours from the time of injection.
After the NM scan, patients are advised not to get in close contact with babies, children and pregnant ladies for 24 hours from the time of injection and breastfeeding activity is advised to stop for 24 hours. As radiation is involved, pregnant patients are advised to inform their doctor and radiographers as the gamma rays may be harmful to the unborn child.
Preparation for NM
Most of the NM scans do not require patient preparation. If necessary, some may require fasting and to stop certain medication prior to the scan. For cardiac scans, patients are required to avoid caffeinated drink for 12 hours before the scan.
Angiography
What is
Angiography?
Angiography is the X-ray imaging of blood vessels using contrast agents injected into the bloodstream through a thin plastic tube (catheter) that is placed directly in the blood vessel and the images taken are known as Angiograms.
What is
Angiography used for?
Angiography provides information about blood vessel abnormalities, such as narrowing, blockage, inflammation, abnormal widening and bleeding. The contrast agents are injected into the blood vessels to make them visible on X-rays. Angiography is also used to guide procedures that treat blood vessel abnormalities. For instance, if the artery is narrowed, a tiny balloon can be inflated or occasionally a piece of metal tubing called a stent can be inserted to widen the artery and restore normal blood flow in the procedure called angioplasty.
Preparation for Angiography
The radiography department will advise of the preparations required in individual cases.
Intravenous Urogram (IVU)
What is
IVU?
Intravenous Urogram (IVU) is a radiological procedure used to visualize abnormalities of the urinary system, including the kidneys, ureters and bladder in which a contrast agent is used to highlight the urinary tract. In this procedure, the contrast agent injected into the body will be cleared by the kidneys and excreted out as part of the urine.
What is IVU used for?
This procedure is perform on patients with severe abdominal pain caused by presence of stones , blood in urine (Haematuria) as well as other medical conditions in the urinary system. A series of X-ray examinations is performed during the procedure to detect any abnormality.
Preparation for IVU
Patients are advised to fast before the test. Diabetic patients are advised to inform the radiography department prior to the procedure as they may need different instructions on the preparations. Pregnant female patients are advised to inform the radiographers prior to the procedure due to the radiation involved which may be risky to the unborn baby.
