Department of Radiology,
Lister Hospital,
Stevenage,
Herts SG1 4AB

Email: Dr. Amerasekera
Tel: 01438 781 028
Fax: 01438 781 176

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The North Herts Radiology Group

Adult Nuclear Medicine

Nuclear Medicine is a specialised procedure using a small amount of a radioactive substance which allows us to investigate the bones or organs of the body, using a Gamma Camera linked to a computer.

The types of examinations that a person might encounter in a nuclear medicine department are:

Bone scan to identify stress fractures in joggers, dancers, or gymnasts.
Bone scan to determine if cancer is spreading to the bones (metastatic disease).
Gallbladder study to see if there are gall stones blocking bile flow.(HIDA)
Kidney scan to analyse renal function or obstruction to the flow of urine.
Gallium scan or labeled white blood cells to evaluate infection.
Thyroid uptake and scan to evaluate lumps in the gland.
Lung scan to analyze respiratory problems, e.g., blood clots (PE) in the lung.
SPECT Scan
PET Scanning and PET/CT
Tc-99m Sestamibi Parathyroid Scan

Thyroid scan

Liver scan

Lung scan

Kidney scan

Hands and feet

What kind of equipment is used in a nuclear medicine department?

Gamma cameras are used to get images of the body, organs, and/or specific diseases states.
Computers enhance imaging capabilities and quantify results.

Is Radiation Dangerous?

The truth is that any type of radiation has the potential of being dangerous, but it depends on the type of radiation, the amount received, and the amount of time exposed. Ironically, we are exposed to radiation every moment of our lives from what is defined as background radiation. Some sources of background radiation include: radioactive materials in the soil, sunlight, even flying in an airplane. A better question to ask is, "What level of radiation is considered safe and is nuclear medicine within the safety limit?" Nuclear medicine is considered safe because the amount of radiation administered is limited and the time in which it is in the human body is lessened by the short half-life of the radiopharmaceutical. In fact, many nuclear medicine exams contain less radiation than certain types of radiology procedures.

How Does Nuclear Medicine Work?

Nuclear medicine studies require the oral or intravenous introduction of very low-level radioactive chemicals (called radionuclides, radiopharmaceuticals or radiotracers) into the body. Radiopharmaceuticals are specially formulated to be collected temporarily in the specific part of the body to be studied. The radionuclides are taken up by the organs in the body and then emit faint radiation signals which are measured by the gamma camera. The gamma camera has a large crystal detector (called a scintillation crystal). These crystals detect the emitted radiation signal and convert that signal into faint light. The light is then converted to an electric signal, which is then digitized (converted into a computer signal) and reconstructed into an image by a computer. The resulting image is viewed on the system monitor and can be manipulated (post-processed) and filmed. The radiographer positions the patient and begins the nuclear medicine examination. A radioactive material is introduced into the patient, and is then detected by a machine called a gamma camera. The radiation which is emitted by the body during nuclear medicine imaging are gamma rays. These rays are similar to x-rays but have a shorter wavelength. The radionuclide substances used in nuclear medicine imaging are usually either synthesized radioactive substances, like technetium, or radioactive forms of elements that are naturally found in the body, such as iodine. The levels of radiation involved in nuclear medicine studies is usually considerably lower than a patient would receive in a conventional x-ray study or CT scan. Modern nuclear medicine equipment provides all digital (computerized) images. This means that it is possible for the nuclear medicine images to be: conveniently stored on various archive media or in multiple locations networked or sent to other locations within an imaging center.

Photograph of the scanner

Preparing For Your Scan

At Home
Just relax, go about your normal routine and continue to take any prescribed medicine If there is any specific preparation for your scan, a separate instruction sheet will be enclosed for you to follow
At the Department of Radiology
Report to the Nuclear Medicine Department. which is situated within the imaging Department adjacent to Radiology, for your appointment
Will I have to undress?
Normally, you will not be required to undress for your Nuclear medicine scan but may be asked to remove any metallic items
What Does the Procedure Involve?
An injection of the radioactive substance is given into a vein in the arm Pictures are taken using a Gamma Camera You will be required to sit or stand next to the Camera positioned near you You will feel no discomfort from this Depending on the type of scan which has been requested, the pictures may be taken immediately or after a delay, as indicated by the scan time of your appointment During this time, you may leave the Department
How Long Does it Take?
You can expect to be in the Department approximately 30 minutes for the injection and approximately 1 hour for the scan Occasionally, emergency cases arise which cause unavoidable delay to booked patients
Will it be Painful?
After the injection you will feel no ill-effects and the procedure is not painful. The Radiographer will ask you to keep very still during the scan, as movement will blur the pictures.
Who Does The Scan?
The person who carries out the examination is a qualified Radiographer with specialised training in Nuclear Medicine.
Are You breast Feeding?
You are advised not to breast feed for 24 hours after the scan. Please inform this Department before you come, so alternative arrangements can be discussed with you.
Are You Pregnant?
If you think you may be pregnant, please inform this Department before you come for this examination. Like X-Ray examinations, Nuclear Medicine Scans involve radiation and are best avoided during pregnancy.
Are There Any Precautions?
The radiation dose is low. ‘You will be mildly radioactive, however, for 24 hours after the injection. You should avoid close contact with children under 12 years and pregnant women for 6 hours after the infection. You should avoid any other treatment or examinations outside of the radiology department on the day of your Nuclear Medicine Scan. For women of child bearing age, you must be within 28 days of your period having started.
After The Scan
You may eat and drink normally and it will be safe to drive. The Consultant Radiologist, a Doctor specialising in Nuclear Medicine, will study the pictures and send a report directly to your Doctor. That is why you may have to wait a few days for your results.

VENTILATION / PERFUSION LUNG SCAN

Ventilation/Perfusion lung scans are one of the most important tests available for the diagnosis or exclusion of pulmonary embolism (PE), and provides a safe method for monitoring response to therapy. A prescan chest x-ray is mandatory to exclude readily identifiable non-embolic causes of abnormal perfusion, and this should be performed within 24 hrs of the lung scan (or V/Q scan). Perfusion images are acquired after injecting the patient with a radiopharmaceutical(Tc-99m MAA). This demonstrates the blood supply to the lungs. The Ventilation part of the study is performed by getting the patient to inhale a radioactive gas , thus allowing visualisation of the patient's airways.

What is Pulmonary Embolus?

It is a blockage of an artery in the lungs by fat, air, tumor tissue, or blood clot.

What causes Pulmonary Embolus?

Pulmonary emboli are caused by clots from the venous circulation, from the right side of the heart, from tumors that have invaded the circulatory system, or from other sources such as amniotic fluid, air, fat, bone marrow, and foreign substances. Most are caused from clots originating in the lower extremities called deep vein thrombosis(DVT), and many resolve on their own. Sudden death can occur as a result of pulmonary embolism. The risk factors include prolonged bed rest or inactivity, oral contraceptive use, surgery, child birth, cancer, stroke, heart attack, heart surgery, and fractures of the hips or femur.

How can you prevent Pulmonary Embolus?

Early detection and treatment of DVT(clots of the legs) of patients who are at risk by early walking and activity after surgery can reduce the risk of pulmonary embolus. Other clot-preventive measures include leg exercises and elastic support stockings as appropriate. Subcutaneous heparin therapy (low doses of heparin injected under the skin) may be used for those on prolonged bedrest.

What are the symptoms of Pulmonary Embolus?

Bloody sputum, sudden onset of shortness of breath at rest or with exertion Lightheadedness, fainting, dizziness and chest pain:

ISOTOPE BONE SCANS

Bone scans are usually undertaken using diphosphonates labelled with 99 Technetium. This is injected intravenously. Early perfusion scans can be taken immediately after injection using the Gamma camera. More commonly the scans are obtained 4 hours after injection. The normal skeleton is demonstrated on bone scans due to uptake of isotope by the osteoblasts which are constantly replacing and remodelling bone. The normal skeleton should be completely symmetrical. Asymmetry should be regarded with suspicion. In addition there is excretion via the renal tract and the kidneys and bladder are seen on normal scans.

This test can detect changes in bone metabolism (growth). It identifies cancer, infections, or the cause of unexplained bone pain, such as a break that didn't show up on an X-ray. This is done by seeing how a radioactive isotope, collects in the bone.

SPECT SCAN (single photon emission computed tomography)

A SPECT Scan is capable of providing information about blood flow to tissue. It is a sensitive diagnostic tool used to detect stress fracture, spondylosis, infection (e.g. discitis), and tumour (e.g. osteoid osteoma).

Brain SPECT

A SPECT scan is a nuclear medicine study that measures blood flow and activity levels in the brain. Because the SPECT scan provides information about how the brain works, it is an excellent diagnostic tool for identifying behavioural and cognitive problems in persons with brain injury.

It is a useful procedure to evaluate memory loss and to diagnose Alzheimer's, neurodegenerative diseases, strokes and seizures. Brain SPECT scans may also be used to evaluate brain injury.

Parathyroid SPECT

There is evidence to show that SPECT scanning for parathyroid disease enables them to increase the accuracy of routine Sestamibi scanning by about 2 to 3 percent. The most important use for SPECT scanning is when ordinary Sestamibi scans are inconclusive or when a more detailed anatomic localisation is necessary before surgery.

POSITRON EMISSION TOMOGRAPHY (PET Scans)

PET images of the brain

What Is A PET Scan?

Positron Emission Tomography (PET) is a state-of-the-art imaging technique. Unlike any other modality, a PET scan combines medicine with computer technology to image tissue and organ function.
For a PET scan, the patient receives a dose of a radiopharmaceutical. This is a substance that can be absorbed by certain cells in the body, concentrating it there. A normal molecule of glucose, the basic energy fuel of cells, artificially attached to a radioactive isotope is often used. The stages involved are:
(1) label a selected compound with a positron- emitting radionuclide
(2) administer this compound to the subject of study
(3) image the distribution of the positron activity as a function of time by emission tomography
(4) elicit, through the application of a suitable model, from the information thus acquired an understanding of the biological handling of the compound.

A PET Scanner

PET for the Body
The body metabolizes this substance allowing professionals to accurately identify even the smallest areas of abnormal metabolic activity, which is associated with several disease processes. With its powerful imaging capability, aided by sugar-laden tracking elements (tracers) injected into a patient, the PET scanner can see what X-rays, CT scanners and MRIs cannot...the presence of the most micro-sized of malignant tumors that have eluded other computerized scanners. Consuming and metabolizing more sugar than the healthy cells around them, the cancer become obvious as the PET equipment scans the body. A computer reassembles information received from the tracers into images demonstrating the shape and size of the tumors or lesions, which are viewable on a computer screen. Among the tremendous advantages it offers, the equipment will also show doctors if and how chemotherapy is progressing in a patient. It can also possibly make exploratory surgery unnecessary for some patients, whose tumors have become too extensive to permit surgical cure. Malignant tumors found early by PET scanning may be more completely eradicated because of their smaller size at the time of diagnosis.
"PET scanning will enable a more accurate diagnosis and staging of cancers, which allows better individualized treatment decisions and better results for patients. This substance will cause no side effects during or after your PET scan.

Ovarian cancer with spread shown in red

PET for the Brain
PET allows us, for the first time, to measure in detail the functioning of distinct areas of the human brain while the patient is comfortable, conscious and alert. We can now study the chemical process involved in the working of healthy or diseased human brains in a way previously impossible. Before the advent of the PET scanner, we could only infer what went on within the brain from post-mortems (dissections after death) or animal studies.
PET represents a new step forward in the way scientists and doctors look at the brain and how it functions. An X-ray or a CT scan shows only structural details within the brain. The PET scanner gives us a picture of the brain at work.
PET for the heart
Positron emission tomography, also known as a PET scan, is used for a variety of purposes. Researchers use it to study the metabolism of the heart. Pet scans can also be used in lieu of the standard stress test
The most common use of PET scans in cardiology is to identify heart muscle that is weakened but not irreversibly damaged by blocked arteries. Patients in this situation are likely to benefit from an angioplasty or bypass operation whereas people whose heart muscle is irreversibly damaged are less likely to benefit from these procedures. Similar information can be obtained from stress nuclear or stress echo tests but the PET scan is felt to be the most reliable of the three.
The PET scan is performed by injecting one or more substances that emit positrons ( a subatomic particle) into a vein in the arm. The blood stream then carries these substances to the heart muscle. These substances have no known side effects. A camera that detects the emitted positrons then constructs a picture of the heart. Sometimes, an intravenous medicine is used to stress the heart in conjunction with the PET scan. These are the same medicines used for stress tests in people who are unable to run on a treadmill.

Having a PET Scan
During a scan the patient reclines on a couch with his or her head inside the large, doughnut-shaped Positron Emission Tomograph. While the patient's head must be kept very still, the only real discomfort involved may be the pinprick of a hypodermic needle as a minute amount of radiopharmaceutical is injected. The radiopharmaceutical could be administered as an intravenous injection or inhaled as a gas. How it is administered depends on the radiopharmaceutical. Which one is chosen depends on what function the doctor wants to study.

PET/CT Scan

Using the PET/CT system, radiologists are able to more accurately describe tumours and determine whether the tumour has invaded other nearby structures or spread elsewhere in the body.

This information helps physicians decide whether biopsy or surgery is appropriate, and helps determine how well patients are responding to chemotherapy or other treatment regimens.

The PET/CT scanner integrates PET and CT technologies into a single device, making it possible to collect both anatomical and biological information during a single examination. This integrated information permits accurate tumour detection and localisation for a variety of cancers, including breast, oesophageal, cervical, melanoma, lymphoma, lung, colorectal, head and neck, and ovarian cancer.

The entire examination is generally performed in less than an half an hour, providing comprehensive diagnostic information

Tc-99m SESTAMIBI PARATHYROID SCAN

Tc-99m sestamibi scan for diagnosis of parathyroid adenoma Recently Tc-99m sestimibi has been introduced for parathyroid imaging. It was previously used as a radiotracer for myocardial perfusion studies. It is a monovalent cation and a member of isonitriles chemical family. The selective nature of Tc-99m sestamibi uptake by different tissues has not been investigated.It moves out of the blood by passive diffusion and localizes in mitochondria. Since the oxyphilic cells of parathyroid glands have many enlarged mitochondria, they have high tissue uptake for Tc-99m sestimibi compared to thyroid gland and other cervical tissues. In addition, Tc-99m sestamibi is washed out from thyroid and surrounding tissues faster than parathyroid glands. Also it has been showed that the uptake of Tc-99m sestamibi by abnormal parathyroid tissue (parathyroid adenoma and hyperplasia) is significantly higher than other tissues in the neck.

Sensitivity and specificity of Tc-99m sestamibi scan in parathyroid adenoma Tc-99m is the most accurate tool which can be used as a single modality to preoperative localization of parathyroid. The sensitivity of this method is 80-90% and it depend to the size of adenomatus parathyroid tissue.

Advantages and disadvantages of Tc-99m sestamibi scan in parathyroid adenoma

Advantages The most accurate noninvasive study Easy to interpret Ectopic parathyroid can be visualized SPECT capability Simple (no subtraction and computer processing) Low cost compared to Thallium-Tc subtraction Disadvantages Low specificity

parathyroid adenoma

False positives in Tc-99m sestamibi scan:

Hyperplasia Metastatic thyroid cancer Parathyroid carcinoma Hyperactive bone due to hyperparathroidism

False negative in Tc-99m sestamibi scan

Small size of lesion

HIDA SCAN FOR THE GALL BLADDER

A HIDA image

A HIDA scan is an imaging test used to examine the gallbladder and the ducts leading into and out of the gallbladder. In this test, also referred to as cholescintigraphy, the patient receives an intravenous injection of a radioactive material called hydroxy iminodiacetic acid (HIDA). The HIDA material is taken up by the liver and excreted into the biliary tract. In a healthy person, HIDA will pass through the bile ducts and into the cystic duct to enter the gallbladder. It will also pass into the common bile duct and enter the small intestine, from which it eventually makes its way out of the body in the stool. The HIDA scan is useful for several investigations. It can be used to evaluate suspected acute cholecystitis, post-operative bile leaks, biliary patency, jaundice, and jaundice pain in post biliary surgery patients. The patient must not eat for six hours prior to the scan. The scan itself takes approximately two hours. After the patient receives an injection, images will be taken every 5 or 10 minutes until completed.

GALLIUM SCAN

What is a gallium scan? Gallium is a radioactive compound which is injected in the vein of your arm. Once injected, gallium is slowly distributed in different organs in the body. Usually, the scan is performed 2-3 days after the injection of gallium. Depending on the information desired by your physician and depending on the findings on the initial scan, additional imaging is sometimes performed on subsequent days.

Why is a gallium scan useful? Like other applications in nuclear medicine, gallium imaging is based on physiology and its alterations, whereas X-rays, CT scans etc are based on anatomy and its alterations. Gallium scan is useful in certain disease processes where physiologic but not anatomic alterations occur. When is a gallium scan useful? There are various conditions where a gallium scan is useful. These include but are not limited to,

1. In patients with lymphoma, gallium scan is useful in the follow-up of the patients to determine response to therapy.

2. In patients with fever, when physical examination and other diagnostic tests do not help to determine the cause of fever.

3. Sometimes in patients with skin/soft tissue infection, gallium scan is useful to determine if the infection has spread to the bone.

4. In patients with AIDS, gallium scan is frequently used in the diagnostic work-up, such as in the diagnosis of Pneumocystis Carinii Pneumonia (PCP). 5. In patients with sarcoidosis, gallium scan is useful to determine the extent of active disease.

How long does it take to perform a gallium scan? When you first come to the nuclear medicine department you will receive intravenous injection of gallium in the vein of your arm. You will then be asked to come 2-3 days after the injection for the scan. Depending on your clinical condition and information desired by your referring physician, it may take anywhere from 30 to 90 minutes to perform the gallium scan. You will be provided with an estimate of how long it will take in your case, that way you can plan your day ahead of time. What are the side effects? Side effects are rare, and include allergic reactions, skin rash and nausea. If you are pregnant, suspect you may be, or are a nursing mother, please discuss this with your doctor and the Radiologist before scheduling the test.

What type of preparation is required for a gallium scan? There is no preparation prior to a gallium scan. If you are taking any medications routinely, you can continue to do so on the day of the gallium scan. Unless you are having another procedure that requires you to avoid food, you can have your regular meals before coming to the department. In some of the patients who may be required to come back for additional imaging after the initial scan is completed, a mild laxative or a fleet enema may be required before returning for the additional imaging so that the gallium is cleared from the bowel loops, thereby providing a better image of your abdomen.

WHITE CELL SCAN

What is a white cell scan?

This is an investigation used to show sites of infection. Pictures are taken with a special camera after you have received a small injection of a radioactive material which has been labelled with a sample of white cells from your blood.

What preparation is required?

On arrival in the nuclear medicine department, a sample of blood will be taken from a vein in your arm. The white cells will be removed from this blood sample and added to a small amount of a radioactive material. You will be asked to return to the department one and a half hours later. On your return, the labelled white cells will be re-injected into your arm. Pictures of the affected area will then be taken at 4 and 24 hours.

Is there any special preparation for this scan?

No, there is no special preparation for this scan. The injection will not impair your ability to drive a vehicle.

N.B. If you are pregnant or if there is any possibility that you may be pregnant please tell us before you receive your injection.

Should I take any precautions after having a white cell scan? Some of the radioactive material will remain in your body for approximately 48 hours after the scan. Since it emits a small amount of radiation you should take the following precautions during this period:

1. Drink plenty of fluids and empty your bladder as frequently as possible. When using the toilet you should avoid spills, flush the toilet twice and wash your hands thoroughly.

2. If possible avoid contact with infants and children.

3. If you are brest feeding please inform the Radiologist or Radiographer

The results will be sent to your doctor who will discuss the results with you.

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