What is Nuclear Medicine and Molecular Imaging?
Nuclear Medicine and Molecular Imaging performs non-invasive, painless imaging tests that can reveal important information about your child's health.
Nuclear medicine uses short-lived radiopharmaceuticals and specialized cameras to create images of the human body. The images show blood flow and functional and metabolic activity within organs and lesions. This technology allows early diagnosis and monitoring of disease and can often make invasive procedures unnecessary. It also complements information obtained from X-rays, computed tomography (CT), ultrasound, and magnetic resonance imaging (MRI).
Some applications of nuclear medicine are used for treatment of certain specific diseases.
How is nuclear medicine different from other types of imaging?
Unlike other imaging technologies that diagnose disease based on anatomy or structural appearance, nuclear medicine determines the cause of a medical problem based on organ function. Nuclear medicine images can be digitally combined with computed tomography (CT) or magnetic resonance imaging (MRI) to give the most complete picture of the tissues or lesions being evaluated.
How does nuclear medicine imaging work?
The patient is given a very small amount of a radiopharmaceutical, a substance that contains an extremely short-lived radioisotope (tracer, radionuclide) that localizes in specific parts of the body. The radiopharmaceutical emits invisible energy called gamma rays, which can be seen by special cameras called gamma cameras or PET scanners. These cameras map the radiopharmaceutical's flow and distribution within the body or within a specific organ or tissue.
Radiopharmaceuticals are most often given through a vein (intravenously) using a small needle. Depending on the exam, they might also be administered orally, mixed in food or drink, administered via a small catheter placed into the bladder or stomach, or by inhalation. For studies of the gastrointestinal tract, for example, the radiopharmaceutical is taken with food; for studies of the lungs, it is inhaled through a breathing mask.
In some nuclear medicine examinations, images are obtained immediately after the radiopharmaceutical is administered. In other imaging studies, a waiting period is necessary to allow the radiopharmaceutical time to reach the desired organ or lesion. Imaging time may take from two minutes to two hours, depending on the type of study. In some cases, it is necessary to take images at different time intervals.
At Boston Children's Hospital, we have two types of equipment that can "see" radiopharmaceuticals: gamma cameras, which can create two- and three-dimensional images, and a positron emission tomography (PET) scanner, which creates three-dimensional images. The main difference between the two is the type of radiopharmaceutical used. The movement and positioning of the camera vary with the type of scan. For all tests, the patient must lie still on an imaging bed.
In a planar scan, the camera remains stationed over a specific part of the body or moves slowly across it. Three-dimensional images taken with a gamma camera are known as SPECT (single photon emission computed tomography) scans. For a SPECT image, the camera rotates around the patient to take many pictures, which together are used to construct a three-dimensional image.
- Positron emission tomography (PET) scanner
Boston Children's Hospital is the only facility in New England that has a PET scanner dedicated solely to children. In PET imaging, the patient is surrounded by a ring of detectors. A powerful computer system then converts this information into 3D images that physicians use for diagnosis.
What kinds of diseases can nuclear medicine diagnose?
Nuclear medicine procedures can provide early diagnosis of many diseases and have become essential to specialists in urology, orthopedics, oncology, cardiology and neurology. They can determine whether certain organs are functioning normally, monitor the effects of surgery or medical treatment, and identify tumors deep within the body. For example, nuclear medicine can:
show whether or not the heart muscle is receiving adequate amounts of blood in patients with congenital heart disease or following cardiac surgery
assess the blood flow to the brain
tell doctors whether kidneys are functioning normally
locate bone stress before it can be seen on an X-ray in young athletes
detect infection within the bones
assess the function of renal, cardiac and liver transplants
see the exact location in the brain where a seizure originated
determine which parts of a tumor are growing the fastest.
How is nuclear medicine used to treat diseases?
Radiopharmaceuticals can target a specific organ or lesion with enough radiation to destroy the abnormal tissue. Common pediatric applications include the treatment of hyperthyroidism (overactive thyroid) and thyroid cancer. Researchers are developing new and innovative treatments that may be available in the future.