Expanding Diagnostic Capabilities with SPECT/CT
Since mid 2006, Adventist Medical Center's Nuclear
Medicine Department has been pleased to offer new
technology and capabilities to Portland and the Northwest
Region. Cutting edge molecular technologies such as SPECT/CT
(Single-Photon Emission Computed Tomography/Computed Tomography
CAT scan) help to provide improved detection, diagnosis, and
therapy planning for cardiac, oncology, and neurology diseases
as well as many other disease problems.
The Symbia T® SPECT/CT system is the most sophisticated of its
kind in the Northwest and first SPECT/CT scanner in Portland.
This technology combines the important technologies of SPECT
and CT to create an important new diagnostic imaging system.
The anatomical information from a CT scan is merged with
biological function recorded by a SPECT scanner to produce an
image that records the shape and functional processes of living
tissues. By bringing together a CT scan's anatomical detail
that helps to pinpoint the location of abnormal tissue with
SPECT technology's ability to detect changes in patients'
molecular activity, SPECT/CT systems improve image clarity and
detail and help physicians make earlier more accurate
Patient benefits include earlier diagnosis, accurate staging
and localization, more precise treatment and patient
monitoring. With the state-of-the-art images that SPECT/CT
provides, patient outcomes are enhanced and unnecessary
procedures are avoided. Additionally, the system features a
comfortable patient opening and is designed to be very
accessible, flexible and comfortable while also providing
exceptional image quality and accuracy of diagnostic
A versatile system, the SPECT/CT scanner is used to image
patients with a variety of diseases including cardiac disease,
cancer and neurological disorders such as Alzheimer's disease.
In fact, one of the key advantages of the SPECT/CT, is the
ability to use a multitude of FDA- approved tracers to target
various tumors at their source and detect metastatic cancer
-sometimes too small to see otherwise- that has spread to other
parts of the body. The precise anatomic localization of cancers
and infections that the SPECT/CT systems provide enable
physicians to enhance therapy planning for individual patients
and accurately assess treatment.
Adventist Medical Center has provided comprehensive
nuclear medicine healthcare services to the Portland community
for more than 40 years. Expanding our diagnostic
capabilities with the addition of the Siemens Symbia T®
SPECT/CT will ensure our ability to continue to serve the
community with high-quality services and cost-effective care to
What is nuclear medicine?
Nuclear medicine is a specialized area of radiology that uses
very small amounts of radioactive materials, or
radiopharmaceuticals, to examine organ function and
structure. Nuclear medicine imaging is a combination of many
different disciplines, including chemistry, physics,
mathematics, computer technology, and medicine. This branch
of radiology is often used to help diagnose and treat
abnormalities very early in the progression of a disease,
such as thyroid cancer.
Because X-rays pass through soft tissue, such as intestines,
muscles, and blood vessels, these tissues are difficult to
visualize on a standard X-ray, unless a contrast agent is
used, which allows the tissue to be seen more clearly.
Nuclear imaging enables visualization of organ and tissue
structure as well as function. The extent to which a
radiopharmaceutical is absorbed, or "taken up," by a
particular organ or tissue may indicate the level of function
of the organ or tissue being studied. Thus, diagnostic X-rays
are used primarily to study anatomy, whereas nuclear imaging
is used to study organ and tissue function.
A tiny amount of a radioactive substance is used during the
procedure to assist in the examination. The radioactive
substance, called a radionuclide (radiopharmaceutical or
radioactive tracer), is absorbed by body tissue. Several
different types of radionuclides are available, including
forms of the elements technetium, thallium, gallium, iodine,
and xenon. The type of radionuclide used will depend on the
type of study and the body part being studied.
After the radionuclide has been administered and has
collected in the body tissue under study, radiation will be
given off. This radiation is detected by a radiation
detector. The most common type of detector is the gamma
camera. Digital signals are produced and stored by a computer
when the gamma camera detects the radiation.
By measuring the behavior of the radionuclide in the body
during a nuclear scan, the doctor can assess and diagnose
various conditions, such as tumors, abscesses, hematomas,
organ enlargement, or cysts. A nuclear scan may also be used
to assess organ function and blood circulation.
The areas where the radionuclide collects in greater amounts
are called "hot spots." The areas that do not absorb the
radionuclide and appear less bright on the scan image are
referred to as "cold spots."
In planar imaging, the gamma camera remains stationary. The
resulting images are two-dimensional (2D). Single photon
emission computed tomography, or SPECT, produces axial
"slices" of the organ in question because the gamma camera
rotates around the patient. These slices are similar to those
performed by a CT scan. In certain instances, such as PET
scans, three-dimensional (3D) images can be performed using
the SPECT data.
Scans are used to diagnose many medical conditions and
diseases. Some of the more common tests include the
Renal scans. These are used to examine the kidneys and to
detect any abnormalities, such as tumors or obstruction
of the renal blood flow.
Thyroid scans. These are used to evaluate thyroid
function or to better evaluate a thyroid nodule or mass.
Bone scans. These are used to evaluate any degenerative
and/or arthritic changes in the joints, to detect bone
diseases and tumors, and/or to determine the cause of
bone pain or inflammation.
Gallium scans. These are used to diagnose active
infectious and/or inflammatory diseases, tumors, and
Heart scans. These are used to identify abnormal blood
flow to the heart, to determine the extent of the damage
of the heart muscle after a heart attack, and/or to
measure heart function.
Brain scans. These are used to investigate problems
within the brain and/or in the blood circulation to the
Breast scans. These are often used in conjunction with
mammograms to locate cancerous tissue in the breast.
How are nuclear medicine scans done?
As stated above, nuclear medicine scans may be performed on
many organs and tissues of the body. Each type of scan
employs certain technology, radionuclides, and procedures.
A nuclear medicine scan consists of three phases: tracer
(radionuclide) administration, taking images, and image
interpretation. The amount of time between administration of
the tracer and the taking of the images may range from a few
moments to a few days, depending on the body tissue being
examined and the tracer being used. Some scans are completed
in minutes, while others may require the patient to return a
few times over the course of several days.
One of the most commonly performed nuclear medicine
examinations is a heart scan. Myocardial perfusion scans and
radionuclide angiography scans are the two primary heart
scans. In order to give an example of how nuclear medicine
scans are done, the process for a resting radionuclide
angiogram (RNA) scan is presented below.
Although each facility may have specific protocols in place,
generally, a resting RNA follows this process:
The patient will be asked to remove any jewelry or other
objects that may interfere with the procedure.
If the patient is asked to remove clothing, he or she
will be given a gown to wear.
An intravenous (IV) line will be started in the hand or
The patient will be connected to an electrocardiogram
(ECG) machine with electrodes (leads) and a blood
pressure cuff will be attached to the arm.
The patient will lie flat on a table in the procedure
The radionuclide will be injected into the vein to "tag"
the red blood cells. Alternatively, a small amount of
blood will be withdrawn from the vein so that it can be
tagged with the radionuclide. The radionuclide will be
added to the blood and will be absorbed into the red
After the tagging procedure, the blood will be returned
into the vein through the IV tube. The progress of the
tagged red blood cells through the heart will be traced
with a scanner.
During the procedure, it will be very important to lie as
still as possible, as any movement can adversely affect
the quality of the scan.
The gamma camera will be positioned over the patient as
he or she lies on the table, and will obtain images of
the heart as it pumps the blood through the body.
The patient may be asked to change positions during the
test; however, once the position has been changed, the
patient will need to lie still without talking.
After the scan is complete, the IV line will be
discontinued, and the patient will be allowed to leave,
unless the doctor gives different instructions.