February 23, 2011
Diagnostic Imaging Tests
Imaging tests are used to diagnose diseases, determine treatment plans, assess response to therapy and observe for disease recurrence. Here are a few common imaging techniques:
X-Rays consist of a small burst of radiation aimed at and passed through the body. Different body parts absorb the x-rays in varying degrees. Bones appear white, soft tissue shows up in shades of gray, and air appears black. X-rays are useful for viewing the skeletal system and investigating problems with soft tissues.
MRI (Magnetic Resonance Imaging) uses a powerful magnetic field and radio frequency pulses to produce detailed pictures of organs, soft tissues, bone and other internal body structures. The MRI scanner creates a strong magnetic field, exposing hydrogen atoms in water molecules in the body to radio waves and causing them to move into different positions. The way these hydrogen atoms move and then move back into their original position once the scanner is turned off provides information about tissue density in the area that has been scanned.Some MRI examinations may require the patient to swallow contrast material or receive an injection of contrast into the bloodstream. Detailed images from MRIs allow physicians to better evaluate various parts of the body and determine the presence of certain diseases that may not be assessed adequately with other imaging methods.
CAT or CT (Computerized Axial Tomography) scans combine a series of X-ray views taken from many different angles to produce cross-sectional images of the bones and soft tissues inside your body. Numerous x-ray beams and a set of electronic x-ray detectors rotate around you, measuring the amount of radiation being absorbed throughout your body. At the same time, the examination table is moving through the scanner, so that the x-ray beam follows a spiral path. An iodine dye (contrast material) is often used to make structures and organs easier to see on the CT pictures. The dye may be used to check blood flow, find tumors, and look for other problems. If contrast material is used, it will be swallowed, injected through an intravenous line (IV) or administered by enema, depending on the type of examination.
PET (Positron Emission Tomography) scans are used to detect cancer and to examine the effects of cancer treatment. The scan is used to characterize metabolic (charges in cells as they use energy to grow) changes, rather than structural (size or texture of tissues/organs) changes. PET scans use a radioactive substance tagged with a glucose derivative. All tissues use glucose for energy but cancerous tissue uses more glucose than normal tissue to grow and divide, and will show up as a bright (hypermetabolic) spot on the PET. Our physicians use PET/CT scans. This means the images from both PET and CT are fused to show what tissue is metabolically active (PET) and the location (CT).
MUGA (Multiple Gated Acquisition) scans check to see if your heart is pumping blood properly. During the test, a small amount of a radioactive material, called a tracer, is injected into a vein, usually in your arm. This material is much like a dye and binds to your red blood cells (blood cells that carry oxygen throughout your body), making it easier to see how blood moves through your heart. After you have received the tracer, you will lie on a table and the technician will put a gamma camera (a special camera that uses gamma rays together with a tracer) above you and take pictures of your heart.
Biopsy is the removal of a sample of tissue from the body for examination. The tissue will be examined under a microscope to assist in diagnosis. Therefore, only very small samples are needed. Any organ in the body can be biopsied using a variety of techniques, some of which require major surgery while others do not even require local anesthesia. After the biopsy specimen is obtained by the doctor, it is sent for examination to another doctor, called a pathologist, who prepares a written report (pathology report) with information designed to help the primary doctor manage the patient’s condition properly.
Ultra Sound involves exposing part of the body to high-frequency sound waves to produce pictures of the inside of the body. Because ultrasound images are captured in real-time, they can show the structure and movement of the body’s internal organs, as well as blood flowing through blood vessels. Sound waves are sent through the body and the echoing waves are recorded. As the sound waves bounce off internal organs, fluids and tissues, tiny changes in the sound’s pitch and direction are recorded and turned into a real-time picture. Ultrasound can detect changes in appearance of organs, tissues, and vessels or detect abnormal masses, such as tumors.
BUN/CREAT test is a blood test used to measure kidney function. This is a necessary test if you are going to have a scan with contrast. It is ordered as part of the Basic or Comprehensive Metabolic Panel (BMP or CMP). Your blood must be tested within 30 days of the scan.
Insurance Authorizations
MRIs, CT scans, PET scans and MUGA scans have to be pre-authorized with certain insurance companies. Please be sure that the front desk is aware of any tests you are having so we can contact your insurance company if necessary.
(Information adapted from: www.radiologyinfo.org and www.healthcommunities.com)
April 21, 2010
Understanding Blood Counts
The results from a CBC (Complete Blood Count) test can help provide basic information about your health.
- It can detect a health condition before symptoms arise
- Confirm a health condition exists
- Identify the cause of symptoms
- Test if your medication is working
- Rule out a disease
- Establish a baseline comparison for future tests
The following is an explanation of certain items included in a CBC test report:
White Blood Cells (normal range = 4.3-11.0)
WBC’s are part of your immune system and help the body fight illness or infection. An increase in WBC’s means you may have an infection, and a decrease in WBC’s means you may by at risk of getting an infection.
Hemoglobin (normal range = 14-18 for males; 12-16 for females)
Hemoglobin is an iron-rich protein that carries oxygen and makes blood red.
Hematocrit (normal range = 42-54% for males; 36-48% for females)
Hematocrit reflects the amount of space in the blood that is occupied by Red Blood Cells (RBC’s carry oxygen from the lungs to the rest of the body).
Low hemoglobin and hematocrit may be cause by anemia, massive bleeding, malnutrition, kidney or liver disease, and medications used to treat cancer. An increase in hemoglobin and hematocrit may be cause by dehydration or by certain diseases.
Platelets (normal range = 150-450)
Platelets are sticky cells that help to clot blood, which stops or prevents bleeding. A decreased platelet count is associated with bleeding, and an increased platelet count is associated with clotting disorders.
For further information on blood test, contact your healthcare provider.
Source: Quest Diagnostics. (2010). ”Understanding Your Blood Test” brochure.
March 29, 2010
PET and PET/CT Scans
Many different imaging techniques can be used in cancer management including; X-Ray, MRI, Ultrasound, CT (CAT) Scan, PET Scan, and PET/CT. Tests are used to diagnose and stage cancer, determine treatment plans, assess response to therapy and observe for disease recurrence. The following post focuses on information about PET/CT Scans, taken from a lecture given by Dr. Lisa Flaum.
PET (Positron Emission Tomography) scans are used to detect cancer and to examine the effects of cancer treatment. The scan is used to characterize metabolic (charges in cells as they use energy to grow) changes, rather than structural (size or texture of tissues/organs) changes. PET scans use a radioactive substance tagged with a glucose derivative. All tissues use glucose for energy but cancerous tissue uses more glucose than normal tissue to grow and divide, and will show up as a bright (hypermetabolic) spot on the PET.
Our physicians use PET/CT scans. This means the images from both PET and CT are fused to show what tissue is metabolically active (PET) and the location (CT) of the abnormality, on a single set of images. Metabolic changes tend to occur more rapidly than structural changes, so PET scans are useful in identifying if a patient is responding to treatment, or if he/she needs to change to an alternate therapy. Scans can also help to avoid unnecessary surgery or other procedures and to distinguish between tumors and scar tissue.
Uses of a PET Scan
- Diagnosing cancer
- Staging cancer
- Monitoring response to treatment
- Restaging after treatment is completed
- Observing for recurrence
- Planning for radiation treatment
Getting ready for your PET Scan
- Bring with you, or fax ahead of time, a written order from the referring doctor
- Have your doctor’s office obtain prior authorization if your insurance requires
- Fast for at least 4 hours
- Drink a lot of water and empty the bladder right before
- Avoid strenuous exercise for at least 24 hours prior
At the Imaging Center
- A radioactive sugar (FDG) will be injected into your body
- You will rest for 1 hour while the FDG circulates into your tissues
- Your body will be scanned from mid-thigh to head
- The scan itself takes approximately 25 minutes
The images are then processed, interpreted and generated into a report for your physician to go over with you. Reports are completed approximately 48 hours after the scan.
What diagnostic tests are best for you can only be determined by you and your physician. For specific questions on PET scans, ask your physician or the facility where you are planning on having the scan done.
