I Have Cancer - What Imaging Tests Will I Be Getting?
The multitude of medical imaging techniques provide a visual picture that permits analysis of internal organs, tissues, and structures. Medical imaging establishes a repository of normal anatomy and physiology that, by comparison make it possible to identify abnormalities and disease. In principle, imaging tests to identify a suspected tumor begins with the simplest tests initially and proceed in an orderly stepwise manner to more involved and costly procedures. In general radiography provides information in the following circumstances:
· To diagnostically define the presence or absence of a tumor
· In situations in which a tumor is identified imaging techniques are used as staging tests to determine the presence or absence of metastatic spread
· In patients with cancer imaging is used to determine response to therapy and follow-up
An ultrasound exam uses high-energy sound waves that echo off tissues inside your body. The echoes are aggregated by a computer, and pictures, referred to as a sonogram are generated. The ultrasound is an excellent non-invasive screening exam to identify potential tumors, lumps, masses, and lymph nodes.
There are two forms of radiographic images, projection radiography and fluoroscopy. Both modalities use a low dose of penetrating electromagnetic radiation to create 2-D pictures inside your body. Projectional radiographs produce two-dimensional images that are useful in the detection of pathology of the skeletal system, lungs, as well as for detecting some disease processes in soft tissue. A routine chest X-ray, the most common radiograph, used to identify lung diseases such as pneumonia, lung cancer, or pulmonary edema; an abdominal x-ray, can detect bowel (or intestinal) obstruction, free air (from visceral perforations), and free fluid (in ascites). X-rays may also be used to detect pathology such as gallstones and kidney stones.
Fluoroscopy produces real-time images of internal structures of the body in a similar fashion to radiography, but employs a constant input of x-rays, at a lower dose rate. Contrast media, such as barium, iodine, and air are used to visualize internal organs as they work. Fluoroscopy is also used in image-guided procedures when constant feedback during a procedure is required.
A CT scan, or computed tomography (CT) is an imaging procedure that uses special x-ray equipment to create detailed images of areas inside the body. A CT scan uses an x-ray machine linked to a computer to take a series of pictures, at different angles, to define internal organs and structures. of your organs from different angles. These pictures are used to create detailed 3-D images of the inside of your body. A dye is often administered to swallow by mouth, or intravenously to enhance the images. In addition to its use in cancer, CT is widely used to help diagnose circulatory system diseases and conditions, such as coronary artery disease blood vessel aneurysms, blood clots, spinal conditions and a multitude of diseases of the bowel, kidneys, skeletal system and brain.
An MRI uses a powerful magnet to generate radio waves to polarize and excite hydrogen nuclei of water molecules in human tissue, producing a detectable signal which is spatially encoded, resulting in images of the body which can show the difference between healthy and unhealthy tissue. Like CT scans, an MRI traditionally creates a 3-D images; however, unlike CT, MRI does not involve the use of ionizing radiation and is therefore not associated with the same health hazards. The MRI produces different pulse sequences that can be used for specific diagnostic imaging to differentiate tissue characteristics. The applications of MRI detecting disease in various organs continues to expand, including liver studies, breast tumors, pancreatic tumors, and assessing the effects of chemotherapy agents on cancer tumors.
A nuclear scan referred to as a radionuclide scan
uses radioactive material to take pictures the inside of body including areas and structures where cancer cells may exist. Radionuclide scanning is used to diagnose, stage, and monitor disease. The scan requires the intravenous administration of a small of a radioactive chemical. Different radionucleotides travel through the bloodstream and aggregate in different organs and structures. A specialized camera detects the radionucleotide and a computer forms images of the aggregated chemical tracer build up. After the scan, the radioactive material in your body will lose its radioactivity over time. It may also leave your body through your urine or stool.
Bone scans are a specific type of nuclear scan that utilize the isotype Technetium to locate abnormal areas or damage in the skeletal system that may represent cancer in a bone. These areas are called “hot spots.”
A PET scan is a procedure in which a small amount of radio-labeled glucose is intravenously injected and the scanner is used to make detailed, 3-D, computerized pictures of areas inside the body where glucose is concentrated. Because cancer cells take up more glucose than normal cells, the pictures can be used to find cancer cells in the body. Modern scanners integrate PET-CT and PET-MRI functionality to optimize the image reconstruction involved with positron imaging. The resultant hybrid of functional and anatomic imaging information is a useful tool in non-invasive diagnosis and patient management.