Bone Metastasis Diagnosis
There are a number of ways to diagnosis bone metastasis:
Laboratory tests include the sampling of blood, urine, or other substances in the body. The results of these tests can be useful in a number of ways. Doctors can monitor a patient's disease over time and get an idea of the patient's response to medication(s) by drawing labs. If necessary, lab results can also help your doctor to make changes in your current course of treatment.
Your doctor may sample your blood and/or urine to help in diagnosing bone metastasis. A high level of an enzyme called alkaline phosphatase in the blood is common among bone metastasis patients. When abnormal bone tissue is being formed by cancer cells, levels of alkaline phosphatase increase. Therefore, high levels of this enzyme could suggest that a patient has bone metastasis. However, a high level of the enzyme is also found in growing children and in people with fractured bones that are healing. Therefore, a large amount of alkaline phosphatase in the blood does not always mean that a patient's cancer has metastasized to the bone.
A condition called hypercalcemia can also be detected through blood testing. Hypercalcemia results when there is a high level of calcium in the blood. An elevated level of calcium can alert your doctor to possible bone metastasis. However, hypercalcemia can result from other medical conditions as well.
Other procedures are usually done with lab tests to confirm a bone metastasis diagnosis.
Lytic lesions are most often detected through radiographic examination, also known as X-rays. The damaged area or lesion in the bone usually shows up as a dark spot on X-ray film. X-rays can provide information on the location of the tumor as well as it is general size and shape. Since this exam produces a two-dimensional or flat image, X-rays are often used with other diagnostic procedures. In this way, your doctor can gather more information for diagnosis or treatment of your bone metastasis.
Computerized Axial Tomography (CAT
CAT scans use X-ray images to look at organs and bones in the body. During the CAT scan, the machine actually rotates around the patient to produce multiple images. A computer then takes all of the images and makes them into a single image. In this way, a three-dimensional or more cubic view of the bone is produced. CAT scans are generally more sensitive than X-rays. Therefore, the scans can more clearly show the shape of the tumor and its exact location in the body. Your doctor can also tell the stage (extent) of the cancer by looking at your scan. If you will be undergoing radiation or surgical therapy, CAT scans can help your doctor plan your course of treatment. In this way, the cancer can be targeted and the healthy tissue preserved.
Magnetic Resonance Imaging (MRI)
Patients who experience bone pain but have normal bone scans may be referred for MRI. MRI can detect changes in the bone marrow caused by tumors or infections. Unlike the other diagnostic tests, MRI does not involve the use of radiation. Instead, it uses a magnetic field to image bones and tissues. It is helpful for imaging soft tissues such as that of the marrow, but CAT scans are better at imaging the bones.
Bone Marrow Aspiration and Biopsy
A sample of bone marrow is obtained through bone marrow aspiration or biopsy. Bone marrow samples can provide information on how much the cancer has spread and/or the stage of the metastasis. Bone marrow aspiration involves the insertion of a needle into the center of a bone, usually the hip bone. A pathologist then looks at the removed sample under a microscope. The pathologist can tell whether the marrow contains cancer or normal cells and can also determine the extent of the metastasis. Bone biopsy, however, involves the actual removal of a piece of tissue from the bone. Again, a pathologist can determine where the cells originated.
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