PAGET'S DISEASE SCANS, X-RAYS BLOOD TESTS EXPLAINED

Bone Scan | X-Rays | Blood and Urine Tests

BONE SCAN

• Commonly performed to diagnose the extent and activity of Paget’s disease.
• After diagnosis repeat scans are not necessary unless there is a marked increase in pain at the site of Paget's.
• This scan uses radiation to identify areas of bone where the cells are unusually active.
• A small amount of mildly radioactive chemical called an isotope is injected into a vein and then travels to the bones via the bloodstream.
• Abnormal bone absorbs more radioactivity than normal bone, so these areas are highlighted and picked up by the scanner as bright spots.
• Following the injection there is usually a wait of about 3 hours before the scan itself is taken by a “Gamma Camera”.
• There is no need to undress and apart from the injection (similar to having a blood test) it does not involve any pain.
• Although radiation is involved this exposure is minimal and safe.

Front and back views showing Paget’s in skull, left hip, tibia &shoulder, right ankle & pelvis

SCANS NOT ROUTINELY USED TO DIAGNOSE PAGET'S DISEASE

Magnetic resonance imaging (MRI) scanning

• Uses a strong magnetic field and radio waves
• Produces detailed pictures of soft tissue such as ligaments and muscles.
• Does not provide information about bone but can identify fractures
• May be useful in diagnosis of Paget’s in skull if there is nerve damage
  

Bone density (DXA) scanning

• Most commonly used diagnostic technique for osteoporosis.
• Measures bone density
• Usually scans bones in the lower spine and hip, two of the main areas at risk of fracture

Computed tomography (CT) scanning

• Uses several beams of x-rays simultaneously
• Gives very detailed pictures.
• Higher doses of radiation therefore only used for a very good medical reason.

X-RAYS

• An x-ray may be performed if Paget’s disease is suspected but it is often seen by chance when an x-ray has been performed for another reason.
• An x-ray only confirms the presence of Paget’s disease in one bone and therefore if it is suspected elsewhere an isotope bone scan may also be performed.
• X-ray appearances will vary depending on the severity of the disease but it is usually possible to see areas of expanded bone with thickening and disruption of the different layers of bone.
• Fissure fractures (cracks) that can occur if the bone is deformed and complete fractures can be seen on x-ray.
• Sarcoma which is an exceedingly rare type of cancer associated with Paget’s disease presents a different picture on x-ray.

BLOOD AND URINE TESTS

• Blood tests alone cannot diagnose Paget’s disease but when used in conjunction with scans, x-rays and medical examination they help to confirm the diagnosis. They are also helpful in measuring response to treatment.
• The most relevant marker for Paget’s disease is alkaline phosphatase which is an enzyme produced by bone. As there is increased activity in bone cells in Paget’s disease this alkaline phosphatase is often raised.
• The level for a person 60 years or older ranges from 20-120 units depending on the testing method used and a measurement twice the usual amount is strongly suggestive of Paget’s disease. If Paget’s disease is present in several bones rather than in a single bone alkaline phosphatase is likely to be higher.
• A raised alkaline phosphatase level can also be caused by liver problems or may present when a fracture is healing and this may need to be considered.
• A blood test measuring alkaline phosphatase can be performed at a GP’s surgery or at a hospital clinic. Due to a variety of measuring techniques, alkaline phosphatase ranges may vary slightly between different laboratories but this should not cause any major problems.
• Bone and cartilage contain collagen, which is released when bone tissue breaks down with fragments of collagen possibly being found in urine. High levels of these substances in the urine may indicate Paget's disease.
• A urine test is not generally used alone to diagnose the disease but may be used to monitor response to treatment.
  This test is more likely to be available in specialist hospital centres only.

Bone Scan | X-Rays | Blood and Urine Tests