Scott L. Havsy, DO, JD, DAAPM
Certified in Pain Management

 

 

What is a Bone Scan?

A bone scan is a nuclear scanning test that identifies new areas of bone growth or bone destruction.  The test is performed to evaluate damage to the bones, detect cancer that has spread (metastasized) to the bones, and monitor conditions that can affect the bones including infection, inflammation or trauma such as occult stress fractures.  A bone scan can often detect a problem days to months earlier than a regular X-ray test.

To perform the test, a radioactive tracer substance is injected into a vein in the arm.  The tracer then travels through the bloodstream and into the bones.  Areas that absorb little or no amount of tracer appear as dark or "cold" spots, which may indicate a lack of blood supply to the bone (bone infarction) or the presence of certain types of bone cancer. Areas of rapid bone growth or repair absorb increased amounts of the tracer and show up as bright or "hot" spots in the pictures.  Hot spots may indicate the presence of a tumor, a fracture, or an infection.  A bone scan may be done on the entire body or just a part of it.

Why Perform a Bone Scan?

A bone scan can:

  • Determine whether a cancer from another area, such as the breast, lung, kidney, thyroid gland, or prostate gland, has spread to the bone.  
  • Help diagnose the cause or location of unexplained bone pain, such as ongoing low back pain.  A bone scan may be done initially to help determine the location of an abnormal bone in complex bone structures such as the foot or spine.  Follow-up evaluation then may be done with a computed tomography (CT) scan or magnetic resonance imaging (MRI).
  • Help diagnose broken bones, such as a hip fracture or a stress fracture, not clearly seen on X-ray.
  • Detect damage to the bones caused by infection or other conditions.

How A Bone Scan is Performed?

  • A bone scan is usually done by a nuclear medicine technologist. The scan pictures are usually interpreted by a radiologist or nuclear medicine specialist.

  • A radioactive tracer is injected into a vein and it takes about 1 to 3 hours for the tracer to move throughout your body.  The procedure is performed with you lying on your back on a table while a large scanning camera will be positioned closely above you.  It may move slowly above and around your body, scanning for radiation released by the tracer and producing pictures as the tracer moves into your bones.  The imaging device does not produce any radiation, so there is no additional radiation exposure.

  • You may be asked to move into different positions so the area of interest can be visualized from multiple angles.  The procedure takes about 1 hour to complete.

Risks of a bone Scan:

  • Allergic reactions to the tracer are rare. Most of the radioactive tracer will be eliminated from your body within a day. The amount of radiation is so small that it is not a risk for people to come in contact with you following the test.

  • There nay be some soreness or swelling may develop at the injection site.  There is always the possibility of a slight risk of damage to cells or tissue from being exposed to any radiation, including the low level of radiation released by the radioactive tracer used in a bone scan.

Results:

A bone scan identifies new areas of bone growth or breakdown.

Bone scan

Normal Result:

The radioactive tracer is evenly distributed among the bones.  There are no areas of abnormally high or low accumulation are seen.

Abnormal Result:

The tracer may accumulate in certain areas of the bone, indicating one or more hot spots.  A hot spot may be caused by a fracture that is healing, bone cancer, bone infection (osteomyelitis), arthritis, or a disease of abnormal bone metabolism).

There may be a cold which indicates certain areas of the bone may lack the presence of the tracer. A cold spots may be caused by a certain type of cancer (such as multiple myeloma) or lack of blood supply to the bone (bone infarction).

 Additional areas to think about:

 

 

What is an MRI scan?

MRI (magnetic resonance imaging) is an imaging technique that has been in use since the beginning of the 1980s.  The MRI scan uses magnetic and radio waves so there is no exposure to harmful X-rays.

How does an MRI scanner work?

  • The patient lies inside a large, cylinder-shaped magnet tube structure.  Radio waves that are many thousands of times stronger than the magnetic field of the earth are then sent through the body.  These waves affect the body's atoms, forcing the nuclei into different positions.  As the atoms move back into place, they send out radio waves of their own. The scanner then picks up these signals and a computer turns them into a picture.  

What does an MRI scan show?  

  • Using an MRI scanner, it is possible to make pictures of almost all the tissue in the body.  Our body consists mainly of water, and water contains hydrogen atoms.  The tissue that has the least hydrogen atoms (such as bones) turns out the darkest, while the tissue that has many hydrogen atoms (such as fatty tissue) looks much lighter.  By changing the timing of the radio wave pulses, it is possible to gain information about the different types of tissues that are present.

  •  MRI scans also provide clear pictures of other parts of the body that are surrounded by bone tissue, so the technique is useful when examining the brain and spinal cord.

  • Because the MRI scan gives very detailed pictures, it is very useful when it comes to finding tumors (benign or malignant abnormal growths) in the brain. If a tumor is present the scan can also be used to find out if it has spread to nearby brain tissue.  MRI's can also be used to examine the joints, spine and sometimes the soft parts of your body such as the liver, kidneys and spleen.

 How does an MRI scan differ from a CT scan?  

  • With an MRI scan it is possible to take pictures from almost every angle; however, a CT scan only shows pictures in a horizontal direction.  The difference between normal and abnormal tissue is often clearer on the MRI scan than on the CT scan.

How is an MRI scan performed?

  • The scan is usually done as an outpatient procedure, which means that the patient can go home after the test.  During the scan, it is important to lie completely still.  For this reason it might be necessary to take a mild CNS sedative or an anti-anxiety agent.  For those who are claustrophobic (have a fear of confined places) open MRI's are available.  The resolution is less but the scans are still considered very good.  Lately, standing or sitting MRI's have become available.  These are useful when the affect of gravity is important.  For example, a sitting MRI scan is useful to demonstrate instability in the spine.  Flexion and extension views can also be performed with the newer MRI scans. 

Cautions:

  • Since you are exposed to a magnetic field during the MRI scan, it is important not to wear jewelry or any other metal objects.

  •  It is also important for the patient to inform medical staff if they use electrical appliances, such as a hearing aid or pacemaker, or have any metal in their body such as surgical clips.  Orthopedic metal ware such as artificial hips or bone screws is not normally a problem.

Is an MRI scan dangerous?

  • There are no known dangers or side effects connected to an MRI scan. The test is not painful as you cannot feel it. Since radiation is not used, the procedure can be repeated without problems.  There is a small theoretical risk to the fetus in the first 12 weeks of pregnancy, and therefore scans should not performed on pregnant women during this time.

     

 

What is a CT Scan?

Computed Tomography, sometimes called a CAT scan, uses special x-ray equipment to obtain images from different angles around the body and then uses a computer to process the information showing a cross-section of body tissues and organs.

CT imaging is particularly useful because it can show several types of tissue such as bone, soft tissue and blood vessels with increased clarity as compared to plain x-rays. Using specialized equipment and expertise to create and interpret CT scans of the body, radiologists can more easily diagnose problems such as cancer, trauma and musculoskeletal disorders.

What are some common uses of the procedure?

  • CT scanning is one of the best tools for studying the chest and abdomen because it provides detailed, cross-sectional views of all types of tissue.  CT examinations are often used to plan and properly administer radiation treatments for tumors, to guide biopsies and other minimally invasive procedures and to plan surgery and determine surgical resectability.  CT can clearly show even very small bones as well as surrounding tissues such as muscle and blood vessels.  This makes it invaluable in diagnosing and treating spinal problems such as stenosis or narrowing of the spinal canal as well as injuries to the hands, feet and other skeletal structures.  CT images can also be used to measure bone mineral density for the detection of osteoporosis.  In cases of trauma CAT scans can quickly identify injuries to the liver, spleen, kidneys or other internal organs.

How does the procedure work?

  • Very small, controlled amounts of x-ray radiation are passed through the body as different tissues absorb radiation at different rates.  As with plain radiology, an image of the inside of the body is captured when special film is exposed to the absorbed x-rays; however, with a CT scan, the film is replaced by an array of detectors that measure the x-ray profile.

  • A rotating gantry inside the CT scanner has an x-ray tube mounted on one side and an arc-shaped detector mounted on the opposite side.  An x-ray beam is emitted in a fan shape as the rotating frame spins the x-ray tube and detector around the patient.  Each time the x-ray tube and detector make a 360-degree rotation and the x-ray passes through the patient's body, the image of a thin section is acquired.  During each rotation the detector records about 1,000 images (profiles) of the expanded x-ray beam.  Each profile is then reconstructed by a dedicated computer into a two-dimensional image of the section that was scanned.  Multiple computers are typically used to control the entire system, resulting in a very detailed, multidimensional view of the body's interior.

  • A relatively new technique, spiral (helical) CT has improved the accuracy of the CT for many diseases.  The term "spiral CT" comes from the shape of the path taken by the x-ray beam during scanning.  The examination table advances at a constant rate through the scanner gantry while the x-ray tube rotates continuously around the patient, tracing a spiral path through the patient. This spiral path gathers continuous data with no gaps between images.

  • With the spiral CT, refinements in detector technology support faster, higher-quality image acquisition with less radiation exposure.  These instruments provide either faster scanning or higher resolution images.  A spiral scan can usually be obtained during a single breath hold.  This allows scanning of the chest or abdomen in 10 seconds or less. Such speed is beneficial in all patients but especially in elderly, pediatric or critically ill patients, populations in whom the length of scanning was often problematic. The multidetector CT also allows applications like CT angiography to be more successful.

  • With conventional CT, small lesions may go undetected when a patient breathes differently on consecutive scans because lesions may be missed by unequal spacing between scans. The speed of spiral scanning and a single breath hold increase the rate of lesion detection.

How is the CAT scan performed?

  • A CT examination often requires the use of different contrast materials to enhance the visibility of certain tissues or blood vessels.  The contrast material may be swallowed, injected through an IV directly into the blood stream or administered by enema, depending on the type of examination.  

  • A CT examination usually takes five minutes to half an hour. When the exam is over the patient may be asked to wait until the images are examined to determine if more images are needed.

What are the benefits vs. risks?

  • Benefits

    • Unlike other imaging methods, CT scanning offers detailed views of many types of tissue including the lungs, bones, soft tissues and blood vessels.

    • CT scanning is painless, noninvasive and accurate.

    • CT examinations are fast and simple. For example, in trauma cases they can reveal internal injuries and bleeding quickly enough to help save lives.

    • Diagnosis made with the assistance of CT can eliminate the need for invasive exploratory surgery and surgical biopsy.

    • CT scanning can identify normal and abnormal structures, making it a useful tool to guide radiotherapy, needle biopsies and other minimally invasive procedures.

    • CT has been shown to be a cost-effective imaging tool for a wide range of clinical problems.
       

  • Risks
     

    • CT does involve exposure to radiation in the form of x-rays, but the benefit of an accurate diagnosis far outweighs the risk.  The effective radiation dose from this procedure is about the same as the average person receives from background radiation in three years.


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What is a Plain X-ray?

  • X-ray examinations can identify many structures in the body.  They are especially good at looking at the chest, limbs and the spine.  The test relies on the fact that different parts of the body stop x-rays better than others.  Lungs are mostly gaseous in nature and will appear black as the x-rays pass straight through. Since bones are high in calcium, they stop x-rays and will appear white.

  • X-rays are ionizing radiation, generated by an x-ray tube.  The rays are directed by shielding down a narrow pathway towards the part of the body being examined.  On the opposite side of the body, an x-ray film is positioned in the path of the x-rays and the film becomes exposed.  The x-ray film is then processed and an image is generated.  Where the x-ray passes through the body easily, that part of the film will end up black. Where x-rays are stopped, the film will be white.

  • Depending on the X-ray requested by your doctor, the exam can take anywhere from 2-3 minutes up 20 minutes per examination.  Depending on the area examined, multiple views may be taken.  In the cervical and lumbar spine, lateral sidebending views are ordered to assess loss of motion, while flexion and extension views assess instability. 

  • Unlike MRI scans, plain X-rays give off a lot of radiation and special care should be taken depending on your situation.

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What is a Nerve Study?

Nerve studies are indicated to access complaints of numbness or tingling in the arms or legs as well as muscle weakness.  Nerves control the muscles in the body using electrical impulses, and these impulses cause the muscles to react in certain ways.  Pain due to a neuropathy or radiculopathy can be quite painful.

There are three types of nerves studies which include Electromyography (EMG), nerve conduction studies (NCV) and Current Perception Threshold (CPT) testing.  All access various aspects of the nervous system,

Why Perform Nerve Studies?
 

  • Nerve studies are performed to access the integrity of the nerve or the motor endplate of the corresponding muscle.  A normal study does not exclude the likelihood of nerve damage as there may not be enough Wallerian degeneration present. 

  • EMG abnormalities are late stage findings of nerve damage, therefore in a normal EMG study, nerve damage may be present.  Since nerve conduction tests measures only the C-fibers which account for only 10% of the actual nerve bundle, a normal nerve conduction test does not rule out nerve damage as it does not test nearly 90% of the other nerve fibers present, i.e. the A-beta and A-delta fibers.

What are the Types of Nerve Studies?
 

  • An electromyogram (EMG) measures the electrical impulses of muscles at rest and during contraction phase, while nerve conduction studies measure the nerve conduction velocity, and helps determine how well individual nerves can transmit electrical signals.  The major drawback to the nerve conduction velocity is that this test measures the myelinated C-fibers which account for only 10% of the nerve bundle.  This means that the test can miss 90% of nerve injuries. 

  • Measuring the electrical activity in muscles and nerves can help detect the presence, location, and extent of diseases that can damage muscle tissue or nerves.  In the case of nerve injury, the actual site of nerve damage can often be located. EMG and nerve conduction studies are usually done together to provide more complete information.

An electromyogram (EMG) is done to:
 

  • Diagnose diseases that damage muscle tissue, nerves, or the junctions between the nerve and muscle (neuromuscular junctions).  These disorders include a herniated disc.
  • Evaluate the cause of weakness, paralysis, involuntary muscle twitching, or other neurological symptoms such as problems stemming from muscles, nerves supplying a muscle, the spinal cord, or the area of the brain that controls a muscle function.

Nerve conduction studies are done to:
 

  • Detect and evaluate damage to the peripheral nervous system, which includes all the nerves that lead away from the brain and spinal cord and the smaller nerves that branch out from those nerves.  Nerve conduction studies are often used to help diagnose nerve disorders, such as carpal tunnel syndrome.
  • Identify the location of abnormal sensations, such as numbness, tingling, or pain.
  • Current Perception Testing (CPT) is performed to evaluate symptoms such as arm and leg pain or numbness, Carpal Tunnel Syndrome and polyradiculopathy due to metabolic conditions such as diabetes.  CPT testing measures all the associated nerve bundles and is highly specific for nerve injuries, especially in the acute phase.

How an Electromyogram is Performed?
 

  • After the skin over the areas to be tested is cleaned with an antiseptic solution, an electrode that is attached by wires to a recording machine that combines the reference point and a needle for recording is inserted into a specific muscle to be tested.

  • The electrical activity in that muscle is then recorded while the muscle is at rest. You will be asked to contract the muscle gradually increasing the force while the electrical activity in the muscle is recorded.  The needle may be repositioned a number of times to record the electrical activity in different areas of the muscle or in different muscles.

  • The electrical activity in the muscle is displayed as wavy and spiky lines on a special monitor.  You may also hear machine gun-like popping sounds when you contract the muscle on a loudspeaker.  An EMG may take 30 to 60 minutes and is often uncomfortable, requiring an analgesic.

How a Nerve Conduction Study is Performed?
 

  • For this test, several flat metal disc electrodes are attached to the skin.  A shock-emitting electrode is placed directly over the nerve to be studied, and a recording electrode is placed over the muscles supplied by that nerve. Brief electrical pulses are administered to the nerve, and the time it takes for the muscle to contract in response to the electrical pulse is recorded.  The speed of the response is called the conduction velocity.  The corresponding nerves on the other side of the body may be studied for comparison.

  • Nerve conduction studies are usually done before an EMG if both tests are being performed on the same day. Nerve conduction testing may take from 15 minutes to 1 hour or more, depending upon how many areas of the body are studied.

  • With the nerve conduction studies, you will feel a brief, burning pain, a tingling sensation, and a twitching of the muscle each time the electrical pulse is applied.  This testing can also be quite uncomfortable.

How is a CPT Exam Performed?
 

  • After the skin is cleaned, gold plated electrodes with gel are placed over the areas to be tested and these electrodes are connected wires to the CPT testing device.  After an intensity alignment which measures the minimal stimulus the test subject can perceive, each nerve is tested by producing a stimulus that hones in on the actual perception threshold.  The recorded information is then inputted into the computer software which analyzes each measurement.   A report is then produced which analyzes each nerve measurement.

What is Current Perception Testing (CPT)?
 

  • Neurometer CPT electrodiagnostic devices perform sensory nerve conduction threshold (sNCT) evaluations by determining current perception threshold (CPT) levels which measures the amount of electrical impulses necessary to stimulate a nerve fiber at various frequencies. 

  • The Neurometer CPT/C device utilizes three unique neuro-selective electrical stimuli to perform extremely sensitive quantitative assessments of all major subpopulations of sensory nerve fibers at any cutaneous site.  The non-invasive, painless stimulus makes the Current Perception Threshold (CPT) examination an ideal replacement for procedures hampered by low patient compliance.  The extreme sensitivity of the CPT evaluation enables quantification of the hyperesthesia that precedes progressive nerve impairment, as well as hypoesthetic conditions.

Modes of operation include single and double blind, manual and automated CPT determinations, with customizable application-specific modes available.  The Ranged CPT (RCPT) mode allows fast and accurate evaluations in only minutes per site subject. The nociceptive (NCPT) and pain perception threshold (PTT) mode provides a reproducible, non-invasive and atraumatic method for obtaining pain thresholds in small and large fibers (if present).

Risks:
 

  • Though an electromyogram (EMG) is very safe, you can develop small bruises or swelling at some of the needle insertion sites.  Since the needles are sterilized, there is little chance of developing an infection.

  • There are no risks associated with nerve conduction studies.  Nothing is inserted into the skin, so there is no risk of infection.  The voltage of electrical pulses is not high enough to cause an injury or permanent damage.

  • As with NCV testing, there are no risks with CPT testing.  The amount of stimulus is very much less than the NCV test and is in essence a painless test that yields more information.

 

What the Results Mean

  • Abnormal Results:

    • Spontaneous electrical activity detected in a muscle at rest suggests that there is a problem with the nerve supply to the muscle in an EMG.  This kind of activity can also be caused by inflammation or disease in the muscle tissue.  Abnormal levels and duration of electrical discharges during muscle contraction suggests the presence of a muscle or nerve disorder, such as a herniated disc.

    • In nerve conduction studies, the speed of nerve impulse transmission (i.e. conduction velocity) may be slower or faster than what is considered normal for the tested nerve.  Slower conduction velocities may be caused by injury such as carpal tunnel syndrome).

    • In CPT testing, the test results are compared to a normative database and measurements are determined that include comparing the nerves tested to different nerves tested on the same side as well as the opposite corresponding nerve as well as to matched nerves on the opposite extremity or area.

    • The software then determines if the CPT measurement is hyperesthetic (requiring less than normal stimulation), hypoesthestic (requiring more than the normal stimulus) or normal. 

    • As with all nerve testing, the results should be correlated with other tests such as MRI and CT scans and a physical exam and history of the patient.

 

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About Blood Tests?

  • Blood tests are often non-specific for any particular condition; however they assist the doctor in diagnosing medical problems (such as ruling in or ruling out certain conditions).

  • For example, when taking narcotics or anti-inflammatories long term, a Chemistry profile would be indicated to assess the status of liver and kidney functions, where a CBC would determine if you are anemic.

  • Certain blood tests such as a sedimentation rate (ESR) may be elevated in certain inflammatory diseases while an HLA-B27 test may be positive for those suffering from an inflammation of the sacral iliac joint.

  • Other tests such as an ANA (anti-nuclear antibody) and RA Latex help the physician determine if you are suffering from rheumatoid arthritis of one its variations. Tests such as a Serum Protein Electrophoresis help determine if you are suffering from multiple myeloma, a cancerous cause of bone pain.

  • Often times, when drawing blood tests for one problem, the results may lead a physician to evaluate another area. Regardless, in the chronic pain setting, blood tests, along with a history and physical exam, as well as other medical tests, are used to help diagnose your medical problem.
     

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