AN IMAGE OF HEALTH
During the course of your care, your primary physician or physiotherapist may send you to a medical imaging clinic for an scan. These scans may be X-Rays, Ultrasounds, or other kinds of investigations. The kind of scan you are asked to complete will depend on the problem your clinician is trying to investigate, and it's important to know the reason behind undertaking that particular scan.
THE WHY
Your clinician may ask you to have a scan to get more information about a problem. Scans allow us to see beneath the level of the skin, and to look at the muscles, bones, joints, vessels and nerves that make up the human body in great detail. When we look at these images, we can see if things are out of order or not quite right, and this information is put into a report that provides more information to your clinician, and which helps them choose the right course of care for you.
The important thing to remember is that a scan shows what's going on in a part of your body at the time the scan is taken. It's like a photograph: the information is frozen in time and so if you have another problem in that same place, the same scan might be repeated to see changes. A good example of this is X-Rays which are taken when a doctor suspects someone has a broken bone. An X-Ray will be taken to diagnose the nature of the break and to determine the initial course of treatment; it may be surgical or non-surgical, but this decision can only be made by looking beneath the surface of the skin and at the specific structures under investigation. If the bone is broken, more X-Rays may be taken as time progresses, to see how the bones are repairing and to make sure that everything is going well. In this way, scans and imaging are used to see what the problem is, how that problem evolves, and how treatment can be adjusted to address this evolution. All of this gives your clinician the tools they need to make informed decisions about your treatment, and how best to address the needs of your life.
Another important thing to remember is that scans may not always show anything wrong. Scans are pictures taken of parts of the body which are then interpreted by professionals who are skilled in reading those images. There may be something wrong, there may be nothing wrong, or the scan may be inconclusive and not say anything one way or the other. This is all valuable information, and discussing these results with your clinician can help you make sense of the findings in the report. It's important that your doctor, your physiotherapist, or whoever you are working with, takes time to explain the findings and discuss the impact that those findings have on your treatment - it's how you make informed decisions about your course of care.
THE HOW
You may be asked to complete different scans depending on the specific problem you are experiencing. This is because different scans reveal different information about what is going on within your body, which can then be used to refine your course of care. The investigations discussed below are a small sample of what your clinician might use to find out more about your problem - make sure to ask questions if you'd like to know more.
1. X-RAY
You may have had an X-Ray scan when your doctor thought you may have broken a bone. X-Ray scans use radiation to look beneath the skin and examine the bones and joints to see if there are any breaks (fractures) or abnormalities with the bone. An X-Ray uses a beam of radiation which is projected toward the area under investigation. Most of the radiation passes through the area, but some X-Ray energy is absorbed by structures like bones, surgical metallics like screws, and sometimes dense tissue. The difference between which X-Rays are absorbed and which are not is detected by either a photographic film or a computer, and used to produce an image of the object under analysis. Simply put, and X-Ray scan is useful for looking at bones and bony landmarks. You will most commonly have an X-Ray if your doctor suspects you have a broken bone, or if your physiotherapist thinks that a bony issue is contributing to your problem.
X-Ray imaging is not very good at showing problems with muscles or blood vessels. This is because muscles and blood are not as dense as bone, and X-Rays pass through them without being absorbed. In some cases, you may be asked to consume a drink with non-toxic ingredients that can absorb X-Rays, if your doctor wants to investigate issues with your stomach or intestines. This drink will cause the X-Rays to display a picture of your intestines on the detector, and can be used to assess any deviations or constrictures in your stomach organs.
When you finish your X-Ray, you may get plain films in a folder, and you may get a report. It's important to discuss both the films and the report with your treating doctor or physiotherapist, and ask any questions you may have about the results.
2. ULTRASOUND
You may have had an Ultrasound scan when your doctor thought there may be a problem with your muscles. Ultrasounds are also done on pregnant women, to assess the growth and health of the foetus as it develops within the mother's womb. In both of these cases, Ultrasound is used to investigate the tissues in the area under analysis. Ultrasound can also detect bone, but it is poorly suited to this, and so other scans are used to detect problems with bones. An Ultrasound assessment uses waves of sound whose frequencies are higher than what can be heard normally. These sound waves are produced by an ultrasound probe, and are projected into tissues in the area under investigation. These sound waves are reflected off the tissues in this area, and these reflections are detected by the probe. The detected reflected sound waves are then interpreted by a computer, and are used to construct images of the area under analysis. This is similar in principle to the echolocation used by some animals to find their way in the dark or underwater. It is also functionally similar to the SONAR system used by submarines and ships. For this reason, Ultrasound is also called Sonography, or Ultrasonography. Ultrasound is useful for seeing if there are issues with tissues or structures that are not bone, or if your physiotherapist thinks that a soft-tissue or bursitic issue is contributing to your problem.
Ultrasound is not very good at detecting problems in tissues behind bones. This is because bones reflect the sound waves back at the probe, leaving very little to penetrate below the bone and deeper down. Additionally, ultrasound waves lose their strength quickly, and so cannot be used to detect problems deep within the body as well as they can detect muscular problems. This can be a problem for patients who are overweight, as the sound waves must first penetrate the layer of fat before reflecting off the structures that may be under investigation. For this reason, Ultrasound is best used for muscle and tissue problems that are close to the skin - like shoulder bursitis, wrist tendonitis, or ligament sprains.
When you finish your Ultrasound, you may get a printout of ultrasound images as well as a written report. It's important to discuss both the printouts and the report with your treating doctor or physiotherapist, and ask any questions you may have about the results.
3. CT - COMPUTED TOMOGRAPHY
You may have had a CT scan on your back if you have had neck pain or headache pain for a long time. A CT scan uses X-Ray radiation to build a comprehensive picture of the body. It does this by moving the X-Ray beam and detector around the body, continually projecting X-Ray radiation into the area under investigation, and continually detecting the difference between hard bony and soft muscular tissue. This information is then processed in a computer, and can be used to create a three-dimensional image of the area that has been investigated. A CT allows the investigator to create many different images in cross-sectional (Tomographic) slices, and then arrange these slices into a more complete picture to see more of what is going on.
A CT scan is much more than a more complicated X-Ray. CT scanning can be used to see soft tissue, including looking at the brain, the lungs, the heart and the organs inside our stomach. A CT scan will also show this information in great detail: while an X-Ray wouldn't be able to show detailed information regarding what is going on in the brain, A CT scan can be used to comprehensively assess everything inside the skull. CT scans can also be looked at in many different orientations - an X-Ray can only be looked at from one direction, which is the direction the beam strikes the object. Because a CT consists of many images all digitally knitted together, a CT scan can be looked at from the front, the sides, top-down or bottom-up. This gives your doctor or your physiotherapist an incredible amount of information about your problems and the areas under assessment. Despite these benefits, your clinician will still refer you for X-Ray scans for simple bony issues. This is because X-Rays can be completed faster than CT scans, with less cost and more simplicity, and are appropriate to use for simple fractures.
When you finish your CT scan, you may get a printout of the CT images, or the report may be copied to a CD and given to you with a written report. It's important to give the CD as well as the report to your doctor or physician and spend time going through the details, answering any questions you may have and evaluating how the findings relate to your course of care.
4. MRI - MAGNETIC RESONANCE IMAGING
An MRI is used to produce comprehensive and highly-detailed images of structures within the human body. You may have had an MRI if you have had a hard blow to the head, if you have ever had cancer, or if you have had a disc prolapse in your spine. An MRI scan uses powerful magnets and radiowaves to see inside your body. For this reason, if you have magnetic metallics in your body like screws or bolts, or metal shavings in the case of steelworkers, you will not be able to have an MRI as these magnets are powerful enough to rip these objects out of your body. Despite their power, the magnets are very finely tuned, and are used to produce a detailed image of all of the tissues in the area of analysis. MRI scans of the head and spine display all of the bones, muscles, joints and thick nerves in high detail, and make problems easy to assess and observe. For this reason, MRI scanning is the imaging technique of choice for any investigation relating to the brain, the spine, and neurological cancers. MRI scanning is significantly more sensitive than CT scanning, and offers better images of small structural abnormalities that may cause big problems.
MRI scans are highly accurate, but this is offset by the cost of running a scan and the amount of time needed to process the results in a computer, and subsequently generate an image. Additionally, some patients cannot tolerate the MRI machine as it can be quite claustrophobic, loud, and intimidating. Another issue is that the patient must lie still to complete the scan: those with Parkinson's Disease and other writhing movements may not be able to successfully complete the scan.
When you finish your MRI scan, you may get a printout of the MRI images, or the report may be copied to a CD and given to you with a written report. It's important to give the CD as well as the report to your doctor or physician and spend time going through the details, answering any questions you may have and evaluating how the findings relate to your course of care.
5. BONE SCANS
You may know a relative with Osteoporosis or Osteoarthritis who has had a bone scan as part of their treatments. You may also have had a bone scan completed if you have ever experienced stress-fractures in your legs or arms like boot-top fractures. There are many different types of Bone Scan that can be performed, and which one is used depends on the nature of the problem you are experiencing and how your doctor wants to investigate it. Two forms of Bone Scans are Radio-labelled Bone Scans, and DEXA scans.
Radio-labelled Bone scans use a radioactive compound to identify areas of healing and activity within the bone. These scans work by taking blood from the patient and mixing it with a radioactive tag. This radioactive compound emits gamma radiation which can be picked up by a detector. The blood is then returned to the patient, and as this blood circulates through the body, the blood tagged by the radioactive compound is absorbed at the bone. The radiation at the site of the injury can then be detected. A bone scan can be beneficial in determining injury to the bone within the first 24-48 hours of injury or when the displacement is too small to be detected by an x-ray or CT scan.
Another form of Bone Scans is the DEXA scan. A DEXA scan uses X-Rays in low doses to see if there are any areas in the bone that are weaker, depleted, or otherwise abnormal and which may be causing problems right now, or may cause problems later. A DEXA scan is performed in a functionally similar way to an X-Ray: X-Rays are projected at the body, and the amount of X-Rays that pass through the body at different places is collected by a detector and processed, to give an indication of bone density. This bone density is then compared with the expected density for someone of your age and biological sex, and used to assess the presence or absence of bone weakness or wasting.
These scans can provide your treating clinician with more information regarding your general state of bone health, and can be used to make decisions regarding your continued management.
THE WHAT
Medical imaging is useful because it tells your physiotherapist, your doctor, and your surgeon what is going on in a particular place in your body, at a particular time. Based on the type of information your clinician gets and how they make sense of it, your treatment plan may be adjusted to accommodate for this information. It's important to remember that at the end of the day, results are reflective of that point in time only - the human body is a collection of living tissues and structures whose appearance, function, and arrangement change subtly, over the course of our lives and over the course of the day. The harmony of the body can be disrupted by disease, trauma, or can be degraded by the simple act of living in the world. Medical imaging is an invaluable tool that allows us to look beneath the skin and see what's going on beyond plain sight, and to take those deeper changes into account so that you as the patient can get the best care you can.
If you have any questions, feel free to pop into the clinic.
Door's always open!
- Alex