Imaging…An image of what?

As medicine has evolved throughout the 21 century, as has the way we use imaging to further patient care. Common types of imaging used today include, but are not limited to; X-ray, CT scan, MRI (MRI with Injection), Bone Scan and DEXA scans, and diagnostic ultrasound.  While this is in no way an exhaustive list, it does contain several of the types of images that are prevalent in athletics and common for the athletic population.

The most basic imaging is the x-ray (Arm X-ray). With an x-ray, radiation is “shot” through a tube aimed at a specific body part and an image is caught on the receptor plate, film, or other media. A standard x-ray shows images in black and white, with black being areas that absorbed little to no x-ray and white being areas that absorbed the majority of the x-ray. An area of high density, i.e. bone, will show up white on x-ray. Lower density areas will show up with no discernible image, as they are not absorbing much of the x-ray, therefore they do not stand out and produce as great of an image. X-rays have also evolved to being used in coordination with real time procedures by adding the use of fluoroscopy which can provide high contrast images under x-ray, during arterial procedures for example.

CT Scans (also known as CAT Scans) use similar technology as plain film x-rays, but they are assisted by the addition of computers that process all of the images together to create more of a 3-D image (Head CT Scan) This image can be very beneficial to physicians, especially those in the emergency departments, because they can provide a wealth of information very quickly. They have a multitude of different uses ranging from scans of the head, lungs, heart, abdomen, and extremities. A few drawbacks include:  they are bulky, expensive to purchase, and can produce varied results due to spinning magnets and patient movement. New technology has helped to alleviate some of the shortcomings; however the newer units are even more expensive and require a sizeable amount of space.

MRI’s are one of the most common types of imaging sources that people tend to hear about. These units use magnets and radio frequencies to help pick up individual atoms within the body and create a visual picture of underlying tissues using “slices” that then get placed together by a computer to create a series of images that can be scrolled through to produce a full view of a structure (MRI- knee single slice). There are different types of images produced by a standard scan that show water and fat in different contrasts. MRI’s are effective at confirming diagnoses, however studies and articles (Dr. Andrews article) disputing their effectiveness have become stronger as of late. That being said, they are a useful tool to create a picture of varying structures in the body. They can image both soft tissue and bones, which make them a valuable tool in orthopeadics, regardless of their shortcomings. One way to maximize their effectiveness is to useMRI in conjunction with injections. Common solutions include standard saline and gadolinium. It is believed that by distending a joint with saline prior to imaging, you get a clearer look at the underlying structures. With gadolinium injections, the reactive fluid provides a more concise picture of the underlying tissues and the path of the fluid can be traced throughout a joint and the soft tissue surrounding it.

Bone scans (Bone Scan) and DXA Scans (DXA Scan) are similar, but quite different at the same time. Both are used to study bone, with bone scans looking for abnormalities in the bone related to healing and DXA scans identifying bone density in an individual. DXA scans are also gaining favor for their ability to study body composition and fat content. Besides the specifics of what they study, these two studies vary in the way information is gained. DXA scans provide a “still picture” while bone scans provide an overall look at functional metabolic processes of the skeletal system. DXA scans use x-rays to gain an image while bone scans use a radioactive fluid to show contrast when shot with photons. Both of these studies view bone, but they have widely varying uses and information that can be gained from them.

The final type of imaging that we are going to discuss is diagnostic ultrasound (Diagnostic Ultrasound of elbow). While ultrasound has been around for many years, using it in a clinic for acute injury evaluation is relatively new. Ultrasound uses inaudible sound waves to create a visual representation of body structures. It is gaining popularity in the orthopeadic world due to the speed in which it can be done, the image quality, and its non-invasiveness. The real key to the diagnostic ultrasound is in the technician performing the test and the individual that is reading the real-time results. The uses are man, and ways it can be used include: injury assessment, guidance of an injection needle, and tracking injury healing from visit to visit.

As you can see, there are many different forms of imaging that are common place in sports medicine, but each has its own place, complete with their own strengths and weaknesses. While this list is in no way exhaustive, we hope that it has provided you with an idea of what different test are out there and what they are each used to discover. Please feel free to leave us comments on what tests you have found especially helpful or which tests you have found that have little clinic efficacy. Thanks for reading!

X-Ray

CT Scan

MRI

Bone Scan

DXA Scan

Diagnostic Ultrasound

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