Imaging
Allow me to start out by restating an old adage as it applies to the field of imaging, “Absence of evidence of a condition is not evidence of absence of the condition.” In other words, just because you take an image (i.e. CT Scan, X-ray, MRI, etc.) and it’s reported the test was negative does not mean nothing is wrong.
Imaging is the area where your care giver(s) wish to have a ‘closer look’ inside you courtesy of the more popular methods of imaging such as X-rays, CT Scans, MRI’s, Bone Scans and electrode testing (ie. Nerve conduction velocity and/or emg’s). Suffice to say the list of imaging and or testing methods is much greater, but here we will focus on the basics of the more common forms used in whiplash. Remember textbooks are written on each type. We are only trying to introduce you to the basics so you can ask more informed questions as to why a type of imaging has/has not been utilized in your case.
X-rays
They are probably the easiest form of imaging to access. Suffice to say a standard X-rays may not seem ‘sexy’, but they can still tell us much on their own. They are relatively inexpensive, easy to access and non-invasive. By law, the minimum number of X-rays that can be ordered for any part of the body is 2 views taken perpendicular (at 90 degrees) to each other. For the most part the taking of X-rays is for 1 of 2 reasons; to rule out serious disease (i.e. tumor)/ injury (i.e. fracture) or to assess biomechanics (i.e. body part positions, such as spinal bone positions, leg bone heights). X-rays remain the mainstay when it comes to imaging the cervical spine (neck), following a whiplash injury, not to mention most other traumas to the neck.
Let’s just cut to the chase regarding how X-rays can be of the most benefit to those involved in a typical whiplash injury. As helpful as the ‘routine’ views are there is an area of injury that is all too often overlooked by the general medical community when ordering X-ray films. That injury is called instability. It is due to the injury to the ligaments (the strong soft tissue that holds the bones together and is naturally loaded with mechanoreceptors and pain receptors). Understand the mechanism of injury, in a ‘whiplash’ (more correctly called a Cervical Acceleration-Deceleration, CAD), is so specific that there is literally no other way to sustain this type of injury than being struck from behind. It is because what is called the ‘Instantaneous Axis if Rotation’ elevates from its normal pivot point, located near the middle of the 6th bone in the neck ->to the middle of the 5th. The end result is the normal gliding motion, of C5 over C6, is replaced with the bottom facet joints C5 literally pivoting directly into the top facet joints of C6.
To determine if instability is present you require a couple of additional X-ray ‘pictures’ to be taken. The films are taken of the side of your neck (called a lateral view) with you directing your chin towards your chest (a ‘full flexion’ view) and the other is with you directing your head/neck as far into extension (backwards) as possible (an ‘extension’ view). NOTE: If your doctor has ordered X-rays on you and not ordered the flexion and extension views at the same time you might want to ask why. In the doctors defense often your pain level is such that you can’t get into the full forward flexion, and extension, positions because of too much pain. If that’s the case then it is totally acceptable to order them at a later date such as when your neck range of motion will allow. It should be pointed out that standard medical school training in back/neck biomechanics, and their injuries, typically rivals their training in dentistry so don’t be surprised if you have to ask for them to order the films. It’s not the doctors fault that their not trained in these injuries. Their medical school training is predominantly in disease and the vast majority of neck conditions are not disease. That’s why all too often you’re given the same medication for your neck/back pain as you would receive for foot, or any other joint for that matter, pain.
Now with the flexion and extension views having been taken Instability can be ruled out. If the condition is present it shows itself as one spine bone (vertebrae) literally moving far further forward and or backwards than if should. As such you now have what is called objective evidence that you were injured. All too often those with a vested interest in minimizing the possibility that you could have been injured will often state “How could you have been injured when there is no/hardly any damage to the back of your vehicle?” Let them know young health crash testing volunteers have been injured in rear-impact collisions at speeds as low as 2.5 mph! Now take a middle aged female, with X-ray confirmed Osteoarthritis (degeneration), who was out of position (at the time of impact), totally unaware of the impending collision, had been in a prior rear-impact collision a few years earlier (to name but a few of a long list of risk factors for injury) and you can see that anyone attempting to convey the message of crash testing studies don’t demonstrate injuries at low speeds verges on ludicrous.
With objective evidence in hand one it can be confidently stated you have, and put on paper, that you have ligament damage to your neck. It should be mentioned that if the instability (and resultant abnormal biomechanical vertebrae motion) is evident at about 4 months post collision then said changes are likely permanent. It can also be put on paper that you are now likely to undergo early onset degenerative arthritis. Again, all stemming from a low speed rear-impact collision which results in minimal/no damage to the back of your vehicle.
If you require the next level of imaging, to compliment the flexion and extension views, then you would undergo Videofluoroscopy (formerly known as Cineradiography if anyone cares). Basically it demonstrates your instability in motion. It actually shows the bones and how they move. Said ‘movie’ allows direct evaluation of very subtle abnormal motion through the entire neck’s range of motion from full flexion through to full extension.
As far as my world, Victoria, B.C., is concerned the above discussion is more the exception than the norm. Don’t be surprised if, after reviewing this ‘page’ you know more about Instability than your doctor, lawyer and insurance representative. Email or phone me if I you would like greater clarification.
Now for an area that I am often asked about in my whiplash classes. That area of interest is the taking of X-rays pre and post treatment. Those practicing in this manner are of the opinion that marking and measuring spinal bones (vertebrae) misalignments offers them an insight into your condition. They feel it greatly assists in the detection of what are called, in chiropractic circles, ‘Subluxations’ (not quite a dislocation. In other words a stuck bone) and guides how they are going to treat it. Please understand that the health care discipline of chiropractic encompasses more than one technique. There are some that espouse the taking of X-rays both after as well as before every treatment or every few treatments. This is a bit of a touchy subject so I will try to tread as delicately as possible while still enlightening you on what those who know more about this topic than I have to say.
To the best of my knowledge there is not a single DACBR (Chiropractic Radiologist) that promotes the routine use of X-rays in clinical practice. If fact, officially they caution against it. They point out that such practice is directly advised against in what are called clinical practice guidelines due to the potential health risks and quite frankly they are clinically irrelevant.
When we talk about health risks the present acceptable exposures, in Canada, for those working with X-rays is 50mSv/year. For the general population the exposure maximum is 5mSv/year. For those interested it was 500mSv/year in 1931!
Low back, pelvis and hip X-ray exam recipients are the most at risk because that is typically where the tissue is thickest and requires greater X-ray doses to penetrate it. In the United Kingdom just these 3 types of X-ray studies account for an extra 40 and 30 cancers, for every million taken, respectively every year. In other words the exams themselves cause cancer. For those angered by my pointing these stats out, don’t shoot the messenger as this is all public knowledge, I’m just weaving it into the discussion.
Diagnostic radiation is also responsible for 1% of all Leukemia and the same for all breast cancers. Even colon cancer numbers are affected as it is the most common cancer caused by diagnostic radiation in women and the 2nd most common in men. Sadly, in Canada, every year 784 (406 men and 378 women) experience radiation induced cancers every year.
The only across the board condition that it is acceptable to use X-rays to assess a biomechanical condition is to rule out/assess Scoliosis. What we have been discussing is what is referred to as ‘Radiographic Analysis Systems’. Such X-ray film analysis methods are only taught in approximately 25% of all chiropractic colleges worldwide, none of which are located in Canada.
A few years ago, in the Netherlands, the government prohibited the countries chiropractors from owning X-ray equipment due to their widespread inappropriate use.
CT Scan
CT Scans are the imaging modality of choice when the goal is to image cortical bone such as when your goal is to rule out; a fracture central canal and laterat recess stenosis, facet hypertrophy, bony alterations due to osteoarthritis, a fractures impact on nerves, to name but a few. One would think an MRI would suffice. The problem with MRI’s is rely on how what are called hydrogen ions react in a magnetic field, upon the introduction of a radiowave, and bone does not have mobile hydrogen so an MRI is not appropriate when you want to image bone specifically. There’s more on MRI’s further down. If bone diseases, such as cancers, are the issue then CT Scans are the way to go.
A CT Scan uses the same ionizing radiation as standard X-rays, but at a much higher dose. Scan slices can be as thin as 1 mm. and they demonstrate the most amazing detail of bony anatomy. They also allow you to see if a spinal cord is compressed or displaced, but forget it if the goal is visualize the actual details of the spinal cord.
I should point out that yes a CT Scan will allow you to visualize soft tissue swelling and hemorrhage, but not where near that of an MRI. So if you are on the list for a CT Scan and bone is not the reason for it being ordered you might wish to clarify why it’s on the menu (vs. an MRI) especially in light of what’s in the next paragraph.
Recall that a CT Scan creates its images with the help of ionizing radiation, just like an X-ray. The interesting part is that ct scans are virtually unregulated in Canada! It is estimated that at least 20% in Canada and 33% in the United States are unjustified!!
With that in mind an interesting stat is that the number of them ordered tripled between 1991 and 2002. Still not enough, for the years 2004-2005 there were 2.7 million ordered which was an increase of >8% over the previous year. To bring that number into focus, a standard abdominal CT Scan generates 500 times the radiation compared to a standard abdominal X-ray.
A study published in 2004 reviewed stats from the early 90’s. They concluded that diagnostic radiation caused 1/100cancers equaling 784 cases of cancer a year in Canada. There was another study, published in 2006, that found that some hospitals abdominal CT Scans were exposing patients to 8X more radiation that was actually required. To conclude, if the dosage was reduced by just 5% you would actually save 125 lives a year.
So the next time you’re telling your family doctor that you want a CT Scan it might be best to keep the above stats in mind.
MRI’s
Now for the Lexus of imaging the almighty Magnetic Resonance Image (MRI). It used to be Cadillac, but with all the trouble GM is in let’s just go with the former. Let us start by pointing out that an MRI does not utilize ionizing radiation to generate an image. If anyone cares, the patient is put inside a magnet and a radiowave is sent in -> energy is absorbed mobile hydrogen go from a state of low energy to a state of higher energy -> radiowave pulse is stopped -> the hydrogen ions revert back to a low energy state and the difference is recorded as an image.
It is best when visualizing soft tissues is the goal. It can differentiate between blood vessels, muscles and fat due to their respective different concentrations of hydrogen ions. As stated earlier, bone can’t imaged by MRI, because it contains am minimal concentration of hydrogen ions. Enough of that as stated earlier entire textbooks are dedicated to explaining how images are generated.
Understand from the outset that even those who are responsible for ordering images are often confused on whether or not to order and MRI or a CT Scan. If a CT Scan is ordered you might be inclined to ask what their looking for and if it’s soft tissue, ask why. Often times it’s an access issue that being it’s easier to get a CT Scan than an MRI.
As mentioned earlier CT Scans do allow one to view discs, but not to the degree of an MRI. MRI is the call when discopathies (protrusions, herniations, extrusions), rotator cuff, brain injuries, ligament injuries, muscle injuries, carpal tunnel syndromes and the list goes on.
One of the key points of contention I wish to discuss is what is called a ‘Dynamic MRI’. Remember earlier, in the X-ray section, that full flexion and extension views were invaluable to rule out Instability, the same can be said for dynamic (full flexion and extension views) MRI. The problem has been in positioning inside the MRI’s magnet is very tight. In the United States, dynamic MRI is the standard. In Canada, your lucky if you can get a standard (‘Neutral’) MRI.
Neutral position is basically the position you are in when you are standing in a balanced manner. That is the position that you are in when positioned in an MRI unit in Canada. Here’s the caveat, they only show a portion of the overall picture, in cases of longstanding pain and disability, when disc’s morphology (form and structure) is under question.
The problem has always been the equipment used to position the patient when in the MRI. They manufacture equipment that allows for the MRI to be taken with the neck in full flexion and full extension. As far as I know, at the time of writing this section of the web site, such equipment has only recently been available here.
Here’s why, this is such an important issue, all too often the patient has received a standard ‘neutral’ position MRI and been told there is nothing of note that could be the cause of their long term pain and disability. With the advent of equipment for dynamic MRI cervical (neck) discopathies often reveal themselves.
It is now well documented, in the biomechanical literature, that a disc herniation that is slight-to nonexistent in neutral actually disappears in flexion and is visually evident in extension. Therefore, if you’re long awaited MRI studies report’s based on neutral positioning only and you’re told they didn’t find anything. They cannot report there’s nothing there because a full MRI study was not performed.
Now you should understand the opening statement about “Absence of evidence… is not evidence of absence.” All of these points, and more, are covered in our whiplash classes.