Introduction by Stephen Strauss
It is almost incomprehensible how much medical imaging — the ability to peer inside the body by exploiting the laws of physics — has revolutionized not just the way doctors practise but what patients expect to experience when being treated for...well, almost everything.
And that is because we have been in the midst of not so much an imaging revolution as successive, ever more profound imaging revolutions. Consider that it is less than 120 years since Wilhelm Röntgen first passed the strange forces he called “X-rays” through his wife Anna Bertha’s hand and, in so doing, revealed both the bone structure within and what it takes to win the first Nobel Prize in Physics.
Over the past 50 years, in addition to Röntgen’s X-rays, magnetic resonance imaging (MRI), computed tomography (CT) scans, ultrasound and positron emission tomography (PET) scans have allowed doctors to see the heart beating, the lungs breathing, the brain thinking, the stomach digesting, cancers growing and a host of other bodily activities taking place.
One obvious sign of the new imagers’ importance is how routine imaging scans have become in medical practice.
The Canadian Institute for Health Information (CIHI) reported last February that in 2011-12, some 1.7 million MRI exams and 4.4 million CT exams were performed in Canada and that the MRI number is nearly double the figures reported in 2003-04. And this doesn’t take into account the even larger numbers of dental X-rays, mammograms and sonograms of fetuses given to Canadians yearly.
With medical imaging’s various revolutions has also come the near elimination of what was standard procedure in the days before doctors could see what was going on inside the body from the outside — exploratory surgery, the cutting open of patients not to heal them but, rather, just to view what could be causing their ills.
“Medical imaging has caused a really dramatic fall in the number of exploratory surgeries,” says Howard Leong-Poi, head of the Division of Cardiology at St. Michael’s Hospital in Toronto, Ont. “Two words should be emphasized here: really dramatic.”
While the notion that the rise of medical imaging would transform medicine now seems obvious, the huge technological advances that allowed the change often aren’t appreciated. When the first image inside of the human body was created using MRI in 1977, for example, it took more than four hours to complete. Now, the same scanning of a body using resonance from a large magnet can be done in about half an hour — and done in three dimensions and without any of the radiation worries associated with X-rays.
Similarly, when CT scans, which use a stream of X-rays to make images of “slices” of parts of the body, were introduced in hospitals in the 1970s, it took hours to create a single cross-section. Today’s CT scanners do the same thing in less than a second.
And when ultrasound, which bounces sound waves off tissues to indicate their shape, was introduced in the 1950s, only static images could be produced. All that changed when active images could be created and, later, when colour was added, allowing for things like blood flow and a fetus’s motions to be observed.
The different technologies for medical imaging have regularly and often spectacularly been combined. For example, a technology that marries a PET scan (in which a small amount of a radioactive tracer is injected into the blood) with a CT scan to clearly reveal both metabolic processes and anatomical details at the same time was named Time magazine’s Invention of the Year for Medical Science in 2000.
Along with the normalization of imaging in medicine has come what some have characterized as the failures of over success. Critics worry that the ease of taking a scan can lead to the procedure being overused and that the consequences risk going beyond health-care costs if too frequent X-rays, for example, wind up causing diseases like cancer, which they are designed to find. Others fear that “seeing” something is not the same as knowing whether it is harmful — a debate that has led to more stringent guidelines for prescribing and interpreting mammograms for the detection of breast cancer.
Despite this, the frontiers of imaging the human body continue to expand, and it would be hard to argue that medicine isn’t better for it. Real-time scans in the operating room allow surgeons to tailor incisions to include not only what they actually see but what imaging tells them is there. Electronic health programs can interpret scans for doctors and also advise them ahead of time when those scans shouldn’t be given. And there are continued efforts to make every imaging procedure smaller and more portable; think ultrasound machines the size of a tablet computer.
In this in-depth report, we highlight how Canada is leading the way in many aspects of research into medical imaging: Click on the stories to the right to learn about some of the work being done in the largest medical-imaging research labs in Canada, watch a video for a glimpse at another leading-edge medical imaging research project, spend some time with our infographic to find out more about the evolution of this fascinating field, and read our interview with Western University’s Ting-Yim Lee to get to know one of Canada’s medical imaging research leaders.
Lee’s research is also part of a recent unique collaborative study undertaken by the CFI and the Canadian Institutes of Health Research. This report seeks to unearth the socioeconomic benefits of innovation in medical imaging for Canadians. Find out more here.
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