Wave - ONLINE EDITION
Dr. Marco Essig is working to advance the science of magnetic resonance imaging, a move that will help improve care for patients suffering from cancer, stroke and degenerative brain disease
Wave, January / February 2014
Dr. Marco Essig fires up the computer and selects an MRI from a folder.
With the click of a mouse, an image appears on the screen, a mix of colours - pink, green, orange, blue and white - all coming together in the unmistakable form of a human brain.
In this case, the brain belongs to a patient who arrived at Health Sciences Centre Winnipeg earlier in the day after suffering a seizure. The case is a bit unusual. Normally, a patient experiencing a seizure will have a history of epilepsy. This patient has no such record, nor had they ever had a seizure.
But the mystery does not take long for Essig to solve. A careful review of the image reveals the source of the problem: a malignant tumour in the left hemisphere of the brain.
A few years ago, using a standard black and white MRI to locate the position of a tumour was pretty much all a radiologist could do. But things have changed. Advances in MRI technology and techniques mean radiologists are now able to learn much more about what is going on inside a patient's head. To the trained eye, the multi-coloured images produced today using recently developed functional imaging techniques, such as perfusion or MR spectroscopy, can provide critical insights into the nature of a tumour, including its blood supply, cellular density, and how fast it might grow.
The MRI on Essig's screen illustrates the point. Each colour in the image indicates blood flow levels in the brain and within the tumour. As he studies the MRI, Essig can see that parts of the tumour are shaded in brighter colours. This suggests that these areas of the tumour are receiving high levels of blood flow - a strong indication of a very aggressive and very dangerous malignant growth.
Information of this kind is invaluable to oncologists. The more they can learn about a patient's tumour, the better chance they have of developing a successful treatment plan, as would be the case in this instance.
As it turns out, Winnipeg is well-positioned to take advantage of new MRI technologies and techniques for the diagnosis and treatment of patients, especially those suffering from cancer, stroke and degenerative brain diseases.
One reason is that HSC, the city's largest hospital, is now home to the Centre for Surgical Innovation, which opened last fall. While Winnipeg has a number of high-end MRIs in place, this technological jewel is different. Located on the second floor of HSC's Kleysen Institute for Advanced Medicine, the suite consists of four rooms. One room houses an "intraoperative" MRI mounted on tracks built into the ceiling. It is located between two adjoining rooms - one for catheter angiography, the other for neurosurgery - next to the control room.
Leveraging some of the latest hardware and software technology available, the suite's MRI is capable of providing more detailed images than some of the other MRIs in use, allowing radiologists to get a better read on important indicators, such as the amount of blood flowing to a tumour. But what makes the suite special - it is the only one of its kind in Canada - is that the MRI can be moved along its tracks into either of the two operating rooms to scan a patient while they are undergoing a procedure, hence the name "intraoperative" MRI.
A second reason is Essig himself. Recently recruited from Germany to take on the dual appointments of Chairman of the Department of Radiology at the University of Manitoba's Faculty of Medicine and Medical Director of Diagnostic Imaging for the Winnipeg Health Region, Essig is a leading expert in the field of MRI and neuroimaging.
Over the years, his research has helped advance the use of MRI techniques to better diagnose and treat brain, breast and prostate cancers. His work has also enhanced the medical world's understanding of degenerative brain diseases, such as Alzheimer's. His dual role means he will be responsible for leading the diagnostic imaging operations for the Region as well as ensuring students at the University of Manitoba are trained in the latest MRI technology and techniques.
In addition, Essig will continue to carry out his research. Currently, he is chairing an international group of radiologists who are writing new protocols for the use of MRIs. Once completed, the protocols will serve as a guide for radiologists around the world as they strive to advance the science of reading MRIs, which, in turn, will lead to better treatments for cancer, strokes, infections or degenerative brain disorders, here and elsewhere.
As Essig explains, MRIs are made by different companies that have different specifications. This can result in differences in the interpretation and quantification of data.
"We all have different scanners - one from GE, the other from Siemens, one from Phillips - with different field strengths," he says about the ongoing study. "With our patients, every tumour is very different and every patient's treatment and outcome are different," he says. "We're currently working on a standardization process for acquiring and processing data so we can have standardized results that we can then apply to each individual patient's needs."
Radiology - the use of imaging technologies to diagnose and treat disease - has been around since German physicist Conrad Röntgen produced the first X-rays in the 1890s. Since then, advances have led to better X-rays as well as the advent of other imaging technologies, including MRI (magnetic resonance imaging), CT (computed tomography), PET (positron emission tomography), ultrasound and, could lead to long-term problems, such as seizures or permanent loss of important functions like speech. Most types of chemotherapy will cause people to lose their hair or experience extreme nausea. Some types of chemotherapy may cause long-term negative effects, such as heart failure.
Radiation therapy also has its risks because it increases the likelihood a patient will develop cancer elsewhere in the body years later because of exposure to radiation.
Unfortunately, as helpful as biopsies are, they do not always provide accurate assessments of a tumour's biological makeup. Tumours are often heterogeneous, meaning a single tumour can have many different types of cells.
"For example, if you take the biopsy a few millimetres to the left, you will find a low-grade tumour," Essig says. "If you took the biopsy a few millimetres to the right, you would find a high-grade tumour." In other words, it is possible to diagnose a tumour as low-grade instead of high-grade, leading to a less aggressive treatment or even a "watch and wait" approach instead of a more robust treatment plan.
This is where the most recent advances in MRI technology come into play.
The key breakthrough came in the 1990s when scientists figured out that the magnetic properties that produced detailed pictures could also be used to show differences in blood flow or other tissue characteristics.
Advances since then have included the recent development of new functional imaging techniques, such as dynamic contrast enhanced sequence MRI or dynamic susceptibility-contrast MRI. These new techniques provide radiologists with greater insight into the nature of tumours.
"(The new techniques)mean we can characterize the kind of tumour we find in a patient," says Essig. "We now know, because of the new technology, much more about the internal genetics of tumours. They don't have homogenous genetics. They are much more heterogeneous," Essig says. "They have parts that are aggressive and others that aren't. We can now better say whether this is malignant or benign and we can better predict the grade of the tumour and help guide the treatment, outcome and management of the patient."
In addition to learning more about tumours, Essig says new MRI technology and techniques can be used in other ways to benefit patients. Take an example of a patient who receives a blood test with a high prostate specific antigen level (PSA), which is usually associated with a risk of prostate cancer.
Using a perfusion MRI, the radiologist can map the prostate's vascularization (blood vessels) revealing areas of increased blood supply that are often indicative of cancer. Using these enhanced images, a surgeon can target the trouble spots when performing a biopsy procedure.
"Previously, the risk was the surgeon would miss the tumour. Then what does he do? He does another 30 biopsies," he says. "I've seen patients that have had close to 100 biopsies taken from their prostate, and that's nearly close to a complete resection."
With the new diagnostic imaging approach, the procedure is much less invasive, often with only one biopsy sample needed to confirm a tumour instead of dozens, Essig says.
As one might expect, better diagnosis of a tumour leads to better treatments.
"In oncology, there is a golden rule that says that the outcome of the patient is very dependent on the first line of treatment," Essig says. "It's very important to know from the very beginning where the malignant parts of the tumour are to develop an optimized treatment plan."
If the first treatment proves ineffective, the cancer will often grow during that period, making it more difficult to treat. Moreover, patients are generally weakened by the side-effects of the ineffective treatment.
New MRI technology is also a big help in the operating room. The detailed images produced by functional techniques allow surgeons to remove cancerous growth with greater precision by helping them distinguish what is normal tissue and what isn't. For example, during the course of surgery to remove a tumour, a surgeon might put the extracted tissue under a microscope in the operating room to ensure they have removed all of the malignant growth. But sometimes it is difficult to distinguish between normal and abnormal tissue. "The distinction is so fine that it's impossible for human eye to tell the difference," says Essig.
The MRI in the new Centre for Surgical Innovation is particularly useful in dealing with these types of situations because it can be moved into an adjoining operating room during a procedure without disturbing the patient to determine whether the malignant tissue has been removed.
"They will scan sometimes two or three times during the operation because they want to resect as much malignant tissue as possible," says Essig.
New MRI techniques can also be used to help patients with other brain injuries. For example, doctors can use MRIs to peer inside the head of a stroke patient to determine which parts of the brain are experiencing a blockage in blood flow. This allows surgeons to employ an advanced clot-busting treatment that involves inserting a small device in a blood vessel to cut through a blockage.
Even after treatment, new MRI techniques play an important role because they allow doctors to monitor the outcome and effectiveness of the treatment, including whether the patient is experiencing any post-treatment side-effects, such as seizures and headaches.
"Our clinical partners want to know if the treatment was successful or not, and they also want to know if there were any side-effects from the treatment," Essig says. "A patient may come with new symptoms after the treatment, and we do some imaging to differentiate whether this is a temporary effect of the treatment."
Part of Essig's role at the Region is to ensure new imaging techniques are implemented for the greatest benefit of patients. To this end, he has started meeting with local specialists from different disciplines, such as oncology and neurology, to discuss how perfusion MRI techniques can improve care.
One example of this collaboration is the weekly "tumour rounds," which provide an opportunity for Essig and representatives of the departments of pathology, oncology and radiology to discuss the course of treatment for new patients. "We talk about the next step for these patients, and how we can best manage their disease," he says. "We all sit in one boat so we want to row together by sharing this information and eventually getting feedback about whether our decisions have been correct or not."
In his capacity as chairman of the Radiology Department at the University of Manitoba, Essig is responsible for ensuring students get the best training available.
To that end, he is working to launch virtual anatomy and virtual pathology programs that will use MRI images to help students better understand the anatomy of the human body and the development of diseases. The idea is to give students a half-hour lecture on a particular issue and then let them go through specially developed data sets of images to learn the detailed anatomy and, in cases of disease, to locate a tumour, for example.
Slides from any scanner can be used to create the data sets, provided one has the proper software. As it turns out, Essig had just this type of software when he taught at the University of Heidelberg, and he is now working to import the technology to the University of Manitoba.
"It was developed with a technical university in a town nearby. I've already spoken with them, and they are willing to bring it over," he says, adding that the virtual programs are fairly new.
Essig's training and clinical responsibilities fit hand in glove with his research.
"That's the nice thing about radiology - your field of research is so wide. You can work on technical improvements. You can work on better image quality. You can work on correlation between imaging findings and other lab findings, clinical findings, pathology findings," he says.
In addition to his work as chair of the international committee writing MRI protocols, Essig is already thinking about studies he would like to carry out with his Winnipeg research team, which includes radiology residents and others at the University of Manitoba.
He sees an opportunity for leveraging imaging technology for advancing other areas of medicine, including testing the effectiveness of the latest treatments.
As Essig explains, functional MRIs can confirm whether the treatment is working by indicating, for example, whether blood flow to the most malignant parts of the tumour tissue has been reduced. The question is: what is a significant reduction in blood flow?
"Is it 20 per cent, 30 per cent or 40 per cent reduction?" asks Essig. "We don't know unless we have a standardized measure where we can say this patient has a 50 per cent reduction in his blood supply, and this is effectively treating the tumour."
With well-established standards for new treatments, oncologists would be able to determine more quickly whether a treatment works for a particular patient. Just as importantly, if it's not working, doctors can change course more quickly rather than waiting months down the road.
"We have the tools, but the problem is they're not the standard practice yet, and that's where our research comes in," Essig says. "We're working on this so we have better insight into this whole process."
Winnipeg, says Essig, is an ideal location to further this research.
"Many people have asked, 'Why are you going to Winnipeg?' And I tell them that it's because it allows me to combine clinical work with academic work in an optimal environment."
Joel Schlesinger is a Winnipeg writer.
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