Tag Archives: Nuclear Medicine

CNA2016

When Seconds Count

Strokes.

They happen when the blood that is circulating within the brain is cut off or reduced in an area resulting in a loss of oxygen to that part of the brain. If not treated right away the brain can die.

Thanks to nuclear medicine, doctors can better assess and treat stroke patients, saving lives.

With a stroke, every second counts.  Neurons or nerve cells are lost at a rate of 1.9 million per minute when the brain is deprived of oxygen. The loss of these and other key brain transmitters, or synapses leads to accelerated aging in the brain.

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(Chart Courtesy of Dr. Timo Krings, Head of Neuroradiology, Joint Department of Medical Imaging, Toronto Western Hospital & University Health Network)

Dramatic treatment is required to save a patient’s life, everything has to move rapidly.

“2:00am: I was called for a stroke at the hospital. By 2:20 the team was at the hospital and by 2:40 we had removed the blood clot and the patient was off the operating table,” states Dr. Timo Krings, Head of Neuroradiology, University Health Network, Toronto Western Hospital.

From initial imaging to opening the blocked blood vessel and restoring blood flow happens in just a matter of minutes.

The proper diagnosis and successful treatment of strokes is thanks to a branch of Radiology known as Interventional Neuroradiology.

Interventional radiology involves a uses modern Nuclear Magnetic Resonance Imaging or Computed Tomography to identify where the blockage is within the brain and its size.

As Dr. Krings points out, imaging plays a major role in proper diagnosis and treatment.

“The imaging part is just as important because if we choose the wrong patient we can make things worse,” he explains. “If we open a vessel that was occluded for too long, l the dead brain won’t recover but the patient can be in danger because blood will rush to the dead brain, which can lead to a hemorrhage. Therefore the correct identification of right patients is as important as the treatment itself.”

Once the scan identifies a suitable patient, the treatment can begin.

Interventional Neuroradiology involves a minimally invasive procedure whereby an artery is punctured and small tubes known as catheters are placed into the blood vessels. In these small tubes, doctors can push in stents or devices into the blood vessels in order to treat the blood vessel from the inside out.

Symptoms you may be having a stroke: FAST

Face: Drooping eyelid or numbness on one side of your face. Vertigo or a whirling loss of balance

Arm: Unable to move your hand or arm on one side of your body

Speech: You can’t speak properly or speech is garbled

Time: Time is of essence and you should telephone 9-1-1 , if you think you may be having a stroke call 9-1-1

Dr. Krings points to a chain of stroke awareness and treatment. Beginning with the patient to be able to identify the symptoms of a stroke to emergency medical service (EMS) workers who can rapidly identify and take patients to stroke centers where emergency room (ER) teams can fast track patients into imaging.

“It’s a team effort between the patient, EMS, the ER doctor, neurologist, radiologist, dietician and rehab specialists. All of them have to play together to get the best outcome,” says Krings.

New Canadian guidelines call for the two pronged technique of imaging and interventional radiology as the best life-saving method to for the diagnosis and treatment of strokes.

 

CNA2016

Radioactivity Fighting Cancer

Brachytherapy, or internal radiation, is proving successful in treating certain tumors.

Cancer is very complex. Curing patients without causing side effects means that the treatments must be very targeted.

BrachytherapyMen“Not all cancers are the same,” according to Dr. Michael Milosevic, a radiation oncologist at the Princess Margaret Cancer Center in Toronto. “Cancer is not one diagnosis. Each individual cancer is different.”

For patients diagnosed with cancer, surgery, radiation treatment and drug treatment (chemotherapy) are frequently used. External radiation, a beam targeted to a tumor that travels to the tumor from outside of the patient’s body comprises 80-90% of radiation therapies.

Brachytherapy, on the other hand, involves inserting the radiation into the center of the tumor and irradiating the cancer cells from the inside out.  The treatment has proven successful in fighting prostate and cervical cancers.

“With brachytherapy, you can kill the cancer but spare the normal surrounding areas,” says Milosevic. “The likelihood of curing the cancer goes way up and the side effects way down.”

There are two methods of using Brachytherapy-temporary and permanent implants

Temporary implants use special catheters inserted into the tumor. They connect to a machine to deliver the radiation treatments. A temporary implant is a day procedure. The radiation is delivered over a very short period of time, usually a few minutes, and then the catheters are removed.

BrachytherapyWomenPermanent implants directly insert small radioactive “seeds,” each about the size of a grain of rice, into the tumor. In the case of prostate cancer treatment, about 100 seeds are placed into the prostate gland, usually when the patient is asleep.  The seeds remain in the prostate gland for the remainder of the patient’s life and give off a continuous flow of radiation that is highest immediately after insertion and declines to zero over a few months.

The uses for brachytherapy continue to develop. It has proven useful in treating some breast, head and neck cancers. Perhaps one of the biggest developments, as Dr. Milosevic points out, is the shift to magnetic resonance imaging (MRI). The Princess Margaret Cancer Centre  is home to three MRI units that help to deliver brachytherapy.

“With Brachytherapy you put the radiation in the center of the tumor so you can kill the cancer but spare the normal surrounding areas. The likelihood of curing goes way up and side effects go down.”

CNA2016

MUGA: For The Health Of Your Heart

Chemotherapy for cancer can actually cause your heart muscle to weaken.  A nuclear medicine test can tell the condition of your heart muscle according to Dr. Terry Ruddy, a Nuclear Cardiologist at the Ottawa Heart Institute.

Cardiotoxicity is the presence of toxins in the heart, which can cause the heart muscle to weaken. Chemotherapy, or the process of killing cancer cells with pharmaceuticals, can also cause damage to your heart. The risk of damage increases as the cycles of chemotherapy go up. For example, a patient who is starting their first cycle of chemotherapy will be at a lower risk for heart damage compared to a patient who is undergoing a fourth cycle of chemotherapy.

“The heart always has blood in it” according to Dr. Ruddy. “Think of it as a balloon, it has a collection of blood or a blood pool. Blood goes in, fills the heart, heart squeezes and blood goes out into the body. When hearts get weak, it doesn’t pump as well so it pumps less blood out into the body.”

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According to Dr Ruddy, under normal conditions, the heart will empty about 50% of the blood inside of it into other parts of the body before refilling again. The portion of the blood that is emptied is known as an ejection fraction.

A test that can help to determine the health of your heart muscle is called MUGA. The term was trademarked by Siemens when it was introduced in the 1980s; it stands for multi-gated acquisition scan.

In the world of nuclear medicine the more popular term is RNA or radionuclide angiogram.

A MUGA looks at the pooling or collection of red blood cells.

The test takes pictures of the heart when the heart is filled with blood and again once the blood has been squeezed from the heart and into outlying areas. Then doctors calculate the difference.

Ruddy goes onto say, “We measure weakness or strength by this fraction. If you have a weak heart muscle with a low ejection fraction we call that heart failure. People with heart failure die within 5 years. Mortality is directly related to how low the fraction is. Lower the ejection fraction the higher the death rate.”

There is hope however for those with a weak heart. Medications can make a big difference and improve ejection fraction.

A device, known as an internal cardiac defibrillator can be placed into patients who have weak heart muscles. Wires extend from a battery pack that is inserted near the heart which can both help the heart beat more uniformly and see if the heart is beating irregularly. These devices can shock the heart from inside the body.

The Ottawa Heart Institute does about 1,000 tests per year to help determine a treatment course for those patients already diagnosed with weak hearts. Thanks to advances in technology, a MUGA can be administered with a lower radiation dose than in the past.

“It’s a Heart Institute first, says Ruddy. We have reduced the radiation by 50% for all our nuclear tests.”

 

CNA2016

Nuclear Medicine and Your Pet

For 153 years, since 1862, the Ontario Veterinary College, has led the way ini Canada for animal medicine, improving the lives of four legged friends and their humans.

OVC ranks fourth in the world for veterinary medicine and includes a nuclear medicine division.

Dr. Alex Zur Linden is an assistant professor in the Diagnostic Imaging department at OVC where he assesses patients using tools such as Computed Tomography (CT) scans, a nuclear technology tool. The scan allows physicians to get a 360-degree snapshot of what is happening inside the animal.  But as Dr. Zur Linden points out, the work poses some unique challenges.

“Prior to a scan taking place the animals are sedated. We do this so that they won’t move off the table and to minimize their respiratory motion because unlike humans you can’t ask them to hold their breath,” says Dr. Zur Linden.

catdogAnother area of veterinary nuclear medicine is in the treatment for cats with hyperthyroid. A condition in which the thyroid overproduces a hormone known as thyroxine, this can cause the body processes to speed up.

Signs of hyperthyroidism in cats include faster heart rate, vomiting and diarrhea. If left untreated it can lead to blindness.

Once diagnosed, usually following a blood test, treatment can begin. A common method of treatment is something known as radioiodine therapy. A non-invasive procedure, patients do not have to undergo the stress of sedation or an operation.

Instead, radioactive iodine is injected into the cat where it is absorbed by the thyroid. The radioactive iodine is able to destroy the infected cells and patients usually see a return to normal hormonal levels with a week or two of treatment.

The cross over applications between research amongst humans and animals has meant the ability to better diagnose and treat patients. One such application is a procedure known as microwave ablation (MWA). Primarily used in humans, due to its expensive cost, MWA involves using microwave energy to heat and destroy tumors.

“One promising area is with cancer in the lungs. Right now there is not much we can do, however, with microwave ablation, you can kill the tumor. It’s been done in people,” Zur Linden goes onto say, “it’s likely palliative therapy but has the potential to be curative as well.”

As outlined in The National Research Council’s Committee on the National Needs for Research in Veterinary Science it was through work with chickens that the cancer causing virus, sarcoma was discovered. An immune suppressing virus in cattle was discovered years before HIV or AIDS would be diagnosed in humans. Advances in one stream have had numerous benefits in another. However, according to Zur Linden,while in the past advances were often made in the animal world first, that is changing.

“Nowadays veterinary medicine is catching up to the technology which is tested in people first and then applied to animals.”

CNA2016

For the Health of Your Lungs

According to the National Blood Clot Alliance, once every six minutes, someone dies from a blood clot and blood clots lead as the number one killer of new mothers during and after childbirth.

According to Massachusetts General Hospital, a pulmonary embolism or PE is a blood clot that develops in the blood vessels elsewhere in the body and travels to an artery of the lung. A PE is a blood clot once it has lodged itself in the lung and formed a blockage of the artery.

While there are numerous risk factors for developing a PE, the most common include:

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“Pregnancy puts a woman at increased risk of pulmonary embolism, so careful evaluation of pregnant patient is vital when they present with symptoms of chest pain and shortness of breath,” says Dr. Ravi Mohan, a radiologist and nuclear medicine specialist with the Joint Department of Medical Imaging for the University Health Network.

Left untreated mortality rates from pulmonary embolisms can be as high as 25 per cent. However, with the proper therapy, the rate of mortality decreases by nearly two-thirds to between two and eight per cent

One way to detect a potential clot in the body is known as a VQ or ventilation/perfusion scan. As Dr. Mohan points out, “nuclear medicine works from the inside out.”

In the case of a VQ scan two agents are given to the patient, one that looks at the airways (technegas) and the other to look at the blood vessels (Technetium 99m particles).  As the agents, decay they give off gamma rays.  These rays are in turn picked up by cameras, allowing physicians to detect abnormalities in the lungs.

These abnormalities are often seen as a decrease in the amount of perfusion or blood flow to a particular area in the patient while the ventilation or air flow will appear normal. It is this difference between the two parts of the tests that allows doctors to discover a blockage in the lung and thereby treat it.

Some of the symptoms may include.

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It is important to point out that not all clots will present with symptoms in the patients regardless of size or location of the blood clot.  “Patients may present with hypotension and shock in larger areas where as in patients with smaller blockages they have relatively few symptoms or no symptoms at all,” says Dr. Mohan

Treating pulmonary embolisms will vary from patient to patient but may include surgery, medications and oxygen therapy.

CNA2015

Radiopharmaceuticals and Disease Diagnosis

Nuclear medicine, already well-established in cancer diagnostics and treatment, has started to play a role in other diseases, like Alzheimer’s.

Doctors are using medications that contain radioactive materials so they can get an inside look at how your body operates. Patients receive these radiopharmaceuticals by injection, or by inhaling or swallowing the medication.

pharmaceuticalslabRADIO

As oncologist Sandy McEwan explains, “It circulates and binds at the site of the target and then we measure the distribution of the injection in space or time to understand what changes or functions are occurring.”

Dr. McEwan is a professor and chair of the department of oncology at the University of Alberta’s Cross Cancer Institute in Edmonton. He is also a member of the Canadian Nuclear Safety Commission, the independent nuclear regulator.

Dr. McEwan says advances in nuclear medicine are growing thanks to strong and active research and development.

The U.S. Food and Drug Administration (FDA) recently approved the use of radiopharmaceuticals to help evaluate patients for Alzheimer’s disease and dementia.

Advances are also being made in other areas such as cancer behaviours, according to Dr. McEwan.

“Tumors tend to use more glucose or sugar than regular cells,” Dr. McEwan says. “Using radiopharmaceuticals, doctors can measure how much glucose is being used by a tumor. The more sugar used by the cancerous cell, the worse the tumor is.”

These new medicines aren’t just used for diagnoses. Their very nature allows doctors to tailor them to individual patients.

“It’s personalized medicine,” says Dr. McEwan. “The right dose of the right drug, at the right time, for the right patient.”