Dr. Barry Dworkin » Technology

New technologies in cardiac imaging research

Dr. Barry Dworkin — Sun, 20 Aug 2006 14:43:14 +0000

What are some of the means at our disposal to assess how well our hearts are functioning? What new technologies are available and what are some of the promising avenues in imagiing research and development. Dr. Robert Beanlands will also be presenting at the World Society of Cardio-Thoracic Surgeons conference and the title of his presentation is What’s New in Imaging For The Cardio-Thoracic Surgery Patient?

Dr. Robert Beanlands, M.D., F.R.C.P.(C) [UOHI],
Chief, Cardiac Imaging
Director, Cardiac PET Centre
Professor of Medicine (Cardiology)/Radiology (Cross-Appointment)
Division of Cardiology – University of Ottawa Heart Institute

Revolutionary treatments near for tumours

Dr. Barry Dworkin — Sun, 07 Aug 2005 03:41:22 +0000

Originally published in The Ottawa Citizen, August 6, 2005
Original Title: Sounds Like a Good Idea

New ultrasound technologies offer valuable diagnostic tools

The application of new technologies and research has the potential to revolutionize medical diagnostic imaging, diagnosis and treatment.

My last column looked at the amazing progress being made to restore lost sight. Exciting research and development is happening in the field of therapeutic ultrasound technology to treat prostate cancer and diagnostic ultrasound.

A new type of diagnostic ultrasound technology, reported in the April 16 issue of the New Scientist, is close to entering clinical trials. Dr. Vasilis Marmarelis, a professor of biomedical engineering, and his research team at the University of California’s Viterbi School of Engineering have created high-resolution ultrasonic transmission tomography (HUTT).

What makes the HUTT system different from conventional ultrasound is that it relies on the organs and tissue’s sound absorption qualities as opposed to sound reflection. Approximately 2,000 times as much sound passes through the organs and tissues than reflects back. Each tissue type absorbs a specific sound frequency akin to a “fingerprint” or sound biomarker. Dr. Marmarelis states that the system will be able to differentiate between benign and malignant tumours.

What is remarkable is that in addition to the ability to look at different structures with the same organ, the resolution is greater than magnetic resonance imaging. MRI images have a resolution of about two millimetres; it will image tumours or structures greater than two millimetres in size. MRIs take slices through the body like a stack of pancakes. Across the breadth of each pancake you have a two-millimetre resolution, but the space between the pancake layers is five millimetres.

The HUTT system resolves images as small as 0.4 millimetres across and between the slices, thus improving the image resolution. The rendered image is a smooth, high-resolution, three-dimensional picture. The machine appears similar to an MRI but, instead of lying down inside a drum, the patient remains standing.

The cost of the device is estimated to be five to 10 times less expensive than an MRI. Dr. Marmarelis is hopeful the HUTT system will become commercially available within 18 to 24 months.

Prostate cancer is the second most common malignancy in males worldwide. Men with early stages of prostate cancer now have another treatment option offered at the Don Mills Surgical Unit in Toronto. Although this treatment has been used in Europe for years, Toronto is the first city in North America to have this facility.

The treatment consists of using high-intensity focused ultrasound (HIFU) to destroy the tumour. The procedure can last between 90 minutes to three hours. A probe is inserted into the rectum after spinal or epidural anesthesia. It will image the gland and show the physician the location of the tumour in the prostate.

The probe will then emit sound waves that are focused into a tight beam targeting only the tumour. The focused beam heats the tumour to 85C, rapidly destroying the cancerous cells.

The HIFU system is indicated for men with stage T-1 or T-2 prostate cancer and for curative salvage therapy for local recurrence of the tumour after external beam radiation therapy. Studies are ongoing evaluating the long-term success rates of treatment.

The addition of new imaging software and technological improvements to the hardware continue to improve treatment outcomes.

One HIFU study done in Europe with 137 patients showed that 93 per cent had negative biopsies of the prostate gland five years after HIFU. Eighty-seven per cent had Prostatic Specific Antigen (PSA) levels of less than one microgram per litre five years after having the HIFU treatment. This evidence indicates a cancer-free state. Studies continue to follow these patients over the longer term. Retreatment rates are approximately 10 per cent.

Dr. John Warner, a Memorial Sloan-Kettering trained uro-oncologist practising in Vancouver, says HIFU is a clinically proven treatment for stage T-1 and T-2 tumours and is a revolutionary advance in their eradication.

The advantages to the patient are that it is non-invasive; there is no direct cutting into the tissue or ionizing radiation used, side effects are minimal, recovery is quick, there is less damage to the surrounding healthy tissue, and other treatment options can continue to be used to destroy the cancer.

Each patient is unique and requires special consideration. Consult your urologist about whether this would be an option for you. More information can be found on the website www.hifu.ca .

Medical advances restore vision for the future

Dr. Barry Dworkin — Tue, 26 Jul 2005 03:37:48 +0000

Originally published in The Ottawa Citizen, July 25, 2005
Original title: Future Visions Now a Reality

Four exciting good-news medical stories warrant more exposure. Two of the stories report research into restoring the sight of visually impaired people. The other two stories demonstrate ultrasound technology advances to treat prostate cancer and improve medical diagnostic imaging.

The eyes have it.

Researchers at the Centre for Sight, Queen Victoria Hospital, in East Grinstead, West Sussex, spent five years perfecting a technique to restore the vision of patients who suffered severe corneal damage from acid, alkali and molten metal burns or from congenital disorders. These people were told at the time of their injury they had little hope of regaining their sight.

The cornea is the clear “window” covering the centre of the eye. When damaged, it can scar blocking light from passing through the pupil to the retina.

The treatment process involves harvesting stem cells that come from the eyes of donors. The cells, in turn, are grown into sheets. Once the sheet is complete, they are placed onto the surface of the eye and held in place by an amniotic membrane. This special membrane dissolves once the sheet fuses to the eye.

An unexpected outcome of the procedure was that the rejection rate of the transplanted tissue was almost nil. A year after the transplant, DNA analysis of the transplanted tissue showed no trace of the stem cell donor’s DNA; there was no donor tissue left. The recipient’s eyes took over the healing process and repaired the damage. This meant there was no need for long-term use of anti-rejection drugs to suppress the immune system.

Edward Bailey, who suffered a caustic acid injury to his left eye and lost his sight, said the operation has transformed his life. “It was the most emotional moment,” Mr Bailey, 65, said. “I couldn’t believe it. For 10 years all I had seen was shades of black and grey, then after I had the operation, the nurse came by and I saw a flash of blue from her uniform.

“I went home and when I took the patch off my eye, I had my vision back. It is only when you lose something like sight that you realize how precious it is.”

The team is now looking at other avenues to apply this technology to other damaged tissue around the body.

Another sight restoration procedure was reported by scientists from the University of Southern California and the Doheny Retina Institute in May at the annual meeting of the Association for Research in Vision and Ophthalmology. Six patients with retinitis pigmentosa, a progressive degeneration of the light-sensing cells of the retina, were given artificial retina implants or intraocular retinal prostheses.

The retinal prosthesis, developed and created in conjunction with Second Sight Medical Products of California, is a four-by-four grid of platinum electrodes set in a thin silicone rubber sheet about the thickness of Scotch tape. The sheet is implanted directly onto the retina.

The grid remains in constant wireless communication with a small external computer controller that is attached to the recipient’s belt. The image data is sent to the computer via a tiny video camera attached to special glasses worn by the patient. The computer digitizes the image and sends it to the platinum grid. The grid then stimulates the eye’s photoreceptor cells just like the retina once did. The signal is then carried to the brain’s vision centre to process the image.

Although the grid contains only 16 electrodes proving only 16 pixels of resolution (today’s consumer digital cameras typically have three million to five million pixels), patients were able to detect light, identify objects and even tell if an object was in motion.

In 2002, after being blind for more than 50 years, the first patient to receive the implant was able to see large letters and distinguish between a cup, a plate and a knife.

Mark Humayun of Johns Hopkins University, who has a doctorate in bioengineering and surgical training and started this project, will begin the next step to improve pixel density. This year he plans to use an implant that has 60 to 100 electrodes but is a quarter of the size of the original model. He hopes that 200 to 400 electrode models will be available in three years and plans to develop a prototype for a 1,000-electrode implant in five years.

The hope is that these devices will help restore the sight for people with retinitis pigmentosa and macular degeneration.

In the next column, we’ll look at amazing things you can do with ultrasound.

The upside to medical technological advancement

Dr. Barry Dworkin — Mon, 19 Jan 2004 22:46:33 +0000

Originally published in The Ottawa Citizen January 19, 2004
Original Title: Medical technological advancement redux

Genius… means little more than the faculty of perceiving in an unhabitual way. – William James, 1842-1910

We are living in an exciting age of new therapies and medical technological advancement. This advancement is due to ongoing research and development in areas such as microchip design, medical imaging (e.g. MRI and PET scans), materials science, biological agents, genetics, virology, microbiology, tissue receptor identification, stem cells and nanotechnology among others.
The exponential growth of computing power has enhanced the pace of this research.

New diagnostic tests may improve early detection of cancer, diabetes, heart disease and others. New medical technologies have the potential to supplant or complement standard treatments for these complex diseases. What are some of these exciting developments?

The Ottawa Regional Cancer Centre’s promising research into vaccines to combat specific cancers epitomizes intellectual achievement. The idea is logical and straightforward; alter the structure of a harmless virus and literally teach it to seek out and destroy cancer cells and leave normal cells unharmed. Should the Cancer Centre’s clinical trials prove successful, the vaccine treatment might reduce the dose of chemotherapy medications or eliminate the need for them. The side effects from certain chemotherapeutic agents could be all but eliminated. Morbidity (the harm from the disease and treatment side effects) will be lessened and survival rates will improve. Absolutely marvelous.

The use of radiation to destroy cancerous tumours is a delicate balance of irradiating as much of the tumour as possible while minimizing the dose on adjacent healthy tissue. The most common cause of side effects of radiotherapy is the result of damage to normal tissue. The trick is to find a way to target the cancer with more powerful doses of radiation without the concomitant damage to the surrounding area. If the area exposed to treatment can be reduced, more powerful radiation beams will increase the likelihood of tumor destruction.

In 1946, Robert Wilson, a Cornell physicist postulated that protons (a subatomic particle with a positive electrical charge) could help cancer patients. Forty years of research on the effect of high speed protons is leading to medical applications to combat inoperable cancers.

Proton beam therapy research shows great promise. A cyclotron is used to accelerate the protons to speeds needed to penetrate tissue. The protons can be focused onto a small target area of cells destroying them yet leaving the surrounding tissue unharmed.

It has successfully treated certain brain tumours in children adjacent to the eyes and ears. Other conditions that respond to treatment include malformations of the arteries and veins of the brain that can bleed if left untreated, acoustic neuromas, tumours of the head and neck, medically inoperable non-small cell lung cancer and prostate cancer among others.

There are only three centres in the United States that offer proton beam therapy because of the prohibitive cost of constructing the cyclotron.

Preventive measures to detect early stage colon cancer include colonoscopy, an indispensable and gold-standard procedure. This invasive procedure remains foreboding to many patients. It can be painful and requires pre-test laxatives to empty the bowel. There is a small risk of bleeding or bowel perforation during the procedure.

A recent Chicago meeting of the Radiological Society of North America reviewed a study on the use of 3-D computed tomography (CT) virtual colonoscopy compared to standard colonoscopy when screening for colorectal polyps.

The study compared 1,233 asymptomatic adults (mean age, 57.8 years) who underwent same-day virtual and conventional colonoscopy. Virtual colonoscopy was first performed by the radiologist to check for polyps. The colonoscopy specialist followed with an identical investigation of the colon unaware of the virtual colonoscopy findings.

The term sensitivity for any test refers to the likelihood a positive result is indeed positive. Specificity means the likelihood a negative result is truly negative. As values approach 100 per cent, the more reliable they become.

The sensitivity of 3-D CT virtual colonoscopy for adenomatous polyps was 93.8 per cent for polyps at least ten millimeters in diameter, 93.9 per cent for polyps at least eight millimeters in diameter and 88.7 per cent for polyps at least six millimeters in diameter. Convention colonoscopy produced sensitivities of 87.5 per cent, 91.5 per cent and 92.4 per cent for the three polyp sizes, respectively.

The specificity of virtual colonoscopy for adenomatous polyps was 96 per cent for polyps at least 10 millimeters in diameter, 92.2 per cent for polyps at least 8 millimeters in diameter and 79.6 per cent for polyps at least 6 millimeters in diameter.

“Virtual colonoscopy is a very promising tool for cancer screening because it is minimally invasive and certainly less invasive than conventional colonoscopy,” said lead study author Dr. Perry Pickhardt, an associate professor of radiology at the University of Wisconsin medical school. “It would reduce the number of negative conventional colonoscopies being performed, and also hopefully encourage more patients to seek out screening.”

These