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 .
© Dr. Barry Dworkin 2005