Schulich School of Dentistry and Medicine Biomedical Engineering Faculty of Engineering

Imaging

The last two decades have witnessed an unprecedented growth in the development of new imaging systems such as computed tomography (CT), ultrasound, digital radiography, magnetic resonance imaging and spectroscopy (MRI & MRS), functional magnetic resonance imaging (fMRI) and tomographic radioisotope imaging.

These new techniques have revolutionized diagnostic radiology, providing the clinician with new information about the interior of the human body that has never before been available. Applications and innovations in radiological imaging are not abating but are in fact accelerating and, therefore, advances in image production and visualization will continue.

Our interdisciplinary teams of researchers have access to all available imaging modalities to study important disease problems. The goal of our imaging research team is to study important diseases through the combination of scientific disciplines and imaging techniques and to develop new imaging techniques for the improvement of diagnosis and treatment of human diseases.

Research Directions

Opportunities for the advancement of technology in the field of diagnostic imaging are numerous. Five imaging modalities under investigation are:

Computed Tomography (CT)

Three types of CT systems are under development:

  • High resolution table-top 3D CT with a resolution of approximately 0.02 x 0.02x 0.02 mm3 for use in imaging of research animals, specimens and for use in non-destructive testing;
  • Coherent scatter CT which extends the use of x-ray CT to provide information on the micro- structure;
  • Computed Rotational Angiography, which uses a neuro-angiographic system to produce 3D CT images of patients.

Ultrasound (US)

Ultrasound imaging is a non-invasive imaging technique, which makes use of ultrasound to image the human body. It is currently the primary clinical technique for the measurement of blood flow in the arteries. We have undertaken to develop quantitative techniques using Doppler ultrasound to investigate the flow patterns in human arteries, and compare them to those found with MRI and x-ray angiography. 
The other major program is focused on the development of 3D ultrasound imaging techniques for use in diagnosis and image-guided therapy. The scientists at the IRL are pioneers in this field with 14 patents filed and one spin-off company. The major applications of ultrasonography being explored are: diagnosis and image-guided biopsy in breast cancer, diagnosis and image-guided therapy of the prostate (brachytherapy, PDT, photocoagulation and thermal therapy), vascular imaging (vascular morphology, plaque rupture assessment, and 3D blood velocity vector field).

Magnetic Resonance Imaging (MRI)

MRI is the latest tool available to the radiologist for non-invasive diagnosis of disease. This imaging technique uses a strong magnetic field and radio-frequency energy, rather than x-radiation, and therefore poses no ionizing radiation risk to the patient. MRI has already exceeded the capabilities of other imaging techniques in the diagnosis of certain disorders, notably those of the central nervous system such as multiple sclerosis, brain tumours and spinal cord lesions. With the installation of a clinical 1.5T MRI unit at University Hospital in 1986, a research only 1.5T human cardio-vascular unit in July 1998, a 4T whole body unit at the IRL, as well as the small bore MRI/MRS system at the LRI in late 1998, the basic facilities, personnel and motivation required to investigate and develop advanced MRI/MRS techniques are in place.

Functional Magnetic Resonance Imaging (fMRI)

fMRI is a revolutionary extension of MRI technology applied to the study of human brain function. First demonstrated in 1992, this technique has largely replaced positron emission tomography (PET) for studies of how the brain processes information. This is because fMRI is non-invasive and offers much higher spatial and temporal resolution than previous brain mapping techniques, combined with exceptional anatomic localization. Research in the laboratory for fMRI research is aimed at pushing the frontiers of this technology, understanding its origins and applying it to studies of normal subjects and patient populations in collaboration with an extensive group of psychologists, physiologists, ophthalmologists, neurosurgeons and other clinicians. Research is performed on a 4T whole body research scanner installed in the RRI in 1996 and on a 3T head only installed at the LRI in 1999.

Magnetic Resonance Spectroscopy (MRS)

MRS is an innovative means of studying the biochemical regulation of living tissue. With this technique, researchers can observe metabolism in isolated organ preparations, experimental animals and also in humans. It is non-invasive and non-destructive and thus there are a number of medical problems that in vivo MRS methods are uniquely able to address. The Imaging Group is presently using MRS to study metabolism in the brain, heart and skeletal muscle, under a wide range of conditions using the 4T system at the RRI and 1.5T and 1.89T systems at the LRI.

Nuclear Medicine

Nuclear Medicine Imaging is an imaging modality with the potential to produce quantitative 3D maps of function and biochemistry within the human body. Emphasis has been to improve the quantification of SPECT brain and heart imaging. This relatively inexpensive technology has the potential for the early diagnosis and treatment assessment in neuro-degenerative and psychiatric diseases, but its widespread use is limited by errors. Current research indicates that the necessary improvements in quantification, needed for widespread application of brain SPECT, can be achieved. Studies are now underway in patients using new detector systems, modified reconstruction algorithms and new post quantification methods. Recently a patent has been filed to protect some of this new technology.