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High resolution contrast angiography of organ circulatory systems
Neural and hormonal factors regulate blood flow throughout the body, and provide a sensitive means
of controlling the distribution of blood to different organ systems. To better understand the causes
of cardiovascular disease and the efficacy of novel therapies we use the power of high energy x-rays
to investigate the control of the microcirculation in real time, in live animals.
In many chronic disease states such as hypertension and diabetes the regulation of blood flow
is disturbed by changes in the balance of endothelial vasodilator and vasoconstrictor mechanisms.
More importantly, using techniques such as laser Doppler many researchers have shown that
circulatory regulation mechanisms differ between organ systems in health and disease states.
To obtain new insights into circulatory dysfunction however, requires knowledge of how different
blood vessel types and sizes are regulated. We have developed synchrotron contrast angiography
protocols to investigate the control of blood flow to the vital organs, such as the brain, lungs,
heart and kidneys in small animal models. Using conventional iodinised contrast agent the rapid
imaging and high spatial resolution of this approach allows us to visualise small arteries and
arterioles ~30 μm in diameter in some organ systems.
This figure shows a subtracted angiogram of the mid-brain region of a rat.
Lowering the oxygen content of the inhaled air increases blood flow to the brain, and in
particular the medullary region (an important cardiovascular control centre), as indicated
by the arrows.
Some of our research objectives are to identify vascular reactivity and the adequacy of blood
perfusion in models of arterial hypertension and diabetes. With other colleagues in the
Physiology Department we are investigating regional control of blood flow in the kidney
(Assoc. Prof. Roger Evans and
Dr Gabriela Eppel) and ureter
function (Dr Rick Lang).
Other areas of research effort include heart disease. Currently, we are investigating coronary
artery dysfunction following myocardial infarction, and how pro-inflammatory factors and oxidative
stress contribute to chronic heart failure. New image enhancement approaches are being developed in
collaboration with the Department of Mechanical Engineering (Dr David Lo Jacono, Dr Andreas Fouras
and Prof. Kerry Hourigan) to improve the accuracy of our analyses of vessel vasomotor function. These
approaches are now being applied to projects that will investigate new therapies to improve heart
function through improved coronary blood flow and reduced systemic vascular resistance.
This figure shows a synchrotron angiogram of a rat heart. The highlighted region shown on the right
illustrates an enhanced edge detection method being developed at Monash University for more accurate
image analysis.
Monash researchers involved:
External collaborators:
- Dr Amanda Edgley, Department of Medicine, St Vincent's Institute, Melbourne
- Dr Daryl O. Schwenke, Department of Physiology, Otago University, New Zealand
- Prof. Mikiyasu Shirai, Department of Clinical Radiology, Hiroshima International University, Japan
- Dr Keiji Umetani, Japan Synchrotron Radiation Research Institute (SPring-8), Japan
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This image shows arteries in the brain of a rat with high blood
pressure. It was taken using synchrotron light.
High blood pressure causes stiffening and narrowing of the arteries which in turn
affects blood flow and can lead to conditions like stoke and brain damage.
Using this technique it is possible to see blood vessels in living organisms
that are less than 0.1mm thick.
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