Light and Sound for Better Medical Imaging

The prototype system has been developed by medical physics and bioengineering experts at University College London. It is soon to undergo trials in clinical applications, with routine deployment in the healthcare sector envisaged within around 5 years.

The system uses extremely short pulses of low-energy laser light to stimulate the emission of ultrasonic acoustic waves from the tissue area being examined. These waves are then converted into high-resolution 3D images of tissue structure.

This method can be used to reveal disease in types of tissue that are more difficult to image using techniques based on x-rays or conventional ultrasound. For example, the new system is supposed to be better at imaging small blood vessels, which may not be picked up at all using ultrasound. This is important in the detection of tumours, which are characterised by an increased density of blood vessels growing into the tissue.

The emission of an acoustic wave when matter absorbs light is known as the photoacoustic effect. Harnessing this basic principle, the new system makes use of the variations in the sound waves that are produced by different types of soft human tissue to identify and map features that other imaging methods cannot distinguish so well.

By appropriate selection of the wavelength of the laser pulses, the light can be controlled to penetrate up to depths of several centimetres. The technique therefore could have potential for the better imaging of conditions that go deep into human tissue, such as breast tumours, and for contributing to the diagnosis and treatment of vascular disease.

The prototype instrument, however, has been specifically designed to image very small blood vessels with diameters measured in tens or hundreds of microns that are relatively close to the surface. Information generated about the distribution and density of these microvessels can in turn provide valuable data about skin tumours, vascular lesions, burns, other soft tissue damage, and even how well an area of tissue has responded to plastic surgery following an operation.

MEDICA.de; Source: Engineering and Physical Sciences Research Council