Fraunhofer will showcase its MARIUS project which combines magnetic resonance imaging (MRI) and ultrasound at MEDICA 2013 in Düsseldorf from 20 to 23 November.
In the joint MARIUS project, experts from both the Fraunhofer Institute for Biomedical Engineering IBMT in St. Ingbert and the Fraunhofer Institute for Medical Image Computing MeVis in Bremen are working together to provide an alternative method to carry out tumour biopsies.
Currently, doctors take biopsies using ultrasound to guide the needle, or, failing that, with an MRI scan. Around 30 per cent of all tumours are invisible to ultrasound; however, guiding the needle with an MRI scan is a two-step process which often has to be repeated several times before the sample is finally taken.
The new technique would require just one scan of the patient’s entire chest at the beginning of the procedure. Doctors would have both the live ultrasound scan and a corresponding MRI image available to guide the biopsy needle and display exactly where the tumour is located.
While the MRI is performed the patient lies face down, but during the biopsy the patient lies on their back. This change of position alters the shape of the patient’s breast and shifts the position of the tumour significantly. To track these changes accurately, ultrasound probes are attached to the patient’s skin to provide a succession of ultrasound images during the MRI scan. This produces two comparable sets of data from two separate imaging techniques.
When the patient undergoes the biopsy in another examination room, the ultrasound probes remain attached and continually record volume data and track the changes to the shape of the breast. Algorithms analyse these changes and update the MRI scan accordingly.
When the biopsy needle is inserted into the breast tissue, the doctor can see the reconciled MRI scan along with the ultrasound image on the screen, improving the accuracy of needle guidance towards the tumour.
'We’re currently working on an ultrasound device that can be used within an MRI scanner,’ says IBMT project manager Steffen Tretbar. ‘These scanners generate strong magnetic fields, and the ultrasound device must work reliably without affecting the MRI scan.’
The primary objective of MARIUS is to develop ultrasound tracking to aid breast biopsies, but the developed components could also be used in other applications. The movement-tracking software could allow slow imaging techniques such as MRI or positron emission tomography (PET) to track the movements of organs that shift even when a patient is lying still. The heart would appear well defined on MRI scans instead of being blurred due to movement. The jointly developed technology could also be applied to treatments that use particle or X-ray beams. For tumours located in or on a moving organ, the new technology could target the rays so that they follow the movement. These beams could hit the tumour with more precision than currently possible and reduce damage to healthy surrounding tissue.
