Scientists from Finland, Germany and the European Synchrotron Research facility (ESRF) have developed a new technique that could enable doctors to detect tumours with greater precision than is currently possible using X-ray mammography.
The technique itself allows a 3D image of the breast to be created with a high spatial resolution. Better yet, it is extremely sensitive to alterations in the tissue, such as those generated by cancer.
Although X-ray mammography is currently the most widely used tool in diagnostic radiology, it fails to identify about 10 to 20 per cent of palpable breast cancers. This is because some breasts, especially in young women, are very dense. Therefore, on mammograms, glandular tissues can mask cancer lesions.
Better results are obtained using X-ray computed tomography (CT). CT imaging could produce accurate 3D images of the entire breast, improving the detection of early diseases in dense breasts. However, its use in breast imaging is limited by the radiation dose delivered to a radiosensitive organ such as the breast.
But using a new CT technique has allowed the scientists to overcome this problem. The researchers, including physicists, surgeons, radiologists and pathologists, used the technique, called Analyzer-Based X-ray Imaging (ABI), on an in vitro specimen at the ESRF, using a radiation dose similar to that of a mammography examination. The dose corresponded to a quarter of that required for imaging the same sample with a conventional CT scanner and the spatial resolution of the ABI images was seven times better.
For the experiment, researchers chose a particularly challenging specimen: a breast invaded by a lobular carcinoma (a diffusely growing cancer), the second most common form of breast cancer, which is also very difficult to visualise in clinical mammography. In this kind of sample, the determination of the extension of the cancer frequently fails in X-ray mammograms and ultrasonographs of the breast.
The results showed that high-spatial-resolution ABI-CT makes visible small-size and low-contrast anatomic details that could otherwise only be seen by the microscopic study of an extracted sample of the breast tissue (histopathology).
‘We can clearly distinguish more microcalcifications – small deposits of minerals that can indicate the presence of a cancer – than with radiography methods and improve the definition of their shapes and margins,’ said researcher Jani Keyriläinen.
He added: ‘If we compare the images with X-ray mammograms and conventional CT images, we can confirm that this technique performs extremely well.’
An image of a breast using the new ABI technique. The arrow shows the location of the tumour
Despite having studied only in vitro samples, the team is optimistic that the technique will be applied in the future in clinics. They hope that the current worldwide development of compact, highly intense X-ray sources will someday enable the clinical use of the technique.
Once the technique has been confirmed and tabletop synchrotrons are on the market, progress could be rapid.
‘With such machines it would definitely be possible to apply this technique in clinical practice’, said Alberto Bravin, scientist in charge of the biomedical beamline at the ESRF.