Pristina
Breast-cancer screening breakthrough
He identifies two aspects of mammography as critical to accurate, early — before you may even feel a lump — detection of breast cancers: medical-image quality and adherence of women between the ages of 40 and 74 to bi-annual screening.
In February this year, O’Connor’s Coastal Medical Imaging and László Tabár Breast Centre became the first Australian site, and the third medical-imaging clinic in the world, to instal imaging technology that significantly improves the outcomes of both clarity of breast images, and the level of comfort and care that women experience during screening.
GE’s Senographe Pristina officially launched in March 2017, turned O’Connor, who is respected internationally for his groundbreaking work in breast radiology, into an advocate for 3D tomosynthesis.
“The Senographe Pristina’s 3D tomosynthesis, with its sub-millimetre slices is the biggest thing for us. We use it on every single patient and we realistically find cancers that other people did not,” he says.
New procedure, clearer outcomes
O’Connor says recent years have seen global expert debate on the benefits of 3D tomosynthesis versus the widely used 2D digital mammography. Until 2017, he agreed with BreastScreen Australia that “2D digital mammography remains the most effective screening test” for breast cancer. “I’ve had competitors who’ve had 3D tomography for years, but I refused to buy into it because I didn’t think that the existing 3D products were to the standard of GE Senographe Essential.” Coastal Imaging has long deployed the GE Senographe Essential digital mammography system to generate high-quality 2D images.
With a growing number of studies in Europe and the US showing 3D mammography detects more cancers than 2D, and that it also reduces the incidence of false cancer diagnoses, BreastScreen Victoria is now trialling 3D tomosynthesis, for effectiveness and feasibility in the broad Australian context.
In tomosynthesis the x-ray tube moves in an arc over the compressed breast to capture multiple images from different angles. The reconstructive algorithm then “synthesises” these images into a set of three-dimensional views in which tissue overlap is minimised. Tissue overlap is one barrier to distinguishing cancers from benign lumps, and can also hide cancers from view.
Among the differences between previous 3D tomography technology and the Senographe Pristina, says O’Connor, “is that this is a purpose-built machine — it hasn’t had 3D cobbled onto it”. Importantly, he says that the acquisition of submillimetre image slices of the breast, and subsequent submillimetre accuracy in reconstruction of the 3D view using GE’s ASiR iterative reconstruction algorithm, result in much clearer visualisation of breast abnormalities than was previously possible, with superior reduction of distracting artefacts.
A no-fear experience to keep women coming back
Of course, image quality means nothing if women don’t show up for screening. The biannual call to have a mammogram has long been regarded with fear — of the outcomes — and loathing of the uncomfortable, often painful, procedure.
Purpose built for 3D-image acquisition Senographe Pristina is purpose designed to reshape the mammography experience, taking into account women’s feedback on screening to date. The result is a uniquely appealing-looking system — slim line, not monstering; curved, not hard edged — that allows technicians to set up the patient for imaging in a more empathetic way — face to face and with easy access for the technician to every part of the machine.
O’Connor identifies Pristina’s soft-plastic face shield as a particularly inspired design element, the use of which is intuitive to patients and helpful to technologists: “You lean your face into it, and its positioning means you and the technician don’t have to worry about your face blocking the image acquisition.”
“We wanted to build a machine that changed the subjective perception of the mammogram and spoke to the woman, to make her feel reassured,” says industrial designer Aurelie Boudier, one of the women on the team that developed Pristina.
Insights from more than 1,200 doctors, technicians and patients surveyed by GE suggested that willingness to return for regular mammograms is affected by women’s initial experience of compression of their breasts to achieve what’s known as a minimum diagnostic thickness. GE approached this problem in two ways, by making the paddles that compress the breast more flexible, and by putting compression control in the hands of the patient.
Says O’Connor: “When you have really rigid paddles and you compress the breast, you’re squishing it in a vice, and what hurts is not the compression itself but the shearing as parts of your breast move to the left and parts of your breast move to the right. GE has developed a paddle that has flexibility, resulting in much less of that shearing effect, but which still gives good compression.” Pristina’s soft armrests which replace the more common hand grips, also help women to relax their muscles, easing discomfort and aiding clear image acquisition.
Sharing control enhances imagery
The addition of Senographe Pristina Dueta, a remote control that allows women to determine the pressure applied for compression, again improves women’s experience and delivers better images. “We compress the breast to a minimum diagnostic thickness of 3cm to 4cm, and then we say to the woman, ‘Every Newton of extra pressure we get will increase our diagnostic sensitivity and specificity.’” Studies have shown and O’Connor’s experience confirms that, on average, patients will apply an extra 30% of pressure when thus engaged in the acquisition of their mammograms
O’Connor adds that although the Pristina gathers a more detailed and comprehensive set of images, the ergonomics of the machine from an operator perspective, and the intuitive and sensitive design of the machine as experienced by patients, actually reduces the time needed to position each woman and acquire images. For Coastal Medical Imaging that means more time spent engaging with patients and understanding their medical history and circumstances.
“We’ve shortened our imaging time, and our mammographers’ work time going in and setting up the machine. It’s that much easier to use that we could see more patients if we wanted to, but we’ve taken that extra time to spend it with the patient as an individual,” he says.
That Senographe Pristina delivers superior diagnostic accuracy at the same small radiation dose as 2D Full Field Digital Mammography addresses women’s concerns to maintain low radiation exposure over their lifetime. O’Connor believes, “Having a machine that uses almost half the radiation of its nearest 3D competitor will also help decrease women’s screening interval, and we know that decreasing the screening interval saves lives.”
For more information on the importance of regular breast screening, visit BreastScreen Australia.