A portable ultrasound scanner for the early detection of breast cancer

Researchers at the Mass­a­chu­setts Insti­tute of Tech­nol­o­gy (MIT) have devel­oped a 3D-print­ed patch that can be attached to a bra using mag­nets. This inno­v­a­tive device is based on the same tech­nol­o­gy as con­ven­tion­al ultra­sound scan­ners used in hos­pi­tals today. The dif­fer­ence is that it is made from a new piezo­elec­tric mate­r­i­al, which makes the device much more com­pact and portable. These mate­ri­als are wide­ly used as trans­duc­ers and sen­sors in med­ical ultra­sound imag­ing sys­tems. By react­ing to exter­nal mechan­i­cal stress and then sep­a­rat­ing pos­i­tive and neg­a­tive elec­tri­cal charges, they can con­vert the mechan­i­cal ener­gy of vibra­tions into elec­tri­cal energy.

Breast can­cer is the most com­mon can­cer in women. If diag­nosed at an ear­ly stage, the sur­vival rate is close to 100%. How­ev­er, if it is detect­ed lat­er, it drops to 25%. Ear­ly detec­tion is there­fore vital. The inter­stices (also known as matri­ces) in the hon­ey­comb struc­ture of the new patch allow it to con­tact the skin. The device is insert­ed into a small trac­er that can be moved into dif­fer­ent posi­tions to obtain images of the entire breast from dif­fer­ent angles. The images pro­duced have a res­o­lu­tion sim­i­lar to that of con­ven­tion­al ultra­sound probes.

Anoth­er advan­tage of the patch is that it does not require any spe­cial exper­tise to use. In con­trast, con­ven­tion­al scan­ners require high­ly qual­i­fied per­son­nel. The device can also be used repeat­ed­ly, and could there­fore serve as a pre­ven­tive imag­ing device for women at high risk of breast can­cer. It could also diag­nose tumours in women who do not have access to con­ven­tion­al screening.

In col­lab­o­ra­tion with MIT’s Cen­ter for Clin­i­cal and Trans­la­tion­al Research, the researchers, led by Canan Dagde­viren, test­ed their device on a 71-year-old woman with a his­to­ry of breast cysts. They found that their device could detect cysts as small as 0.3 cm in diam­e­ter, which is the same size as ear­ly-stage tumours. They were also able to image tis­sue to a depth of eight cen­time­tres – about as deep as you can get with a con­ven­tion­al ultra­sound scanner.

Ear­ly detec­tion is key to increas­ing sur­vival rates.

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« In cur­rent ultra­sound breast imag­ing tech­nolo­gies, although hand­held ultra­sonog­ra­phy (HHUS) and auto­mat­ed breast ultra­sound (ABUS) are the pre­ferred meth­ods, there are still tech­ni­cal gaps that need to be over­come for ultra­sound to become a reli­able option for breast can­cer screen­ing, » explains Canan Dagde­viren. « These gaps are: HHUS relies heav­i­ly on the exper­tise and train­ing of tech­ni­cians to man­u­al­ly scan the whole breast by apply­ing strong com­pres­sion, which is uncom­fort­able for the patient; and ABUS can scan the whole breast at once, but skin con­tact remains poor (due to the use of a liq­uid medi­um between the tis­sue and the sta­tion­ary machines used in a hos­pi­tal setting). »

The new device is the first ultra­sound tech­nol­o­gy to fill both these gaps. It offers a non-inva­sive, wide-field-of-view, real-time and con­tin­u­ous mon­i­tor­ing of curved breast tis­sue. This could pro­vide doc­tors with reli­able, cost-effec­tive and acces­si­ble breast imag­ing for ear­ly detec­tion of breast abnor­mal­i­ties. Canan Dagde­viren adds, « Our work rep­re­sents a fun­da­men­tal change in the way clin­i­cians and patients can screen for, detect and diag­nose breast can­cer, espe­cial­ly as ear­ly detec­tion is key to increas­ing sur­vival rates. »

The bra/patch con­sists of a trac­er that moves over the breasts, fol­low­ing a spe­cif­ic tra­jec­to­ry to allow for a max­i­mum field of vision. By being con­nect­ed to the “Vera­son­ics” sys­tem, the matrix in the patch can send high-fre­quen­cy puls­es to the patch’s piezo­elec­tric com­po­nents and receive an ‘echo’ from oth­er com­po­nents. « We then gen­er­ate images by com­bin­ing all the pulse-echo sig­nals using a spe­cial­ly designed algo­rithm, » explains Canan Dagde­viren. « The images of the breast tis­sue are record­ed by the sys­tem and the cysts can be observed on a screen.”

A num­ber of chal­lenges need to be addressed if the portable ultra­sound patch is to become a mar­ketable prod­uct. First­ly, it will have to be minia­turised even fur­ther. This will involve inte­grat­ing com­plex ultra­sound com­po­nents, such as trans­duc­ers and elec­tron­ics, into a com­pact, light­weight struc­ture, with­out com­pro­mis­ing image qual­i­ty. Ide­al­ly, the qual­i­ty of the ultra­sound image should be com­pa­ra­ble to that obtained with tra­di­tion­al ultra­sound scanners.

A wear­able patch also obvi­ous­ly needs to be com­fort­able for the wear­er, and achiev­ing a bal­ance between flex­i­bil­i­ty, soft­ness and ade­quate adhe­sion to ensure prop­er con­tact with the breast with­out cre­at­ing dis­com­fort remains challenging.

« We need to cre­ate a user-friend­ly inter­face too, » explains Canan Dagde­viren. « This should allow health­care pro­fes­sion­als to mon­i­tor and inter­pret the device’s out­put. The patch itself need to be designed with ease of use in mind, so that it can be eas­i­ly inte­grat­ed into med­ical workflows.

The researchers also hope to devel­op a method in which arti­fi­cial intel­li­gence (AI) can be used to analyse changes in images over time. This would offer more accu­rate diag­noses than com­par­ing images tak­en months or even years apart.

Final­ly, the device will need to be clin­i­cal­ly val­i­dat­ed, she adds. « Any med­ical device, includ­ing such a wear­able ultra­sound patch, must under­go rig­or­ous clin­i­cal test­ing and val­i­da­tion to ensure its safe­ty and effi­ca­cy in real-world sce­nar­ios. This means work­ing close­ly with med­ical pro­fes­sion­als and patients. »

Devel­op­ing a portable sys­tem for dai­ly self-screen­ing is also a sub­ject of study for the research team. « Such a sys­tem will allow for indi­vid­u­alised ultra­sono­graph­ic pro­file gen­er­a­tion along with big data col­lec­tion (that is, images of tis­sue and results analysed by AI) to send to doc­tors for rapid and objec­tive assess­ments. »  It could also be inte­grat­ed into a wire­less com­mu­ni­ca­tion sys­tem to mon­i­tor the devel­op­ment of tumours over time or in response to med­ical therapies.

Isabelle Dumé

Ref­er­ence : Sci­ence Advances