Matthew Armstrong

Introduction: Breast cancer is the second most prevalent cause of cancer deaths in women.¹  Given the high metastatic potential and frequency of this disease, millions of women are screened every year through x-ray mammography. Where this method is highly established in genotypical and minimal risk populations, for women with dense breasts, mammogram interpretation becomes increasingly difficult and is often an indication for supplemental imaging methods. According to the USPSTF, this population of women with “heterogeneously dense” or “extremely dense” breast tissue comprises 43% of the US population.2 This population is not only more difficult to screen but has higher relative hazard for breast cancer at 1.83 or 1.50 in different age categories.³   From an engineering standpoint, the scope of the clinical problem might be lensed: the need for a high-resolution, low-cost, non-irradiating imaging screening method for at-risk patients that is easy to interpret, comfortable, and effective in patients with elevated breast density. One alternative method looks to involve transmission acoustic contrast as a means of improving diagnostic yield in patients in this risk category without radiation, compression, or high cost. Methods: A company named QT Ultrasound has been testing and validating a system that utilizes transmission ultrasound science to produce images that contrast tissues based on the speed of sound propagation through them. During initial stages of testing, they configured a prototype apparatus that generated low-res 394×394 pixel images that plotted speed of sound (SOS) values from transmission calculations. After testing on calibrated phantoms and cadaveric representations of benign fibroadenoma and simple cysts, SOS values were compared to literature standards.⁴   In another study post FDA-approval, they performed blinded clinical trials in interpreting lesion diagnosis between cystic and solid breast masses from 17 radiologists across 37 different cases under QT scanning with biopsy confirmed results to verify.⁵   Results: Among other modes of testing, verification with literature values under different tissue conditions confirmed calculated speed-of-sound accuracy under different pathologic conditions by transmission ultrasound spectral data. Their first clinical trial between cyst and solid yielded an average interpreter accuracy of 0.92 with sensitivity and specificity 0.933 and 0.920, respectively.⁵   Conclusions: Though not exhaustively tested yet, the QT ultrasound technology holds promise as an adjunctive breast cancer screening modality. Given preliminary accuracy ratings and contrast means in the presence of dense fibroglandular tissue, the QT device may yet provide the missing screening tool.

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2. Melnikow J, Fenton JJ, Whitlock EP, et al. Supplemental Screening for Breast Cancer in Women With Dense Breasts: A Systematic Review for the S. Preventive Services Task Force. Ann Intern Med. 2016;164(4):268-278. doi:10.7326/M15-1789
3. Fahad Ullah Breast Cancer: Current Perspectives on the Disease Status. Adv Exp Med Biol. 2019;1152:51-64. doi:10.1007/978-3-030-20301-6_4
4. Wiskin J, Borup DT, Johnson SA, Berggren M. Non-linear inverse scattering: high resolution quantitative breast tissue J Acoust Soc Am. 2012;131(5):3802-3813. doi:10.1121/1.3699240
5. Iuanow E, Smith K, Obuchowski NA, Bullen J, Klock Accuracy of Cyst Versus Solid Diagnosis in the Breast Using Quantitative Transmission (QT) Ultrasound. Acad Radiol. 2017;24(9):1148-1153. doi:10.1016/j.acra.2017.03.024