In vivo Breast Sound-Speed Imaging with Ultrasound Tomography

• Published in: Ultrasound in medicine & biology Vol. 35; no. 10; pp. 1615 - 1628
• Main Authors: Li, Cuiping, Duric, Nebojsa, Littrup, Peter, Huang, Lianjie
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.10.2009
• Subjects: Adult; Algorithms; Breast imaging; Breast Neoplasms - diagnostic imaging; Carcinoma, Ductal, Breast - diagnostic imaging; Cohort Studies; Diagnosis, Differential; Female; Fibroadenoma - diagnostic imaging; Humans; Image Interpretation, Computer-Assisted - methods; Middle Aged; Patient Selection; Phantoms, Imaging; Radiology; Sound-speed; Tomography - instrumentation; Tomography - methods; Total-variation; Ultrasonography, Mammary - instrumentation; Ultrasonography, Mammary - methods; Ultrasound tomography; Ultrasound tomography; Sound-speed; Total-variation; Breast imaging
• ISSN: 0301-5629; 1879-291X; 1879-291X
• DOI: 10.1016/j.ultrasmedbio.2009.05.011

We discuss a bent-ray ultrasound tomography algorithm with total-variation (TV) regularization. We have applied this algorithm to 61 in vivo breast datasets collected with our in-house clinical prototype for imaging sound-speed distributions in the breast. Our analysis showed that TV regularization could preserve sharper lesion edges than the classic Tikhonov regularization. Furthermore, the image quality of our TV bent-ray sound-speed tomograms was superior to that of the straight-ray counterparts for all types of breasts within BI-RADS density categories 1 through 4. Our analysis showed that the improvements for average sharpness (in the unit of ( m · s) −1) of lesion edges in our TV bent-ray tomograms are between 2.1 to 3.4-fold compared with the straight ray tomograms. Reconstructed sound-speed tomograms illustrated that our algorithm could successfully image fatty and glandular tissues within the breast. We calculated the mean sound-speed values for fatty tissue and breast parenchyma as 1422 ± 9 m/s (mean ± SD) and1487 ± 21 m/s, respectively. Based on 32 lesions in a cohort of 61 patients, we also found that the mean sound-speed for malignant breast lesions (1548 ± 17 m/s) was higher, on average, than that of benign ones (1513 ± 27 m/s) (one-sided p < 0.001). These results suggest that, clinically, sound-speed tomograms can be used to assess breast density (and therefore, breast cancer risk), as well as detect and help differentiate breast lesions. Finally, our sound-speed tomograms may also be a useful tool to monitor the clinical response of breast cancer patients to neo-adjuvant chemotherapy. (E-mail: lic@karmanos.org)