Ensuring the consistency of spectral-based quantitative ultrasound estimates in vivo necessitates accounting for diffraction, system effects, and propagation losses encountered in the tissue. Accounting for diffraction and system effects is typically achieved through planar reflector or reference phantom methods; however, neither of these is able to account for the tissue losses present in vivo between the ultrasound probe and the region of interest. In previous work, the feasibility of small titanium beads as in situ calibration targets (0.5–2 mm in diameter) was investigated. In this study, the importance of bead size for the calibration signal, the role of multiple echoes coming from the calibration bead, and sampling of the bead signal laterally through beam translation were examined. This work demonstrates that although the titanium beads naturally produce multiple reverberant echoes, time-windowing of the first echo provides the smoothest calibration spectrum for backscatter coefficient calculation. When translating the beam across the bead, the amplitude of the echo decreases rapidly as the beam moves across and past the bead. Therefore, to obtain consistent calibration signals from the bead, lateral interpolation is needed to approximate signals coming from the center of the bead with respect to the beam.

During the treatment of breast cancer via neoadjuvant chemotherapy (NAC), radiological clips are used to track lesions. Marking lesions allows them to be located and distinguished from their surroundings post-NAC, but morphological changes to the treated regions due to NAC can affect the visibility of marking clips in ultrasound, sometimes to a degree which requires the use of alternative, less comfortable modalities to visualize the clips in preparation for procedures, such as surgical resection or biopsy. In previous work, we proposed an electronic clip design leveraging active communication with an ultrasound imaging probe, improving visibility and differentiation of clips in ultrasound. The transmitted signal in a prototype of this design was successfully localized and identified by the ultrasound system in post-processing. Presently, we refine the device design by using pseudorandom noise (PN) codes as the ultrasonic identification signals to improve localization, and adjust the system design to allow multiple clips to be active and identified with greater accuracy in the imaging field in real time. [Work supported by a grant from the NIH (R21EB030743) and a fellowship from the Cancer Center at Illinois (CST EP082021).]

Radiological clips are commonly used to track and identify lesions in breast cancer patients receiving neoadjuvant chemotherapy. Available radiological clips often suffer degradation of visibility in ultrasound during the course of treatment, thus requiring more involved localization procedures to identify regions prior to resection. Furthermore, upon localization, additional markers are placed to aid surgeons during resection. We describe a biocompatible electronic device which transmits a unique identification signal when imaged with ultrasound pulse inversion, i.e ., ultrasound identification (USID). The USID clip provides better localization and visualization of the clip compared to passive clips. Furthermore, the ultrasound systems can be programmed to produce an audible indicator of a specific clip’s presence and proximity to the probe, thereby eliminating the need for insertion of additional markers. This concept is tested using a microcontroller and a direct digital synthesis board connected to two sonomicrocrystals, a Verasonics research system, and tissue mimicking phantoms. Clips with six different USID tags were successfully visualized at 10 dB above the background signal. Localization and identification are demonstrated using pulse inversion and image processing techniques.