![]() |
Stephanie Totten Research Scientist/Engineer III sitotten@apl.uw.edu Phone 206-543-7875 |
Education
A.A. Veterinary Technology, Nebraska College of Technical Agriculture, 2013
B.S. Veterinary Technologist, University of Nebraska - Lincoln, 2014
Publications |
2000-present and while at APL-UW |
![]() |
Advancing boiling histotripsy dose in ex vivo and in vivo renal tissues via quantitative histological analysis and shear wave elastography Ponomarchuk, E., G. Thomas, M. Song, Y.-N. Wang, S. Totten, G. Schade, J. Thiel, M. Bruce, V. Khokhlova, and T. Khokhlova, "Advancing boiling histotripsy dose in ex vivo and in vivo renal tissues via quantitative histological analysis and shear wave elastography," Ultrasound Med. Biol., 50, 1936-1944, doi:10.1016/j.ultrasmedbio.2024.08.022, 2024. |
More Info |
1 Dec 2024 ![]() |
![]() |
|||||
Objective |
![]() |
Histotripsy-induced bactericidal activity correlates to size of cavitation cloud in vitro Ambekar, P.A., Y.-N. Wang, T.D. Khokhlova, G.P.L. Thomas, P.B. Rosnitskiy, K. Contreras, D.F. Leotta, A.D. Maxwell, M. Bruce, S. Pierson, S. Totten, Y.N. Kumar, J. Thiel, K.T. Chan, W.C. Liles, E.P. Dellinger, A. Adedipe, W.L. Monsky, and T.J. Matula, "Histotripsy-induced bactericidal activity correlates to size of cavitation cloud in vitro," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 71, 1868-1878, doi:10.1109/TUFFC.2024.3476438, 2024. |
More Info |
9 Oct 2024 ![]() |
![]() |
|||||
Large abscesses are walled-off collections of pus and bacteria that often do not respond to antibiotic therapy. Standard of care involves percutaneous placement of indwelling catheter(s) for drainage, a long and uncomfortable process with high rehospitalization rates. The long-term goal of this work is to develop therapeutic ultrasound approaches to eradicate bacteria within abscesses as a noninvasive therapeutic alternative. Inertial cavitation induced by short pulses of focused ultrasound (histotripsy) is known to generate lethal mechanical damage in bacteria. Prior studies with Escherichia coli (E. coli) in suspension demonstrated that bactericidal effects increase with increasing peak negative amplitude, treatment time, and duty cycle. The current study investigated correlates of bactericidal activity with histotripsy cavitation cloud size. Histotripsy was applied to E. coli suspensions in 10-mL sample vials at 810 kHz, 1.2 MHz, or 3.25 MHz for 40 min. The cavitation activity in the sample vials was separately observed with high-speed photography. The cavitation cloud area was quantified from those images. A linear relationship was observed between bacterial inactivation and cavitation cloud size ( R2 = 0.98 ), regardless of the acoustic parameters (specifically frequency, pulse duration, and power) used to produce the cloud. |
![]() |
Dynamic mode decomposition based Doppler monitoring of de novo cavitation induced by pulsed HIFU: An in vivo feasibility study Song, M., O.A. Sapozhnikov, V.A. Khokhlova, H. Son, S. Totten, Y.-N. Wang, and T.D. Khokhlova, "Dynamic mode decomposition based Doppler monitoring of de novo cavitation induced by pulsed HIFU: An in vivo feasibility study," Sci. Rep., 14, doi:10.1038/s41598-024-73787-w, 2024. |
More Info |
27 Sep 2024 ![]() |
![]() |
|||||
Pulsed high-intensity focused ultrasound (pHIFU) has the capability to induce de novo cavitation bubbles, offering potential applications for enhancing drug delivery and modulating tissue microenvironments. However, imaging and monitoring these cavitation bubbles during the treatment presents a challenge due to their transient nature immediately following pHIFU pulses. A planewave bubble Doppler technique demonstrated its potential, yet this Doppler technique used conventional clutter filter that was originally designed for blood flow imaging. Our recent study introduced a new approach employing dynamic mode decomposition (DMD) to address this in an ex vivo setting. This study demonstrates the feasibility of the application of DMD for in vivo Doppler monitoring of the cavitation bubbles in porcine liver and identifies the candidate monitoring metrics for pHIFU treatment. We propose a fully automated bubble mode identification method using k-means clustering and an image contrast-based algorithm, leading to the generation of DMD-filtered bubble images and corresponding Doppler power maps after each HIFU pulse. These power Doppler maps are then correlated with the extent of tissue damage determined by histological analysis. The results indicate that DMD-enhanced power Doppler map can effectively visualize the bubble distribution with high contrast, and the Doppler power level correlates with the severity of tissue damage by cavitation. Further, the temporal characteristics of the bubble modes, specifically the decay rates derived from DMD, provide information of the bubble dissolution rate, which are correlated with tissue damage level—slower rates imply more severe tissue damage. |