@misc{9234890,
  abstract     = {{Magnetomotive ultrasound (MMUS) is a developing imaging modality using magnetic nanoparticles (MNPs) as contrast agent. MNPs are accumulated at a tissue target and set in motion by a time-varying magnetic field. The resulting displacement spreads to surrounding tissue and is detected with ultrasound. The objective of this modality is to transition medical ultrasound from structural to molecular specific imaging, with application potential for cancer cell detection and drug administration. An existing MNP detection method is based on quadrature demodulation and phase gating. However, the detection limit remains constrained by the method’s sensitivity to noise. Additionally, cardiorespiratory rhythms increase the risk of spectral leakage in the detection of fixed frequency magnetic excitation commonly used for MMUS. To overcome these limitations, I implemented three strategies to improve the detection of MNPs in MMUS and evaluated their efficiency with a contrast-to-noise ratio (CNR) on tissue-mimicking phantoms with descending MNP concentrations. The first strategy was frequency modulated magnetic excitation signals, specifically linear bidirectional chirp signals generated with a rotating permanent magnet. Secondly, I developed a matched filter algorithm that correlates phase oscillation in ultrasound radio frequency (RF) data with a magnetic force reference. The resulting normalized correlation was employed as a probability mask, where each pixel value represents the likelihood of MNP presence, used for weighting the results of the previous detection method. The third strategy was implementation of thresholding for segmentation and morphological filtering to suppress noise and refine object boundaries on the mask. The chirp excitation signals did not substantially improve the visibility of accumulated MNP regions compared to fixed frequency excitation signals. Thus, the use of these signals is not justified. When the previous detection method was combined with the probability mask from the matched filter, the CNR increased by 6.6 dB for 0.5 mg/ml of MNPs, 7.6 dB for 0.3 mg/ml of MNPs and 12.6 dB for 0.1 mg/ml of MNPs. Segmentation and morphology further improved the CNR with 1.6 dB for 0.5 mg/ml of MNPs, 1.7 dB for 0.3 mg/ml of MNPs and 16 dB for 0.1 mg/ml of MNPs. These results demonstrate that the matched filter algorithm and image processing enhance noise suppression and spatial specificity in MMUS, likely allowing detection of lower MNP concentrations.}},
  author       = {{Stickel, Sophia}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Strategies for Improving Detection of Magnetic Nanoparticles in Magnetomotive Ultrasound}},
  year         = {{2026}},
}