Contrast-enhanced magnetomotive ultrasound imaging (CE-MMUS) for colorectal cancer staging : assessment of sensitivity and resolution to detect alterations in tissue stiffness

Sjöstrand, Sandra and Evertsson, Maria and Thring, Claire and Bacou, Marion and Farrington, Susan and Moug, Susan and Moran, Carmel and Jansson, Tomas and Mulvana, Helen; (2019) Contrast-enhanced magnetomotive ultrasound imaging (CE-MMUS) for colorectal cancer staging : assessment of sensitivity and resolution to detect alterations in tissue stiffness. In: 2019 IEEE International Ultrasonics Symposium, IUS 2019. IEEE International Ultrasonics Symposium, IUS . IEEE Computer Society Press, GBR, pp. 1077-1080. ISBN 9781728145969

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    Abstract

    A key challenge in the treatment of colorectal cancer is identification of the sentinel draining lymph node. Magnetomotive ultrasound, MMUS, has identified lymph nodes in rat models: superparamagnetic iron oxide nanoparticles (SPIONs) accumulated in the lymph are forced to oscillate by an external magnetic field; the resulting axial displacement is recovered allowing structure delineation with potential to indicate alterations in tissue stiffness, but it is limited by small vibration amplitudes. We propose CE-MMUS using SPION loaded microbubbles (SPION-MBs) to enhance sensitivity, reduce toxicity, and offer additional diagnostic or perfusion information. Laser doppler vibrometry measurements was performed on SPION containing tissue mimicking material during magnetic excitation. These measurements show a vibration amplitude of 279 ± 113 μm in a material with Young's modulus of 24.3 ± 2.8 kPa, while the displacements were substantially larger, 426 ± 9 μm, in the softer material, with a Young's modulus of 9.6 ± 0.8 kPa. Magnetic field measurement data was used to calibrate finite element modelling of both MMUS and CE-MMUS. SPION-MBs were shown to be capable of inducing larger tissue displacements under a given magnetic field than SPIONs alone, leading to axial displacements of up to 2.3x larger. A doubling in tissue stiffness (as may occur in cancer) reduces the vibration amplitude. Thus, there is potential for CE-MMUS to achieve improved stiffness sensitivity. Our aim is to define the potential contribution of CE-MMUS in colorectal cancer diagnosis and surgical guidance.