Palpation is an established screening procedure for the detection of
several superficial cancers including breast, thyroid, prostate, and liver
tumors through both self and clinical examinations. This is because solid masses
typically have distinct stiffnesses compared to the surrounding normal tissue.
In this paper, the application of Harmonic Motion Imaging (HMI) for tumor
detection based on its stiffness as well as its relevance in thermal treatment
is reviewed. HMI uses a focused ultrasound (FUS) beam to generate an oscillatory
acoustic radiation force for an internal, non-contact palpation to internally
estimate relative tissue hardness. HMI studies have dealt with the measurement
of the tissue dynamic motion in response to an oscillatory acoustic force at the
same frequency, and have been shown feasible in simulations, phantoms, ex vivo
human and bovine tissues as well as animals in vivo. Using an FUS beam, HMI can
also be used in an ideal integration setting with thermal ablation using
high-intensity focused ultrasound (HIFU), which also leads to an alteration in
the tumor stiffness. In this paper, a short review of HMI is provided that
encompasses the findings in all the aforementioned areas. The findings presented
herein demonstrate that the HMI displacement can accurately depict the
underlying tissue stiffness, and the HMI image of the relative stiffness could
accurately detect and characterize the tumor or thermal lesion based on its
distinct properties. HMI may thus constitute a non-ionizing, cost-efficient and
reliable complementary method for noninvasive tumor detection, localization,
diagnosis and treatment monitoring.