Detecting small targets using windowed time-reversal MUSIC imaging: A phantom study

Time reversal with multiple signal classification (TR-MUSIC) is a super-resolution imaging method for detecting targets smaller than the ultrasound wavelength. This method is valid only when the number of targets is fewer than the number of transducer elements used to interrogate the medium. We develop a windowed TR-MUSIC imaging method for obtaining high-resolution images even when the number of targets exceeds the number of transducer elements. Our method is based on dividing the imaging plane into sub-regions and applying the TR-MUSIC algorithm to the windowed backscattered signals corresponding to each sub-region. The images of all sub-regions are then combined to form the total image. We use tissue-mimicking phantom data acquired with a synthetic-aperture ultrasound system to demonstrate the significantly improved quality and resolution of the images obtained with the windowed TR-MUSIC method, particularly when the number of targets are larger than the number of transducer elements.