LAUSR

HighlightsF‐DMAS non‐linear beamforming is applied to ultrasound Tissue Harmonic Imaging.Its performance in harmonic mode is experimentally compared to that of DAS.The generation of other higher‐order harmonics with F‐DMAS is also investigated.Experimental results show that F‐DMAS achieves superior contrast resolution in THI.Using other harmonics generated by F‐DMAS operations, also speckle quality improves. ABSTRACT Tissue Harmonic Imaging (THI) mode is currently one of the preferred choices by the clinicians for its ability to provide enhanced ultrasound images, thanks to the use of the second harmonic component of backscattered echoes. This paper aims at investigating whether the combination of THI with Filtered‐Delay Multiply And Sum (F‐DMAS) beamforming can provide further improvements in image quality. F‐DMAS is a new non‐linear beamformer, which, similarly to THI, is based on the use of the second harmonics of beamformed signals and is known to increase image contrast resolution and noise rejection. Thus, we have first compared the images obtained by using F‐DMAS and the standard Delay And Sum (DAS) beamformers when only the second harmonics of the received signals was selected. Moreover, possible improvements brought about by other harmonic components generated by the combined use of the fundamental plus second harmonics and F‐DMAS beamforming have been explored. Experimental results demonstrate that, as compared to standard harmonic imaging with DAS, THI and F‐DMAS can be joined to improve the −20 dB lateral resolution up to 1 mm, the contrast ratio up to 12 dB on a cyst‐phantom and up to 9 dB on in vivo images.