Micro-elasticity (μ-E): CNR and resolution of acoustic radiation force impulse imaging and single- and multiple track location shear wave elasticity imaging for visualizing small targets

Acoustic radiation force impulse (ARFI) imaging and shear wave elasticity imaging (SWEI) use the dynamic response of tissue to impulsive mechanical stimulus to characterize local elasticity. A variant of conventional, multiple track location SWEI (MTL-SWEI), denoted single track location SWEI (STL-SWEI) offers the promise of creating speckle-free shear wave images. This work compares the three imaging modalities using a high push and track beam density combined acquisition sequence to image stiff inclusions with diameters of 1.5 and 6 mm. STL-SWEI is shown to have significantly higher CNR than MTL-SWEI, allowing for operation at higher resolution. ARFI and STL-SWEI perform similarly in the 6 mm inclusions, but STL-SWEI images the 1.5 mm targets with the highest CNR and best resolution. The processing trade-offs between CNR and resolution for each modality are discussed.