On the Use of Spatial Coherence for in Situ Peak Rarefaction Pressure Estimation
Tissue harmonic image quality has been shown to increase with elevated pressure output. The Peak Rarefaction Pressure (PRP) for a given transmit, however, is limited by the Mechanical Index (MI) guideline. We have previously demonstrated that the MI overestimates in situ PRP for tightly focused beams such as F/1.5 because it does not account for phase aberration. In this study, we propose a new spatial coherence based metric to estimate phase aberration and predict in vivo PRP. We show harmonic Short Lag Spatial Coherence (SLSC) to linearly correlate with in situ PRP with a 0.86 coefficient of determination across 11 different body walls. This correlation suggests the potential for more accurate PRP estimation in situ than the current MI scheme, allowing patient specific acoustic output.
