3D-sLSCI: Three-dimensional Surface Laser Speckle Contrast Imaging of Blood Flow using Phase-shifting Profilometry.

Laser Speckle Contrast Imaging (LSCI) is a non-invasive, label-free technique that provides high-resolution 2D imaging of blood flow perfusion. In practical applications, however, target tissues typically exhibit 3D morphological surfaces. When LSCI is applied to such tissues, 2D blood perfusion images fail to accurately reflect the 3D spatial distribution of blood flow. Moreover, as tissue curvature increases, spatial compression in the image plane leads to significant overestimation of blood flow speed, which would mislead clinical diagnoses and research. To resolve these issues, in this paper, we proposed a new technology, namely 3D-sLSCI, with aim to correct the influence of tissue curvature on LSCI. Specifically, we developed a 3D-sLSCI measurement system through integrating LSCI with Phase-shifting profilometry (PSP) technology, permitting the simultaneous acquisition of blood flow and surface morphology information. Additionally, we established a theoretical model and correction algorithm to improve blood flow estimation within the curved tissues. The proposed correction algorithm is then incorporated into the 3D-sLSCI system to compensate the measurement errors induced by curvature changes. Experimental results from phantom and in vivo showed that 3D-sLSCI enhances measurement accuracy within the curved tissues and provides reliable 3D surface-rendered blood perfusion information. This work contributes to the improvements of LSCI precision in geometrically complicated, variable environments, expanding its potential applications in biomedical imaging.