Laser speckle imaging (LSI) is a full-field blood flow imaging technique with high spatio-temporal resolution and easily controlled imaging area. It has attracted extensive attention in biomedical applications,such as intraoperative imaging, mechanism of neurovascular coupling and evaluating drug efficiency. However, this method suffers from the problem of shallow sampling depth of blood flow, so it mainly reflects the superficial blood flow information of biological tissue.

Prof. Pengcheng Li, Dr. Heng He et al. from Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, present a line beam scanning method which combined with the lateral laser speckle contrast analysis to improve the sampling depth of blood flow. The lateral laser speckle contrast analysis method only analyzes the information of the indirectly illuminated area.

The improvement of sampling depth obtained by lateral speckle contrast analysis is demonstrated by Monte Carlo simulation, animal experiments and phantom experiments. The improvement of sampling depth estimated by the phantom experiment is about 280 μm.

This study is published in Optics Letters (vol. 37, Issue 18, pp. 3774-3776). This work is supported by Science Fund for Creative Research Group of China (Grant No.61121004), the Program for New Century Excellent Talents in University (Grant No. NCET-08-0213), the National Natural Science Foundation of China (Grant Nos. 30970964, 30800339).

Fig. 1. (a)–(c) Blood flow images obtained bytraditional method, the lateral speckle contrast analysis methodweighted with constant and deep depth sensitivity curves, respectively.(d) Profiles of the velocity along the horizontaldashed lines indicated in (a)–(c).