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Consequences of the laser speckle imaging computation method on analysis of renal autoregulation dynamics
Author(s) -
Scully Christopher,
Mitrou Nicholas,
Waring Jennifer,
Braam Branko,
Cupples William A.,
Chon Ki H.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.690.12
Subject(s) - pixel , speckle pattern , aliasing , image resolution , temporal resolution , artificial intelligence , data set , computer science , computer vision , optics , physics , undersampling
Laser speckle imaging generates a surface perfusion map by analyzing speckle contrast pattern statistics over either a spatial or temporal set of pixels. Use of a spatial set reduces spatial but increases temporal resolution, while a temporal set increases spatial but decreases temporal resolution. We have found, for renal autoregulation frequencies, signals from single pixels have low signal‐noise ratio (SNR), but averaging pixels in each frame increases the SNR. We compared the moorFLPI (Moor Instruments, UK) imager choice of spatial or temporal statistics for analyzing renal autoregulation in terms of: 1) which provides minimal spatial resolution to achieve adequate SNR and 2) the influence of cardiac pulse aliasing on frequency analysis. Long‐Evans rat kidneys ( n =12) were stabilized in vivo, and imaged with the moorFLPI temporal (576×768 pixels, 1Hz) and spatial (113×152 pixels, 25Hz) methods. NxN pixels (N=1…100) in each frame were averaged to generate time‐series, and the power spectrum of each was computed to determine the SNR. We found an adequate SNR was reached at a lower N for the moorFLPI temporal method. Use of the temporal method resulted in cardiac pulse aliasing, but may be used if renal blood flow records are available to identify aliasing. Otherwise, it may be necessary to use the spatial method to prevent aliasing at the expense of spatial resolution. This research was supported by CIHR MOP‐102694.