We report holistic quantification of cutaneous microcirculation with spatial frequency domain imaging (SFDI) and coherent hemodynamics spectroscopy (CHS) based on a dynamic microcirculation PIPE model. A simple device was developed to induce periodic variations in cutaneous blood volume and flow velocity. Both baseline and dynamic features of cutaneous microcirculation for healthy subjects were completely quantified. The CHS findings were further related to SSMD-SFDI imaging of the same healthy subjects under reactive hyperemia protocol. The results demonstrate spatial frequency domain imaging and coherent hemodynamics spectroscopy based on the dynamic microcirculation PIPE model provides a valuable tool for functional studies with hemodynamic-based techniques.
Laser speckle contrast imaging (LSCI) has been widely used in monitoring blood flow in brain, skin, and retina etc with the advantages of being a wide field imaging modality of high spatial and temporal resolution, useful in investigating functional activities of tissues, exploring mechanisms of diseases, and evaluating drug efficiency. Despite its wide applications and long history, however, there is no systematic study and recommended recipes to obtain absolute flow velocity from LSCI measurement, in particular, when the accuracy of the current LSCI of flow is compounded by static scattering and measurement noise.
In this presentation, we analyzed laser speckle flow imaging from the first principle and provided a complete procedure covering the LSCI system calibration, static scattering removal, and measurement noise estimation and removal to obtain a genuine flow speckle contrast and the flow speed. We demonstrated the power of our recommended LSCI analysis recipes by imaging Intralipid-2% suspension moving at varying speeds. Experimental results show that our recipe greatly enhances the linear sensitivity of the flow index (defined as the inverse decorrelation time) and the linearity covers the full span of flow speeds from 0mm/s to 40mm/s. The determination of the flow speed is also not affected by the overlying static scattering layers. Our proposed LSCI analysis procedure hence paves the way to estimate the true flow speed in applications.
We present a spatial frequency domain imaging (SFDI) study of local hemodynamics in the human finger cuticle of healthy volunteers performing paced breathing and the forearm of healthy young adults performing normal breathing with our recently developed Real Time Single Snapshot Multiple Frequency Demodulation – Spatial Frequency Domain Imaging (SSMD-SFDI) system. A two-layer model was used to map the concentrations of deoxy-, oxy-hemoglobin, melanin, epidermal thickness and scattering properties at the subsurface of the forearm and the finger cuticle. The oscillations of the concentrations of deoxy- and oxy-hemoglobin at the subsurface of the finger cuticle and forearm induced by paced breathing and normal breathing, respectively, were found to be close to out-of-phase, attributed to the dominance of the blood flow modulation by paced breathing or heartbeat. Our results suggest that the real time SFDI platform may serve as one effective imaging modality for microcirculation monitoring.
We have presented a novel Single Snapshot Multiple Frequency Demodulation (SSMD) method enabling single snapshot wide field imaging of optical properties of turbid media in the Spatial Frequency Domain. SSMD makes use of the orthogonality of harmonic functions and extracts the modulation transfer function (MTF) at multiple modulation frequencies and of arbitrary orientations and amplitudes simultaneously from a single structured-illuminated image at once. SSMD not only increases significantly the data acquisition speed and reduces motion artifacts but also exhibits excellent noise suppression in imaging as well. The performance of SSMD-SFDI is demonstrated with experiments on both tissue mimicking phantoms and in vivo for recovering optical properties. SSMD is ideal in the implementation of a real-time spatial frequency domain imaging platform, which will open up SFDI for vast applications in, for example, mapping the optical properties of a dynamic turbid medium or monitoring fast temporal evolutions.
We present a spatial frequency domain imaging (SFDI) study of local hemodynamics in the forearm of healthy volunteers performing paced breathing. Real time Single Snapshot Multiple Frequency Demodulation - Spatial Frequency Domain Imaging (SSMD-SFDI) was used to map the optical properties of the subsurface of the forearm continuously. The oscillations of the concentrations of deoxy- and oxyhemoglobin at the subsurface of the forearm induced by paced breathing are found to be close to out-of-phase, attributed to the dominance of the blood flow modulation by paced breathing. The properties of local microcirculation including the blood transit times through capillaries and venules are extracted by fitting to Simplified Hemodynamics Model. Our preliminary results suggest that the real time SSMD-SFDI platform may serve as one effective imaging modality for microcirculation monitoring.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.