Sidestream dark field images of the microcirculation: intra-observer reliability and correlation between two semi-quantitative methods for determining flow

Abstract

BackgroundSince analysis of Sidestream Dark Field images still requires subjective interpretation, we wanted to determine intra-observer repeatability and to estimate the correlation between different evaluation methods.MethodsFifty-four Sidestream Dark Field videos were analyzed twice by the same blinded observer using validated software. Vessels were detected, generating the parameter Total Vessel Density (TVD), and flow was determined by (i) classifying each vessel separately, generating the parameters Perfused Vessel Density (PVD) and Proportion of Perfused Vessels (PPV), and by (ii) the “Boerma” method, generating a Microvascular Flow Index (MFI) by quadrants.ResultsIntraclass Correlation Coefficients (ICCs) were above 0.9 for TVD and above 0.8 for PDV and PPV. MFIby quadrants had the lowest reliability (ICC = 0.52 for capillaries and ICC = 0.59 for all vessels), significantly lower than for PVD (ICC = 0.89, p < 0.001 for capillaries and ICC = 0.90, p < 0.001 for all vessels) and PPV (ICC = 0.82, p = 0.003 for capillaries and ICC = 0.83, p = 0.01 for all vessels). Correlation coefficient (r) between PPV and MFIby quadrants corrected for measurement error was 0.39 (0.10 – 0.64) for capillaries and 1.01 (0.85 – 1.16) for all vessels.ConclusionsIntra-observer reliability for full evaluation of Sidestream Dark Field images was good for vessel detection and for flow classification but significantly poorer for the faster “Boerma” method. Furthermore, the Boerma method is likely to estimate different aspects of capillary flow than do the standard methods.

Videomicroscopy as a tool for investigation of the microcirculation in the newborn

“…In keeping with our findings, measures of small vessel density appear to be most related to physiological changes (Alba-Alejandre et al 2013; Nussbaum et al 2014). This is a similar finding to a recent review of sidestream dark-field videomicroscopy that also concluded that the quantitative assessments may be more reliable than some of the indexing methodologies (Petersen et al 2014).…”

“…This is a similar finding to a recent review of sidestream dark‐field videomicroscopy that also concluded that the quantitative assessments may be more reliable than some of the indexing methodologies (Petersen et al. ).…”

“…The large vessels parameters were very variable, both in the presence and number, between recordings. These vessels were largely negatively correlated with the smaller vessel changes (data not shown), which have been recommended as the vessels of most interest (Petersen et al 2014). In addition, the nature of these large vessels, essentially venules, means they were continuously perfused and contributed little to the variation in functional indices.…”

Sublingual microcirculatory blood flow and vessel density in Sherpas at high altitude

“…The "vessel-by-vessel" approach to MFI calculation (11,12) was utilized in this study, in which the mean value of the MFIs in each individual vessel is calculated. This approach has been shown to provide the best correlation with both the erythrocyte velocity and the proportion of perfused small vessels (36) and, furthermore, demonstrates the closest intraobserver reliability for vessel detection and flow classification (35).…”

Evaluation of Sidestream Darkfield Microscopy for Real-Time Imaging Acellular Dermal Matrix Revascularization

“…14 The aim of the present study is to assess the safety, feasibility, and efficacy of sidestream darkfield (SDF) microscopy, an advanced imaging technique which meets the above criteria, to investigate the revascularization of ADM, a core component of ADM biointegration, in the context of ADM-assisted breast reconstruction at the time of tissue expander to implant exchange. 14,15 The SDF microscopic image acquisition uses a type of orthogonal polarization spectral imaging, which represents a noninvasive real-time method of imaging the microcirculation in nonkeratinized epithelial surfaces. 16 The SDF image acquisition has been used previously to assess changes in the microcirculation of sublingual mucosa and serosal tissues in the setting of cardiac surgery, thoracic surgery, shock, and systemic inflammatory response syndrome.…”