Single Snapshot Imaging of Optical Properties (SSOP) for Perfusion Assessment during Gastric Conduit Creation for Esophagectomy: An Experimental Study on Pigs

Anastomotic leakage (AL) is a serious complication occurring after esophagectomy. The current knowledge suggests that inadequate intraoperative perfusion in the anastomotic site contributes to an increase in the AL rate. Presently, clinical estimation undertaken by surgeons is not accurate and new technology is necessary to improve the intraoperative assessment of tissue oxygenation. In the present study, we demonstrate the application of a novel optical technology, namely Single Snapshot imaging of Optical Properties (SSOP), used to quantify StO2% in an open surgery experimental gastric conduit (GC) model. After the creation of a gastric conduit, local StO2% was measured with a preclinical SSOP system for 60 min in the antrum (ROI-A), corpus (ROI-C), and fundus (ROI-F). The removed region (ROI-R) acted as ischemic control. ROI-R had statistically significant lower StO2% when compared to all other ROIs at T15, T30, T45, and T60 (p < 0.0001). Local capillary lactates (LCLs) and StO2% correlation was statistically significant (R = −0.8439, 95% CI −0.9367 to −0.6407, p < 0.0001). Finally, SSOP could discriminate resected from perfused regions and ROI-A from ROI-F (the future anastomotic site). In conclusion, SSOP could well be a suitable technology to assess intraoperative perfusion of GC, providing consistent StO2% quantification and ROIs discrimination.

Intra-Individual Variability in Cognitive Performance Can Befuddle the Study of Cognitive Impairments and Decline

Using group-aggregated results and snapshot assessments of cognitive performance may prove problematic if the assessed construct shows substantial and rapid variation over time. To illustrate the significance of this issue, we analyzed cognitive performance data of ten older adults undergoing daily computerized cognitive assessments (CogState Brief Battery) for 36–93 days. In all cases, the day-to-day intra-individual variability was substantial when compared with group-level, between-person variability. This indicates that the results of studies using single snapshot assessments of cognitive functioning should be interpreted with caution. Additionally, group-aggregated measures of cognitive performance may not directly extrapolate to an individual.

Single snapshot quantitative phase imaging with polarization differential interference contrast

We present quantitative phase imaging with polarization differential interference contrast (PDIC) realized on a slightly modified differential interference contrast (DIC) microscope. By recording the Stokes vector rather than the intensity of the differential interference pattern with a polarization camera, PDIC enables single snapshot quantitative phase imaging with high spatial resolution in real-time at speed limited by the camera frame rate alone. The approach applies to either absorptive or transparent samples and can integrate simply with fluorescence imaging for co-registered simultaneous measurements. Furthermore, an algorithm with total variation regularization is introduced to solve the quantitative phase map from partial derivatives. After quantifying the accuracy of PDIC phase imaging with numerical simulations and phantom measurements, we demonstrate the biomedical applications by imaging the quantitative phase of both stained and unstained histological tissue sections and visualizing the fission yeast Schizosaccharomyces pombe's cytokinesis.