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Tumor microcirculatory characteristics until now have only been assessed by histological examination of biopsies or invasive imaging technique. The recent introduction of orthogonal polarization spectral (OPS) imaging as a new tool for in vivo visualization of human microcirculation makes it possible to acquire high resolution images of the oral mucosa. In this study we report the microcirculatory changes in ten patients with oral squamous cell carcinoma of the tongue and compared the images to the normal contralateral side as the control. All carcinomas were T2 tumors without evidence for lymph node metastasis. The carcinomas were characterized by chaotic and dilated vessels accompanied by numerous areas of haemorrhage. The OPS technique seems very promising in the assessment of oral squamous cell carcinoma microcirculatory characteristics and may possibly play a future role in both the detection of early oral mucosal vascular aberrations and the effect of anti-tumor agents on the tumor microvasculature.

ObjectiveIn this study we evaluated the inter-observer agreement in the assessment of gingival capillary density using Orthogonal Polarization Spectral Imaging.MethodsIn this study gingival capillary density of 100 healthy subjects was determined by 2 independent observers. Agreement was quantified by calculation of the mean differences between the observers and the standard deviation of this difference and the limits of agreement. Reliability was quantified by means of the intraclass correlation coefficient (ICC).ResultsFifty males and 50 females were included in the study. The mean age for males was 20 ± 1.2 years and for females 20 ± 1.4. OPS images showed remarkable good quality images of the gingival microcirculation. The interclass correlation between the 2 observers was 0.63 while the interclass correlation for the 6 measurements in observer 1 was 0.95 and 0.94 for observer 2. The mean capillary density for females in observer 1 was 83.69 ± 16.4 and 83 ± 16.0 in observer 2, versus 60.55 ± 12.3 for observer 1 and 60.4 ± 12.1 for males. The mean quantitative functional capillary density in male students was 60.48 ± 10.7, compared to 83.45 ± 13.5 in female students.ConclusionsOPS imaging enabled for the first time direct in vivo visualization and quantification of human functional gingival capillary density in healthy medical students. The inter-observer agreement was found to be good to fair on the quantification of gingival capillary density between the two independent observers. The intracorrelation coefficient (0.95) was excellent when assessing the reliability of one observer.

Objective To investigate in vivo the function of the microcirculation of the skin in pregnancy and pregnancy complicated with pre-eclampsia. Design Case–control study. Setting Academic Medical Centre. Participants A group of 10 women with pre-eclampsia and a healthy control group of 10 pregnant women. Methods The microcirculation of the skin of the finger at rest and during venous occlusion was studied with laser Doppler fluxmetry and orthogonal polarisation spectral imaging. By inflating a cuff around the upper arm to a pressure of 50mmHg, causing venous occlusion, the local sympathetic veno-arteriolar reflex was provoked. With laser Doppler fluxmetry the blood flow of the skin at a depth of 1–2mm was measured at rest and during venous occlusion. Orthogonal polarisation spectral imaging was used to assess red blood cell velocity at rest and during venous occlusion of the nutritive capillaries of the skin. Results Laser Doppler fluxmetry showed no significant difference between the normotensive group and the group with pre-eclampsia. Using orthogonal polarisation spectral imaging, venous occlusion produced a significantly greater decrease in red blood cell velocity in the control group than in the women with pre-eclampsia: (84% (81–88)(median and interquartile range) vs 58% (45–88), P=0.0029). No differences in absolute red blood cell velocities were observed between groups either at rest or during venous occlusion. Conclusion This study shows an impaired local veno-arteriolar reflex in pre-eclampsia at the nutritive, but not at the thermoregulatory, level of the microcirculation of the skin.

Background This study sought to describe and quantify microcirculatory changes in the mucosal surfaces of patients with severe malaria, by direct in vivo observation using orthogonal polarization spectral (OPS) imaging. Methods The microcirculation in the rectal mucosa of adult patients with severe malaria was assessed by use of OPS imaging, at admission and then daily. Comparison groups comprised patients with uncomplicated falciparum malaria, patients with bacterial sepsis, and healthy individuals. Results Erythrocyte velocities were measured directly in 43 adult patients with severe falciparum malaria, of whom 20 died. Microcirculatory blood flow was markedly disturbed, with heterogeneous obstruction that was proportional to severity of disease. Blocked capillaries were found in 29 patients (67%) and were associated with concurrent hyperdynamic blood flow (erythrocyte velocity, >750 mm/s) in adjacent vessels in 27 patients (93%). The proportion of blocked capillaries correlated with the base deficit in plasma and with the concentration of lactate. Abnormalities disappeared when the patients recovered. In healthy individuals and in patients with uncomplicated malaria or sepsis, no stagnant erythrocytes were detected, and, in patients with sepsis, hyperdynamic blood flow was prominent. Conclusion Patients with severe falciparum malaria show extensive microvascular obstruction that is proportional to the severity of the disease. This finding underscores the prominent role that microvascular obstruction plays in the pathophysiology of severe malaria and illustrates the fundamental difference between the microvascular pathophysiology of malaria and that of bacterial sepsis.

Introduction The introduction of orthogonal polarization spectral (OPS) imaging in clinical research has elucidated new perspectives on the role of microcirculatory flow abnormalities in the pathogenesis of sepsis. Essential to the process of understanding and reproducing these abnormalities is the method of quantification of flow scores. Methods In a consensus meeting with collaboraters from six research centres in different fields of experience with microcirculatory OPS imaging, premeditated qualifications for a simple, translucent and reproducible way of flow scoring were defined. Consecutively, a single-centre prospective observational validation study was performed in a group of 12 patients with an abdominal sepsis and a new stoma. Flow images of the microcirculation in vascular beds of the sublingual and stoma region were obtained, processed and analysed in a standardised way. We validated intra-observer and inter-observer reproducibility with kappa cross-tables for both types of microvascular beds. Results Agreement and kappa coefficients were >85% and >0.75, respectively, for interrater and intrarater variability in quantification of flow abnormalities during sepsis, in different subsets of microvascular architecture. Conclusion Semi-quantitative analysis of microcirculatory flow, as described, provides a reproducible and transparent tool in clinical research to monitor and evaluate the microcirculation during sepsis.

Orthogonal polarization spectral (OPS) imaging is a new clinical technique for observation of the microcirculation of organ surfaces. For validation purposes, we compared OPS images of the nailfold skin with those obtained from conventional capillary microscopy at rest and during venous occlusion in 10 male volunteers. These images were computer analyzed to provide red blood cell velocity and capillary diameters of the same nailfold capillaries at rest and during venous occlusion. Results showed that OPS images provided similar values for red blood cell velocity and capillary diameter as those obtained from capillary microscopy images. OPS imaging, however, provided significantly better image quality, as shown by comparison of image contrast between OPS imaging and capillary microscopy. This made image analysis better and easier to perform. It is anticipated, therefore, that OPS imaging will become a new and powerful technique in the study of the human microcirculation in vivo because it can be used on human internal organs.

Orthogonal Polarisation Spectral imaging is a new clinical technique that uses polarised light to visualise the microcirculation of organ surfaces. We have used this technique to compare the functional microcirculatory properties of three types of brain tumour with those of the normal cortex. Meningiomas were characterised by chaotic and dilated vessels with almost no erythrocyte movement and a dark background, glioblastoma by few vessels with low flow and a background close to that of the healthy cortex, and metastases by a very dark background, almost no flow, and a chaotic vascular pattern. This technique could provide useful information about microcirculatory morphology and kinetics for diagnostic use during neurosurgery.

The introduction of orthogonal polarization spectral (OPS) imaging in clinical research has elucidated new perspectives on the role of microcirculatory flow abnormalities in the pathogenesis of sepsis. Essential to the process of understanding and reproducing these abnormalities is the method of quantification of flow scores. In a consensus meeting with collaboraters from six research centres in different fields of experience with microcirculatory OPS imaging, premeditated qualifications for a simple, translucent and reproducible way of flow scoring were defined. Consecutively, a single-centre prospective observational validation study was performed in a group of 12 patients with an abdominal sepsis and a new stoma. Flow images of the microcirculation in vascular beds of the sublingual and stoma region were obtained, processed and analysed in a standardised way. We validated intra-observer and inter-observer reproducibility with kappa cross-tables for both types of microvascular beds. Agreement and kappa coefficients were >85% and >0.75, respectively, for interrater and intrarater variability in quantification of flow abnormalities during sepsis, in different subsets of microvascular architecture. Semi-quantitative analysis of microcirculatory flow, as described, provides a reproducible and transparent tool in clinical research to monitor and evaluate the microcirculation during sepsis.