Mapping port wine stain in vivo by optical coherence tomography angiography and multi-metric characterization

Port wine stain (PWS) is a congenital cutaneous capillary malformation composed of ecstatic vessels, while the microstructure of these vessels remains largely unknown. Optical coherence tomography angiography (OCTA) serves as a non-invasive, label-free and high-resolution tool to visualize the 3D tissue microvasculature. However, even as the 3D vessel images of PWS become readily accessible, quantitative analysis algorithms for their organization have mainly remained limited to analysis of 2D images. Especially, 3D orientations of vasculature in PWS have not yet been resolved at a voxel-wise basis. In this study, we employed the inverse signal-to-noise ratio (iSNR)-decorrelation (D) OCTA (ID-OCTA) to acquire 3D blood vessel images in vivo from PWS patients, and used the mean-subtraction method for de-shadowing to correct the tail artifacts. We developed algorithms which mapped blood vessels in spatial-angular hyperspace in a 3D context, and obtained orientation-derived metrics including directional variance and waviness for the characterization of vessel alignment and crimping level, respectively. Combining with thickness and local density measures, our method served as a multi-parametric analysis platform which covered a variety of morphological and organizational characteristics at a voxel-wise basis. We found that blood vessels were thicker, denser and less aligned in lesion skin in contrast to normal skin (symmetrical parts of skin lesions on the cheek), and complementary insights from these metrics led to a classification accuracy of ∼90% in identifying PWS. An improvement in sensitivity of 3D analysis was validated over 2D analysis. Our imaging and analysis system provides a clear picture of the microstructure of blood vessels within PWS tissues, which leads to a better understanding of this capillary malformation disease and facilitates improvements in diagnosis and treatment of PWS.

The relationship between retinal microcirculation and right heart catheterization and echocardiography findings in patients with idiopathic pulmonary arterial hypertension

OBJECTIVE

To determine the possible alterations of retinal microcirculation associated with right-sided intracardiac pressures in patients with IPAH.

METHODS

Twenty patients with IPAH and 20 age- and sex-matched healthy controls were included in the study. Hemodynamic data were obtained from the most recent right heart catheterization. Echocardiographic examination was performed within 24 h of ophthalmological examination. For the right eyes of all participants, high-resolution scans of chorioretinal microvascular networks at different depths of the retina were captured via OCT angiography.

RESULTS

The perfusion of the superficial and deep capillary plexus (SCP and DCP), and choriocapillaris (CCP) flow area were significantly lower than those in healthy control subjects (p < .05 for all). In IPAH group, PVR and mPAP were correlated significantly with the perfusion measurements at SCP and DCP (r = .461, r = .626 and r = .625, r =0.730, respectively, p < .05). sPAP and TRV were positively correlated with the perfusion measurements at SCP and DCP (r = .600, r = .662 and r = .670, r = .655 p < .05).

CONCLUSIONS

The positive correlation of retinal perfusion at SCP and DCP with right-sided echocardiographic and hemodynamic measurements unveiled that retinal microcirculation is affected by the pressure alterations in the pulmonary circulation of IPAH patients.

Double-pulse laser illumination method for measuring fast cerebral blood flow velocities in the deep brain using a fiber-bundle-based endomicroscopy system

We present a new fiber-bundle-based endomicroscopy system to measure the fast cerebral blood flow (CBF) velocity in blood vessels located between the surface and the deep brain of living animals. The CBF velocity is obtained by measuring the displacement of the partially overlapped red blood cell images directly, using double-pulse 532-nm laser illumination. The proposed method could measure CBF in blood vessels with diameters ranging from 4 μm to 42 μm and could measure CBF velocities up to 3.2 μm/ms for different vessel diameters at a depth of 2.1 mm from the brain surface in a living mouse.