Application of the Full-Width-at-Half-Maximum Image Segmentation Method to Analyse Retinal Vascular Changes in Patients with Diabetic Retinopathy.

This study used spectral domain optical coherence tomography (SD-OCT) and full-width-at-half-maximum image segmentation to investigate the morphological changes of retinal blood vessels in patients with diabetic retinopathy (DR). Seventy-five patients with type 2 diabetes mellitus (T2DM) without DR and 65 patients with DR were studied. Vascular images of superior temporal region B of the retina were obtained by SD-OCT. The edges of retinal vessels were identified by the full-width-at-half-maximum image segmentation method. The lumen diameter, wall thickness (WT), wall cross-sectional area (WCSA), and wall-to-lumen ratio (WLR) were investigated. We found that, compared with the no diabetic retinopathy (NDR) group, patients in the DR group had an increased retinal arteriolar lumen diameter (RALD), retinal arteriolar outer diameter (RAOD), and WT (128.80 µm versus 104.88 µm; 147.01 µm versus 135.60 µm; 18.29 µm versus 15.26 µm, P < 0.05, respectively). The retinal venular lumen diameter (RVLD), retinal venular outer diameter (RVOD), and venular WT in the DR group were also increased (146.17 µm versus 133.66 µm; 180.20 µm versus 156.43 µm; 17.01 µm versus 11.38 µm, P < 0.05, respectively). The morphological changes in retinal vessels were significantly correlated with DR stage. In conclusion, in diabetic patients with DR, both retinal arteries and veins are widened and exhibit increased vascular thickness.

Author Correction: A full-width half-maximum method to assess retinal vascular structural changes in patients with ischemic heart disease and microvascular angina.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A full-width half-maximum method to assess retinal vascular structural changes in patients with ischemic heart disease and microvascular anginga.

Chest pain patients without obstructive ischemic heart disease (IHD) have increased attention in the clinical practice as carrying higher cardiovascular (CV) risk and impaired life quality. Retinal vasculature is a novel but reliable risk factor of atherosclerosis and systemic vascular diseases. However, the association of retinal blood vessels and unobstructed IHD, as known as microvascular anginga (MA) is poorly understood. This study compared retinal vascular structures of obstructive IHD and MA using spectral domain optical coherence tomography (SD-OCT) and full-width half-maximum (FWHM) methods to provide new risk predictive evidence of MA. Fundus vessels of 120 IHD patients, including 91epicardial IHD and 29 MA patients, and 66 control subjects were evaluated. Significant differences in the retinal arterial lumen diameter (RALD), retinal arterial outer diameter (RAOD), and arteriovenous ratio (AVR) have been found (P < 0.05). The severity of IHD was negatively correlated with diameters of RAOD, RALD and AVR (P < 0.05). In conclusion, there were significant differences in the retinal vascular structure between IHD patients and patients with MA. Thus, assessment of retinal vascular structure is suggested to evaluate CV risk of IHD patients, despite having no obstructive IHD.

Retinal Arteriolar Morphometry Based on Full Width at Half Maximum Analysis of Spectral-Domain Optical Coherence Tomography Images.

OBJECTIVES: In this study, we develop a microdensitometry method using full width at half maximum (FWHM) analysis of the retinal vascular structure in a spectral-domain optical coherence tomography (SD-OCT) image and present the application of this method in the morphometry of arteriolar changes during hypertension. METHODS: Two raters using manual and FWHM methods measured retinal vessel outer and lumen diameters in SD-OCT images. Inter-rater reproducibility was measured using coefficients of variation (CV), intraclass correlation coefficient and a Bland-Altman plot. OCT images from forty-three eyes of 43 hypertensive patients and 40 eyes of 40 controls were analyzed using an FWHM approach; wall thickness, wall cross-sectional area (WCSA) and wall to lumen ratio (WLR) were subsequently calculated. RESULTS: Mean difference in inter-rater agreement ranged from -2.713 to 2.658 µm when using a manual method, and ranged from -0.008 to 0.131 µm when using a FWHM approach. The inter-rater CVs were significantly less for the FWHM approach versus the manual method (P < 0.05). Compared with controls, the wall thickness, WCSA and WLR of retinal arterioles were increased in the hypertensive patients, particular in diabetic hypertensive patients. CONCLUSIONS: The microdensitometry method using a FWHM algorithm markedly improved inter-rater reproducibility of arteriolar morphometric analysis, and SD-OCT may represent a promising noninvasive method for in vivo arteriolar morphometry.

Update on retinal vessel structure measurement with spectral-domain optical coherence tomography.

This study was conducted to demonstrate a new scan method for retinal vessel structure measurement in a specific region of fundus (zone B) using spectral-domain optical coherence tomography (SD-OCT), and to assess its reliability. One temporal superior retinal vessel pair passing through a concentric ring (zone B), which was defined between half and one disc distance from the optic disc border, was chosen for the measurement using a volume scan in SD-OCT. On the SD-OCT image, retinal arteriolar outer diameter (RAOD), retinal arteriolar lumen diameter (RALD), retinal venular outer diameter (RVOD) and retinal venular lumen diameter (RVLD) were measured. Retinal vessel diameters on color fundus photographs were also analyzed. Fifty-five healthy individuals were recruited to evaluate intraobserver and interobserver reproducibility between the two examiners. The intraobserver intraclass correlation coefficient (ICC) ranged from 0.972 to 0.981, and the interobserver ICC ranged from 0.968 to 0.980. In the Bland-Altman plot, the 95% limits of interobserver agreement for the RAOD, RALD, RVOD and RVLD were -5.60 to 4.84µm, -5.78 to 5.05µm, -7.52 to 5.62µm and -7.10 to 5.63µm, respectively. The retinal arteriolar and venular lumen diameters on the SD-OCT image were close to the mean arteriolar and venular diameters obtained from the color fundus photographs. Volume scan method produced better images of retinal vessels showing the fine structures of the vessel wall, and provided reliable retinal vessel structure measurement in zone B with good repeatability and reproducibility.