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An optimized segmentation and quantification approach in microvascular imaging for OCTA-based neovascular regression monitoring.
Wu, S, Wu, S, Feng, H, Hu, Z, Xie, Y, Su, Y, Feng, T, Li, L
BMC medical imaging. 2021;(1):13
Abstract
BACKGROUND Quantification of neovascularization changes in terms of neovascular complex (NVC) acquired from the optical coherence tomography angiography (OCTA) imaging is extremely important for diagnosis and treatment monitoring of proliferative diabetic retinopathy (PDR). However, only few vessel extraction methods have so far been reported to quantify neovascular changes in NVC with proliferative diabetic retinopathy PDR based on OCTA images. METHODS Here we propose an optimized approach to segment blood vessels, which is based on an improved vascular connectivity analysis (VCA) algorithm and combined with morphological characterization and elimination of noise and artifacts. The length and width of vessels are obtained in the quantitative assessment of microvascular network. The feasibility of the proposed method is further studied by a treatment monitoring and statistical analysis process, as we have monitored and statistically analyzed the changes of NVC based on sampled OCTA images of PDR patients (N = 14) after treatment by intravitreal injection of conbercept. RESULTS The proposed method has demonstrated better performance in accuracy compared with existing algorithms and can thus be used for PRD treatment monitoring. Following the PDR treatment monitoring study, our data has shown that from the 1st day to 7th day of treatment, the averaged (arithmetic mean) length of NVC has been substantially shortened by 36.8% (P < 0.01), indicating significant effects of treatment. Meanwhile, the averaged (arithmetic mean) width of NVC from the 1st day to 7th day of treatment has been increased by 10.2% (P < 0.05), indicating that most of the narrow neovascularization has been reduced. CONCLUSION The results and analysis have confirmed that the proposed optimization process by the improved VCA method is both effective and feasible to segment and quantify the NVC with lower noise and fewer artifacts. Thus, it can be potentially applied to monitor the fibrovascular regression during the treatment period. Clinical Trial Registration This trial is registered with the Chinese Clinical Trial Registry (Registered 27 December 2017, http://www.chictr.org.cn , registration number ChiCTR-IPR-17014160).
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Quantitative susceptibility mapping as a monitoring biomarker in cerebral cavernous malformations with recent hemorrhage.
Zeineddine, HA, Girard, R, Cao, Y, Hobson, N, Fam, MD, Stadnik, A, Tan, H, Shen, J, Chaudagar, K, Shenkar, R, et al
Journal of magnetic resonance imaging : JMRI. 2018;(4):1133-1138
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Abstract
BACKGROUND Quantitative Susceptibility Mapping (QSM) MRI allows accurate assessment of iron content in cerebral cavernous malformations (CCM), and a threshold increase by 6% in QSM has been shown to reflect new symptomatic hemorrhage (SH) in previously stable lesions. PURPOSE/HYPOTHESIS It is unclear how lesional QSM evolves in CCMs after recent SH, and whether this could serve as a monitoring biomarker in clinical trials aimed at preventing rebleeding in these lesions. STUDY TYPE This is a prospective observational cohort study. POPULATION 16 CCM patients who experienced a SH within the past year, whose lesion was not resected or irradiated. FIELD STRENGTH/SEQUENCE The data acquisition was performed using QSM sequence implemented on a 3T MRI system ASSESSMENT The lesional QSM assessments at baseline and yearly during 22 patient-years of follow-up were performed by a trained research staff including imaging scientists. STATISTICAL TESTS Biomarker changes were assessed in relation to clinical events. Clinical trial modeling was performed using two-tailed tests of time-averaged difference (assuming within-patient correlation of 0.8, power = 0.9 and alpha = 0.1) to detect 20%, 30% or 50% effects of intervention on clinical and biomarkers event rates during two years of follow-up. RESULTS The change in mean lesional QSM of index hemorrhagic lesions was +7.93% per patient-year in the whole cohort. There were 5 cases (31%) of recurrent SH or lesional growth, and twice as many instances (62%) with a threshold (6%) increase in QSM. There were no instances of SH hemorrhage or lesional growth without an associated threshold increase in QSM during the same epoch. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018;47:1133-1138.
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Intrasession and Between-Visit Variability of Retinal Vessel Density Values Measured with OCT Angiography in Diabetic Patients.
Czakó, C, Sándor, G, Ecsedy, M, Récsán, Z, Horváth, H, Szepessy, Z, Nagy, ZZ, Kovács, I
Scientific reports. 2018;(1):10598
Abstract
In clinical practice the measurement error of an instrument has special importance in analyzing and interpreting data, and acknowledging limitations. The purpose of this study was to evaluate intrasession and between-visit reproducibility of OCT angiography measurements in diabetic patients. A total of 54 eyes of 27 diabetic patients underwent OCT angiography imaging. Foveal avascular zone (FAZ) area and superficial retinal vessel density (VD) at 3 mm were calculated using the AngioAnalytics software. Three consecutive images were acquired at first visit and one image 1 month later. Intrasession and between-visit reproducibility of parameters were characterized by intraclass correlation coefficient (ICC), coefficient of variation (CV), and coefficient of repeatability (CR) values. We measured excellent (>0.90) ICC values both in intrasession and between-visit comparisons. CV was higher for the FAZ area compared to VD both in intrasession (7.79% vs. 2.87%) and in between-visit (12.33% vs. 2.95%) comparisons. Between-visit CR value for VD was 4.53% (95% CI: 3.72-5.79%). These data suggest that OCT angiography shows excellent repeatability in diabetic patients, indicating that this non-invasive technology might be suitable for longitudinal assessment of microvascular complications.
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Parallelism for quantitative image analysis of photoreceptor-retinal pigment epithelium complex alterations in diabetic macular edema.
Uji, A, Murakami, T, Unoki, N, Ogino, K, Horii, T, Yoshitake, S, Dodo, Y, Yoshimura, N
Investigative ophthalmology & visual science. 2014;(5):3361-7
Abstract
PURPOSE To propose a new method to quantitatively and comprehensively evaluate photoreceptor-RPE complex alterations on spectral-domain optical coherence tomography (SD-OCT) imaging in eyes with diabetic macular edema (DME). METHODS Spectral-domain OCT images from a consecutive series of 90 eyes in 79 patients with DME and 30 healthy eyes in 30 volunteers were analyzed retrospectively. The subfoveal area covering the photoreceptor layers was skeletonized and the orientation of the segmented lines was termed "parallelism," which reflects image complexity. Photoreceptor layer status at the fovea was categorized by graders, including continuity of the external limiting membrane (ELM) line, inner segment ellipsoid line, and the presence of hyperreflective foci in the outer retinal layers. The relationships among parallelism, visual acuity, and photoreceptor layer status were evaluated. RESULTS Parallelism was significantly lower in eyes with DME than in normal eyes (P < 0.0001), and correlated strongly with visual acuity in eyes with DME (R = -0.592; P < 0.0001). Eyes with an intact inner segment ellipsoid line or ELM line had significantly better visual acuity (VA) and higher parallelism than eyes with a discontinuous or absent inner segment ellipsoid line or ELM line. Parallelism was significantly higher (P < 0.0001) and logMAR VA significantly better (P < 0.0001) in the group without hyperreflective foci in the outer retinal layers than in the group with hyperreflective foci in the outer retinal layers. CONCLUSIONS Parallelism has the potential to reflect structural changes of the photoreceptor layers in DME.