Validation Of Optical Coherence Tomography Research Articles

Development and validation of optical coherence tomography (OCT) and OCT angiography prediction model for short-term vitreous haemorrhage secondary to polypoidal choroidal vasculopathy

AimsTo construct and validate an optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) image model for predicting the occurrence of short-term vitreous haemorrhage (VH) in polypoidal choroidal vasculopathy...

Re-analysis Of Coronary Intravascular Lithotripsy - Can It Be Used In All Comers?

In severely calcified lesions, the intravascular lithotripsy (IVL) can be an effective therapy for preparation of the lesion so that drug eluting stent (DES) can be deployed optimally, and the future events of stent failure can be minimized. From the recent studies with IVL we can certainly say it is a novel therapy. The mechanism as depicted by optical coherence tomography (OCT) is found to be calcium fractures induced by shockwaves. The above said modification is done with minimal complications of perforation, no reflow, low incident of flow limiting dissection and myocardial infarctions. The other methods like cutting or scoring balloons, rotational atherectomy have also shown to improve luminal diameter, but other complications like distal embolization is a challenge of concern. This review reports a single centre study to all comer patients even with complex characteristics. This therapy was found to be very effective and with minimal complications. In this article we describe the mechanism of action, about IVL catheter, its OCT validation, clinical uses, its comparison with other calcium modifying technologies and what other future directions can be utilized to improve the technology and can it be used in all comers with calcified coronaries.

Retina tissue validation of optical coherence tomography determined outer nuclear layer loss in FTLD-tau

Alzheimer’s disease (AD) is associated with inner retina (nerve fiber and ganglion cell layers) thinning. In contrast, we have seen outer retina thinning driven by photoreceptor outer nuclear layer (ONL) thinning with antemortem optical coherence tomography (OCT) among patients considered to have a frontotemporal degeneration tauopathy (FTLD-Tau). Our objective was to determine if postmortem retinal tissue from FTLD-Tau patients demonstrates ONL loss observed antemortem on OCT. Two probable FTLD-Tau patients that were deeply phenotyped by clinical and genetic testing were imaged with OCT and followed to autopsy. Postmortem brain and retinal tissue were evaluated by a neuropathologist and ocular pathologist, respectively, masked to diagnosis. OCT findings were correlated with retinal histology. The two patients had autopsy-confirmed FTLD-Tau neuropathology and had antemortem OCT measurements showing ONL thinning (66.9 μm, patient #1; 74.9 μm, patient #2) below the 95% confidence interval of normal limits (75.1–120.7 μm) in our healthy control cohort. Postmortem, retinal tissue from both patients demonstrated loss of nuclei in the ONL, matching ONL loss visualized on antemortem OCT. Nuclei counts from each area of ONL loss (2 – 3 nuclei per column) seen in patient eyes were below the 95% confidence interval (4 – 8 nuclei per column for ONL) of 3 normal control retinas analyzed at the same location. Our evaluation of retinal tissue from FTLD-Tau patients confirms ONL loss seen antemortem by OCT. Continued investigation of ONL thinning as a biomarker that may distinguish FTLD-Tau from other dementias is warranted.

At-line validation of optical coherence tomography as in-line/at-line coating thickness measurement method.

Optical Coherence Tomography (OCT) is a promising technology for monitoring of pharmaceutical coating processes. However, the pharmaceutical development and manufacturing require a periodic validation of the sensor's accuracy. For this purpose, we propose polyethylene terephthalate (PET) films as a model system, to periodically validate the measurements during manufacturing. This study proposes a new approach addressing the method validation requirement in the pharmaceutical industry and presents results for complementary methods. The methods investigated include direct measurement of the layer thickness using a micrometer gauge as reference, X-ray micro computed tomography, transmission and reflectance terahertz pulsed imaging, as well as 1D- and 3D-OCT. To quantify the significance of OCT for pharmaceutical coatings, we compared the OCT results for commercial Thrombo ASS and Pantoloc tablets with direct measurements of coating thickness via light microscopy of microtome cuts. The results of both methods correlate very well, indicating high intra- and inter-tablet variations in the coating thickness for the commercial tablets. The light microscopy average measured coating thickness of Thrombo ASS (Pantoloc) was 71.0 µm (83.7 µm), with an inter-coating variability of 8.7 µm (6.5 µm) and an intra-coating variability of 2.3 µm to 9.4 µm (2.1 µm to 6.7 µm).

Optical coherence tomography of the retina, nerve fiber layer, and optic nerve head in dogs with glaucoma.

To evaluate the retina and optic nerve head (ONH) in canine eyes predisposed to glaucoma using optical coherence tomography (OCT). Twenty-five eyes (24 dogs). Measures of peripapillary retinal, retinal nerve fiber layer (RNFL), and ganglion cell complex (GCC) thickness and ONH parameters were obtained in vivo by OCT of the unaffected eye in dogs diagnosed with unilateral primary glaucoma (predisposed; n=12) and compared with measures of healthy control eyes (normal; n=13). Repeatability and intrarater reliability were explored using intraclass correlation coefficients (ICC). Compared to normal eyes, predisposed eyes had a thinner retina in the temporal (P=0.005), inferior quadrants (P=0.003), and decreased inner retinal thickness (superior: P=0.003, temporal: P=0.001, inferior: P<0.001, nasal: P=0.001). Predisposed eyes had a thinner RNFL compared to normal eyes (P=0.005), and when analyzed in quadrants, it was thinner in the superior (P<0.001), temporal (P=0.034), and nasal quadrants (P=0.001). Repeatability (ICC 0.763-0.835) and intrarater reliability (ICC 0.824-0.942) were good to excellent for measures of retinal thickness and adequate for RNFL measurements (ICC 0.701-0.798). Reliable measurements of optic disk area were obtained and were similar between groups (P=0.597). Measurements of parameters relying on automated software detection (GCC, optic cup, optic rim) had inadequate repeatability and reliability. Statistically significant differences in retinal and RNFL thicknesses were identified in normal and predisposed eyes. Reliable and consistent measurements of variables with manual adjustment of software detected parameters were obtained. Validation of OCT as a diagnostic tool for clinical assessment in canine glaucoma is warranted.

Impact of the Balloon Inflation Time and Pattern on the Coronary Stent Expansion.

Objectives To assess the expansion pattern of coronary stents by using different balloon inflation times and pressures. Background The selection of coronary stent size and its proper deployment is crucial in coronary artery interventions, having an impact on the success of the procedure and further therapy. Methods Ten pairs of different stents were deployed under nominal pressure using sequential (5, 5, 10, and 10 seconds of repeated inflations, thus 30 seconds of summarized time) and continuous (30 seconds) deployment pattern. After each given time-point, intraluminal stent measurements were performed by optical coherence tomography (OCT) and intravascular ultrasound (IVUS). Results Both in-stent diameters and cross-section areas (CSA) of paired stents measured by OCT at all sequential time-points were significantly smaller compared to given manufacturers charts' values (90% to 94% for diameters and 81% to 88% for CSA, p<0.05). Significant increase of in-stent diameter and CSA was observed across the step-by-step deployment pattern. In-stent lumen measurements were significantly larger when sequential deployment pattern was applied compared to continuous deployment. Additional measurements were also done for overlapping segments of stents, showing smaller in-stent measurements of the latter compared to nonoverlapping segments. Validation of OCT and IVUS measurements using a phantom metallic tube showed perfect reproducibility with OCT and overestimation with IVUS (8% for diameters and 16% for CSA). Conclusions Stent diameter after deployment is time-dependent and not only pressure-dependent. Different stent expansion behavior, depending on the applied deployment pattern (sequential and nonsequential), was observed.

Evaluation of marginal and internal fit of acrylic bridges using optical coherence tomography.

The potential of non-invasive optical coherence tomography (OCT) as a tool for assessment of fit of indirect reconstructions is not fully explored. The objectives were to investigate the feasibility and validity of OCT, and to measure the internal and marginal fit of acrylic bridges fabricated using direct and indirect digitalisation. The accuracy of the employed swept source OCT (wavelength: 1310nm) was assessed by comparing with an object with known dimensions. Validity was assessed by measuring an OCT measurements on replica, mimicking the cement film thickness, with stereomicroscopic measurements. The reconstructions were placed on the abutments without cementation. The internal and marginal fit of acrylic bridges from direct and indirect digitalisation techniques were then assessed by obtaining 5 OCT B-scans per abutment tooth at pre-defined positions located 250μm apart. The marginal and internal cement gaps were measured using image-processing software (ImageJ). Mean and standard deviation were calculated for both groups and t test assuming unequal variances was carried out. The level of significance was defined at 0.05. A strong linear correlation (r=0.865) between OCT and stereomicroscopy was found. T test showed significantly (P<0.01) better internal fit of bridges made from indirect digitalisation, but no difference in marginal fit. OCT is a feasible and valid tool for investigating internal and marginal fit of acrylic dental reconstructions. Better internal fit was observed in bridges fabricated using the direct digitalisation technique. No difference in marginal fit was found between the two fabrication methods.

In vivo tissue characterization of human atherosclerotic plaques by optical coherence tomography: A directional coronary atherectomy study with histopathologic confirmation

BackgroundThe histopathological validation of optical coherence tomography (OCT) in visualizing atherosclerotic plaques has been reported only in ex vivo studies. We sought to evaluate the accuracy of OCT in tissue characterization in vivo. Methods and resultsA total of 25 patients with stable angina pectoris who underwent directional coronary atherectomy (DCA) were included in the investigation, whereby OCT was performed before and after a single debulking. The debulked region was determined on OCT and classified into fibrous tissue, lipid, calcification, thrombus, and macrophage accumulation, which were compared with histology. Changes in OCT signal intensity in the deeper intimal region after DCA were also visually evaluated. Fibrous tissues were detected in all cases, while thrombus was identified only in 1 case, by both OCT and histology. The sensitivity, specificity, positive and negative predictive values, and predictive accuracy for lipid detection by OCT were 88.9%, 75.0%, 66.7%, 92.3%, and 80.0%; those for calcification were 50.0%, 100%, 100%, 91.3%, and 92.0%; and those for macrophage accumulation were 85.7%, 88.9%, 75.0%, 94.1%, and 88.0%, respectively. The false positive diagnoses for lipid were mostly attributed to the extracellular matrix accumulation containing less collagen. The false negative diagnoses for calcification were explained by the presence of lipid around the calcification. The OCT signal intensity in the deeper intimal region substantially increased after DCA in all cases. ConclusionsThe current study showed excellent predictive accuracy of in vivo OCT in tissue characterization, whereas the limitations of OCT were highlighted by an over-detection of lipid, under-detection of calcification, and underestimation of the deeper intimal matrix.

No evidence of disease activity is associated with reduced rate of axonal retinal atrophy in MS.

To explore, in a longitudinal study, the usefulness of optical coherence tomography (OCT) in monitoring people with multiple sclerosis (MS) by testing the association between retinal nerve fiber layer (RNFL) thinning and clinical and brain MRI criteria of no evidence of disease activity (NEDA). OCT, visual evoked potentials (VEPs), and disability, using the Expanded Disability Status Scale (EDSS), were tested at baseline and after 2 years in 72 patients, 63 with routine yearly brain MRI. Longitudinal mean binocular RNFL thinning, in absence of optic neuritis during follow-up, was correlated with EDSS worsening, also controlling for baseline EDSS, RNFL, disease duration, and MS subtype (Spearman ρ -0.462, p < 0.001; partial correlation coefficient -0.437, p < 0.001). At follow-up, patients classified as NEDA (20; 31.7%) had RNFL loss of -0.93 μm ± 1.35 SD, while patients with active disease had -2.83 μm ± 2 SD thinning (t test; p < 0.001). At logistic regression, mean RNFL reduction correctly classified 76.2% of patients as NEDA at 2 years (R2 0.355; p = 0.003). A cutoff of -1.25 μm RNFL loss classified NEDA status with specificity 81.4% and sensitivity 80% (receiver operating characteristic curve: area under the curve 0.8; p < 0.001). No significant longitudinal correlations were found between changes in RNFL and in VEP latencies or scores. NEDA is associated with a relatively preserved RNFL over 2 years. A greater neuroretinal loss was detected even in patients with clinical evidence of disease activity independently from changes in brain MRI lesions, prompting further validation of OCT as an additional tool in MS monitoring.

COMPARISON OF IN VIVO OPTICAL COHERENCE TOMOGRAPHY DERIVED PLAQUE PHENOTYPE AND BURDEN WITH HISTOLOGY IN A PORCINE MODEL OF ADVANCED CORONARY ATHEROSCLEROSIS

Background: In vivo validation of optical coherence tomography (OCT) against histology and the effects of plaque burden (PB) on plaque classification remain unreported. We investigated this in a porcine model with human-like coronary atherosclerosis. Methods: Five female Yucatan D374Y -PCSK9

Customized Tool for the Validation of Optical Coherence Tomography in Differentiation of Prostate Cancer.

To design and demonstrate a customized tool to generate histologic sections of the prostate that directly correlate with needle-based optical coherence tomography pullback measurements. A customized tool was created to hold the prostatectomy specimens during optical coherence tomography measurements and formalin fixation. Using the tool, the prostate could be sliced into slices of 4 mm thickness through the optical coherence tomography measurement trajectory. In this way, whole-mount pathology slides were produced in exactly the same location as the optical coherence tomography measurements were performed. Full 3-dimensional optical coherence tomography pullbacks were fused with the histopathology slides using the 3-dimensional imaging software AMIRA, and images were compared. A radical prostatectomy was performed in a patient (age: 68 years, prostate-specific antigen: 6.0 ng/mL) with Gleason score 3 + 4 = 7 in 2/5 biopsy cores on the left side (15%) and Gleason score 3 + 4 = 7 in 1/5 biopsy cores on the right side (5%). Histopathology after radical prostatectomy showed an anterior located pT2cNx adenocarcinoma (Gleason score 3 + 4 = 7). Histopathological prostate slides were produced using the customized tool for optical coherence tomography measurements, fixation, and slicing of the prostate specimens. These slides correlated exactly with the optical coherence tomography images. Various structures, for example, Gleason 3 + 4 prostate cancer, stroma, healthy glands, and cystic atrophy with septae, could be identified both on optical coherence tomography and on the histopathological prostate slides. We successfully designed and applied a customized tool to process radical prostatectomy specimens to improve the coregistration of whole mount histology sections to fresh tissue optical coherence tomography pullback measurements. This technique will be crucial in validating the results of optical coherence tomography imaging studies with histology and can easily be applied in other solid tissues as well, for example, lung, kidney, breast, and liver. This will help improve the efficacy of optical coherence tomography in cancer detection and staging in solid organs.

Detection of diabetic macular oedema: validation of optical coherence tomography using both foveal thickness and intraretinal fluid.

No studies have yet evaluated jointly central foveal thickness (CFT) and the presence of intraretinal fluid (PIF) to diagnose diabetic macular oedema (DMO) using optic coherence tomography (OCT). We performed a cross-sectional observational study to validate OCT for the diagnosis of DMO using both CFT and PIF assessed by OCT (3D OCT-1 Maestro). A sample of 277 eyes from primary care diabetic patients was assessed in a Spanish region in 2014. Outcome: DMO diagnosed by stereoscopic mydriatic fundoscopy. OCT was used to measure CFT and PIF. A binary logistic regression model was constructed to predict the outcome using CFT and PIF. The area under the ROC curve (AUC) of the model was calculated and non-linear equations used to determine which CFT values had a high probability of the outcome (positive test), distinguishing between the presence or absence of PIF. Calculations were made of the sensitivity, specificity, and the positive (PLR) and negative (NLR) likelihood ratios. The model was validated using bootstrapping methodology. A total of 37 eyes had DMO. AUC: 0.88. Positive test: CFT ≥90 µm plus PIF (≥310 µm if no PIF). Clinical parameters: sensitivity, 0.83; specificity, 0.89; PLR, 7.34; NLR, 0.19. The parameters in the validation were similar. In conclusion, combining PIF and CFT provided a tool to very precisely discriminate the presence of DMO. Similar studies are needed to provide greater scientific evidence for the use of PIF in the diagnosis of DMO.

Validity of Optical Coherence Tomography as a Diagnostic Method for Diabetic Retinopathy and Diabetic Macular Edema.

To validate optical coherence tomography (OCT) for the diagnosis of referable retinopathy (severe, very severe or proliferative retinopathy, and macular edema) in diabetic patients.We performed a cross-sectional observational study. A random sample was analyzed comprising 136 eyes of diabetic patients referred to the hospital in Elche (Spain) with suspected referable retinopathy between October 2012 and June 2013. Primary variable: Referable retinopathy measured by ophthalmological examination of the retina. OCT data included: central foveal thickness, presence of intraretinal fluid, and fundus photographs. The receiver operating characteristic (ROC) curve was calculated to determine the minimum thickness value with a positive likelihood ratio >10. To determine the validity of OCT, the following diagnostic test was defined: Positive: if the patient had at least 1 of these criteria: foveal thickness greater than the point obtained on the previously defined ROC curve, intraretinal fluid, abnormal fundus photographs; Negative: none of the above criteria. Sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios, and Kappa statistic were determined.Of the 136 eyes, 48 had referable retinopathy (35.3%, 95% confidence interval [CI]: 27.3–43.3). The minimum thickness value with a positive likelihood ratio >10 was 275 μm. The diagnostic test constructed showed: sensitivity, 91.67% (95% CI: 79.13–97.30); specificity, 93.18% (95% CI: 85.19–97.20); positive predictive value, 88.00% (95% CI: 75.00–95.03); negative predictive value, 95.35% (95% CI: 87.87–98.50); positive likelihood ratio, 13.44 (95% CI: 6.18–29.24); negative likelihood ratio, 0.09 (95% CI: 0.03–0.23). The Kappa value was 0.84 (95% CI: 0.75–0.94, P < 0.001.This study constructed a diagnostic test for referable diabetic retinopathy with type A evidence. Nevertheless, studies are needed to determine the validity of this test in the general diabetic population.

Validation of Optical Coherence Tomography against Micro–computed Tomography for Evaluation of Remaining Coronal Dentin Thickness

IntroductionOptical coherence tomography (OCT) is a noninvasive modality to obtain in-depth images of biological structures. A dental OCT system has become available for chairside application. This in vitro study hypothesized that swept-source OCT can be used to measure the remaining dentin thickness (RDT) at the roof of the dental pulp chamber during excavation of deep caries. MethodsHuman molar teeth with deep occlusal caries were investigated. After obtaining 2-dimensional and 3-dimensional OCT scans using a swept-source OCT system at a 1330-nm center wavelength, RDT was evaluated by image analysis software. Microfocus x-ray computed tomographic (micro-CT) images were obtained from the same cross sections to confirm OCT findings. The smallest RDT values at the visible pulp horn were measured on OCT and micro-CT imaging and compared using the Pearson correlation. Pulpal horns and pulp chamber roof observation under OCT and micro-CT imaging resulted in comparable images that allowed the measurement of coronal dentin thickness. ResultsRDT measured by OCT showed optical values range between 140 and 2300 μm, which corresponded to the range of 92–1524 μm on micro-CT imaging. A strong correlation was found between the 2 techniques (r = 0.96, P < .001). ConclusionsFurther analysis indicated linear regression with a slope of 1.54 and no intercept, closely matching the bulk refractive index of dentin. OCT enables visualization of anatomic structures during deep caries excavation. Exposure of the vital dental pulp because of the removal of very thin remaining coronal dentin can be avoided with this novel noninvasive technique.

CRT-105 Comparison of Vascular Healing after DES Implantation Utilizing Optical Coherence Tomography and Grey-Scale Signal Intensity Analysis in Atherosclerotic Rabbits, Human Autopsy Specimens and Man

To validate optical coherence tomography (OCT) data for assessment of vascular healing in a preclinical animal model and to translate these findings to the assessment of vascular healing after drug eluting stent (DES) implantation in human autopsy cases and clinical practice. The validation of OCT

Effect of Optic Disc Size and Disease Severity on the Diagnostic Capability of Glaucoma Imaging Technologies in an Indian Population

To evaluate the influence of optic disc size and disease severity on the diagnostic validity of optical coherence tomography (Stratus OCT), scanning laser polarimetry [GDx variable corneal compensator (VCC)], and confocal scanning laser ophthalmoscopy [Heidelberg retina tomograph II (HRT II)] in Indian eyes with glaucoma. Ninety-five normal and 125 glaucoma patients underwent imaging with Stratus OCT, GDx VCC, and HRT II. One eye of each person was randomly selected for analysis. Using disc area determined on HRT II, discs were classified as small (<2 mm), moderate (2 to 3 mm), and large (>3 mm). The parameter with the best sensitivity for each device, at a fixed specificity, was compared for different disc sizes. Logistic marginal regression was used to study the effect of disc size and disease severity (mean deviation on standard automated perimetry) on the diagnostic performance of these imaging devices. At a fixed specificity of 84.2%, the sensitivity of HRT II was significantly different for varying disc sizes (P=0.0004). The sensitivities for dissimilar disc sizes were not significantly different for the GDx VCC (P=0.928) or Stratus OCT (P=0.381). Logistic marginal regression also showed that sensitivity of HRT II increased with increasing disc size, whereas sensitivity of OCT and GDx were independent of the disc size. The sensitivity of all 3 technologies increased with increasing disease severity (decreasing mean deviation). Optic disc size affects the diagnostic capability of HRT II but not that of GDx VCC or Stratus OCT. The sensitivity of all 3 imaging technologies increased with increasing disease severity.