Infrared Transillumination Research Articles

Enhancing the detection of proximal cavities on near infrared transillumination images with Indocyanine Green (ICG) as a contrast medium: In vitro proof of concept studies

ObjectivesThe use of near infrared transillumination for caries detection is gaining recognition in daily practice. Differentiation between cavitated and non cavitated proximal lesions is recognized as a threshold for restorative treatment. This investigation focused on the use of a near infrared absorbent dye which may enhance the detection of cavitation on near infrared transillumination images. Materials and methods1: Natural teeth with artificial proximal cavitation were images with 3 different dyes to establish that near infrared absorbent dye can act like a contrast medium. 2: Natural teeth with natural cavitated lesions were used to investigate the contrast enhancing effect of indocyanine green (ICG) on near infrared transillumination images. 3: Artificial teeth with artificial cavitations were used to determine the best consistency of ICG as a contrast medium. 4: natural teeth with proximal lesions were used to confirm that ICG can differentiate between cavitated and non cavitated proximal lesions. Results1: ICG enhanced the contrast of cavitations compared to other dyes (ANOVA; p < 0.05). 2: ICG enhanced the contrast of the cavitated area on natural lesions but not significantly (t-test; p > 0.05). 3: ICG in a gel form enhanced the detection of cavitated lesions when compared to liquid ICG (t-test; p < 0.05). 4: ICG gel was able to differentiate between cavitated and non cavitated proximal lesions (ANOVA; p < 0.05). ConclusionICG can potentially be used as a contrast medium to enhance the detection of cavitated proximal lesions in vitro on near infrared transillumination images. A clinical study is required to validate these results in vivo.

Near infrared transillumination compared with radiography to detect and monitor proximal caries: A clinical retrospective study

ObjectiveTo compare near infrared transillumination device, DIAGNOcam (DC) and bitewing radiography (BW) for the detection of proximal caries. Materials and methodsThis retrospective analysis of DC and BW images of 18 students in dental medicine who had consented to the anonymous use of their dental record. The data included BW and DC images performed for a check-up in 2013, and corresponding follow-up images performed in 2015. Two observers rated 376 proximal surfaces on a 4-level dentin lesion scale and reached a unanimous rating for each surface. Calculated measures of agreement for each assessment method over time provided the reproducibility of the information obtained by each method. ResultsAgreement between 2013 and 2015 within each method was excellent (intraclass correlation coefficient, BW: 0.86, DC: 0.90). Agreement between DC and BW was similar for dentin lesion detection, but was low for enamel caries detection; DC detected more enamel caries than BW. Agreement between DC and BW was modest (0.33 in 2013 and 0.36 in 2015), chiefly because DC identified more enamel caries. ConclusionThis study shows that DC is as reliable as BW to detect proximal dentin lesions. DC detects proximal enamel lesions at an earlier stage than BW. DC enables clinicians to differentiate lesions limited to the enamel from lesions that have reached the enamel dentin junction. Regular monitoring with DC should help provide individualized preventive measures and early non-invasive caries management. Clinical significanceThe early detection of enamel lesions with near infrared transillumination can help clinicians undertake early non invasive treatments to prevent or slow down the progression of initial proximal lesions.

In vivo Near-IR Imaging of Occlusal Lesions at 1310-nm.

Several in vitro studies have demonstrated the potential for transillumination imaging and optical coherence tomography operating at 1310-nm for imaging caries lesions on tooth proximal and occlusal surfaces. Recently, we demonstrated that lesions on proximal surfaces could be imaged in vivo using NIR transillumination and that PS-OCT can be used in vivo to measure early demineralization on tooth buccal and occlusal surfaces. In this paper we report the first in vivo measurements using OCT and NIR imaging of occlusal lesions that have been scheduled for restoration. Occlusal lesions were chosen that were scheduled for restoration based on conventional diagnosis that consists of visual and tactile examination. Occlusal lesions were visible in the NIR. OCT looks promising for confirming the lateral spread of occlusal caries under the dentinal-enamel junction adjacent to fissures. These studies suggest that both near infrared transillumination imaging at 1310-nm and OCT provide valuable information about the severity of caries lesions.

Development of a transillumination infrared modality for differential vasoactive optical imaging

We present the development and implementation of a new near infrared transillumination imaging modality for tissue imaging. Exogenous inhaled hyperoxic and hypercarbic gases are used as "vasoactive contrast agents" via the production of changes in concentration of the endogenous HbO(2) and Hb in blood. This vasoactive differential imaging method is employed to acquire data and for subsequent image analysis. Spectroscopic changes obtained from transillumination measurements on the palms of healthy volunteers demonstrate the functionality of the imaging platform. This modality is being developed to monitor suspect breast lesions in a clinical setting based on the hypothesis that the atypical tumor vascular environment will yield sufficient contrast for differential optical imaging between diseased and healthy tissue.

System for long-term measurement of cerebral blood and tissue oxygenation on newborn infants by near infra-red transillumination.

The technique of near-infra-red spectroscopy allows safe continuous monitoring of changes in blood and tissue oxygenation on an intact organ. This is made possible by observing spectral changes in the tissues caused by oxygenated haemoglobin [HbO2], deoxygenated haemoglobin [Hb] and cytochrome aa3 [Cyt aa3]. The paper describes the design and performance of an instrument that has been developed to apply this technique to the monitoring of the brain in newborn infants. The instrument monitors optical transmission changes across a newborn infant's brain at four wavelengths. A standard deviation in error of 1 per cent (0·01 optical density OD) is achieved on measurements of transmission changes at 20s intervals. This performance is obtained at a mean attenuation of 10 OD, the approximate attenuation across a term infant's head. Long-term monitoring is possible as instrumental drift is less than 0·004 OD per hour.

Incomplete cerebral ischemia in the rat: vascular and metabolic changes as measured by infrared transillumination in vivo.

Cerebral blood volume, hemoglobin saturation and the cytochrome a, a3 redox state were monitored simultaneously by using three wavelengths of light in the near infrared portion of the spectrum for transillumination of the intact skull of rats. The changes in these parameters following incomplete cerebral ischemia were assessed in Wistar and Long-Evans rats submitted to carotid ligation. Another group of Wistar rats was submitted to vertebral + carotid occlusion. The experiments, performed under N2O/O2 anesthesia, showed that in all three groups carotid occlusion induced a decrease in blood volume, Hb saturation and a reduction of cyt. a, a3. However, the cytochrome redox state tended to normalize during ischemia as a consequence of higher O2 extraction from blood. The primary finding of this study was the marked hyperoxidation of cyt. a, a3 which occurred after reestablishing of the carotid blood supply, in spite of a secondary post-ischemic hypoperfusion of the brain. Although uncoupling of oxidative phosphorylation cannot be excluded the dissociation between blood supply and metabolism could well be due to ischemia-induced hypermetabolism of the central nervous tissue. In view of the marked oxidation of cyt. a, a3 during the reperfusion period as compared with the small extent of its reduction during the ischemic episode, the data also support the hypothesis that under steady state conditions in vivo, cytochrome oxidase is mainly reduced.

Infra-red transillumination stereophotography of the iris in Fuchs's heterochromic cyclitis.

The structural pattern of the iris in 13 patients with Fuchs's heterochromic cyclitis (FHC) was studied by infra-red transillumination stereophotography. All eyes with FHC showed atrophic changes of the iris. Extensive iris atrophy appeared as light, even translucence of the iris, associated in some cases with occasional dense small patches or pigment clumps. Moderate punctate, patchy or radiate, or extensive atrophy of the sphincter muscle was seen in all eyes with FHC. Radial contraction folds of Schwalbe, structural folds of Schwalbe, and circular contraction folds on the posterior surface of the iris were visualised in few eyes with FHC, whereas they were seen in most contralateral eyes. The results suggest that infra-red transillumination sterophotography can be used as a diagnostic method in FHC.