Validity of near-infrared light transillumination for the assessment of proximal caries in permanent teeth.

PURPOSE: The aim of this study was to evaluate the performance of DIAGNOcam (DC) in diagnosing proximal caries and to compare its effectiveness with the International Caries Detection and Assessment System (ICDAS) and bitewing radiography (BWR). METHODS: 118 premolars extracted for orthodontic reasons were included and examined using three detection methods and validated by histological sections as the gold standard. The sensitivity, specificity and areas under the ROC curve (Az value) at the outer half enamel (D1), inner half enamel (D2) and dentine (D3) thresholds were compared between different methods. RESULTS: At all categories, the specificity of DC was almost as high as ICDAS and BWR. DC showed a significantly higher sensitivity (0.68) than both visual (0.33) and radiographic examination (0.47) at the D1 threshold. DC presented the highest Az value (area under the ROC curve) at the D1 and D2 threshold (0.81, 0.86), while BWR showed the greatest Az values at D3 (0.94). Furthermore, DC had the highest association strength with the gold standard (Spearman's ρ = 0.80). CONCLUSIONS: It can be concluded that DC could detect proximal caries effectively and showed comparable or even better performance than ICDAS and BWR.

Evaluation of occlusal caries detection and assessment by visual inspection, digital bitewing radiography and near-infrared light transillumination.

AIM: This study compared the diagnostic outcomes of visual inspection (VI), digital bitewing radiography (BWR), and near-infrared light transillumination (NIR-LT, DIAGNOcam, KaVo, Biberach, Germany) for occlusal caries detection and assessment of posterior teeth. PARTICIPANTS AND METHODS: This study included 203 patients (mean age 23.0 years). All individuals received a meticulous VI. Additionally, BWR and NIR-LT images were collected. All BWR and NIR-LT images were blindly evaluated for the presence of enamel caries lesions (ECLs) and dentin caries lesions (DCLs). The descriptive statistical analyses included calculation of frequencies, cross tabulations, and pairwise comparisons using Pearson chi-square tests. RESULTS: The majority of ECLs/DCLs were detected by VI in this low-risk adult population. The additional diagnostic outcomes in terms of ECLs/DCLs amounted to 5.0% (BWR) and 6.8% (NIR-LT). The combined usage of VI/NIR-LT or VI/BWR identified 95.7 and 94.4% of all ECLs/DCLs on occlusal surfaces, respectively. CONCLUSION: This comparative diagnostic study showed that VI detected the majority of occlusal caries lesions. Both additional methods showed limited benefits. Due to the valuable features of NIR-LT, i.e., X-ray freeness and clinical practicability, this method might be preferred over X-ray-based methods. Nevertheless, BWRs should be prescribed in clinical situations where insufficient fillings or multiple (deep) caries lesions are diagnosed or where there is a need to assess the caries extension in relation to the pulp. CLINICAL RELEVANCE: VI has to be understood as caries detection method of choice on occlusal surfaces in low-risk adult population which may help to avoid multiple diagnostic testing, overdiagnosis, and overtreatment.

Interrater agreement and reliability assessment of proximal caries detection tools in mixed dentition: An in-vivo study.

OBJECTIVE: This in-vivo study was performed to assess the interrater agreement and reliability of ICDAS (visual), transillumination, radiographic, and laser fluorescence proximal caries detection tools in between primary and adjacently erupted permanent molars. METHOD AND MATERIALS: This study was in accordance with Guidelines for Reporting Reliability and Agreement Studies. Two calibrated examiners assessed the nonobvious noncavitated apparently sound 100 interproximal sites using predefined criteria. Interrater agreement was analyzed as proportion of agreement. Interrater reliability assessment was performed using weighted kappa statistics and intraclass correlation coefficient. RESULTS: The maximum interrater agreement was projected with conventional bitewing radiography (97%), and the minimum with DIAGNOdent pen (84%), with significant difference (P < .001) in the proportion of agreement. All methods showed substantial interrater reliability, except fiber-optic transillumination. Maximum interrater reliability was noticed for ICDAS (International Caries Detection and Assessment System) method with a weighted kappa value of 0.80 (96% CI, 0.58 - 0.93) followed by conventional and digital bitewing radiography, with values of 0.74 (95% CI, 0.51 - 0.96) and 0.73 (95% CI, 0.43 - 0.92) respectively. CONCLUSION: ICDAS and bitewing radiography seem to be the most reliable methods, with a higher proportion of agreement between the examiners compared to the other methods addressed in this study for proximal caries detection.

Monte Carlo modeling of light propagation in the human head for applications in sinus imaging.

Sinus blockages are a common reason for physician visits, affecting one out of seven people in the United States, and often require medical treatment. Diagnosis in the primary care setting is challenging because symptom criteria (via detailed clinical history) plus objective imaging [computed tomography (CT) or endoscopy] are recommended. Unfortunately, neither option is routinely available in primary care. We previously demonstrated that low-cost near-infrared (NIR) transillumination correlates with the bulk findings of sinus opacity measured by CT. We have upgraded the technology, but questions of source optimization, anatomical influence, and detection limits remain. In order to begin addressing these questions, we have modeled NIR light propagation inside a three-dimensional adult human head constructed via CT images using a mesh-based Monte Carlo algorithm (MMCLAB). In this application, the sinus itself, which when healthy is a void region (e.g., nonscattering), is the region of interest. We characterize the changes in detected intensity due to clear (i.e., healthy) versus blocked sinuses and the effect of illumination patterns. We ran simulations for two clinical cases and compared simulations with measurements. The simulations presented herein serve as a proof of concept that this approach could be used to understand contrast mechanisms and limitations of NIR sinus imaging.

Transillumination imaging for blood oxygen saturation estimation of skin lesions.

Detecting the early stages of melanoma can be greatly assisted by an accurate estimate of subsurface blood volume and blood oxygen saturation, indicative of angiogenesis. Visualization of this blood volume present beneath a skin lesion can be achieved through the transillumination of the skin. As the absorption of major chromophores in the skin is wavelength dependent, multispectral imaging can provide the needed information to separate out relative amounts of each chromophore. However, a critical challenge to this strategy is relating the pixel intensities observed in a given image to the wavelength-dependent total absorption existing at each spatial location. Consequently, in this paper, we develop an extension to Beer's law, estimated through a novel voxel-based, parallel processing Monte Carlo simulation of light propagation in skin which takes into account the specific geometry of our transillumination imaging apparatus. We then use this relation in a linear mixing model, solved using a multispectral image set, for chromophore separation and oxygen saturation estimation of an absorbing object located at a given depth within the medium. Validation is performed through the Monte Carlo simulation, as well as by imaging on a skin phantom. Results show that subsurface oxygen saturation can be reasonably estimated with good implications for the reconstruction of 3-D skin lesion volumes using transillumination toward early detection of malignancy.

Voxel-based, parallel simulation of light in skin tissue for the reconstruction of subsurface skin lesion volumes.

Early detection and diagnosis of skin cancer is essential to treating the malignancy and preventing death. Subsurface features and depth information are critical in evaluating a skin lesion for this early malignancy screening. We present a novel voxel-based Monte Carlo simulation of light propagation in skin tissue which runs in a highly parallel environment on desktop graphics processors, resulting in an extremely fast simulation of millions of photons in less than one second. We then use this model in a genetic algorithm for the inverse 3D volume reconstruction of a skin lesion, given a set of multispectral images obtained using non-invasive transillumination imaging. Our method demonstrates improved accuracy at a superior resolution to existing methods.

Solution of the direct problem in turbid media with inclusions using Monte Carlo simulations implemented in graphics processing units: new criterion for processing transmittance data.

The study of light propagation in diffusive media requires solving the radiative transfer equation, or eventually, the diffusion approximation. Except for some cases involving simple geometries, the problem with immersed inclusions has not been solved. Also, Monte Carlo (MC) calculations have become a gold standard for simulating photon migration in turbid media, although they have the drawback large processing times. The purpose of this work is two-fold: first, we introduce a new processing criterion to retrieve information about the location and shape of absorbing inclusions based on normalization to the background intensity, when no inhomogeneities are present. Second, we demonstrate the feasibility of including inhomogeneities in MC simulations implemented in graphics processing units, achieving large acceleration factors ( approximately 10(3)), thus providing an important tool for iteratively solving the forward problem to retrieve the optical properties of the inclusion. Results using a cw source are compared with MC outcomes showing very good agreement.

Relative capacities of time-gated versus continuous-wave imaging to localize tissue embedded vessels with increasing depth.

Surgeons often cannot see major vessels embedded in adipose tissue and inadvertently injure them. One such example occurs during surgical removal of the gallbladder, where injury of the nearby common bile duct leads to life-threatening complications. Near-infrared imaging of the intraoperative field may help surgeons localize such critical tissue-embedded vessels. We have investigated how continuous-wave (CW) imaging performs relative to time-gated wide-field imaging, presently a rather costly technology, under broad Gaussian beam-illumination conditions. We have studied the simplified case of an isolated cylinder having bile-duct optical properties, embedded at different depths within a 2-cm slab of adipose tissue. Monte Carlo simulations were preformed for both reflectance and transillumination geometries. The relative performance of CW versus time-gated imaging was compared in terms of spatial resolution and contrast-to-background ratio in the resulting simulated images. It was found that time-gated imaging offers superior spatial resolution and vessel-detection sensitivity in most cases, though CW transillumination measurements may also offer satisfactory performance for this tissue geometry at lower cost. Experiments were performed in reflectance geometry to validate simulation results, and potential challenges in the translation of this technology to the clinic are discussed.

Spatial resolution in fast time-resolved transillumination imaging: an indeterministic Monte Carlo approach.

The spatial resolution achievable in time-resolved optical transillumination imaging through a turbid (scattering and absorbing) medium has been reassessed theoretically. The temporal point spread function was constructed assuming a delta function input pulse, a approximately 50 mm thick medium and a small detector with zero risetime. Temporal profiles were derived from an indeterministic Monte Carlo simulation for different time scales. From the temporal point spread function (TPSF), an analytic edge response function from which the spatial resolution was determined was derived. Previous analytical methods for determining the spatial resolution are approximations for very short flight times (sub-100 ps time region). The results show that a spatial resolution of about two millimetres is possible under ideal signal-to-noise ratio conditions and with detector gate times of the order of ten picoseconds. If this predicted spatial resolution can be achieved in an imaging system, it may be possible to improve the diagnosis of breast tumours.

Assessment of the proper depth of endotracheal tube placement with the Trachlight.

STUDY OBJECTIVE: To test the hypothesis that the correct depth of the endotracheal tube can be confirmed by transillumination method using the Trachlight device, which is a newly introduced lighted stylet for guided, blind tracheal intubation. DESIGN: Prospective, nonrandomized pilot-trial. SETTING: University-affiliated hospital. PATIENTS: 72 intubated and mechanically ventilated critically ill adult patients. INTERVENTIONS: Patients were briefly disconnected from the respirator. The centimeter marks of the Trachlight cather were brought into line with those of the endotracheal tube, resulting in congruence of the bulb of the Trachlight and the tube tip. MEASUREMENTS AND MAIN RESULTS: To measure the distance from the tip of the tube to that of the sternal notch, the Trachlight wand was retracted without moving the endotracheal tube until the bright light appeared in the sternal notch. A chest radiograph was taken to measure the distance between the carina and the tip of the tube. The Trachlight showed a distance of 4.0 +/- 1.3 cm from the tip of the tube to the sternal notch. Chest radiography revealed a distance of 3.3 +/- 1.6 cm between the carina and the tip of the tube, so that the calculated distance between sternal notch and carina was 7.3 +/- 1.5 cm. CONCLUSION: To achieve proper depth of the endotracheal tube, it is recommended that the tip of the endotracheal tube be placed 3 cm beyond the sternal notch. The Trachlight provides a simple and easy technique to achieve this goal.

Dental survey at school with the purpose to select children with no actual need of dental treatment.

The purpose of this study was to develop an examination method to select children without from children with need of dental treatment. Furthermore the objective was that these examinations could be performed as a survey at school, without utilizing an expensive and fully equipped dental clinic but still maintain the certainty for the individual not to be at increased risk to be declared false caries-free, in comparison with ordinary examination at a dental clinic. The material comprised 88 children 10-13 years old. The children were subject to a survey-examination at school and a few weeks later at a dental clinic by the same examiner. Initially the children were examined at school by two examiners in order to measure the inter-examiner variability. The results showed that 2 of the 88 examined children (2.3%) were judged false healthy at school examination with respect to caries. The inter-examiner variability in diagnosing caries was greater than the intra-examiner variability between survey at school and examination at the dental clinic.

Transillumination imaging performance: a time-of-flight imaging system.

A series of Monte Carlo simulations have been performed in order to investigate the feasibility of constructing a time-of-flight transillumination imaging system that could be used as an effective tool for screening for breast disease. The conceptual design of such a system is described, and simulated images are presented that demonstrate its likely performance. It is found that, whereas the spatial resolution achievable with such a system is only dependent upon its temporal resolution, the scattering characteristics of the tissue being imaged will strongly affect the ultimate imaging performance of such a system.

Reassessment of transillumination light scanning for the diagnosis of breast cancer.

Transillumination light scanning is a non-x-ray, noninvasive modality that uses low-intensity emissions of red and near infrared light to visualize the tissues of the breast. The absorption characteristics of the emitted light from the breast tissues are fed into a computer that transforms the analog signals into varying degrees of color saturation hues, ranging from blue to red. The basic premise for the use of transillumination is that breast cancer, because of its increased blood supply, absorbs more near infrared radiation than benign tissue. Thus, abnormal or malignant breast tissues appear blue on the light scan, while normal breast tissues appear red. The safety and lack of risk of radiation exposure of this technique have been demonstrated.