Exploring factors that influence the efficacy of functional communication training.

Understanding factors that influence the efficacy of functional communication training has both practical and conceptual benefits. The current study extended research in this area by exploring data from 95 consecutive applications of functional communication training with extinction across two independent clinics. We selected candidate predictor variables based on conceptual analysis, conducted preliminary exploratory analyses, and then selectively applied quantitative methods that are used in precision medicine to examine their accuracy and predictive utility. Treatment outcomes were better when challenging behavior was maintained by a single function than they were when it was maintained by multiple functions; however, these differences were most apparent among cases with an escape function. We also analyzed within-session responding to explore the potential influence of unprogrammed establishing operations on decrements in treatment efficacy. Our within-session measure only distinguished responders from nonresponders when escape was one of the multiple functions. Additional research is needed to validate these findings with an independent sample and to address a number of clinical conceptual issues.

Retrospective consecutive controlled case series of outcomes for functional analyses of severe destructive behavior.

Functional analysis methods allow clinicians to determine the variable(s) that maintain destructive behavior. Previous reviews of functional analysis outcomes have included large samples of published and unpublished data sets (i.e., clinical samples). The purpose of this review was to conduct a large retrospective consecutive controlled case series of clinical functional analyses. We sought to identify the prevalence of differentiation, procedural modifications for undifferentiated and differentiated cases, and identified function(s) of destructive behavior. In addition, we extended the existing literature by determining whether functional analysis differentiation and function varied when single or multiple behavior topographies were consequated in the functional analysis. We discuss our findings considering previously published functional analysis reviews, provide avenues for future research, and offer suggestions for clinical practice.

Experimental validation of a spectroscopic Monte Carlo light transport simulation technique and Raman scattering depth sensing analysis in biological tissue.

SIGNIFICANCE: Raman spectroscopy (RS) applied to surgical guidance is attracting attention among scientists in biomedical optics. Offering a computational platform for studying depth-resolved RS and probing molecular specificity of different tissue layers is of crucial importance to increase the precision of these techniques and facilitate their clinical adoption. AIM: The aim of this work was to present a rigorous analysis of inelastic scattering depth sampling and elucidate the relationship between sensing depth of the Raman effect and optical properties of the tissue under interrogation. APPROACH: A new Monte Carlo (MC) package was developed to simulate absorption, fluorescence, elastic, and inelastic scattering of light in tissue. The validity of the MC algorithm was demonstrated by comparison with experimental Raman spectra in phantoms of known optical properties using nylon and polydimethylsiloxane as Raman-active compounds. A series of MC simulations were performed to study the effects of optical properties on Raman sensing depth for an imaging geometry consistent with single-point detection using a handheld fiber optics probe system. RESULTS: The MC code was used to estimate the Raman sensing depth of a handheld fiber optics system. For absorption and reduced scattering coefficients of 0.001 and 1 mm - 1, the sensing depth varied from 105 to 225 µm for a range of Raman probabilities from 10 - 6 to 10 - 3. Further, for a realistic Raman probability of 10 - 6, the sensing depth ranged between 10 and 600 µm for the range of absorption coefficients 0.001 to 1.4 mm - 1 and reduced scattering coefficients of 0.5 to 30 mm - 1. CONCLUSIONS: A spectroscopic MC light transport simulation platform was developed and validated against experimental measurements in tissue phantoms and used to predict depth sensing in tissue. It is hoped that the current package and reported results provide the research community with an effective simulating tool to improve the development of clinical applications of RS.

Towards a bimodal proximity sensor for in situ neurovascular bundle detection during dental implant surgery.

Proof of concept results are presented towards an in situ bimodal proximity sensor for neurovascular bundle detection during dental implant surgery using combined near infrared absorption (NIR) and optical coherence tomography (OCT) techniques. These modalities are shown to have different sensitivity to the proximity of optical contrast from neurovascular bundles. NIR AC and DC signals from the pulsing of an artery enable qualitative ranging of the bundle in the millimeter range, with best sensitivity around 0.5-3mm distance in a custom phantom setup. OCT provides structural mapping of the neurovascular bundle at sub-millimeter distances in an ex vivo human jaw bone. Combining the two techniques suggests a novel ranging system for the surgeon that could be implemented in a "smart drill." The proximity to the neurovascular bundle can be tracked in real time in the range of a few millimeters with NIR signals, after which higher resolution imaging OCT to provide finer ranging in the sub-millimeter distances.

Multispectral imaging of tissue absorption and scattering using spatial frequency domain imaging and a computed-tomography imaging spectrometer.

We present an approach for rapidly and quantitatively mapping tissue absorption and scattering spectra in a wide-field, noncontact imaging geometry by combining multifrequency spatial frequency domain imaging (SFDI) with a computed-tomography imaging spectrometer (CTIS). SFDI overcomes the need to spatially scan a source, and is based on the projection and analysis of periodic structured illumination patterns. CTIS provides a throughput advantage by simultaneously diffracting multiple spectral images onto a single CCD chip to gather spectra at every pixel of the image, thus providing spatial and spectral information in a single snapshot. The spatial-spectral data set was acquired 30 times faster than with our wavelength-scanning liquid crystal tunable filter camera, even though it is not yet optimized for speed. Here we demonstrate that the combined SFDI-CTIS is capable of rapid, multispectral imaging of tissue absorption and scattering in a noncontact, nonscanning platform. The combined system was validated for 36 wavelengths between 650-1000 nm in tissue simulating phantoms over a range of tissue-like absorption and scattering properties. The average percent error for the range of absorption coefficients (µa) was less than 10% from 650-800 nm, and less than 20% from 800-1000 nm. The average percent error in reduced scattering coefficients (µs') was less than 5% from 650-700 nm and less than 3% from 700-1000 nm. The SFDI-CTIS platform was applied to a mouse model of brain injury in order to demonstrate the utility of this approach in characterizing spatially and spectrally varying tissue optical properties.

Modulated imaging in layered media.

We present forward modeling and measurement of spatially modulated illumination in layered turbid tissue systems. This technique is used to provide quantitative, depth-resolved functional physiologic information with applications in layered tissues including cortex, retina and skin.