We introduce a methodology for acquisition and analysis of infrared (IR) images, picturing the metabolic heat emission from the human skin. Then we analyze the radiometric asymmetries in the patients with DM2 in comparison to the natural asymmetries, represented by the control group. In this regard, we introduce three indices (TAI, SAI, TtAI) with conditions for disclosing asymmetries displayed on images acquired in passive mode (the natural thermal emission, NTE). Then, the indices are adapted for analysis of IR-images acquired in what we brand as active mode (the NTE is altered by means of a controlled external stimulus). Out of the passive mode, the TAI and TtAI indices show the best diagnostic performance, with values of sensitivity and specificity of 89% and 72%, and 83% and 78%, respectively. Instead, from the active mode analysis we get 86% of sensitivity and 83% of specificity for the TRI index. We report data obtained form IR-images of 36 patients with Diabetes Mellitus Type II (DM2) and 18 non-diabetic controls. For both groups the image acquisition is made in passive and active mode, picturing the anterior and posterior views of the lower limbs. With this analysis, we manage to unveil the contra-lateral radiometric asymmetries of the legs, along with the differences between patients and controls. Finally, we report the consistency of these indices with glucose and glycated hemoglobin (HbA1c), known to be the golden clinical variables used to diagnose DM2.

The foremost advanced photoacoustic (PA) transport theory, dealing with image formation, relates to target volumes of shallow depths. It assumes the medium as homogeneous with negligible PA amplitude attenuation. Causal changes in the velocity distribution spectrum, as described in Debye’s theory, and related to propagation distance and sample's density, are also neglected. However, these are relevant for imaging targets at larger depths and improving image resolution of PA images of thick biological tissues. Here we introduce some concepts for extending the PA transport model. These are theoretical and experimental considerations for analysing PA attenuation and the significance of spectral dispersion; and in consequence, disclose those conditions at which they should be included as part of the PA transport theory. Departing from the PA Heaviside telegraph equation and causality conditions, we obtain analytic expressions for associated attenuation and dispersion coefficients. As part of the analysis, we propose expressions for the PA group and PA phase velocities, and for the group velocity dispersion parameter; those in analogy with optical fields. In this way we get a refined description for the spectral dispersion. As proof of consistency, the introduced expressions are tested with experimental data extracted from homogeneous colloid samples. The observed performance is compared against already known general acoustic dispersion theory.

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Abstract. Diabetic foot disease (DFD) is one of the major complications of the Diabetes Mellitus; within which the Diabetic Neurophaty (DN) and the peripheral vascular disease (PVD) (arteriosclerosis mainly) are among the most important causal factors in the pathogenesis of diabetic foot ulcers. Once ulcers are present, the risk of limb amputation is extremely high. A side effect from the DN and PVD is the change of the rate release of metabolic heat at quite specific areas. Here we present early advancements on the pattern recognition on infrared imagenology (thermography) picturing the altered distribution of the metabolic heat release driven by the DFD with arteriosclerosis. The thermograms are compared against corresponding simple-radiology images. As part of the analysis, we apply a computational algorithm to obtain the emission temperature averages, and we qualify the pattern distribution via a quantitative marker. Since the pathology of the limbs does not develop in a symmetric manner, then it is expected that the heat released would exhibit pattern asymmetries. The lasting question rely on the actual significance of the quantitative marker for being a meaningful quantifier on medical infrared imagenology (MIRI).