We report on the first experimental evaluation of pulsed photothermal radiometry (PPTR) using a spectrally composite kernel matrix in signal analysis. Numerical studies have indicated that this approach could enable PPTR temperature profiling in watery tissues with better accuracy and stability as compared to the customary monochromatic approximation. By using an optimized experimental set-up and image reconstruction code (involving a projected nu-method and adaptive regularization), we demonstrate accurate localization of thin absorbing layers in agar tissue phantoms with pronounced spectral variation of a mid-infrared absorption coefficient. Moreover, the widths of reconstructed temperature peaks reach 14-17% of their depth, significantly less than in earlier reports on PPTR depth profiling in watery tissues. Experimental results are replicated by a detailed numerical simulation, which enables analysis of the broadening effect as a function of temperature profile amplitude and depth.

Purpose: To evaluate effect of platelet-rich plasma gel (PRPG), locally administered during the anterior cruciate ligament (ACL) reconstruction, with two MRI methods. The proximal tibial tunnel was assessed with diffusion weighted imaging (DWI) and with dynamic contrastenhanced imaging (DCE-MRI). Materials and Methods:In 50 patients, standard arthroscopic ACL reconstructions were performed. The patients in the PRPG group (n ¼ 25) received a local application of PRPG. The proximal tibial tunnel was examined by DWI and DCE-MRI, which were used to calculate apparent diffusion coefficient (ADC) values, as well as the contrast enhancement gradient (G enh ) and enhancement factor (F enh ) values.Results: At 1 month, the calculated average ADC value in the PRPG group was significantly lower than in the control group. At 2.5 and at 6 months, G enh was significantly higher in the PRPG group. There were no significant differences in F enh between the groups at any control examination.Conclusion: DWI and DCE-MRI measurements indicate a reduced extent of edema during the first postoperative month as well as an increased vascular density and microvessel permeability in the proximal tibial tunnel at 1 and 2.5 postoperative months as the effect of the application of PRPG.

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The use of electric current density imaging (CDI) to map spatial distribution of electric currents through tumors is presented. Specifically, a method previously tested on phantoms was implemented in vivo and in vitro for mapping electric current pulses of the same order of magnitude (j approximately 2500 A/m2) as in electrochemotherapy through T50/80 mammary carcinomas, B-16 melanomas and SA-1 sarcomas. A technically simplified method of electric current density imaging is discussed as well. Three geometries of electrodes (flat-flat, point-point, point-flat) indicate altered electric current distribution for the same tumor. This indicates that the method can be used for monitoring the effects of electrochemotherapy as a function of electrode geometry.