Head-to-head comparison of two online nomograms for prostate biopsy outcome prediction

LEVEL OF EVIDENCE: 2b. What's known on the subject? and What does the study add? In recent years, several nomograms were developed in an effort to decrease the number of unnecessary prostate biopsies. The European SWOP-PRI and the North American PCPT are among the most popular. However, evidence on the relative predictive accuracy is lacking. A head-to-head comparison on the diagnostic accuracy of two previously validated prostate cancer risk predictors on biopsy confirmed the superiority of these tools over PSA alone. Moreover, in the studied population, the European SWOP-PRI proved to be more accurate than the North American PCPT-CRC. OBJECTIVE: To compare the diagnostic accuracy of two previously validated prostate cancer risk predictors on biopsy. PATIENTS AND METHODS: In total, 390 consecutive patients submitted to 10-core systematic transrectal prostate biopsy at our institution were included in this retrospective study. External validation of a European (European Randomized Study of Screening for Prostate Cancer derived Prostate Risk Indicator; SWOP-PRI) and a North American (Prostate Cancer Prevention Trial Cancer Risk Calculator; PCPT-CRC) nomogram was performed. The predictive accuracy of these online available nomograms was calculated based on the area under the curve derived from receiver-operator characteristic curves and then compared using the DeLong method. RESULTS: Both tools were confirmed to be superior to prostate-specific antigen alone. Moreover, the SWOP-PRI (77.9%) displays a 7.96% increase in the predictive accuracy compared to the PCPT-CRC (69.9%) in a statistically significant fashion (P=0.002). CONCLUSIONS: The results obtained in the present study confirm the utility of nomograms with respect to biopsy outcome prediction in patients with suspicion of prostate cancer. In the current sample of patients, the European-based nomogram appears to be more accurate than the North American nonogram, which lacks information regarding prostate volume and prostatic ultrasonographic lesions. • To our knowledge, this is the first study to compare the accuracy of these popular risk calculators in a specific population

Optical clearing mechanisms characterization in muscle

Optical immersion clearing is a technique that has been widely studied for more than two decades and that is used to originate a temporary transparency effect in biological tissues. If applied in cooperation with clinical methods it provides optimization of diagnosis and treatment procedures. This technique turns biological tissues more transparent through two main mechanisms — tissue dehydration and refractive index (RI) matching between tissue components. Such matching is obtained by partial replacement of interstitial water by a biocompatible agent that presents higher RI and it can be completely reversible by natural rehydration in vivo or by assisted rehydration in ex vivo tissues. Experimental data to characterize and discriminate between the two mechanisms and to find new ones are necessary. Using a simple method, based on collimated transmittance and thickness measurements made from muscle samples under treatment, we have estimated the diffusion properties of glucose, ethylene glycol (EG) and water that were used to perform such characterization and discrimination. Comparing these properties with data from literature that characterize their diffusion in water we have observed that muscle cell membrane permeability limits agent and water diffusion in the muscle. The same experimental data has allowed to calculate the optical clearing (OC) efficiency and make an interpretation of the internal changes that occurred in muscle during the treatments. The same methodology can now be used to perform similar studies with other agents and in other tissues in order to solve engineering problems at design of inexpensive and robust technologies for a considerable improvement of optical tomographic techniques with better contrast and in-depth imaging

Optical measurements of rat muscle samples under treatment with ethylene glycol and glucose

With the objective to study the variation of optical properties of rat muscle during optical clearing, we have performed a set of optical measurements from that kind of tissue. The measurements performed were total transmittance, collimated transmittance, specular reflectance and total reflectance. This set of measurements is sufficient to determine diffuse reflectance and absorbance of the sample, also necessary to estimate the optical properties. All the performed measurements and calculated quantities will be used later in inverse Monte Carlo (IMC) simulations to determine the evolution of the optical properties of muscle during treatments with ethylene glycol and glucose. The results obtained with the measurements already provide some information about the optical clearing treatments applied to the muscle and translate the mechanisms of turning the tissue more transparent and sequence of regimes of optical clearing

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Software development for estimation of optical clearing agent’s diffusion coefficients in biological tissues

The study of chemical diffusion in biological tissues is a research field of high importance and with application in many clinical, research and industrial areas. The evaluation of diffusion and viscosity properties of chemicals in tissues is necessary to characterize treatments or inclusion of preservatives in tissues or organs for low temperature conservation. Recently, we have demonstrated experimentally that the diffusion properties and dynamic viscosity of sugars and alcohols can be evaluated from optical measurements. Our studies were performed in skeletal muscle, but our results have revealed that the same methodology can be used with other tissues and different chemicals. Considering the significant number of studies that can be made with this method, it becomes necessary to turn data processing and calculation easier. With this objective, we have developed a software application that integrates all processing and calculations, turning the researcher work easier and faster. Using the same experimental data that previously was used to estimate the diffusion and viscosity of glucose in skeletal muscle, we have repeated the calculations with the new application. Comparing between the results obtained with the new application and with previous independent routines we have demonstrated great similarity and consequently validated the application. This new tool is now available to be used in similar research to obtain the diffusion properties of other chemicals in different tissues or organs

Kinetics of optical properties of colorectal muscle during optical clearing

In this paper, we describe a simple and indirect method to evaluate the kinetics of the optical properties for biological tissues under optical clearing treatments. We use the theoretical formalism in this method to process experimental data obtained from colorectal muscle samples to evaluate and characterize the dehydration and refractive index matching mechanisms

Diffusion characteristics of ethylene glycol in skeletal muscle

Part of the optical clearing study in biological tissues concerns the determination of the diffusion characteristics of water and optical clearing agents in the subject tissue. Such information is sufficient to characterize the time dependence of the optical clearing mechanisms—tissue dehydration and refractive index (RI) matching. We have used a simple method based on collimated optical transmittance measurements made from muscle samples under treatment with aqueous solutions containing different concentrations of ethylene glycol (EG), to determine the diffusion time values of water and EG in skeletal muscle. By representing the estimated mean diffusion time values from each treatment as a function of agent concentration in solution, we could identify the real diffusion times for water and agent. These values allowed for the calculation of the correspondent diffusion coefficients for those fluids. With these results, we have demonstrated that the dehydration mechanism is the one that dominates optical clearing in the first minute of treatment, while the RI matching takes over the optical clearing operations after that and remains for a longer time of treatment up to about 10 min, as we could see for EG and thin tissue samples of 0.5 mm