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Thermal Analysis of Paraffin-Embedded Tissue Blocks for Anatomic Pathology Processes.

GOAL
We analyze temperature dynamics in anatomic pathology samples to identify the most efficient refrigeration method and to predict the time available for an optimal sectioning before sample heating, thus to get appropriate information for a correct diagnosis by anatomopathologists.


METHODS
A thermal Finite Element (FE) analysis was carried out with COMSOL Multiphysics to evaluate temperature variations in paraffin-embedded tissues, i.e., muscle, bone and fat. Experiments with different tissues and thermocouple-based measurements allowed to validate the FE simulations.


RESULTS
Simulations allowed to estimate the time needed to bring the sample at the optimal temperature for sectioning (-8 - -4 °C) in different conditions: refrigeration on a cold plate, refrigeration in a cooled environment and refrigeration in an environment with a forced convection. Among the three cooling methods tested the last one resulted the most efficient. A cooling temperature of -20 °C was the most effective, among the ones tested. For the different conditions, the time needed for the surface of the tissue block to exit from a temperature corresponding to an optimal cutting, when leaving the sample expose to room temperature after refrigeration, ranged from 12s to 310 s.


CONCLUSIONS
We quantify the time needed to adequately refrigerate paraffin-embedded tissue samples and the time available before they leave the optimal temperature window for sectioning. This information will be helpful in optimizing anatomic pathology processes.