The aim of this study was to illustrate the advances of quantitative shape estimates evaluating regularity of necrosis area after radiofrequency ablation (RFA). We applied freeware version of Principal Component Analysis based frequency domain transform method for evaluation of shape regularity for analysis of animal model results. In all observed cases only few first eigenvalues were showing cumulative sum of nearly 100% and there was no slow decay in their values. So simplest criteria of determining minimal yet sufficient number of principal components – cumulative sum of eigenvalues – was showing significant result. Complexity of the shape of necrosis area after RFA can be determined using minimal yet sufficient number of principal components giving optimal representation of contour shape.