Proper orthogonal decomposition analysis of spatio-temporal behavior of renal scintigraphies

We present a preliminary application of proper orthogonal decomposition (POD) to data sets coming from spatial and temporal evolution of renal scintigraphy. Renal functionalities or pathologies are hardly recognized from the raw scintigraphic images and their identifications could depend on the subjective point of view of the operator. The proposed technique is able to distinguish independent events starting from a more complex phenomenon. The spatio-temporal fields, representing the radiation emitted by the radiopharmaceutical technetium-99m with mercaptoacetiltriglicin (MAG3) within the kidney, have been analyzed for six randomly selected patients. In particular our study was performed on four patients affected by renal pathologies while two scintigraphies refer to healthy patients. First of all POD represents an efficient filtering procedure to cut off noise from the raw images by only selecting the few most energetic modes. When healthy kidneys are analyzed, POD is able to separate the main processes taking place in the organ. When applied to pathological samples, POD underlines the regions of the organ interested by the troubles allowing to analyze them independently. This analysis can be complementary to the identification made by hand by the operator.