In this thesis, we investigated decorrelation (a decrease in corrleation between sequential ultrasound signals) based analysis of Ultrasound (US) signals of urinary flow data to non-invasively diagnose BOO. The work of the thesis is devided into two parts. Part I deals with urethra model studies to provide a base for further in-vivo analysis. Part II describes the results of the cilinical studies done in healthy volunteers and in patients with Lower Urinary Tract Symptoms.