Mechanical properties of Small-Diameter Vessels (SDV) are scarcely studied. The proposed Pressure-Volume (PV) system, developed to evaluate stress-strain (σ-ε) behavior of SDV, allows the controlled variation of internal pressure and simulation of pressure-induced diameter changes of tubes. Measurements were taken from contrast-improved images captured for each internal pressure value. A circular cross-section tube in equilibrium, with elastic wall and known pressures was assumed to determine circumferential stress and strain. σ-ε curves were obtained and validated against tensile uniaxial (TU) testing. Although different behaviors were expected, experimental data is consistent when compared to TU results, differentiating by 5.68 to 12.60 %.