A system includes a probe configured to transmit ultrasound signals to a target blood vessel, and receive echo information associated with the transmitted ultrasound signals. The system may also include at least one processing device configured process the received echo information and generate an ultrasound image of the blood vessel and identify a seed position within the blood vessel based on the ultrasound image. The at least one processing device may further generate an estimated contour for a lumen of the blood vessel based on pixel intensity values associated with the ultrasound image, generate an estimated contour for the blood vessel using the pixel intensity values, determine whether a thrombus exists within the blood vessel and output image information illustrating the estimated contours of the lumen and the blood vessel.