Abstract: A longitudinal position translator includes a probe drive module and a linear translation module. The probe drive module is coupled operatively to an ultrasonic imaging probe assembly having a distally located ultrasound transducer subassembly in such a manner that longitudinal shifting of the transducer subassembly may be effected. The probe drive module is preferably mounted to the linear translation unit so as to be moveable between a condition whereby longitudinal shifting of the transducer subassembly can be conducted either manually or automatically. When in the automatically-operable condition, the probe drive module will be engaged with a motor-driven screw associated with the linear translation module so as to cause the probe drive module to be longitudinally displaced at a constant motor-driven rate. In this manner, the distally located ultrasound transducer is longitudinally shifted during an ultrasound scan of surrounding intravascular (or other) tissue to thereby allow axially-spaced 360.degree.