Abstract: An apparatus and method for determining angular position of a sensor within a catheter. The invention is particularly useful for imaging devices delivered to a body lumen by a catheter, as may be the case for IVUS imaging catheters. The apparatus consists of a catheter having an inner core with an imaging sensor disposed within an inner diameter of a sheath of the catheter. The sheath is also provided with an outer diameter which has a center which it does not share with a center of the inner diameter. As a result, the catheter has a wall of non-uniform thickness. The imaging sensor is able to determine its position within its imaging rotation due to the non-uniform thickness. This positioning characteristic helps eliminate any Non-Uniform Rotational Distortion (NURD), which would otherwise result in undesired and unpredictable compressed and expanded images of vasculature sought to be imaged.