Abstract: An intravascular catheter system capable of mapping thermal variations in the temperature of athrosclerotic plaque, on the athrosclerotic plaque surface, and in the arterial wall of aneurysms and other vascular lesions of the human vasculature is provided. The catheter system incorporates a plurality of thermal sensors fixedly attached along the catheters multi-lumen flexible tubular member which is adapted for insertion into the human body. Optionally, the thermal mapping catheter of the present invention is combined with other features such as intravascular ultrasound, and localized drug delivery, to provide integrated device functions.