Abstract: An ultrasound catheter is configured to be positioned at a treatment site within a patient's vasculature. The catheter comprises an elongate tubular body forming a utility lumen. The catheter further comprises an ultrasound assembly configured to be movably positioned within the utility lumen. The ultrasound assembly includes a plurality of ultrasound radiating members. The catheter further comprises a plurality of fluid delivery lumens formed within the elongate tubular body. Each fluid delivery lumen includes one or more fluid delivery ports configured to allow a fluid to flow from within the fluid delivery lumen to the treatment site. A first fluid delivery lumen includes one or more fluid delivery ports over a first region of the tubular body. A second fluid delivery lumen includes one or more fluid delivery ports over a second region of the tubular body. The first region of the tubular body and the second region of the tubular body have different lengths.