A catheter (102, 402) assembly for an ultrasound system, the catheter (102, 402) assembly comprising: an elongated catheter (102, 402) configured and arranged for insertion into the cardiovascular system of a patient, the catheter (102, 402) having a distal end, a proximal end, and a longitudinal length, the catheter (102, 402) comprising a sheath (302, 404) with a proximal portion and a distal portion, the sheath (302, 404) defining a lumen (304, 406) extending along the sheath (302, 404) from the proximal portion to the distal portion; an imaging core (306, 408) configured and arranged for inserting into the lumen (304, 406) of the catheter (102, 402), the imaging core (306, 408) comprising an elongated, rotatable driveshaft (310, 410) having a proximal end and a distal end, an imaging device coupled to the distal end of the driveshaft (310, 410) with rotation of the driveshaft (310, 410) causing a corresponding rotation of the imaging device, the imaging device comprising at least one transducer (312, 412) configured and arranged for transforming applied electrical signals to acoustic signals and also for transforming received echo signals to electrical signals, and a swellable material disposed on at least the at least one transducer (312, 412) and configured and arranged to rotate with rotation of the driveshaft (310, 410) and to swell upon exposure to a fluid. an elongated catheter (102, 402) configured and arranged for insertion into the cardiovascular system of a patient, the catheter (102, 402) having a distal end, a proximal end, and a longitudinal length, the catheter (102, 402) comprising a sheath (302, 404) with a proximal portion and a distal portion, the sheath (302, 404) defining a lumen (304, 406) extending along the sheath (302, 404) from the proximal portion to the distal portion; an imaging core (306, 408) configured and arranged for inserting into the lumen (304, 406) of the catheter (102, 402), the imaging core (306, 408) comprising an elongated, rotatable driveshaft (310, 410) having a proximal end and a distal end, an imaging device coupled to the distal end of the driveshaft (310, 410) with rotation of the driveshaft (310, 410) causing a corresponding rotation of the imaging device, the imaging device comprising at least one transducer (312, 412) configured and arranged for transforming applied electrical signals to acoustic signals and also for transforming received echo signals to electrical signals, and a swellable material disposed on at least the at least one transducer (312, 412) and configured and arranged to rotate with rotation of the driveshaft (310, 410) and to swell upon exposure to a fluid. an elongated, rotatable driveshaft (310, 410) having a proximal end and a distal end, an imaging device coupled to the distal end of the driveshaft (310, 410) with rotation of the driveshaft (310, 410) causing a corresponding rotation of the imaging device, the imaging device comprising at least one transducer (312, 412) configured and arranged for transforming applied electrical signals to acoustic signals and also for transforming received echo signals to electrical signals, and a swellable material disposed on at least the at least one transducer (312, 412) and configured and arranged to rotate with rotation of the driveshaft (310, 410) and to swell upon exposure to a fluid.