Abstract: An ultrasound imaging device has a stationary, elongated flexible tubular body, a rotatable drive shaft extending through the body, and a nose member located distally of the tubular body. The nose member is mounted on the distal end of the drive shaft to rotate therewith, and an acoustic imaging instrument is incorporated in the nose member for producing acoustic images of adjacent tissue as the drive shaft turns. The nose member is covered with a bio-compatible, acoustically transparent, lubricous coating of hydrophilic material sufficient to shield and space the nose member from the adjacent tissue. The lubricous coating of hydrophilic material covers an area of the surface of the ultrasound imaging device through which the acoustic imaging instrument causes acoustic signals to pass. The coating has sufficient thickness to avoid puncturing of a wall of a blood vessel by the nose member while the nose member rotates within the blood vessel sufficiently close to the wall for puncturing otherwise to occur.