An imaging system for a patient comprises an imaging probe. The imaging probe comprises: an elongate shaft for insertion into the patient and comprising a proximal end, a distal portion, and a lumen extending between the proximal end and the distal portion； a rotatable optical core comprising a proximal end and a distal end, the rotatable optical core configured to optically and mechanically connect with an interface unit； a probe connector positioned on the elongate shaft proximal end and surrounding at least a portion of the rotatable optical core and an optical assembly positioned in the elongate shaft distal portion and proximate the rotatable optical core distal end, the optical assembly configured to direct light to tissue and collect reflected light from the tissue. A shear-thinning fluid can be provided between the elongate shaft and the rotatable optical core, such as to reduce undesired rotational variations of the rotatable optical core.
