A system comprising a rotational device configured to enable assessment of characteristics of a blood vessel in a patient during a rotational medical procedure performed within the blood vessel, the rotational device comprising: a drive shaft configured for insertion into the blood vessel; an abrasive crown attached to the drive shaft; at least one magnet located on, in or near the abrasive crown and configured to be positioned within the blood vessel of the patient and adapted to rotate when the drive shaft rotates; the system further comprising: at least one magnetic field sensor configured to sense a carrier signal emitted by the at least one magnet when it rotates; and a processor configured to estimate the location of the at least one magnet as it rotates based on the carrier signal sensed by the at least one magnetic field sensor, wherein the rotational device is further configured to generate a magnetic field when the drive shaft and the at least one magnet is rotated; and the system characterized in that the processor is further configured to determine, based on the estimated location of the at least one magnet, at least one of the following characteristics of the blood vessel within the group consisting of: the diameter of the blood vessel, the cross-sectional shape of the blood vessel, the cross-sectional shape of an occlusion within the blood vessel, the compliance of the blood vessel, the elastance of the blood vessel, whether the blood vessel is at least partially calcified, the relative amount of calcification, the frequency with which the at least one magnet impacts the wall of the blood vessel. a drive shaft configured for insertion into the blood vessel; an abrasive crown attached to the drive shaft; at least one magnet located on, in or near the abrasive crown and configured to be positioned within the blood vessel of the patient and adapted to rotate when the drive shaft rotates; the system further comprising: at least one magnetic field sensor configured to sense a carrier signal emitted by the at least one magnet when it rotates; and a processor configured to estimate the location of the at least one magnet as it rotates based on the carrier signal sensed by the at least one magnetic field sensor, at least one magnetic field sensor configured to sense a carrier signal emitted by the at least one magnet when it rotates; and a processor configured to estimate the location of the at least one magnet as it rotates based on the carrier signal sensed by the at least one magnetic field sensor, wherein the rotational device is further configured to generate a magnetic field when the drive shaft and the at least one magnet is rotated; and the system characterized in that the processor is further configured to determine, based on the estimated location of the at least one magnet, at least one of the following characteristics of the blood vessel within the group consisting of: the diameter of the blood vessel, the cross-sectional shape of the blood vessel, the cross-sectional shape of an occlusion within the blood vessel, the compliance of the blood vessel, the elastance of the blood vessel, whether the blood vessel is at least partially calcified, the relative amount of calcification, the frequency with which the at least one magnet impacts the wall of the blood vessel.