We also found a statistically significant reduction in noise ( p = 0.0001 ) and increase in CNR ( p0 .003 ) with increasing percentage of ASIR ; in addition , we noted statistically significant increases in image quality scores for the labrum and cartilage , subchondral bone , overall diagnostic quality ( up to 50 % ASIR ) , and subjective noise ( p0 .04 ) , and statistically significant reductions for the trabecular bone and muscles ( p0 .03 ) .