Through years 2 and 3 , osteitis on MRI resolved completely in 56 of 144 ( 38.9 % ) SI joint quadrants and in 20 of 40 ( 50 % ) VUs affected at baseline , while persistent osteitis was found in 24 of 144 ( 16.7 % ) SI joint quadrants and in 8 of 40 ( 20.0 % ) spine VUs .