Vessel , lumen , and stent volume indices increased significantly ( respectively , 17.03.6 to 18.93.7 mm ( 3 ) / mm , P < 0.0001 ; 7.32.0 to 9.22.5 mm ( 3 ) / mm , P < 0.0001 ; and 7.42.0 to 9.62.6 mm ( 3 ) / mm , P < 0.0001 ) .