A contrast base 40 is pushed by the printing head 18K, when the printing head 18K is mounted onto the carriage 16. The carriage is forced toward the guide by a tension generated by deflecting an extending direction of the motion transmitting element. Treatment methods include controlled and safe cryogenic cooling of vulnerable plaque to inhibit release of retained fluid within the vulnerable plaque so as to inhibit acute coronary syndrome and to help maintain patency of a body lumen.