Free Air

60M w/o PMH p/w sudden onset abd pain several hours earlier, rigid abd, found to have free air on upright.  Perfed dudenoal ulcer found on ex-lap.

Spine Sign

40F c h/o CHF p/w SOB and productive cough.  Radiology report made no mention of focal consolidation.  The vertebral bodies should become more lucent the more inferior they are, but you can clearly see they become more opaque in this lateral view - a finding called "the spine sign."  This is consistent with a focal consolidation.