<prompt> Inveed 3 sign seen in -Ampullary CaInsulinomaCa. head pancreasCa. stomach  <response>: Answer is c i.e. Ca head of pancreas Ca of the head of the pancreas frequently causes changes in the duodenal loop. There may be widening of the duodenal loop, a double contour, irregularity of the inner border, and stricturing or distoion of the valvulae conniventes. The reversed 3 sign of Frostberg is often quoted as being characteristic, but is an infrequent finding. - Grainger 