The spheroid sign: a new sign for accurate differentiation of intramural from extramural masses.
Barium-column defects with estimated centers lying within or outside the projected luminal contour of the bowel are likely to be intramural or extramural masses, respectively.  Those with centers lying along the luminal contour are likely to be intramural.  Wehn a mass is viewed partially face-on, 2 defects in the barium column appear.  If either of these has an estimated center lying outside the luminal contour of the bowel, the origin of the mass is extramural.  If both estimated centers lie within the projected luminal contour, the mass arises intramurally.  This "spheroid" sign was tested in a blind study and found to be highly reliable.
D003951:Diagnostic Errors; D004379:Duodenal Neoplasms / Q000000981:diagnostic imaging; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging*; D005069:Evaluation Studies as Topic; D005753:Gastric Mucosa / Q000000981:diagnostic imaging; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D007413:Intestinal Mucosa / Q000000981:diagnostic imaging; D008722:Methods; D010181:Pancreatic Cyst / Q000000981:diagnostic imaging*; D011859:Radiography; D013679:Technology, Radiologic