#negative contrast

• Aerocystography — A radiological method for investigating the urinary bladder consisting of performing radiographs after the bladder cavity has been distended by insufflating a controlled amount of air or another sterile gas. This imaging examination highlights the contour of the bladder walls, detecting radiolucent tumors, calculi, or diverticula, functioning as a negative contrast medium.
• Aeromammography — A historical radiological method or experimental imaging technique for examining the mammary gland, consisting of performing radiographs after the controlled introduction or insufflation of air or another sterile gas as a negative contrast medium into the periglandular tissues or milk ducts, used to highlight tumors before the advent of modern digital mammography.