AbstractTotal body opacification is the radiological phenomenon in which, after intravenous injection, contrast agent opacifies the structures of the body in proportion to their blood supply. Avascular lesions can thus be rendered radiologically visible as lucencies newly contrasting with surrounding opacified structures. Appreciation of the total body opacification effect is widely useful in diagnostic radiology, especially in the delineation and characterization of neonatal abdominal masses.