Intravenous contrast enhancement is often employed in CT examination and it is recognized as an important procedure. When it is performed, the CT value of many tissues increase in various degrees. In this study, “enhancement” was defined as the difference of CT value between plain and enhanced CTs. We mesured the “enhancement” in the parotid and submandibular glands, masseter, medial pterygoid and sternocleidomastoid muscles, and internal jugular vein. We also analysed the factors affecting the “enhancement”. There was no significant difference in the increase of CT value between right and left sides in any tissue measured. The “enhancement” was the largest in the internal jugular vein, followed by the submandibular and parotid glands. The “enhancement” was markedly influenced by the speed of injection of contrast media and the body weight of the patients. Relationship between “enhancement” and time after beginning of injection varied according to the tissue. At a given injection dose, there was a close correlation between “enhancement” in the internal jugular vein and that in other tissues.
