This image shows enlargement of the thyroid gland and extension down behind the breastbone (retrosternal space). The image, called a scintiscan, was generated using a radioactive isotope.
Review Date 2/22/2018
Updated by: Brent Wisse, MD, board certified in Metabolism/Endocrinology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.