Imaging tests include CT scans, ultrasound, and nuclear medicine tests. One type of nuclear medicine test is the thyroid scan. It uses small amounts of radioactive material to create a picture of the thyroid, showing its size, shape, and position. It can help find the cause of hyperthyroidism and check for thyroid nodules (lumps in the thyroid). Another nuclear test is the radioactive iodine uptake test, or thyroid uptake test. It checks how well your thyroid is working and can help find the cause of hyperthyroidism.