Clinical Presentation

A 34-year-old woman presents with a possible right thyroid nodule palpated by the referring physician. Her thyroid function test values are normal.

Fig. 56.1 Right anterior oblique pinhole collimator view, ¹²³I.

Fig. 56.2 Anterior pinhole collimator view, ¹²³I.

Fig. 56.3 Left anterior oblique pinhole collimator view, ¹²³I.

Technique

• 0.300 mCi of ¹²³I administered orally 4 hours before uptake and scan

• Five-minute pinhole collimator images in right anterior oblique, anterior, and left anterior oblique projections

• An appropriately shielded sodium iodide thyroid probe is positioned with the crystal surface 25 cm from the surface being measured. Obtain counts of the following for 2 minutes:

Thyroid bed

Thigh (body background)

Room background

Pill standard (in a neck phantom)

• Calculate the iodine uptake with the following formula:

Image Interpretation

Differential Diagnosis

• Normal thyroid gland

Diagnosis and Clinical Follow-Up

Normal thyroid gland. Diagnosis final, no clinical follow-up.

Discussion

Thyroid scintigraphy is clinically important for the diagnosis and treatment of a variety of benign and malignant thyroid disorders, including the evaluation of goiters, differential diagnosis of hyperthyroidism, and function of thyroid nodules. Optimal thyroid scintigraphy requires an understanding of the two common imaging agents, radioactive ¹²³I and ^99m