Accuracy of ¹²³I Na Thyroid Imaging in calculating thyroid volume

Area of Science:

• Endocrinology
• Nuclear Medicine
• Radiology

Background:

• Radioactive iodine therapy is a primary treatment for hyperthyroidism.
• Accurate thyroid gland volume is crucial for determining therapeutic radioactive iodine (RAI) dose.
• Both ultrasonography and nuclear scintigraphy can estimate thyroid volume.

Purpose of the Study:

• To compare thyroid volume measurements obtained via ultrasonography and nuclear scintigraphy.
• To validate nuclear scintigraphy as a method for estimating thyroid volume in hyperthyroid patients.
• To derive conversion factors between the two modalities for accurate RAI dosing.

Main Methods:

• Prospective study of 110 hyperthyroidism patients undergoing thyroid ultrasound and 123I scintigraphy.
• Thyroid volume calculated using a modified prolate ellipsoid formula from planar scintigraphy images.
• Comparison of volumes by linear regression; ultrasound performed within three months of scintigraphy.

Main Results:

• A linear relationship was observed between ultrasonography and nuclear medicine measurements: log US(g) = 0.841 + 0.649*log NM(g).
• The study included 110 patients (95 female, 15 male), average age 56 years.
• Diagnoses comprised nodular goiter (66) and Graves' disease (44).

Conclusions:

• Nuclear scintigraphy provides validated and accurate thyroid gland volume measurements.
• Derived conversion factors allow accurate estimation of thyroid volume from scintigraphy to ultrasound values.
• This method enhances precision in calculating radioactive iodine dosages for hyperthyroidism treatment.