Measurement of thyroid iodine by CT

Area of Science:

• Nuclear Medicine
• Radiology
• Endocrinology

Background:

• Accurate assessment of thyroidal iodine concentration is crucial for understanding thyroid function and disease.
• Current methods for measuring iodine content in thyroid tissue can be invasive or lack in vivo quantitative capabilities.
• Computed tomography (CT) offers a non-invasive imaging modality with potential for quantitative tissue analysis.

Purpose of the Study:

• To evaluate the feasibility of quantitative in vivo measurement of thyroid iodine concentration using CT.
• To establish a correlation between CT attenuation values and actual iodine concentrations in thyroid tissue.
• To assess the utility of CT-based iodine measurement for evaluating thyroid nodules and diffuse thyroid disease.

Main Methods:

• Quantitative CT scans of the thyroid without contrast enhancement were performed on 18 patients.
• 48 thyroid tissue fragments (without calcification) were surgically obtained and analyzed for iodine content.
• CT attenuation values from regions of interest corresponding to tissue fragments were correlated with measured iodine concentrations.

Main Results:

• A linear correlation was observed between CT attenuation values and thyroid iodine concentration when levels exceeded 0.02 mg/g.
• The established formula: iodine concentration (mg/g) = (CT value-65)/104, accurately predicts iodine levels.
• The correlation between CT values and iodine concentration was consistent across normal thyroids, thyroid nodules, and diffuse thyroid disease.

Conclusions:

• Quantitative CT is a reliable method for in vivo measurement of thyroid iodine concentration.
• This technique can be applied to assess iodine kinetics and characterize thyroid nodules and diffuse thyroid disease.
• CT-based iodine quantification provides a non-invasive tool for thyroidal iodine assessment.