[Imaging in struma diagnosis]

Abstract

Since Cassen and Taylor and Stewart introduced 131iodine scans of the thyroid, these have become an integral part of the routine diagnostic procedures for thyroid disease. Today 131I is no longer used due to its excessive radioactivity; 123iodine or 99mtechnetium are now preferred. Pitfalls in the use of 99mTc are that in some thyroid disorders, such as certain forms of thyroid carcinomas and chronic thyroiditis, a normal iodine trapping (but not organification) may occur. This mechanism can lead to false conclusions. Sonography in the imaging of organ boundaries has been used in Germany for 15 years to an increasing extent. To date following correlations between thyroid disorders and sonographic features have been found: In 80% of patients with Graves' disease the thyroid tissue is characterized by low echogenicity. In over 95% of patients with chronic thyroiditis, combined with hypothyroidism, the same has been observed. Subacute or granulomatous thyroiditis is characterized by regions of low echogenicity, corresponding to areas of inflammation. Thyroid carcinomas have appeared up to now as nodules of low echogenicity. However, the use of high frequency ultrasound imaging has complicated the situation. Nevertheless, nodules of low echogenicity show a higher rate of malignancy than nodules of higher echogenicity.