SPECT-CT in diagnosis of thyroid nodularity and retrosternal goiter

Objectives Thyroid nodules are a common clinical problem. Thyroid scintigraphy can determine the functionality of each nodule larger that 1 cm; hot, isofunctioning or non-functioning. SPECT-CT images show exact topography and size of each nodule and the type of morphological changes that have occurred in the “hot” or “cold” scintigraphis spots. The purpose of this study was tp determine the diagnostic value of SPECT-CT in retrosternal goiter and thyroid nodularity.

Methods 42 pts with thyroid nodularity and 31 pys with retrosternal goiter were studied after i.v. application of 74 MBq 99mTc-pertechnetate. SPECT-CT images were performed on Symbia T2, Siemens SPECT-CT camera (130 KeV, 30 mA). Focal uptake on the fusion images was described as “hot”, “cold”and equal”. Our results were compared to other clinical and laboratory data.

Results Retrosternal goiters were demonstrated by irregular tracer uptake in all 31 pts within the superior mediastinum due to fibrous components. 99mTc-images were heterogeneous, suboptimal and difficult to interpret. CT part of the study was applicable to detect retrosternal goiter tissue and to limit their volume. This was important information to planning the volume of surgical intervention. In 28 out of 42 pts diffuse thyroid enlargement with multiple “hot” functioning or hypofunctioning nodules were detected; a “toxic hot” nodule in one of lobs with uptake suppression of the other was scanned in 6 pts. SPECT images showed “cold”non-functioning thyroid nodules in 8 pts. CT scans allowed to identify morphological patterns of nodules - solid, cystic or complex; available calcifications or capsulation; hyperplastic or autonomously functioning benign tissue. SPECT-CT data were used as a guide to select the most suspicious nodules for FNA or biopsy.

Conclusions SPECT-CT provided additional diagnostic information for successful treatment of pts with retrosternal goiter and thyroid nodularity.