Contribution of SPECT-CT to planar imaging in post-ablation imaging in different thyroid cancers, the clinical significance of the differential diagnosis of neck and thorax uptakes
Öz
Background: The aim of this study is to demonstrate the superiority of Single Photon Emission Computed Tomography-Computed Tomography (SPECT-CT) over planar imaging in distinguishing benign from malignant foci and patient management after 131I ablation therapy in patients with differentiated thyroid cancer (DTC).
Material and Methods: Planar and SPECT-CT imaging findings were retrospectively analyzed in 80 patients who received I-131 therapy for thyroid cancer. Possible foci in whole body scanning (WBS), neck, and thorax were compared with SPECT-CT. Anatomical localization of the foci and differential diagnosis of the benign and malignant lesion was made with SPECT-CT. Those without anatomical counterparts were recorded as equivocal foci. According to the 2015 American Thyroid Association (ATA) guidelines, patients were divided into three groups: High, intermediate, low-risk groups. Interpretation changes between both scannings were recorded as downstage and upstage.
Results: There were 53 female and 27 male patients. The patients' age ranged from 21 to 88 years with a mean age of 47 ±14.2. In 80 patients, 139 foci were detected in planar images and SPECT-CT images (neck: 118, thorax: 21). SPECT-CT revealed that 50% of the lateral neck foci were compatible with pathologies in malignant nature and 50% with pathologies in benign nature. Foci in the middle part of the neck were found to be not only thyroid remnant (56%), but also thyroglossal duct remnant (40%) foci at a significant rate It was determined that 66% of the foci in the thorax region were lung metastases and 34% were bone metastases. It was proved that 33% of the foci in the mediastinal region were lymph nodes. Although only one of the remaining patients had a pathological diagnosis, it was thought that all of them might have thymus pathologies. SPECT-CT images changed the interpretation of 18 patients (22.5%), of which 5 (6.25%) were upstage and 13 (16.25%) were downstage.
Conclusions: The use of SPECT-CT will be very effective, facilitating patient management and avoiding unnecessary procedures, especially in moderate/high-risk patients with suspicious focal lesions. The presence of benign iodine avid foci (thyroglossal duct residue, etc.) in the neck showing iodine uptake other than the thyroid remnant may be effective in making ablation decisions in low-risk patients.
Anahtar Kelimeler
131I, Differentiated Thyroid Cancer, Whole Body Scanning, SPECT-CT
Kaynakça
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