Comparisons of I-123 diagnostic and I-131 post-treatment scans for detecting residual thyroid tissue and metastases of differentiated thyroid cancer

Abstract

Diagnostic scanning with relatively low dose I-123 is not always predictive of subsequent therapeutic I-131 uptake, especially for lymph node and lung metastases of differentiated thyroid cancer.

Clinical Utility of 18F-FDG PET/CT Concurrent with 131I Therapy in Intermediate–to–High-Risk Patients with Differentiated Thyroid Cancer: Dual-Center Experience with 286 Patients

“…TSH-stimulated PET/CT imaging can be performed with pretherapy scanning for detecting iodine-negative lesions before 131 I treatment. However, there is still a debate whether pretherapy 123 I scanning can achieve results comparable to posttherapy 131 I scanning (33)(34)(35). Therefore, careful consideration is needed to diagnose iodine-negative lesions based on pretherapy 123 I scans.…”

Usefulness of 99mTc-pertechnetate whole body scan with neck and chest SPECT/CT for detection of post-surgical thyroid remnant and metastasis in differentiated thyroid cancer patients

“…Furthermore, stunning may occur as shown in some studies presumably from Auger electrons emitted by 123 I [15,16]. In clinical aspect, 123 I pre-ablative scan showed a low concordance rate with 131 I post-treatment scan for detecting lymph node and lung metastases in one study [17].…”

The Utility of I-123 Pretherapy Scan in I-131 Radioiodine Therapy for Thyroid Cancer

“…Part of the reason is that most physicians will routinely perform the posttreatment scan after the high dose of I-131 radioiodine ablation, which has been demonstrated to detect more lesions and to be more sensitive than the pretherapy diagnostic scan (12)(13)(14). For this reason, some insurance companies do not reimburse the pretherapy diagnostic scan, which limits this option.…”