Prognostic Impact of Direct 131I Therapy After Detection of Biochemical Recurrence in Intermediate or High-Risk Differentiated Thyroid Cancer: A Retrospective Cohort Study

Outcome of patients with differentiated thyroid cancer treated with empirical radioiodine therapy on the basis of Thyroglobulin Elevation Negative Iodine Scintigraphy (TENIS) syndrome without structural disease: a retrospective cohort study

BACKGROUND

For differentiated thyroid cancer (DTC) patients with thyroglobulin (Tg) elevation and negative iodine scintigraphy (commonly termed "TENIS" syndrome) after thyroidectomy, radioactive iodine (RAI) therapy, and thyroid-stimulating hormone (TSH) suppression therapy, empirical RAI therapy may be considered. However, the outcome data of TENIS syndrome without structural disease after empirical RAI therapy have not shown clear evidence of improvement in survival. We assessed the efficacy of such empirical RAI therapy in TENIS syndrome without structural disease and evaluated the progression-free survival (PFS).

METHODS

A total of 80 papillary thyroid cancer (PTC) patients with TENIS syndrome without structural disease were included in this retrospective study. 52 patients were treated with empirical RAI therapy while another 28 patients were untreated. The progression-free survival (PFS) of both groups was defined as the main outcome. The secondary outcome was the comparison of serum Tg levels 12 months after being diagnosed as TENIS syndrome.

RESULTS

The PFS of the empirical RAI therapy group was better than the untreated group (p < 0.001). Moreover, there was significant difference in Tg normalization between patients treated with empirical therapy and without treatment (p = 0.001). Empirical RAI therapy (p = 0.001) predicts better PFS. Male gender (p = 0.041) and empirical RAI therapy (p = 0.002) predict better remission in serum Tg level.

CONCLUSION

Patients with TENIS syndrome without structural disease can benefit from empirical RAI therapy in both PFS and Tg normalization.

Personalized Dosimetry in the Context of Radioiodine Therapy for Differentiated Thyroid Cancer

The most frequent thyroid cancer is Differentiated Thyroid Cancer (DTC) representing more than 95% of cases. A suitable choice for the treatment of DTC is the systemic administration of 131-sodium or potassium iodide. It is an effective tool used for the irradiation of thyroid remnants, microscopic DTC, other nonresectable or incompletely resectable DTC, or all the cited purposes. Dosimetry represents a valid tool that permits a tailored therapy to be obtained, sparing healthy tissue and so minimizing potential damages to at-risk organs. Absorbed dose represents a reliable indicator of biological response due to its correlation to tissue irradiation effects. The present paper aims to focus attention on iodine therapy for DTC treatment and has developed due to the urgent need for standardization in procedures, since no unique approaches are available. This review aims to summarize new proposals for a dosimetry-based therapy and so explore new alternatives that could provide the possibility to achieve more tailored therapies, minimizing the possible side effects of radioiodine therapy for Differentiated Thyroid Cancer.

Comparing lesion detection efficacy and image quality across different PET system generations to optimize the iodine-124 PET protocol for recurrent thyroid cancer

Background

In recurrent differentiated thyroid cancer patients, detectability in ¹²⁴I PET is limited for lesions with low radioiodine uptake. We assess the improvements in lesion detectability and image quality between three generations of PET scanners with different detector technologies. The results are used to suggest an optimized protocol.

Methods

Datasets of 10 patients with low increasing thyroglobulin or thyroglobulin antibody levels after total thyroidectomy and radioiodine therapies were included. PET data were acquired and reconstructed on a Biograph mCT PET/CT (whole-body, 4-min acquisition time per bed position; OSEM, OSEM-TOF, OSEM-TOF+PSF), a non-TOF Biograph mMR PET/MR (neck region, 4 min and 20 min; OSEM), and a new generation Biograph Vision PET/CT (whole-body, 4 min; OSEM, OSEM-TOF, OSEM-TOF+PSF). The 20-min image on the mMR was used as reference to calculate the detection efficacy in the neck region. Image quality was rated on a 5-point scale.

Results

All detected lesions were in the neck region. Detection efficacy was 8/9 (Vision OSEM-TOF and OSEM-TOF+PSF), 4/9 (Vision OSEM), 3/9 (mMR OSEM and mCT OSEM-TOF+PSF), and 2/9 (mCT OSEM and OSEM-TOF). Median image quality was 4 (Vision OSEM-TOF and OSEM-TOF+PSF), 3 (Vision OSEM, mCT OSEM-TOF+PSF, and mMR OSEM 20-min), 2 (mCT OSEM-TOF), 1.5 (mCT OSEM), and 1 (mMR OSEM 4 min).

Conclusion

At a clinical standard acquisition time of 4 min per bed position, the new generation Biograph Vision using a TOF-based image reconstruction demonstrated the highest detectability and image quality and should, if available, be preferably used for imaging of low-uptake lesions. A prolonged acquisition time for the mostly affected neck region can be useful.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-021-00361-y.