Assessing Krenning’s score on 68Ga-DOTATATE PET-CT and miPSMA score on 68Ga-PSMA-11 PET-CT in TENIS: a comparison with FDG PET/CT and examining the feasibility of targeted radionuclide therapy

Abstract

Objectives The objective of this study was to assess receptor expression in metastatic differentiated thyroid carcinoma patients with progressive elevated thyroglobulin and negative iodine scintigraphy, we used 68Ga-DOTATATE [Gallium-68 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA)–octreotate (DOTATATE)] (Krenning’s score) and 68Ga-PSMA-11 (Gallium-68 prostate‐specific membrane antigen‐11) PET-computed tomography (CT) [molecular imaging prostate‐specific membrane antigen (miPSMA) score]. Patients with Krenning’s score 3 and above and miPSMA score 2 and above were considered to determine the incidence of patients, who would qualify for treatment with 177Lu-DOTATATE/PSMA [Lutetium-177 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA)–octreotate (DOTATATE)/prostate‐specific membrane antigen]-based therapy. In addition, we compared 68Ga-DOTATATE and 68Ga-PSMA-11 PET-CT with 2-deoxy-2-[F-18]fluoroglucose (18F-FDG) PET-CT (using maximum standardized uptake value). Materials and methods A total of 74 patients with histopathologically proven metastatic differentiated thyroid carcinoma with thyroglobulin elevation and negative iodine scintigraphy syndrome were studied retrospectively. They all had 18F-FDG, 68Ga-DOTATATE, and 68Ga-PSMA-11 PET-CT scans available for undertaking this analysis. The lesions detected by 68Ga-DOTATATE and 68Ga-PSMA-11 were evaluated using Krenning’s and miPSMA scores. In addition, quantitative comparisons of maximum standardized uptake values for 68Ga-DOTATATE and 68Ga-PSMA-11, as well as with 18F-FDG, were conducted. Results Patient-wise analysis revealed positivity rates of 40.5% for 68Ga-DOTATATE, 41.89% for 68Ga-PSMA-11, and 75.67% for 18F-FDG. Among the 74 patients, 14 (18.91%) were deemed eligible for 177Lu-DOTATATE/PSMA-617 therapy based on Krenning’s score of 3 and above both/either miPSMA score of 2 and above on 68Ga-DOTATATE or 68Ga-PSMA-11 PET-CT. Within this subgroup, seven out of 74 patients (9.45%) were eligible for 177Lu-DOTATATE therapy, and nine out of 74 patients (12.16%) were eligible for 177Lu-PSMA-targeted therapy. Four patients were eligible for both therapies. Conclusion Among thyroglobulin elevation and negative iodine scintigraphy patient’s subgroup, 9.45% could qualify for 177Lu-DOTATATE and 12.16% for 177Lu-PSMA-617. Four were eligible for both therapies. Given the lack of effective therapies, this subset of patients warrants consideration for radionuclide therapy exploration.