Comparison of [¹¹¹In]octreotide Scintigraphy and [⁶⁸Ga]DOTATOC PET in Gastroenteropancreatic Neuroendocrine Tumors: Concordance of Krenning Scores and Implications for Peptide Receptor Radionuclide Therapy Eligibility.

Abstract

BackgroundPeptide receptor radionuclide therapy (PRRT) is an established treatment for somatostatin receptor (SSTR)-positive gastroenteropancreatic neuroendocrine tumors (GEP-NETs), with eligibility determined by the Krenning score. While SSTR PET provides greater sensitivity than octreotide scintigraphy, its impact on PRRT eligibility remains unclear. We compared Krenning scores between [111In]octreotide scintigraphy and [68Ga]DOTATOC PET and assessed eligibility under NETTER-1 and NETTER-2 criteria.MethodsWe retrospectively assessed tumor Krenning scores in 115 patients with well-differentiated GEP-NETs who underwent both [111In]octreotide scintigraphy and [68Ga]DOTATOC PET. PRRT eligibility was defined according to NETTER-1 (Krenning ≥2) and NETTER-2 (Krenning ≥3) criteria. Logistic regression identified predictors of Krenning ≥3 on SSTR PET. Quantitative PET analysis was performed for patients with positive baseline [68Ga]DOTATOC PET scans.ResultsMedian Krenning scores were higher with SSTR PET than planar imaging (3 [IQR 3-4] vs. 2 [IQR 0-3], p max discriminated patients with Krenning ≥3 using an optimal threshold of 9.2 (AUC 0.93).Conclusions[68Ga]DOTATOC PET yields higher Krenning scores and increases PRRT eligibility compared with [111In]octreotide scintigraphy. PET may be unnecessary for clearly positive planar studies but identifies additional candidates with borderline or negative planar results.