Comparison of diagnostic accuracy of (111)In-pentetreotide SPECT and (68)Ga-DOTATOC PET/CT: A lesion-by-lesion analysis in patients with metastatic neuroendocrine tumours

Abstract

Objectives To compare the diagnostic accuracy of 111Inpentetreotide-scintigraphy with 68Ga-DOTATOC-positron emission tomography (PET)/computed tomography (CT) in patients with metastatic-neuroendocrine tumour (NET) scheduled for peptide receptor radionuclide therapy (PRRT). Incremental lesions (ILs) were defined as lesions observed on only one modality. Methods Fifty-three metastatic-NET-patients underwent 111In-pentetreotide-scintigraphy (24 h post-injection; planar+ single-photon emission CT (SPECT) abdomen) and whole-body 68Ga-DOTATOC-PET/CT. SPECT and PET were compared in a lesion-by-lesion and organ-by-organ analysis, determining the total lesions and ILs for both modalities. Results Significantly more lesions were detected on 68GaDOTATOC-PET/CT versus 111In-pentetreotide-scintigraphy. More specifically, we observed 1,098 lesions on PET/CT (range: 1–105; median: 15) versus 660 on SPECT (range: 0–73, median: 9) (p<0.0001), with 439 PET-ILs (42/53 patients) and one SPECT-IL (1/53 patients). The sensitivity for PET/CT was 99.9 % (95 % CI, 99.3–100.0), for SPECT 60.0 % (95 % CI, 48.5–70.2). The organ-by-organ analysis showed that the PET-ILs were most frequently visualized in liver and skeleton. Conclusion Ga-DOTATOC-PET/CT is superior for the detection of NET-metastases compared to 111In-pentetreotide SPECT. Key Points • Somatostatin receptor PET is superior to SPECT in detecting NET metastases • PET is the scintigraphic method for accurate depiction of NET tumour burden • The sensitivity of PET is twofold higher than the sensitivity of SPECT