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

To compare the diagnostic accuracy of In-111-pentetreotide-scintigraphy with Ga-68-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. Fifty-three metastatic-NET-patients underwent In-111-pentetreotide-scintigraphy (24 h post-injection; planar+single-photon emission CT (SPECT) abdomen) and whole-body Ga-68-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. Significantly more lesions were detected on Ga-68-DOTATOC-PET/CT versus In-111-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. Ga-DOTATOC-PET/CT is superior for the detection of NET-metastases compared to In-111-pentetreotide SPECT. aEuro cent Somatostatin receptor PET is superior to SPECT in detecting NET metastases aEuro cent PET is the scintigraphic method for accurate depiction of NET tumour burden aEuro cent The sensitivity of PET is twofold higher than the sensitivity of SPECT.