The objective of this study was to evaluate the predictive value of 68Ga-DOTANOC PET/CT in patients with suspected neuroendocrine tumor (NET).
Data of 164 patients (mean age, 42.5 ± 17.3 years; 54.8% male) who underwent 68Ga-DOTANOC PET/CT for suspected NET were retrospectively analyzed. Neuroendocrine tumor was suspected based on clinical features (n = 94) and/or raised biochemical markers (n = 83, serum chromogranin A, gastrin, serum/urinary catecholamines, insulin/C-peptide, and 5-hydroxytrytophan/5-hydroxyindoleacetic acid) and/or imaging findings (n = 93). PET/CT images were reviewed by 2 experienced nuclear medicine physicians, and any nonphysiological 68Ga-DOTANOC uptake was taken as positive for NET. Histopathology (n = 55) and clinical/imaging follow-up (n = 109; median, 11 months) was used as reference standard.
Based on the reference standard, 97 of 164 patients had NET. 68Ga-DOTANOC PET/CT was positive for NET in 101 and negative in 63 patients. Primary tumor was demonstrated in 90 patients (commonest site—pancreas) and metastasis in 30 (commonest site—liver). PET/CT was true positive in 92 patients, true negative in 58, false positive in 9, and false negative in 5. The overall sensitivity was 94.8%, specificity was 86.5%, positive predictive value was 91%, negative predictive value was 92%, and accuracy was 91.4%. The accuracy of PET-CT in patients with clinical features of NET was 90.4%, with raised biochemical markers was 86.7%, and with imaging findings suggestive of NET was 93.5%. No difference was seen in the accuracy in patients with or without clinical symptoms (P = 0.794), raised versus those with normal/unknown biochemical markers (P = 0.094), and suggestive imaging versus those with negative/unavailable imaging (P = 0.420).
68Ga-DOTANOC PET-CT shows high positive and negative predictive values in patients with suspected NET and can be routinely used for this purpose.