Use of full-dose contrast-enhanced CT for extrahepatic staging using Gallium-68-DOTATATE PET/CT in patients with neuroendocrine tumors

Özet

PURPOSEStudies have demonstrated that positron emission tomography/computed tomography(PET/CT) with Gallium-68 (68Ga)-labeled somatostatin analogues are effective at detectingmetastatic disease in neuroendocrine tumors (NET), especially extrahepatic metastases.However, PET in combination with full-dose contrast-enhanced CT (ceCT) exposes patients tohigher radiation (~25 mSv). The use of non-contrast-enhanced low-dose CT (ldCT) can reduceradiation to about 10 mSv and may avoid contrast-induced side effects. This study seeks todetermine whether ceCT could be omitted from NET assessments.METHODSWe retrospectively compared the performance of PET/ldCT versus PET/ceCT in 54 patients(26 male, 28 female) who had undergone a 68Ga-DOTATATE PET/CT. The selection criteria wereas follows: available ldCT and ceCT, histologically confirmed NET, and follow-up of at least 6months (median, 12.6 months; range, 6.1–23.2 months). The PET/ldCT and PET/ceCT imageswere analyzed separately. We reviewed metastases in the lungs, bones, and lymph nodes. Theresults were compared with the reference standard (clinical follow-up data).RESULTSThe PET/ceCT scans detected 139 true-positive bone lesions compared with 140 lesionsdetected by the PET/ldCT scans, 106 true-positive lymph node metastases (PET/ceCT) compared with 90 metastases detected by the PET/ldCT scans, and 26 true-positive lung lesions(PET/ceCT) compared with 6 lesions detected by the PET/ldCT scans. The overall lesion-basedsensitivity for full-dose PET/ceCT was 97%, specificity 86%, negative predictive value (NPV)93%, and positive predictive value (PPV) 93%. The overall lesion-based sensitivity for PET/ldCT was 85%, specificity 73%, NPV 72%, and PPV 85%.CONCLUSIONThis study presents the first evidence that ceCT should not be omitted from extrahepaticstaging using 68Ga-DOTATATE PET/CT in patients with NET. ceCT alone can be used as a follow-up to reduce radiation exposure when the patient has already undergone PET/ceCT andsuffers from non-DOTATATE-avid NET.