Diagnostic and Interventional Radiology
Modality-based (US, CT, MRI, PET-CT) Imaging - Original Article

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

1.

Department of Diagnostic and Interventional Radiology, Helios Hospital Pforzheim, Pforzheim, Germany

2.

Department of Nuclear Medicine, RWTH Aachen University Hospital, Aachen, Germany

Diagn Interv Radiol 2021; 27: 573-579
DOI: 10.5152/dir.2021.19424
Read: 427 Downloads: 109 Published: 20 May 2021

PURPOSE 
Studies have demonstrated that positron emission tomography/computed tomography (PET/CT) with Gallium-68 (68Ga)-labeled somatostatin analogues are effective at detecting metastatic disease in neuroendocrine tumors (NET), especially extrahepatic metastases. However, PET in combination with full-dose contrast-enhanced CT (ceCT) exposes patients to higher radiation (~25 mSv). The use of non-contrast-enhanced low-dose CT (ldCT) can reduce radiation to about 10 mSv and may avoid contrast-induced side effects. This study seeks to determine whether ceCT could be omitted from NET assessments.

METHODS
We 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 were as follows: available ldCT and ceCT, histologically confirmed NET, and follow-up of at least 6 months (median, 12.6 months; range, 6.1–23.2 months). The PET/ldCT and PET/ceCT images were analyzed separately. We reviewed metastases in the lungs, bones, and lymph nodes. The results were compared with the reference standard (clinical follow-up data).

RESULTS
The PET/ceCT scans detected 139 true-positive bone lesions compared with 140 lesions detected 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-based sensitivity 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%.

CONCLUSION
This study presents the first evidence that ceCT should not be omitted from extrahepatic staging 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 and suffers from non-DOTATATE-avid NET.

You may cite this article as: Apitzsch J, Verburg FA, Mottaghy F, Heinzel A. Use of full-dose contrast-enhanced CT for extrahepatic staging using Gallium-68-DOTATATE PET/CT in patients with neuroendocrine tumors. Diagn Interv Radiol 2021; 27:573-579

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