To compare detection rates of NET liver metastases of MRI and Ga-68-DOTATATE PET/CT to provide more clarity when selecting diagnostic imaging tests for NET staging.

In this IRB-approved single-institution retrospective study, all patients with pathology-proven NET who underwent Ga-68-DOTATATE and MRI scans within 8�weeks of each other (3/2017–2/2020) were reviewed. Number of metastases for each patient on diffusion-weighted imaging (DWI), dynamic contrast-enhanced (DCE) MRI, and Ga-68�DOTATATE were recorded by two blinded radiologists, followed by consensus review with two separate blinded readers for MRI and nuclear medicine. Per-lesion and -modality scoring at each lesion location were then performed in consensus. Per-patient linear regression was performed comparing MRI and Ga-68�DOTATATE detection rates for each reader and in consensus, and per-lesion-matched pair difference means were used to compare detection frequency between modalities.

32 patients (mean age 59�years, 59.4% male) and 90 liver metastases were analyzed. Intraclass coefficients (ICC) [95% CI] between the two readers were 0.97 [0.95, 0.99], 0.89 [0.82, 0.94], and 0.98 [0.97, 0.99] for Ga-68�DOTATATE, DWI, and DCE, respectively. Matched per-lesion mean differences were + 0.17 � 0.07 (p = 0.01) and + 0.22 � 0.06 (p =  < 0.001) for DWI versus Ga-68�DOTATATE and DCE vs Ga-68�DOTATATE, respectively, favoring MRI. Case-based linear regressions estimate that DWI and DCE detect 1.28 [1.07, 1.49] and 1.33 [1.12, 1.54] lesions, respectively, for each one detected on Ga-68�DOTATATE.

MRI detects more hepatic NET metastasis in comparison to Ga-68�DOTATATE. Liver MRI should be performed in concert with Ga-68�DOTATATE in NET staging.