68Ga-DOTATATE PET/CT versus MRI in neuroendocrine liver metastases: a comprehensive per-lesion analysis.

PURPOSE: To evaluate the diagnostic performance of 68Ga-DOTATATE PET, contrast-enhanced CT, combined DOTATATE PET/CT, and MRI in detecting neuroendocrine liver metastases on a per-lesion basis and to assess the added value of diagnostic contrast-enhanced CT to PET interpretation as well as influence of lesion size.

MATERIALS AND

METHODS

This retrospective study evaluated patients with histologically-confirmed gastroenteropancreatic neuroendocrine tumors who underwent both contrast-enhanced MRI and 68Ga-DOTATATE PET/CT within 12 weeks between August 2017 and December 2023. Three readers evaluated in consensus MRI, 68Ga-DOTATATE PET, contrast-enhanced CT, and combined PET/CT in separate sessions. Lesions were stratified by size. Diagnostic performance metrics were calculated using generalized estimating equations with reference standard of imaging follow-up or histopathology.

RESULTS

The study included 36 patients (mean age 66.4 ± 10.7 years, 55.6% male) with 720 lesions, of which 582 were metastases. MRI demonstrated superior performance (sensitivity 94.0%, specificity 94.2%) compared to all other modalities (all p < .001). Combined PET/CT showed superior sensitivity (68.1%) compared to PET alone (61.1%) (p < .001). The addition of diagnostic contrast-enhanced CT to PET interpretation identified 41 additional metastases. Size-stratified analysis revealed superior detection of subcentimeter lesions by MRI (sensitivity 83.3% for ≤ 5 mm, 99.6% for 6-10 mm) compared to PET/CT (34.8% and 78.6%, respectively; p < .001). For lesions > 10 mm, both MRI and PET/CT achieved 100% sensitivity, while PET alone reached 94.1% (p = .019).

CONCLUSION

MRI outperforms 68Ga-DOTATATE PET/CT in detecting individual neuroendocrine liver metastases, particularly for subcentimeter lesions. While diagnostic CT improves PET performance, the combination of MRI with 68Ga-DOTATATE PET/CT provides the most comprehensive assessment.