Diagnostic performance of PET/CT in the detection of liver metastases in well-differentiated NETs

Abstract

Background The aim of this retrospective study was to compare the diagnostic accuracy of somatostatin receptor (SSR)-PET/CT to liver MRI as reference standard in the evaluation of hepatic involvement in neuroendocrine tumors (NET). Methods An institutional database was screened for “SSR” imaging studies between 2006 and 2021. 1000 NET Patients (grade 1/2) with 2383 SSR-PET/CT studies and matching liver MRI in an interval of +3 months were identified. Medical reports of SSR-PET/CT and MRI were retrospectively evaluated regarding hepatic involvement and either confirmed by both or observed in MRI but not in SSR-PET/CT (false-negative) or in SSR-PET but not in MRI (false-positive). Results Metastatic hepatic involvement was reported in 1650 (69.2%) of the total 2383 SSR-PET/CT imaging studies, whereas MRI detected hepatic involvement in 1685 (70.7%) cases. There were 51 (2.1%) false-negative and 16 (0.7%) false-positive cases. In case of discrepant reports, MRI and PET/CT were reviewed side by side for consensus reading. SSR-PET/CT demonstrated a sensitivity of 97.0% (95%CI: 96.0%, 97.7%), a specificity of 97.7% (95%CI: 96.3%, 98.7%), a PPV of 99.0% (95%CI: 98.4%, 99.4%) and NPV of 93.0% (95%CI: 91.0, 94.8%) in identifying hepatic involvement. The most frequent reason for false-negative results was the small size of lesions with the majority < 0.6 cm. Conclusion This study confirms the high diagnostic accuracy of SSR-PET/CT in the detection of hepatic involvement in NET patients based on a patient-based analysis of metastatic hepatic involvement with a high sensitivity and specificity using liver MRI imaging as reference standard. However, one should be aware of possible pitfalls when a single imaging method is used in evaluating neuroendocrine liver metastases in patients.

Diagnostic accuracy of SSR-PET/CT compared to histopathology in the identification of liver metastases from well-differentiated neuroendocrine tumors

“…In a large study of 728 NET patients, [ 68 Ga]Ga-DOTA-TATE PET/CT showed high sensitivity, specificity, accuracy, positive predictive value, and negative predictive value (97.0%, 95.1%, 96.6%, 98.5%, and 90.4%) in the detection of overall NET lesions [ 11 ]. Specifically identifying hepatic involvement in NET patients, similar high diagnostic accuracy was reported for SSR-PET/CT compared to the reference standard liver MRI with a sensitivity of 97.0% and a specificity of 97.7%, a PPV of 99.0% and NPV of 93.0% [ 12 ]. Moreover, SSR-PET/CT was found to have an important value in the diagnosis of pulmonary neuroendocrine tumors (carcinoids) and its distant metastases [ 13 , 14 ].…”

Liver-Directed Locoregional Therapies for Neuroendocrine Liver Metastases: Recent Advances and Management

“…Based on the WHO 2022 classification, which accounts for proliferation index (Ki-67) and mitotic information, NETs are categorized into well-differentiated neuroendocrine tumor (NET) grades G1, G2, and G3, and poorly differentiated small and large cell neuroendocrine carcinoma [20]. G1/G2 NETs exhibit high expression of somatostatin receptors on their cell membrane (80-95%) [21]. However, somatostatin receptor-based PET/CT is highly sensitive in detecting G1/G2 but G2 may be less sensitive in tumors with higher Ki-6 [21].…”

“…G1/G2 NETs exhibit high expression of somatostatin receptors on their cell membrane (80-95%) [21]. However, somatostatin receptor-based PET/CT is highly sensitive in detecting G1/G2 but G2 may be less sensitive in tumors with higher Ki-6 [21].…”

Primäre und sekundäre Lebertumore – aus Sicht der Nuklearmedizin

“…Daher wird in aktuellen Empfehlungen auch im Rahmen der PET/CT nach Möglichkeit die Durchführung einer Mehrphasen-CT empfohlen [72]. In einer größeren retrospektiven Arbeit mit 1000 Patienten wurde die Sensitivität und Spezifität der SSA-PET/CT mit der multiparametrischen MRT in insgesamt 2383 Untersuchungen verglichen [73]. Die patientenspezifische Sensitivität und Spezifität der SSA-PET/CT für die Detektion hepatischer Metastasen lag bei 97 bzw.…”