Purpose: Half of pancreatic neuroendocrine tumors (PNET) show metastases at diagnosis, with liver involvement in 28-77% of cases. The aim of the study is to evaluate the relationship of radiological qualitative/quantitative descriptors of liver tumour burden (LTB) and liver metastases distribution pattern (LMDP), with fludeoxyglucose (18FDG) positron emission tomography (PET-CT) findings and histological grading (HG). Material and methods: LTB of 47 patients with metastatic PNET were retrospectively evaluated, before any treatment intervention, on contrast-enhanced computed tomography and/or magnetic resonance. Two skilled radiologists independently assessed LMDP (unifocal, paucinodular, multinodular and bulky), qualitative and quantitative descriptors of LTB. Accuracy in assessing positive PET-CT and HG were calculated. Cohen’s K-coefficient was calculated to measure inter-observer agreement (IOA). Results: The most accurate parameters in assessing PET-CT positivity were late-phase hypodensity (88.9%), venous-phase hypodensity (87.2%), arterial-phase hyperdensity (83.7%), major-axis sum >5 cm (74.5%) and >10 cm (61.7%), arterial-phase inhomogeneity (69.8%) and metastases number >5 (61.7%). In assessing HG only arterial-phase hypodensity (76.7%) and infiltrating margins (71.8%) resulted to be accurate. Multinodular LMDP was the most common pattern reported. A confluent pattern was reported only in aggressive tumours with Ki67 >5%. IOA was higher when evaluating major-axis sum >10 cm (0.96) and >5 cm (0.76), arterial-phase homogeneity (0.83) and arterial-phase hyperdensity (0.63), but lower when evaluating localization (0.51) and late-phase hypodensity (0.36). Conclusion: LTB predicts functional and anatomopathological characteristics of PNETs. Arterial-phase hyperdensity, major-axis sum >5 cm are accurate in evaluating functional characteristics of the tumour, while arterial-phase hypodensity relies on HG. Confluent pattern relies on more aggressive neoplasms with Ki67 >5%
Imaging evaluation of liver tumour burden in metastatic pancreatic neuroendocrine tumours
G. Rizzo;A. Beleù;A. Sarno;N. Cardobi;A. Giaretta;A. Grecchi;I. Testa;R. De Robertis;D'Onofrio M
2019-01-01
Abstract
Purpose: Half of pancreatic neuroendocrine tumors (PNET) show metastases at diagnosis, with liver involvement in 28-77% of cases. The aim of the study is to evaluate the relationship of radiological qualitative/quantitative descriptors of liver tumour burden (LTB) and liver metastases distribution pattern (LMDP), with fludeoxyglucose (18FDG) positron emission tomography (PET-CT) findings and histological grading (HG). Material and methods: LTB of 47 patients with metastatic PNET were retrospectively evaluated, before any treatment intervention, on contrast-enhanced computed tomography and/or magnetic resonance. Two skilled radiologists independently assessed LMDP (unifocal, paucinodular, multinodular and bulky), qualitative and quantitative descriptors of LTB. Accuracy in assessing positive PET-CT and HG were calculated. Cohen’s K-coefficient was calculated to measure inter-observer agreement (IOA). Results: The most accurate parameters in assessing PET-CT positivity were late-phase hypodensity (88.9%), venous-phase hypodensity (87.2%), arterial-phase hyperdensity (83.7%), major-axis sum >5 cm (74.5%) and >10 cm (61.7%), arterial-phase inhomogeneity (69.8%) and metastases number >5 (61.7%). In assessing HG only arterial-phase hypodensity (76.7%) and infiltrating margins (71.8%) resulted to be accurate. Multinodular LMDP was the most common pattern reported. A confluent pattern was reported only in aggressive tumours with Ki67 >5%. IOA was higher when evaluating major-axis sum >10 cm (0.96) and >5 cm (0.76), arterial-phase homogeneity (0.83) and arterial-phase hyperdensity (0.63), but lower when evaluating localization (0.51) and late-phase hypodensity (0.36). Conclusion: LTB predicts functional and anatomopathological characteristics of PNETs. Arterial-phase hyperdensity, major-axis sum >5 cm are accurate in evaluating functional characteristics of the tumour, while arterial-phase hypodensity relies on HG. Confluent pattern relies on more aggressive neoplasms with Ki67 >5%
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