Is visual radiological evaluation of liver tumour burden in patients with neuroendocrine tumours reproducible?

Background: Visual semi-quantitative assessment of liver tumour burden for neuroendocrine tumour liver metastases is often used in patient management and outcome. However, published data on the reproducibility of these evaluations are lacking. Objective: The aim of this study was to evaluate the interobserver and intraobserver agreement of a visual semi-quantitative assessment of liver tumour burden using CT scan. Methods: Fifty consecutive patients (24 men and 26 women, mean aged 54 years) were retrospectively reviewed by four readers (two senior radiologists, one junior radiologist and one gastroenterologist) who assessed the liver tumour burden based on a visual semi-quantitative method with four classes (0-10, 11-25, 26-50 and = 50%). Interobserver and intraobserver agreement were assessed by weighted kappa coefficient and percentage of agreement. The intraclass correlation was calculated. Results: Agreement among the four observers for the evaluation of liver tumour burden was substantial, ranging from 0.62 to 0.73 (P < 0.0001). The intraclass coefficient was 0.977 (P < 0.0001). Intraobserver agreement was 0.78 and ICC was 0.97. Conclusion: Reproducibility of the visual semi-quantitative evaluation of liver tumour burden is good and is independent of the level of experience of the readers. We therefore suggest that clinical studies in patients with neuroendocrine liver metastases use this method to categorise liver tumour burden.