Can histogram analysis of MR images predict aggressiveness in pancreatic neuroendocrine tumors?

Abstract

Objectives

To evaluate MRI derived whole-tumour histogram analysis parameters in predicting pancreatic neuroendocrine neoplasm (panNEN) grade and aggressiveness.

Methods

Pre-operative MR of 42 consecutive patients with panNEN >1 cm were retrospectively analysed. T1-/T2-weighted images and ADC maps were analysed. Histogram-derived parameters were compared to histopathological features using the Mann-Whitney U test. Diagnostic accuracy was assessed by ROC-AUC analysis; sensitivity and specificity were assessed for each histogram parameter.

Results

ADC_entropy was significantly higher in G2-3 tumours with ROC-AUC 0.757; sensitivity and specificity were 83.3 % (95 % CI: 61.2–94.5) and 61.1 % (95 % CI: 36.1–81.7). ADC_kurtosis was higher in panNENs with vascular involvement, nodal and hepatic metastases (p= .008, .021 and .008; ROC-AUC= 0.820, 0.709 and 0.820); sensitivity and specificity were: 85.7/74.3 % (95 % CI: 42–99.2 /56.4–86.9), 36.8/96.5 % (95 % CI: 17.2–61.4 /76–99.8) and 100/62.8 % (95 % CI: 56.1–100/44.9–78.1). No significant differences between groups were found for other histogram-derived parameters (p >.05).

Conclusions

Whole-tumour histogram analysis of ADC maps may be helpful in predicting tumour grade, vascular involvement, nodal and liver metastases in panNENs. ADC_entropy and ADC_kurtosis are the most accurate parameters for identification of panNENs with malignant behaviour.

Key Points

• Whole-tumour ADC histogram analysis can predict aggressiveness in pancreatic neuroendocrine neoplasms.

• ADC entropy and kurtosis are higher in aggressive tumours.

• ADC histogram analysis can quantify tumour diffusion heterogeneity.

• Non-invasive quantification of tumour heterogeneity can provide adjunctive information for prognostication.