Differentiation malignant from benign pericardial effusion with diffusion-weighted MRI

To differentiate malignant from benign pericardial effusion with diffusion-weighted magnetic resonance imaging (MRI).

Retrospective analysis of diffusion-weighted MRI of 41 patients (29 men and 12 women; mean 39 years) with pericardial effusion. Apparent diffusion coefficient (ADC) of pericardial fluid, and associated pericardial mass or pleural effusion was calculated. ADC of pericardial fluid was calculated by two observers and correlated with cytological analysis. Receiver operating characteristic curves and Bland-Altman plots were used.

There was significant differences in the ADCs between benign and malignant pericardial effusions (p=0.001) by both observers. Mean ADC of malignant pericardial effusions was (2.92±0.29 and 2.86±0.33×10^-3 mm²/s) and of benign effusions was (3.36±0.31 and 3.28±0.28×10^-3 mm²/s) for both observers, respectively. The cut-off values of the ADC used for differentiating malignant from benign pericardial effusion were 3.25 and 3.05×10^-3 mm²/s with areas under curve of 0.839 and 0.791, sensitivities of 88.2% and 70.6%, specificities of 69.6% and 73.9%, and accuracies of 78% and 72.5% for both observers, respectively. The overall interobserver agreement of the ADC value of pericardial effusion by both observers was significant (r=0.808, p=0.001). The interobserver agreement of malignant effusion (r=0.861, p=0.001) and benign effusion was significant (r=0.659, p=0.001). The ADC of pleural effusion is well correlated with ADC of pericardial effusion (r=0.088, p=0.001).

The ADC value is a non-invasive imaging parameter that can be used for differentiation of malignant from benign pericardial fluid.