Discrimination between malignant and bland portal vein thrombosis: Could diffusion weighted MRI help

Objective To study the role of DWI in the differentiation between bland and malignant portal vein thrombus in HCC patients. Materials and methods Prospective study carried on 74 HCC patients with associated portal vein thrombus. Dynamic MRI examination and Diffusion imaging were performed for all patients. ADC values and ratios “ratio between the ADC value of HCC and ADC value of the thrombus” were calculated. We use at least two of the following criteria including the size of HCC more than 5 cm, the distance between the portal vein thrombus and the HCC less than 2 cm and the presence of enhancement within the thrombus, as a standard of reference to determine the nature of the thrombus. Results We studied 74 patients; 55 patients diagnosed with malignant portal vein thrombosis and 19 patients diagnosed with bland portal vein thrombosis. We found that the ADC ratio with a cutoff value of 1.2 helped in discriminating the nature of the thrombus with 98% sensitivity and 70% specificity. There was no statistically significant difference in the ADC values of the benign and malignant thrombus. Conclusion DWI can determine the nature of the portal vein thrombus by measuring the ADC ratio between the tumour and the thrombus.