Value of susceptibility-weighted imaging in differentiating benign from malignant portal vein thrombosis

BACKGROUND: Many diseases are accompanied by portal vein thrombosis (PVT), and its nature is closely related to its prognosis and treatment. It is important to evaluate magnetic resonance imaging (MRI) parameters, including susceptibility-weighted imaging (SWI) and qualitative diffusion-weighted imaging (DWI), in the differentiation between benign and malignant PVT. METHODS: In this retrospective study, we collected clinical imaging data from 140 patients with PVTs characterized as benign or malignant based on enhanced MRI between January 2011 and April 2016 and retrospectively analyzed PVTs using SWI and DWI. There were 37 benign and 103 malignant PVTs. Image review was performed by 2 radiologists blinded to clinical information. The signal intensity (SI) of PVTs was recorded on SWI. The apparent diffusion coefficient (ADC) and the ratio of signal intensity (SIR) on SWI (SIR(SWI)) and ADC (SIR(ADC)) between the PVTs and the spinal cord were calculated. Finally, we generated receiver operating characteristic (ROC) curves to evaluate the efficacy of SIR(SWI) and SIR(ADC) for distinguishing benign and malignant PVTs. RESULTS: On SWI and DWI, 100.0% (36/36) and 80.5% (29/36) of benign PVTs were hypointense, respectively. For malignant PVTs on SWI and DWI, 99.0% (103/104) and 89.4% (93/104) were hyperintense, respectively. The SIR(SWI) values of benign and malignant PVTs were 0.58±0.13 and 0.88±0.06, respectively, representing a significant difference (P<0.001). The SIR(ADC) values of benign and malignant PVTs were 0.72±0.32 and 0.62±0.17, respectively, representing a significant difference (P=0.034). The area under the ROC curve (AUROC) for SIR(SWI) [0.990; 95% confidence interval (CI): 0.971–1.000] was significantly higher than that for SIR(ADC) (0.619; 95% CI: 0.500–0.737; P<0.001). The SIR(SWI) had a sensitivity of 100.0% and a specificity of 97.3% with a cutoff value of 0.749, while the SIR(ADC) had a sensitivity of 45.9% and specificity of 83.3% with a cutoff value of 0.791. CONCLUSIONS: The diagnostic performance of SWI is superior to that of DWI in the differentiation of benign and malignant PVTs.