Combined evaluation of US and FDG-PET was a sensitive and accurate method for axillary lymph node staging in breast cancer.
The intrahepatic non-tumorous arterioportal shunt (APS) is one of the important causes of transient hepatic enhancement differences (THED) on dynamic CT or MRI. Most small APSs are located in the peripheral portion of the liver. Because of the parenchymal distortion in the advanced cirrhotic liver, many small APSs tend to show an amorphous or nodular appearance, making them difficult to distinguish from hypervascular tumors. In addition to the use of dynamic CT or MRI, iso-attenuation densities or iso-intensities on pre-contrast and equilibrium phases, MRI using a liver-specific contrast agent can be useful to characterize the hypervascular pseudolesions. Because there is no difference in water diffusion in the hepatic parenchyma in the region of the APS, diffusion-weighted MRI also has great potential to distinguish non-tumorous shunts from true focal lesions. Larger (>2 cm) APSs of direct arterio-portal venous fistulas from extrinsic insults show typical subcapsular wedge-like THEDs that are only temporarily depicted several months after the traumatic event; most of these THEDs gradually decrease in size or vanish completely. By understanding the nature of non-tumorous APSs, radiologists will be able to provide a more accurate assessment of many THEDs during daily interpretations of CT or MR images of the liver.
ObjectiveTo validate the diffusion-weighted MRI (DWI) for differentiation of benign from malignant portal vein thrombosis.Materials and MethodsThe Institutional Review Board approved this retrospective study and waived informed consent. A total of 59 consecutive patients (52 men and 7 women, aged 40–85 years) with grossly defined portal vein thrombus (PVT) on hepatic MRI were retrospectively analyzed. Among them, liver cirrhosis was found in 45 patients, and hepatocellular carcinoma in 47 patients. DWI was performed using b values of 50 and 800 sec/mm2 at 1.5-T unit. A thrombus was considered malignant if it enhanced on dynamic CT or MRI; otherwise, it was considered bland. There were 18 bland thrombi and 49 malignant thrombi in 59 patients, including 8 patients with simultaneous benign and malignant PVT. Mean apparent diffusion coefficients (ADCs) of benign and malignant PVTs were compared by using Mann-Whitney U test. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curve analysis.ResultsThe mean ADC ± standard deviation of bland and malignant PVT were 1.00 ± 0.39 × 10-3 mm2/sec and 0.92 ± 0.25 × 10-3 mm2/sec, respectively; without significant difference (p = 0.799). The area under ROC curve for ADC was 0.520. An ADC value of > 1.35 × 10-3 mm2/sec predicted bland PVT with a specificity of 94.6% (95% confidence interval [CI]: 84.9–98.9%) and a sensitivity of 22.2% (95% CI: 6.4–47.6%), respectively.ConclusionDue to the wide range and considerable overlap of the ADCs, DWI cannot differentiate the benign from malignant thrombi efficiently.
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