Budd-Chiari Syndrome: The “inferior vena cava reverse-flow” sign and “jet-blood” sign on CT and MRI

•There are many familiar imaging features in Budd-Chiari Syndrome(BCS), but sometimes the diagnosis is still difficult because of their limit and possible confusion.•Two new CT and MRI signs of BCS are introduced here: the inferior vena cava(IVC) reverse-flow sign and jet-blood sign.•The former reveals that the contrast agent in IVC can be seen below the level of renal veins in arterial phase of CT/MRI enhancement, while no agent above it at the same time.•The latter shows as: The low density/signal dots appear within full of contrast agent at the superior liver segment IVC on axial slices in arterial phase of CT/MRI enhancement, or the low signal line(s) within agent present above the IVC membrane on coronal image in equilibrium phase of MRI enhancement.•The former is a simple and reliable indirect sign of IVC obstruction type and mixed type BCS; the latter is the special direct sign of IVC membrane-perforated subtype BCS. Whose value are more than the other present known signs. To investigate the CT and MR features of “inferior vena cava(IVC) reverse-flow” sign and “jet-blood” sign in Budd-Chiari Syndrome (BCS). The liver CT and/or MRI plain scan and dynamic enhancement of 107 cases of BCS diagnosed by DSA and/or clinic were collected, including 17 patients with hepatic vein obstruction type, 79 patients with IVC obstruction type, and 11 patients with mixed type. The manifestations of IVC reverse-flow sign and jet-blood sign in the latter two type BCS (90cases) imaging were analyzed. 1) The incidence of IVC reverse-flow sign in the IVC obstruction type and mixed type was 93.3 %(83/90), which was manifested as: The contrast agent was shown below the level of renal veins in the hepatic arterial phase enhancement, while no contrast agent was shown above it at the same time. 2) The incidence of jet-blood sign in membrane-perforated subtype was 100 %(15/15) or 16.7 %(15/90), which was manifested as: The low density/signal dots appeared within full of contrast agent at the superior liver segment IVC on axial slices in arterial phase of CT/MRI enhancement, or the low signal line within agent presented above the IVC membrane on coronal image in equilibrium phase of MR enhancement. 3) Other imaging findings: 75 cases of membrane, 18 cases of membrane calcification, 27 cases of abnormal hepatic vein, 76 cases of abnormal structure of IVC, 18 cases of thrombus/cancer embolus in hepatic vein and/or IVC. There were 65 cases of abnormal liver appearance; 71 cases of a