BACKGROUND: Acute mesenteric vein (SMV)-portal vein (PV) thrombosis is one of the clinical acute abdominal conditions, and although the incidence is low, treatment is tricky, and the prognosis is poor once intestinal necrosis and perforation occur. OBJECTIVE: To evaluate the value of imaging techniques in determining acute and subacute thrombosis of SMV-PV, the reliability of imaging suggestive of intestinal necrosis, and to introduce the strategy, safety and efficacy of interventional treatment of acute and subacute thrombosis of SMV-PV. METHODS: To summarize the experience of 28 patients with acute SMV-PV thrombosis admitted to the Department of Interventional Radiology of the PLA General Hospital in the past 6 years (24 cases received interventional treatment and 4 cases surgical treatment), and to make a comprehensive introduction of the etiology, clinical manifestations, imaging features, treatment and regression of acute SMV-PV, especially the interventional treatment strategy, in combination with the results of animal experimental studies and review of the literature. The main findings: ① Those with an onset of ≤5 d are generally classified as acute and those with 5-14 d as subacute, but judging the newness of thrombosis based only on the duration of the disease (the time of symptom onset in patients) is not entirely reliable. ②The clinical manifestations suggesting intestinal necrosis are obvious abdominal pain, abdominal distension and pressure muscle guards (especially pain in a fixed area, palpable intestinal loops or masses), gradually increasing ascites, accompanied by fever, persistent blood in stool or black stool, and increased WBC and LDH, but mild pressure pain and rebound pain do not necessarily exist irreversible intestinal necrosis. ③CT plain scan thrombus in acute phase shows hypodensity, and thrombus in subacute phase can be high/isodense, in which SMV-PV high density (CT value is 5-15 HU higher than abdominal aorta and inferior vena cava) – “CT plain scan mesenteric venography sign”, is an important sign to diagnose subacute thrombus. MRI of acute thrombosis: thrombus is slightly lower than liver signal on T1-weighted image and higher than liver parenchyma signal on T2-weighted, which is associated with increased cellular components within the thrombus. 7-14 d after thrombus formation, the thrombus showed high signal on both T1- and T2-weighted images, probably due to the oxidation of deoxyhemoglobin to orthohemoglobin in the red blood cells of the thrombus. ⑤ Key points to identify intestinal necrosis: a. Dilation of intestinal lumen: significant dilatation of intestinal lumen, large amount of fluid, liquid-gas surface formation should be alerted to intestinal obstruction, which is one of the signs of intestinal necrosis and poor prognosis. Subacute cases are dominated by intestinal tube gas accumulation. b. Intestinal wall thickening: diffuse intestinal wall thickening is mostly caused by acute bruising and edema, which does not necessarily represent intestinal necrosis. Signs suggesting intestinal necrosis include: significant thickening and fixation of the restricted intestinal canal, continuous enhancement of the segmental intestinal wall, pneumatization of the intestinal wall, limited fluid accumulation between intestinal loops, and pneumatization within the SMV-PV. c. Mesenteric edema: it precedes intestinal tube changes, and the degree of edema is proportional to the extent of obstruction; reduction of edema after treatment is an effective sign; persistent widespread edema is one of the indications of poor prognosis. d, ascites: in general, the prognosis of those without combined ascites is better than those with ascites. A small amount of ascites is mostly of no clinical importance, but an increase in ascites during the course of treatment should alert to intestinal necrosis, perforation and peritonitis. (6) The indications for intervention are early detection, obvious symptoms, and no clear evidence of intestinal necrosis, perforation, and peritonitis, among which the trans-TIPS route is suitable for fresh thrombosis with short duration and extensive involvement, the percutaneous transhepatic perforation portal route is suitable for the absence of ascites, normal coagulation, and PV-SMV trunk embolization, and the intra-SMA route can be used to treat some subacute cases, promote the establishment of collateral branches, and relieve symptoms. The intra-SMA route can be used to treat certain subacute cases, promote the establishment of side branches, and relieve symptoms; whereas systemic anticoagulation is preferred for PV-SMV systemic thrombosis with mild clinical manifestations, well established side branches, or asymptomatic thrombosis. The main conclusions: CT and MRI are valuable for the diagnosis of acute and subacute SMV-PV thrombosis; identification of imaging manifestations suggesting intestinal necrosis is important for the selection of treatment methods and prognosis. Interventional therapy is the preferred method to manage acute – subacute thrombosis of SMV-PV without intestinal necrosis.