The Application Value Of 16-slice Spriral CT Angiography In The Treatment Of Inferior Vena Cava Filter In Acute Deep Vein Thrombosis Animals

Background:Pulmonary embolism(PE)is a clinical and physiopathologic syndrom resulted from pulmonary circulation disorder or failure caused by endogenous or exogenous embolus.PE is the third common disease of cardiovascular system,secondary to coronary diseases and hypertension. About 90%-95%of the embolus are from the deep vein system.So,PE and DVT are considered as different phases of one disease.The inferior vena cava filter is a device used to capture emboli that would result in PE. The introduction of retrievable filters and the ease of insertion have stimulated increased use of these devices,especially in patients with anticoagulant therapy complications,and perhaps for those with recurrent PE despite therapeutic anticoagulation.But there are safty concerns about the IVC filter:Complications related to insertion occur in 4%to 11%of patients with IVC filters.The most common adverse events associated with IVC filter placement are thrombotic complications.An increased frequency of recurrent DVT(5.9%to 35.7%)and postphlebitic syndrome(12.9%to 41%)have also been reported,So it is necessary to show the condition of the IVC and pelvic and thigh vein before and after the operation.CT venography combined with CT pulmonary angiography was a technique developed since 1998 by Loud PA.It provides the images of both the pulmonary arteries and the veins of the pelvic and thigh veins after one injection of contrast material.This study tries to discuss the parameter set and the application of CTPA-CTV in animal module of IVC filter treatment.Purpose:To find the proper delay time for displaying the deep vein in acute DVT(deep vein thrombosis)dog-modules treated with IVC(inferior vena cava)filter using a combination of CTPA and CTV technique on a 16-Slice spiral CT.To compare the value of MPR,MIP and VRT reconstruction methods in showing the PE and DVT.So as to discuss the apllication value of 16-slice CT before and after the IVC filter operation.Methods:20 dogs were separated into experimental group(EG,15 dogs)and control group(CG,5 dogs).Firstly,The CG dogs are used for a test to get a proper delay time for better showing the deep veins using testbolus technique.The details will be mentioned in normal test.The exosomatic and endosomatic thrombus are made.The EG underwent combined CT venography and pulmonary angiography on 16-slice CT twice(before and after the IVC operation).Before the second scanning,the exosomatic and endosomatic thrombus are injected though the femoral vein to make the acute DVT module.The CG received thrombus without IVC.The parameters as following:total contrast volume 30 ml,injection rate 2 ml/ s and 1ml/s (two-phase,from cephalic vein of the front limb),delay time for CTV 120s(a result from the CG test),and the scan for CTPA is triggered by bolus tracking(triggering CT value 100HU);collimation 0.6mm.Scan range of CTV: from popliteal fossa to the upper pole of the left kidney.Postprocessing include MPR,MIP,and VRT.The imagings are bereaved by an experienced radiologist.Results:The technique provides good imagings of the IVC and pelvic and thigh veins.The mean CT value of thrombus and venous vessels are(77±5.7)Hu and (172±8.5)Hu respectively,which showed significant difference(t=56.04,P＜0.001).The three reconstruction methods can all display PE, while the values of displaying DVT for MPR,MIP and VRT are 87%,53%and 20%,respectively.Conclusions:The combination of bolustracking technique and a delay of 120s after contrast media injection provides good imagings of the pulmonary arteries and the deep veins of dog-modules using a 16-Slice spiral CT.It can be used before and after the IVC filter operation.MPR is better at showing small thrombus than MIP and VRT.