Experimental Study On The Value Of Pulmonary Ventilation/Perfusion Imaging And 64-Slice Computed Tomographic Pulmonary Angiography In Acute Pulmonary Embolisms

Object To explore the feasibility of creating rabbit acute pulmonary embolism model by using polyester sponge for embolus. To evaluate the sensitivities and specificities of diagnosis of acute pulmonary embolism with ventilation/perfusion imaging(V/Q) and 64 slices computed tomographic pulmonary angiography(SCTPA). At the same time, to compare imaging appearances with pathologic findings to improve the acknowledgement of using different imaging methods to diagnose PE, give proof for the correct and prompt diagnosis to clinicians.Methods 20 experimental rabbits were divided into 4 groups as experimental groups, and another two rabbits as control group. The animal model of acute pulmonary embolism was prepared by jugular vena catheter using polyester sponges as emboli. Four 2mm×2mm×10mm emboli were injected into each animal. Pulmonary ventilation/perfusion imaging and pulmonary angiography were performed after the operation, then the rabbits were killed at the different study time, the lungs were dissected, removed and examined to find and record the numbers and location of emboli. Observe if there was pulmonary infarction, and the pulmonary tissue was dissected for pathological examination. The rabbits of control group were injected physiological saline solution via catheter after operation, and killed at 24hours and 3days respectively.Results one rabbit died during the operation, 19 of 20 rabbits were made as acute pulmonary embolism model successfully. All rabbits were killed on schedule. 285 pulmonary arteries were anatomized. 74 emboli were found and 61 pulmonary embolism were made. The rabbits of group 2h, 24h displayed swelled lung and deep red colour surface, hyperaemia of lung tissues was seen under microscopy. The group of 3d displayed wine surface containing dark area. Haematose, hemorrhagic and white blood cell soaked lung tissues were seen under microscopy. Infarction area of lung tissues were observed in the group 7d. The imaging process were successful. V/Q imaging detected 65 segmental pulmonary arteries embolism, and another 13 lesions were missed and 17 lesions were wrong. SCTPA found 56 embolism arteries, another 18 lesions were missed and 13 lesions were misdiagnosed. The total sensitivities, specificities and accuracies of V/Q and SCTPA were 78.69% and 70.49%, 92.41% and 94.20%, 89.47% and 89.12%, the value of Kappa were 0.694 and 0.667, respectively in diagnosis of pulmonary artery embolism. However, only 9 lesions of 21 subsegmental pulmonary embolism were detected by SCTPA, the sensitivity was only 42.86%.Conclusions The method of creating rabbits acute pulmonary embolism by using polyester sponges as emboli is simple and with high successful rate. The sensitivities and accuracies of diagnosing pulmonary embolism with pulmonary ventilation/perfusion imaging are superior than 64-slices computed tomographic pulmonary angiography, but inferior in specificity. However, there is no statistical difference. The results of SCTPA and V/Q imaging in diagnosis of PE are consistent with the result of pathologic examination. The sensitivity of SCTPA in diagnosis of subsegmental PE is not satisfied.