The Application Of Muti-slice CT Perfusion Imaging For Differentiating Pulmonary Nodules

The differential diagnosis of benign and malignant pulmonary nodules imaging is a hot topic of imageology in recent years, which is one of the thorny issues of scholars diagnostic radiology. Before the clinical application of High-resolution multi-slice spiral CT, the solitary pulmonary nodule diagnosis and differential diagnosis has been to rely on the morphological analysis .Continuous advancement of imaging techniques puts the diagnosis of pulmonary nodules from the pure form of morphological and functional imaging diagnosis to a combination of age, Multi-slice CT perfusion imaging is a functional imaging. Along with the constant development of CT perfusion imaging technology, the rate of correct diagnosis of SPN has also been increased. The fortes of CT perfusion imaging are short imaging time, without the use of radioisotopes, less interference factors, higher image resolution of space and time. Therefore this research uses CT perfusion imaging to compute blood stream dynamics of process in lung, doing the relevant research of result of analysis and pathology, appraising the clinical significance and practical value of CT perfusion imaging.In this study, 43 patients which are all consistent with solitary pulmonary nodule standards were examined with CT perfusion imaging , in which 38 cases(21 males and 17females) had a good image analysis. Ages of them are from 21 to 72 years and the average age is 46 years. Clinical manifestation: 23 cases cough, 15 cases fever with a cough history, 19 cases chest pain, 19 cases cough with blood-tinged sputum . There are 38 patients: 20 cases malignant lung cancer (9 cases adenocarcinoma , 7 cases squamous cell carcinoma, 4 cases small-cell lung cancer), 8 cases inflammatory nodules (7 cases granulomatous inflammation, 1 case lung abscess), 10 cases benign nodules (9 cases tuberculoma, one case hamartoma). Confirms after the surgery pathology has 19 cases, confirms after the textile fiber bronchoscope has 3 cases, under the CT-guided biopsy has 11 cases, the phlegm falls off the cell inspection to confirm has 5 cases.GE Lightspeed 16-slice sporal CT is used to perform from the chest entrance to the bottom of the lung for the routine scan. Layer thickness is 5mm, and reconstruction interval is 5mm . Then, we selects maximum cross-sectional plane lesions as the scanning centers, setting the scanning range for four stratums. The selected scanning range are performed CT perfusion examine, thickness 5 mm , 4 rangge / circle. Contrast agent is injected though cubital vein by pressure syringes. Contrast agent is 50ml , 3.5~4ml/s velocity, and the perfusion are simultaneous with the injection of contrast agent without delay. Data are collected for treatment. After the perfusion scan, conventional enhancement scanning is performed and scan parameters are the same as the conventional scan,: contrast agent volume 50ml,3.5ml/s injection velocity, the time delay and start scanning using smart tracking completion. Scan data is transmitted to the GE AW4.2 workstations .Then the body CT perfusion-3 tumor perfusion analysis software chooses phases of the lesions showed the greatest level of measurement and analysis aortic draw level with the time-density curve (time-density curve TDC).At last curves are calculated to get various levels of perfusion image and TDC curve drawn lesions and various perfusion parameters is analyzed by the choice of lesion ROI, including Blood flow(BF), Blood volume(BV), Mean Transit Time (MTT) ,Permeability surface area product(PS) and functional image lesions of color simultane- ously.There are significant differences among malignant pulmonary nodules, inflammatory nodules and benign nodules in the perfusion parameters, which is statistically significant (P <0.05). The BV, MTT, PS of malignant nodules are higher than ones of inflammatory nodules ,in which there is a significant difference (P <0.05), while the BF is not (P> 0.05). And the BF, BV, MTT, PS of inflammatory nodules are all higher than those of benign nodules, in which there is a significant difference (P <0.05). This finding demonstrates that in all malignant and inflammatory nodules, when the threshold is BV≥9 ,the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy rate are 92.73%. 76.61%,85.42%,72.36%,and 88.69% ; when the threshold of malignant is PS≥20,the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy rate of 94.27%. 83.24%,90.21%,83.24%,91.1%; when PS≥20 and BV≥9,the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy rate are 4.31%, 86.3%, 92.22%, 86.66%, 93.3% respectively.The time-density curve (TDC) pattern of malignant pulmonary nodules is different from ones of inflammatory nodules and benign nodules. The TDC pattern of malignant nodules raises rapidly first, declines slowly and maintains at a certain degree of stability--speedy rise slowly descending type. While the TDC of inflammatory nodules are continuous to rise, then declining rapidly--speedy rise and drop type. The TDC of benign nodules gently running, no obvious ups and downs which cart for the slow type . In the malignant nodules,17 patients are descending speed type and three cases are fast rise and drop type; In the inflammatory nodules ,six cases are fast rise and drop type, 2 cases are speed up slowly descending type; 10 cases of benign nodules are all flat-type.The appearances of Malignant nodules are homogeneous or heterogeneous enhancement; Ones of inflammatory nodules are homogeneous or around enhancement;Ones of benign nodules are none or around enhanced. The results of this study show: there are 14 cases of malignant nodules homogeneous enhanced, 4 cases heterogeneous enhanced and another 2 cases were enhanced around. In the inflammatory nodules, there are two cases homogeneous enhanced, five cases heterogeneous enhancement and one cases around enhanced. In the benign nodules, there are six cases not enhanced, 1 casecenter strengthened, 3 cases around enhanced.Multi-slice CT perfusion imaging can not only provide precise anatomic structure and morphology information but also provide hemodynamic information, which is an advanced method in identification of benign and malignant pulmonary nodules. With the application of more advanced CT machines and data acquisition, consummation of reconstruction technique, deepening of the understanding of CT perfusion technique, CT perfusion together with the new software developed for use, it can be predicted that this imaging method will have broad clinical application.