| Purpose: To evaluate and compare the efficacy of the performance of first pass and delayed imaging commonly used at dynamic multislice spiral computed tomography (MSCT) for providing quantitative information about blood flow patterns of solitary pulmonary nodules (SPNs) and the correlation of tumor microvessel density (MVD) and the quantifiable parameters of blood flow pattern in SPNs and non—small cell lung cancer , and to illustrate and compare their clinical significance in differential diagnosis between benign and malignant pulmonary nodules , and attempt to determine and compare the correlation of the two dynamic quantifiable parameters and pathologic characteristics in the case of completely resected non-small cell lung cancer patients, and the clinical value in differentiating the N stage and pathological stage .Materials and Methods: 72 patients with solitary pulmonary nodules underwent first pass dynamic multislice spiral computed tomography and delayed imaging with the 40ml bolus injected at 4ml/sec. Afterevaluating and comparing the image quality of the two image acquisition protocols, there are 61 patients with SPNs and 32 patients with non-small cell lung cancer in progression to the next study procedure. Their dynamic images were processed with dynamic evaluation software produced by Siemens corporation. The CT plain scan value, the peak height(PH) and the time to peak(TP) of the SPNs ,non—small cell lung cancer and the aorta of the first pass and delayed imaging were measured. The slope of enhancement (SE) and the ratio of peak height of SPNs or non—small cell lung cancer to that of the aorta (S/A)of the first pass and delayed imaging were caculated. The time—density curve (TDC) of the first pass and delayed imaging of the SPNs were obtained and classified. The quantifiable parameters (the peak height, the slope of enhancement ,the ratio of peak height of the SPNs or non —small cell lung cancer to that of the aorta of the first pass and delayed imaging of the 40 SPNs and 32 non—small cell lung cancer) of blood flow pattern were compared with microvessel densities (MVD) by immunohistochemistry . The significance of the difference between groups were analyzed by independent- sample t test. The relationships between the peak height of the aorta and the peak height of the SPNs of the first pass and delayed imaging, and the relationships between the parameters of SPNs and non—small cell lung cancer and MVD were assessed by means of linear regression analysis. Diagnostic and stage characteristics for differentiation were examined by using threshold values for the peak height, the slope of enhancement ,the ratio of peak height of the SPNs or non—small cell lung cancer to that of the aorta of the first pass and delayed imaging. Receiver operating characteristic curve were caculated to test the usefulness theseparameters.Results: The first pass dynamic multislice spiral computed tomography (3.8800±0.7704) showed higher image qualities than delayed imaging (3.613 ±0.868), but there was no significant difference between the two protocol(P>0.01). The time—density curve (TDC) were classified 3 types(A-C) and 4 types(A-D) by the first pass dynamic contrast enhanced multislice spiral CT and delayed imaging respectively. The mean first pass peak height and delayed peak height of the SPNs and peak height of the aorta were 17.059±12.381 and 22.467 ±12.274 and 227.274 ± 67.290 , respectively. Whereas the delayed peak height of the SPNs was correlated with the peak height of the aorta (r=0.274, p=0.032),the first pass peak height of the SPNs was more closely correlated with (r=0.459, p = 0.000). The mean MVDs, the first pass PH (22.864±13.514HU ), S/A(9.202±4.537%) and delayed PH(26.350 ±12.744 HU) of malignant SPNs were significantly higher than those of benign ones (10.912 ± 5.452 HU , 5.514 ±3.509%, 18.172± 11.567 HU, p < 0.01). The residual quantifiable parameters demonstrating no significant difference between the benign and malignant SPNs ( P>0.01).With 15HU,for the first pass PH; 6.5%, for S/A ; 17HU, for delayed PH as a cutoff value in differatientiation for malignant and benign SPNs, The Sensitivity, specificity, accuracy, positive predictive value, negative predictive value, Az value were 87.5% , 72.41 %, 77.78 %, 84.00 %, 80.33 % and 0.84 .respectively, for the first pass PH; 80.64% , 63.33 % , 72.13%, 69.44%, 76.0% and 0.78 for the first pass S/A; 71.11%, 75.00 %, 72.13%, 88.89%, 48.00%and 0.76 for the delayed PH. There were not significant difference in differatientiation for malignant and benignSPNs between the first pass PH and the first pass S/A, delayed PH (P>0.01) .Among 32 non—small cell lung cancer, There was no significant difference in the different dynamic quantifiable parameters between the squamous cell carcinomas and adenocarcinomas groups, the T1.2 andT3^ stages groups, the high-moderatied grades and low grades groups. The mean MVDs, the first pass PH, SE, T/A and delayed PH , T/A of N,.2 and III~IV stages were significantly higher than those of Noandl~ II stages( p < 0.05). Withl2HU,for the first pass PH; 0.6HU/S, for the SE , 5%, forT/A ; 17HU, for delayed PH; 16, for MVDs as a cutoff value in differatientiation for No and N1-2, The Sensitivity, specificity, accuracy, positive predictive value, negative predictive value, were92.307%, 100%, 87.5%,100%and 75.0%, respectively, for the first pass PH; 96.000%, 100%, 96.875 %, 100%and 87.5% for the first pass SE; 96.000%,100%,96.875 %,100% and 87.5% for the first pass T/A; 85.185%,80%, 84.375 %,95.833% and50% forthe delayed PH; 85.185%, 80% ,84.375 %, 95.833% and 50% for the delayed T/A; 95.833%, 87.5%, 93.750%, 95.833%and 87.5% for the MVDs. The accuracy of mean MVDs, the first pass SE and T/A in differatientiation for No and N1.2 were significantly higher than those of the delayed PH and T/A(PO.05 ). Withl2HU,for the first pass PH; 0.6HU/S, for the SE , 5%, for T/A ; 17HU, for delayed PH; 16, for MVDs as a cutoff value in differatientiation for I ~ II and III—IV stages, The Sensitivity, specificity, accuracy, positive predictive value, negative predictive value, were 84.615%, 100%, 87.5%, 100% and 60%, respectively, for the first pass PH; 87.5%, 87.5%, 87.5%, 95.455% and 70%for the first pass SE ; 88.000%, 100%, 90.625%, 100% and 70% for the first pass T/A ; 78.571%, 100%, 81.25%, 100% and 40% for the delayed PH; 77.778%, 80 %, 75.125%, 95.455% and 40% for the delayed T/A; 87.5%,87.5%,87.5%, 95.455 % and 70% for the MVDs. The accuracy of mean MVDs, the first pass SE and T/A in differatientiation for I ~ II and III ~ IV stages were significantly higher than those of the delayed T/A (P=0.02, P-0.042, P=0.049, respectively) .Conclusion: The quantitative information about blood flow patterns of malignant and benign SPNs is different. The first pass and delayed imaging dynamic contrast enhanced CT all can provide quantitative information about blood flow patterns of SPNs. The first pass dynamic contrast enhanced CT looks more applicable than delayed imaging to evaluate the chateristics of solitary pulmonary nodules and its MVD, The first pass dynamic contrast enhanced CT is proved to be superior to delayed imaging in evaluation of angiogenesis in NSCLC and its pathologic characteristics and might helpful to improve the lymphnode and TNM staging accuracy of conventional CT.
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