Role of the texture features of images in the diagnosis of solitary pulmonary nodules in different sizes

Objective： To explore the role of the texture features of images in the diagnosis of solitary pulmonary nodules （SPNs） in different sizes. Materials and methods： A total of 379 patients with pathologically confirmed SPNs were enrolled in this study. They were divided into three groups based on the SPN sizes： ≤10, 11-20, and 〉20 mm. Their texture features were segmented and extracted. The differences in the image features between benign and malignant SPNs were compared. The SPNs in these three groups were determined and analyzed with the texture features of images. Results： These 379 SPNs were successfully segmented using the 2D Otsu threshold method and the self-adaptive threshold segmentation method. The texture features of these SPNs were obtained using the method of grey level co-occurrence matrix （GLCM）. Of these 379 patients, 120 had benign SPNs and 259 had malignant SPNs. The entropy, contrast, energy, homogeneity, and correlation were 3.5597±0.6470, 0.5384±0.2561, 0.1921±0.1256, 0.8281±0.0604, and 0.8748±0.0740 in the benign SPNs and 3.8007±0.6235, 0.6088±0.2961, 0.1673±0.1070, 0.7980±0.0555, and 0.8550±0.0869 in the malignant SPNs （all P〈0.05）. The sensitivity, specificity, and accuracy of the texture features of images were 83.3%, 90.0%, and 86.8%, respectively, for SPNs sized 〈10 mm, and were 86.6%, 88.2%, and 87.1%, respectively, for SPNs sized 11-20 mm and 94.7%, 91.8%, and 93.9%, respectively, for SPNs sized 〉20 mm. Conclusions： The entropy and contrast of malignant pulmonary nodules have been demonstrated to be higher in comparison to those of benign pulmonary nodules, while the energy, homogeneity correlation of malignant pulmonary nodules are lower than those of benign pulmonary nodules. The texture features of images can reflect the tissue features and have high sensitivity, specificity, and accuracy in differentiating SPNs. The sensitivity and accuracy increase for larger SPNs.

Correlation between the quantifiable parameters of blood flow pattern derived with dynamic CT in malignant solitary pulmonary nodules and tumor size

Objective： To evaluate the correlation between the quantifiable parameters of blood flow pattern derived with dynamic CT in malignant solitary pulmonary nodules and tumor size. Methods： Sixty-eight patients with malignant solitary pulmonary nodules （SPNs） （diameter 〈4 cm） underwent multi-location dynamic contrast material-enhanced （nonionic contrast material was administrated via the antecubitai vein at a rate of 4mL/s by using an autoinjector, 4×5 mm or 4×2.5 mm scanning mode with stable table were performed）. Precontrast and postcontrast attenuation on every scan was recorded. Blood flow （BF）, peak, height （PHSPN）, ratio of peak height of the SPN to that of the aorta （SPN-to-A ratio） and mean transit time （MTT） were calculated. The correlation between the quantifiable parameters of blood flow pattern derived with dynamic CT in malignant solitary pulmonary nodules and tumor size were assessed by means of linear regression analysis. Results： No significant correlations were found between the tumor size and each of the peak height （PHSPN） （35.79±10.76 Hu）, ratio of peak height of the SPN to that of the aorta （SPN-to-A ratio）, （14.27%±4.37） and blood flow （BF） （30.18 mL/min/100 g±9.58） （r=0.180, P=0.142〉0.05; r=0.205, P=0.093〉0.05; r=0.008, P=0.947〉0.05）. Conclusion： No significant correlations were found between the tumor size and each of the quantifiable parameters of blood flow pattern derived with dynamic CT in malignant solitary pulmonary nodules.

Blood flow patterns of solitary pulmonary nodules with enhancement

Objective： To evaluate the efficacy of dynamic multi-slice spiral computed tomography （MSCT） for providing quantitative information about blood flow patterns of solitary pulmonary nodules （SPNs）. Methods： Seventy-eight patients with SPNs （diameter 〈 4 cm; 68 malignant; 10 active inflammatory） were underwent multi-location dynamic contrast material-enhanced serial CT （nonionic contrast material was administrated via the antecubital vein at a rate of 4 mLJs by using an autoinjector, 4 × 5 mm or 4 × 2.5 mm transverse scanning mode with stable table were performed）. Sixteen series CT scans （16 scans each for the first and second series and one scan each for the rest series） were obtained during 9 min scanning period. Precontrast and postcontrast attenuation on every scan was recorded. Perfusion, peak height and ratio of peak height of the SPN to that of the aorta were calculated. Perfusion was calculated from the maximum gradient of the time-attenuation curve and the peak height of the aorta. Results： No statistically significant difference in the peak height was found between malignant （35.79 ± 10.76 Hu） and active inflammatory （39.76 ± 4.59 Hu） （t = 1.148, P = 0.255 〉 0.05）. SPN-to-aorta ratio （14.27% ± 4.37） and perfusion value （30.18 mL/min/100 g ± 9.58） in malignant SPNs were significantly lower than those of active inflammatory （18.51% ± 2.71, 63.44 mL/min/100 g ± 43.87） （t = 2.978, P = 0.004 〈 0.05; t = 5.590, P 〈 0.0001）. Conclusion： The quantitative information about blood flow patterns of malignant and active inflammatory SPNs is different. SPN-to-aorta ratio and perfusion value are helpful in differentiating malignant nodules from active inflammatory.

BLOOD FLOW PATTERN AND QUANTITATIVE STUDY IN SOLITARY PULMONARY NODULES WITH DYNAMIC CONTRAST-ENHANCED MRI

Objective To evaluate the efficacy of contrast enhanced dynamic MRI in differentiating solitary pulmonary nodules（SPNs）. Methods Eighty-three patients with SPNs undertaken contrast enhanced dynamic MRI. Time-signal intensity curve （T-SI Curve） was made. Peak height （PH） , steepest slope （SS）, maximum enhancement （ Emax ） and the enhancement rates of signal intensity were recorded at the frst （ E1 ）, second （ E2 ）, third （ E3 ） , fourth （ E4 ） , fifth （E5）, and sixth （ E6 ） minute after injection. Results Malignant nodules and inflammatory nodules enhanced significantly higher than benign nodules, and malignant nodules and inflammatory nodules showed obviously higher PH, SS, Emax, El-E6 values than benign nodules （ P 〈 0. 01 ）. There were no sig- nificant differences in PH, SS, Emax, E1-E6 values between malignant nodules and inflammatory nodules （P 〉 0. 05）. Conclusion Contrast enhanced dynamic MR imaging can provide SPNs＇ hemodynamic information and is helpful in differentiating SPNs.

Decision-tree analysis for cost-effective management of solitary pulmonary nodules in China

AIM: To analyze the cost-effectiveness of the diagnosis of solitary pulmonary nodule(SPN) in China. METHODS: Decision analysis models were constructed to assess the cost-effectiveness of four strategies for the management of SPN: computed tomography(CT) alone, CT plus CT-guided automated cutting needle biopsy(ACNB), CT plus positron emission tomography/computed tomography(PET/CT), CT plus diffusionweighted magnetic resonance imaging(DWI) plus PET/CT. RESULTS: The prevalence of lung cancer among SPN discovered in the clinical setting was approximately 50%. The CT plus ACNB strategy had higher diagnostic accuracies(87% vs 81%), with a cost saving of $1945 RMB per patient, and reducing unnecessary thoracotomy by 16.5%; this was associated with a 4.5% missed diagnosis rate. CT plus DWI plus PET/CT strategy also had higher accuracies(95% vs 81%), with a cost saving of $590 RMB per patient, and reducing unneces-sary thoracotomy by 13.5%; this was accompanied by 0.3% missed diagnosis rate. CT plus PET strategy is cost effective at a prevalence rate of 0-34%, but there was a larger prevalence range of lung cancer for CT plus ACNB strategy(from 0 to 0.6) and CT plus DWI plus PET/CT strategy(from 0 to 0.64). CONCLUSION: CT plus DWI plus PET/CT strategy was cost-effective, and had a higher accuracy accompanied by a lower missed diagnosis rate than CT plus ACNB strategy.

Dynamic contrast-enhanced MRI versus ^(18)F-FDG PET/CT: Which is better in differentiation between malignant and benign solitary pulmonary nodules?

Objective： To prospectively compare the discriminative capacity of dynamic contrast enhanced-magnetic resonance imaging（DCE-MRI） with that of^18F-fluorodeoxyglucose（^18F-FDG） positron emission tomography/computed tomography（PET/CT） in the differentiation of malignant and benign solitary pulmonary nodules（SPNs）.Methods： Forty-nine patients with SPNs were included in this prospective study. Thirty-two of the patients had malignant SPNs, while the other 17 had benign SPNs. All these patients underwent DCE-MRI and ^18F-FDG PET/CT examinations. The quantitative MRI pharmacokinetic parameters, including the trans-endothelial transfer constant（K^trans）, redistribution rate constant（Kep）, and fractional volume（Ve）, were calculated using the Extended-Tofts Linear two-compartment model. The ^18F-FDG PET/CT parameter, maximum standardized uptake value（SUV（max））, was also measured. Spearman＇s correlations were calculated between the MRI pharmacokinetic parameters and the SUV（max） of each SPN. These parameters were statistically compared between the malignant and benign nodules. Receiver operating characteristic（ROC） analyses were used to compare the diagnostic capability between the DCE-MRI and ^18F-FDG PET/CT indexes.Results： Positive correlations were found between K^trans and SUV（max）, and between K（ep） and SUV（max）（P〈0.05）.There were significant differences between the malignant and benign nodules in terms of the K^trans, K（ep） and SUV（max） values（P〈0.05）. The areas under the ROC curve（AUC） of K^trans） K（ep） and SUV（max） between the malignant and benign nodules were 0.909, 0.838 and 0.759, respectively. The sensitivity and specificity in differentiating malignant from benign SPNs were 90.6% and 82.4% for K^trans; 87.5% and 76.5% for K（ep）; and 75.0% and 70.6%for SUV（max）, respectively. The sensitivity and specificity of K^trans and K（ep） were higher than those of SUV（max）, but there was no significant difference between them（P〉0.05）.Conclusions： DCE-MRI can be used to differentiate between benign and malignant SPNs and has the advantage of being radiation free.

Bronchoscopic Diagnosis of Solitary Pulmonary Nodules with the Use of NIR Spectroscopy

Background: Recently, SPN has become a much more frequently encountered issue in bronchology. Efficient and reliable guidance method for SPN morphological proof is highly needed. Objectives: The aim of study was to compare the diagnostic values of NIR (near infrared) spectroscopy with EBUS for SPN diagnostic. Fluoroscopic guidance with TBB and needle biopsy were done in all patients. Methods: In our study, we used two types of monitoring systems. Fluoroscopic guidance was combined with either a radial EBUS or a NIR spectroscopy probe for tissue confirmation. 139 male and 71 female patients, having a medial age of 68 years with CT/PET findings of metabolically active SPN were examined between 2/2010 and 2/2013. We designed an instrument for measurement of the penetration of the NIR through lung tissue. Indicating and source fibers were navigated towards the SPN. An EBUS radial probe was used, during fluoroscopic navigation. Results: The statistical analysis of the results obtained showed a comparative specificity and sensitivity of the NIR spectroscopy, with radial EBUS. Conclusions: NIR spectroscopy produced similar efficacies as the radial EBUS. However, the number of positive biopsies was more dependent upon the ability to direct the confirmatory device to the SPN during fluoroscopic guidance than on the type of the device.

Neural network-based computer-aided diagnosis in distinguishing malignant from benign solitary pulmonary nodules by computed tomography

Background Computer-aided diagnosis （CAD） of lung cancer is the subject of many current researches. Statistical methods and artificial neural networks have been applied to more quantitatively characterize solitary pulmonary nodules （SPNs）. In this study, we developed a CAD scheme based on an artificial neural network to distinguish malignant from benign SPNs on thin-section computed tomography （CT） images, and investigated how the CAD scheme can help radiologists with different levels of experience make diagnostic decisions. Methods Two hundred thin-section CT images of SPNs with proven diagnoses （135 small peripheral lung cancers and 65 benign nodules） were analyzed. Three clinical features and nine CT signs of each case were studied by radiologists, and the indices of qualitative diagnosis were quantified. One hundred and forty nodules were selected randomly to form training samples, on which the neural network model was built. The remaining 60 nodules, forming test samples, were presented to 9 radiologists with 3-20 years of clinical experience, accompanied by standard reference images. The radiologists were asked to determine whether a nodule was malignant or benign first without and then with CAD output. Diagnostic performance was evaluated by receiver operating characteristic （ROC） analysis. Results CAD outputs on test samples had higher agreement with pathological diagnoses （Kappa=0.841, P〈0.001）. Compared with diagnostic results without CAD output, the average area under the ROC curve with CAD output was 0.96 （P〈0.001） for junior radiologists, 0.94 （P=0.014） for secondary radiologists and 0.96 （P=0.221） for senior radiologists, respectively. The differences in diagnostic performance with CAD output among the three levels of radiologists were not statistically significant （P=0.584, 0.920 and 0.707, respectively）. Conclusions This CAD scheme based on an artificial neural network could improve diagnostic performance and assist radiologists in distinguishing malignant from benign SPNs on thin-section CT images.

A controlled study of positron-emission-tomography and positron-emission-tomography/computed tomography in differential diagnosis of solitary pulmonary nodules—report of 60 cases

The differential diagnosis of solitary pulmonary nodules （SPNs） remains a challenge. It is acknowledged that combining positron-emission tomography （PET） and computed tomography （CT） offers the most reliable noninvasive method for the diagnosis of SPNs. Since Townsend et al1 developed integrated PET/CT in 1999, this technique has increasingly been introduced into clinical practice. To date, nuclear medicine physicians have usually undertaken PET/CT diagnosis, but the question is surfacing as how to make full use of the information of CT image to improve the accuracy of SPN diagnosis. To answer this question, we performed a retrospective study on 60 patients with SPNs.

Receiver operating characteristic curve analysis for image quality in the detection of solitary pulmonary nodules on high resolution paper prints versus dry laser film

Along with the development of digital X-ray imaging technology, a new, economical and practicalpaper-based output system gradually emerged. To reduce cost, more and more radiologic institutions began to change from film copies to lower-priced paper prints for documenting radiologic findings.Therefore, laser paper printers are frequently used as an alternative to duplicating film though the use of printed images is not yet widespread. The aim of this study was to compare the practical value of high-resolution paper printer with dry film copies for detecting small solitary pulmonary nodules （SPNs）.

Comparison of three mathematical prediction models in patients with a solitary pulmonary nodule

Background： Effective methods for managing patients with solitary pulmonary nodules（SPNs） depend critically on the predictive probability of malignancy.Methods： Between July 2009 and June 2011, data on gender, age, cancer history, tumor familial history, smoking status, tumor location, nodule size, spiculation, calcification, the tumor border, and the final pathological diagnosis were collected retrospectively from 154 surgical patients with an SPN measuring 3-30 mm. Each final diagnosis was compared with the probability calculated by three predicted models—the Mayo, VA, and Peking University（PU） models. The accuracy of each model was assessed using area under the receiver operating characteristics（ROC） and calibration curves.Results： The area under the ROC curve of the PU model [0.800; 95% confidence interval（CI）： 0.708-0.891] was higher than that of the Mayo model（0.753; 95% CI： 0.650-0.857） or VA model（0.728; 95% CI： 0.623-0.833）; however, this finding was not statistically significant. To varying degrees, calibration curves showed that all three models overestimated malignancy.Conclusions： The three predicted models have similar accuracy for prediction of SPN malignancy, although the accuracy is not sufficient. For Chinese patients, the PU model may has greater predictive power.Background： Here, we introduced our short experience on the application of a new CUSA Excel ultrasonic aspiration system, which was provided by Integra Lifesciences corporation, in skull base meningiomas resection.Methods： Ten patients with anterior, middle skull base and sphenoid ridge meningioma were operated using the CUSA Excel ultrasonic aspiration system at the Neurosurgery Department of Shanghai Huashan Hospital from August 2014 to October 2014. There were six male and four female patients, aged from 38 to 61 years old（the mean age was 48.5 years old）. Five cases with tumor located at anterior skull base, three cases with tumor on middle skull base, and two cases with tumor on sphenoid ridge.Results： All the patents received total resection of meningiomas with the help of this new tool, and the critical brain vessels and nerves were preserved during operations. All the patients recovered well after operation.Conclusions： This new CUSA Excel ultrasonic aspiration system has the advantage of preserving vital brain arteries and cranial nerves during skull base meningioma resection, which is very important for skull base tumor operations. This key step would ensure a well prognosis for patients. We hope the neurosurgeons would benefit from this kind of technique.Background： The purposes of this study were to explore the effects of high mobility group protein box 1（HMGB1） gene on the growth, proliferation, apoptosis, invasion, and metastasis of glioma cells, with an attempt to provide potential therapeutic targets for the treatment of glioma. Methods： The expressions of HMGB1 in glioma cells（U251, U-87 MG and LN-18） and one control cell line（SVG p12） were detected by real time PCR and Western blotting, respectively. Then, the effects of HMGB1 on the biological behaviors of glioma cells were detected： the expression of HMGB1 in human glioma cell lines U251 and U-87 MG were suppressed using RNAi technique, then the influences of HMGB1 on the viability, cycle, apoptosis, and invasion abilities of U251 and U-87 MG cells were analyzed using in a Transwell invasion chamber. Also, the effects of HMGB1 on the expressions of cyclin D1, Bax, Bcl-2, and MMP 9 were detected. Results： As shown by real-time PCR and Western blotting, the expression of HMGB1 significantly increased in glioma cells（U251, U-87 MG, and LN-18） in comparison with the control cell line（SVG p12）; the vitality, proliferation and invasive capabilities of U251 and U-87 MG cells in the HMGB1 siR NA-transfected group were significantly lower than those in the blank control group and negative control（NC） siR NA group（P〈0.05） but showed no significant difference between the blank control group and NC siR NA group. The percentage of apoptotic U251 and U-87 MG cells was significantly higher in the HMGB1 siR NA-transfected group than in the blank control group and NC siR NA group（P〈0.05） but was similar between the latter two groups. The HMGB1 siR NA-transfected group had significantly lower expression levels of Cyclin D1, Bcl-2, and MMP-9 protein in U251 and U-87 MG cells and significantly higher expression of Bax protein than in the blank control group and NC siR NA group（P〈0.05）; the expression profiles of cyclin D1, Bax, Bcl-2, and MMP 9 showed no significant change in both blank control group and NC siR NA group. Conclusions： HMGB1 gene may promote the proliferation and migration of glioma cells and suppress its effects of apoptosis. Inhibition of the expression of HMGB1 gene can suppress the proliferation and migration of glioma cells and promote their apoptosis. Our observations provided a new target for intervention and treatment of glioma.

Solitary primary pulmonary synovial sarcoma:A case report

BACKGROUND Synovial sarcoma(SS)is an uncommon and highly malignant soft tissue sarcoma in the clinic,with primary pulmonary SS(PPSS)being extremely rare.Here,we describe the clinical characteristics,diagnosis,and treatment of a solitary PPSS case confirmed via surgical resection and fluorescence in situ hybridization(FISH).CASE SUMMARY A 33-year-old man was admitted because of intermittent coughing and hemoptysis for one month,with lung shadows observed for two years.Wholebody positron emission tomography-computed tomography(PET-CT)revealed a solitary mass in the upper lobe of the right lung,with uneven radioactivity uptake and a maximum standardized uptake value of 5.6.The greyish-yellow specimen obtained following thoracoscopic resection was covered with small multinodulated structures and consisted of soft tissue.Hematoxylin and eosin staining revealed spindle-shaped malignant tumor cells.Immunohistochemistry indicated these tumor cells were CD99 and BCL-2-positive.Furthermore,the FISH test revealed synovial sarcoma translocation genetic reassortment,which confirmed the diagnosis of SS.CONCLUSION PPSS is extremely rare and tends to be misdiagnosed as many primary pulmonary diseases.PET-CT,histologic analysis,and FISH tests can be used to differentiate PPSS from other diseases.Surgical resection is regularly recommended for the treatment of solitary PPSS and is helpful for improving the prognosis.

Difference in microvascular structure between benign and malignant pulmonary nodules and its relationship with CT enhancement

Objective： To investigate the enhancement basis and the mechanisms of solitary pulmonary nodules （SPNs） by comparing the differences in microvascular structure between benign and malignant lesions. Methods： Dynamic contrast-enhanced CT scan was performed on 53 patients with SPNs （diameter〈3 cm, 38 peripheral lung cancers, 5 hamartomas, 10 inflammatory lesions） using a Siemens Plus S or a Marconi MX8000 multi slices spiral CT scanner. The time-attenuation curves were interpreted. The microvascular density （MVD） and the continuity of the microvessels＇ basemental membrane in the dissected specimens were observed with the ABC （avldin-biotin complex） immuno-histochemical method in all patients. Results ：The CT enhancement values of lung cancer （49.05± 16.08 HU） and inflammatory lesions （49.59±21.30 HU） were significantly higher than those of hamartoma （8.98±4.56 HU） t=7.48, P〈0.051 t=8.35, P〈0.05）. But the enhancement of lung cancer was similar to that of inflammatory lesions （t=0.76, P±0. 05）. The time attenuation curve of inflammatory lesions tended to increase faster and reached a higher peak compared to the lung cancer, and both of them maintained a high plateau after crossing. The hamartoma showed a slight increase in the time-attenuation curve and demonstrated a lowplateau curve. The MVD of SPNs was positively correlated with CT enhancement （r=0. 8051）. The microvascular counts of peripheral lung cancer （48.45±10. 09） and inflammatory lesions （49. 60±19. 94） were significantly higher than those of hamartoma （8.70±7. 30） （t=11. 64, P〈0.001, t=6. 09, P〈0. 001 ）, but no significant difference was found between lung cancer and inflammatory lesions （t= -0.26, P=0.799）. There was no difference in the continuity of basement membrane between nodules with anen haneement less than 30 HU and those with an enhancement higher than 30HU （X^2=3. 13, P〉0.05 ）. Conclusion： The microvascular counts mainly contribute to the enhancement value of SPNs. The basement membrane is not related to nodule enhancement, but it might influence the pattern of the time-attenuation curve.

Analysis of 96 cases of solitary pulmonary nodule diagnosed by MSCT

Objective:The aim of this study was to explore the diagnostic value of multi-slice computer tomography(MSCT) in solitary pulmonary nodule(SPN).Methods:Contrastive analysis of the differences of CT signs between benign and malignant SPN.Results:The typical sign of pleural indentation was a reliable sign for lung cancers.Vacuole sign suggested lung cancer highly.Blood vessels cluster involving the vein alone had big opportunity to lung cancer.Type I tumor-bronchial relation was the most common relation in lung cancers.Type V tumor–bronchial relation was the most common relation in benign SPN.Conclusion:MSCT had a very high diagnostic value in SPN.

Diffusion-weighted magnetic resonance imaging with short T1 inversion recovery-echo planar imaging combined with dual-head coincidence single photon emission computed tomography for diagnosing solitary pulmonary nodule

Positron emission tomography （PET） using 18F-fluorodeoxyglucose （FDG） has not been widely used in China for expensive cost （$1200）. Dual-head coincidence single photon emission computed tomography （DHC-SPECT） can depict many of the lesions depicted with a PET scanner in the lungs, which is used in place of PET-CT for discriminating malignant from benign pulmonary nodules in many studies. However, DHC-SPECT has inevitable false-negative results because the sensitivity for small lesions less than 2.0 cm is limited, and has high false-positive rate for active inflammatory nodules. Furthermore,DHC-SPECT also has a considerably higher cost （$300 in China） than other imaging examination.

Comparison of Positron Emission Tomography Using 2-[^18F]-fluoro-2-deoxy-D-glucose and 3-deoxy-3-[^18F]-fluorothymidine in Lung Cancer Imaging

Background： The detection of solitary pulmonary nodules （SPNs） that may potentially develop into a malignant lesion is essential for early clinical interventions. However, grading classification based on computed tomography （CT） imaging results remains a significant challenge. The 2-[^18F]-fluoro-2-deoxy-D-glucose （^18F-FDG） positron emission tomography （PET）/CT imaging produces both false-positive and false-negative findings for the diagnosis of SPNs. In this study, we compared 18F-FDG and 3-deoxy-3-[^18F]-fluorothymidine （^18F-FLT） in lung cancer PET/CT imaging. Methods： The binding ratios of the two tracers to A549 lung cancer cells were calculated. The mouse lung cancer model was established （n = 12）, and micro-PET/CT analysis using the two tracers was performed. Images using the two tracers were collected from 55 lung cancer patients with SPNs. The correlation among the cell-tracer binding ratios, standardized uptake values （SUVs）, and Ki-67 proliferation marker expression were investigated. Results： The cell-tracer binding ratio for the A549 cells using the ^18F-FDG was greater than the ratio using 18F-FLT （P 〈 0.05）. The Ki-67 expression showed a significant positive correlation with the ^18F-FLT binding ratio （r = 0.824, P〈 0.01）. The tumor-to-nontumor uptake ratio of ^18F-FDG imaging in xenografts was higher than that of ^18F-FLT imaging. The diagnostic sensitivity, specificity, and the accuracy of ^18F-FDG for lung cancer were 89%, 67%, and 73%, respectively. Moreover, the diagnostic sensitivity, specificity, and the accuracy of ^18F-FLT for lung cancer were 71%, 79%, and 76%, respectively. There was an obvious positive correlation between the lung cancer Ki-67 expression and the mean maximum SUV of ^18F-FDG and ^18F-FLT （r = 0.658, P〈 0.05 and r = 0.724, P〈 0.01, respectively）. Conclusions： The ^18F-FDG uptake ratio is higher than that of ^18F-FLT in A549 cells at the cellular level.^18F-FLT imaging might be superior for the quantitative diagnosis of lung tumor tissue and could distinguish lung cancer nodules from other SPNs.