Pulmonary Nodules: Metabolic And Morphological Characteristics By ¹⁸F-FDG PET-CT And CT

Partâ… The Diagnostic Value of ¹⁸F-FDG PET-CT Combined With Breath-hold Spiral Chest CT in Pulmonary NodulesOBJECTIVE:To prospectively investigate the metabolic and morphological characteristics of pulmonary nodule obtained by ¹⁸F-FDG PET-CT combined with breath-hold spiral chest CT in pulmonary nodules,and evaluate the diagnostic value of ¹⁸F-FDG PET-CT combined with breath-hold spiral chest CT in pulmonary nodules.MATERIALS AND METHODS:One hundred and fifty-four patients with 171 pulmonary nodules(=3cm) were studied.Each patient underwent a ¹⁸F-FDG PET-CT(16 slices) examination during mild respiration and a breath-hold spiral chest CT scan.One hundred and twenty-one patients underwent dual-time-point PET-CT examination.Pulmonary nodule' uptake was interpreted visually and semi quantitatively.Morphological characteristics of pulmonary nodule were obtained by breath-hold spiral chest CT scan.The metabolic and morphological characteristics of pulmonary nodules were both analyzed for diagnosis.To compare the diagnostic sensitivity,specificity,accuracy and Youden's index for malignancy by four methods, which were ¹⁸F-FDG PET-CT combined with breath-hold spiral chest CT,¹⁸F-FDG PET-CT,breath-hold spiral chest CT and taking SUVmax=2.5 as the threshold value for malignancy.All results were proved by pathology or by diagnostic therapy or by clinical follow-up.RESULTS:The diameter was(2.05±0.73)cm(mean±SD) in 118 malignant nodules, and(1.48±0.72) cm in 53 benign nodules.There was a statistical difference in diameter between malignancy and benignity(P＜0.01).No statistical differences were observed between the size and the TNM staging of the nodules(P＞0.05).The diagnostic accuracy of CT was statistical different in nodules' size,while there was no statistical difference in nodules' size of PET-CT combined with breath-hold spiral chest CT.Statistical differences of SUVmax were found both in different density and in different size of the nodules(P＜0.01).The maximum glucose standardized uptake value(SUVmax) of malignancy were 4.51±3.06(mean±SD),while that of benignity were 2.07±1.30.The SUVmax of malignancy was significantly higher than that of benignity(P＜0.01).There were also statistical differences in SUVmax between different pathological results(P＜0.01).The SUVmax of G1/G2/G3/GX grade of adenocarcinoma were 1.80±1.80,3.50±2.01,5.14±2.72,4.72±1.92,respectively.The SUVmax of lower differentiation adenocarcinoma was significantly higher than those of higher differentiation(P＜0.01).No statistical differences of SUVmax were observed in nodules' location,pathological staging and T staging,respectively(P＞0.05).There was a positive correlation between the size and the SUVmax of the nodules(r=0.613,P＜0.01),while there was a negative correlation between the differentiation of adenocarcinoma and the SUVmax(r=-0.452,P＜0.01).The age, sex,weight,location,pathological results and pathological staging had no correlation with the SUVmax(P＞0.05).There were statistical differences between SUVmax routine and SUVmax delay in dual-time-point PET-CT(P＜0.01).The sensitivity, specificity,accuracy and Youden's index of ¹⁸F-FDG PET-CT combined with breath-hold spiral chest CT were higher than the other three methods,which were 95.8%,91.2%and 0.77,respectively.CONCLUSION:The SUVmax of the nodules were significantly statistical different in different size,density,pathological results,staging and grade,respectively.There was a positive correlation between the size and the SUVmax of the nodules,while there was a negative correlation between the differentiation of adenocarcinoma and the SUVmax.The dual-time-point PET-CT was helpful for differential diagnosis.For more morphological information was providing,the ¹⁸FDG PET-CT combined with breath-hold spiral chest CT is superior to ¹⁸FDG PET-CT alone with higher sensitivity, specificity and accuracy in the differentiation of pulmonary nodules,and improve the diagnostic accuracy. Partâ…¡Diagnostic Value of Computer-aided Diagnosis With Three-dimensional Volumetric Measurement in Solid Pulmonary Nodules on Follow-up CTOBJECTIVE:To evaluate the diagnostic value of computer-aided diagnosis with three-dimensional volumetric measurement in solid pulmonary nodules on follow-up CT.MATERIALS AND METHODS:Fifty-four patients with 67 solid nodules were evaluated.Each patient underwent chest CT at least twice.The nodules were=10mm (n=35),11-20mm(n=29) and 21-30mm(n=3) in diameter on baseline CT scan, respectively.The images were reconstructed at a 1.25mm thickness and a 0.6-0.8mm interval with 8 or 16 multi-slice CT scanner(GE LightSpeed Ultra or Pro) and transferred to CT workstations(GE advanced workstation 4.1 or 4.2).The scan parameters were unchanged for the different times used in each patient.The volume, volume doubling time(VDT) and volumetric growth rate(VGR) of nodules were calculated with a three-dimensional volumetric measurement software(advanced lung analysis,ALA).All nodules' final findings were proved by pathology or by diagnostic therapy or by clinical follow-up.RESULTS:The VDT of 16 malignant nodules were all＜500 days,with a range from 45 to 465 days(median,155 days);the VGR ranged from 8%to 329%(median, 33.5%).The VGR of 51 benign nodules ranged from -63%to 44%(median,-4%). The VDT of 25 benign nodules that increased or not changed in size were＞500 days in 22 nodules,with a range from 302 days to 55158 days(median,2365 days);the VGR ranged from 0%to 44%(median,6.5%).Twenty-six nodules that decreased in size had the VGR ranging from -4%to -63%(median,-16.5%),and the VDT of these nodules could not be calculated by software.There were significant statistical differences in VDT between malignant and benign nodules(P＜0.05).No significant statistical differences were observed in VDT and VGR between lung cancer and metastasis(P＞0.05).Taking 500 days,400 days and 300 days as the threshold value for malignancies,respectively,all these threshold value had significant statistical differences between malignant and benign nodules(P＜0.01).The diagnostic sensitivity,specificity,accuracy and Youden's Index were 100.0%,88.0%,92.7% and 0.88,93.8%,92.0%,92.7%and 0.86,81.3%,100.0%,91.7%and 0.81,respectively. The diagnostic accuracy was significantly different between VDT 500 days and VDT 300 days(P＜0.05).CONCLUSION:Taking 500 days as the VDT's threshold value for malignancies has a high diagnostic accuracy.Computer-aided diagnosis with three-dimensional volumetric measurement is sensitive to the volume change of solid pulmonary nodules (especially for those=10 mm in diameter) on follow-up CT,and is helpful in differential diagnosis.