| PART 1 EFFECT OF SLAB THICKNESS ON THE DETECTION OF PULMONARY NODULES BY USE OF CT MAXIMUM AND MINIMUM INTENSITY PROJECTIONPurposeThe purpose of this study was to investigate the effect of slab thickness on the detection of pulmonary nodules by use of maximum-intensity-projection(MIP)and minimum-intensity-projection(MinIP)to process CT images.MethodsChest CT data of 221 patients with pulmonary nodules were retrospectively analyzed.Nodules were categorized into two groups according to density: solid nodules(SNs)and subsolid nodules(GGNs).Pulmonary nodules were independently evaluated by two radiologists using axial CT images with 5mm and 1mm section thickness and MIP and MinIP images.MIP images for SN detection and MinIP images for GGN detection were separately reconstructed with four(5,10,15,20 mm)and three(3,8,15 mm)slab thicknesses.The numbers and locations of detected nodules were recorded,and interobserver agreement was assessed.For each reader,the differences in nodule detection rates were evaluated in different series of images.ResultsAmong the different series of images,interobserver agreements for detecting nodules were all good to excellent(? ? 0.687).For total SNs and SNs with a diameter < 5 mm,detection rates on MIP(10mm)images were significantly higher than those in other series of images(reader 1,84.5%and 83.8%;reader 2,83.6% and 82.2%).For total GGNs and GGNs < 5mm,detection rates on MinIP(3mm)images were significantly higher than those in other series of images,except for 1mm images(reader 1,93.3%and 78.6%;reader 2,95.0% and 81.0%).ConclusionMIP(10mm)images are extremely efficient for detecting SNs.MinIP(3mm)images are more useful for visualizing GGNs,the efficiency being comparable to that achieved by use of 1-mm axial imagesPART 2 CT DIAGNOSIS OF ISOLATED PULMONARY NODULES IN PATIENTS WITH A HISTORY OF MALIGNANT TUMORPurpose To analyze the CT features of solitary pulmonary nodules(SPN)in patients with malignant tumor with the aim of improving its diagnosis and differential diagnosis in this special background.Methods From May 2014 to December 2018,the CT data of 76 pathologically confirmed SPNs in patients with malignant tumor were retrospectively analyzed.The CT features of SPN,including density,morphology and change of peripheral lung field and adjacent structures,were mainly analyzed.The characteristics of different types of nodules and their differences were summarized.Results Among the 76 SPNs,there were 41(53.9%)primary lung cancers,14(18.5%)metastatic tumors,and 21(27.6%)benign lesions(including 12 inflammatory nodules,7 tuberculous nodules and 2 benign tumors).Of all nodules,there were 57(75%)solid nodules,including 23(40.4%)primary lung cancer which mainly manifested as nodules with rough margin,close to adjacent vessel and bronchus and usually had internal or edge features(19,82.6%),14(24.6%)metastatic tumors which mainly showed as round or oval,homogeneous density,smooth margin nodules(12,85.7%),and 18(31.6%)inflammatory nodules which mainly showed as lesions with rough and blurred margin accompanied by peripheral patch or fibrosis(14,77.8%).There were 19(25%)subsolid nodules,including 18(94.7%)primary lung cancers,which mainly manifested as nodules with heterogeneous density and clear border(14,77.8%).There was only 1(5.3%)subsolid inflammatory nodule.Conclusion The pathological nature of SPNs in patients with malignant tumors is various.Understanding their CT characteristics is helpful for diagnosing and differentiating and providing useful information for further treatment. |
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