| Objective:To investigate the displayed difference of LDCT combined with iterative reconstruction in pulmonary nodules of different size,location,type,area and its diagnostic value.Materials and Methods:From July 2019 to August 2020,278 patients with pulmonary nodules were collected for LDCT examination(110k V and 16 m As).Image space iterative reconstruction technique was used to reconstruct the scanned images.204 patients with small pulmonary nodules and baseline conventional CT findings were selected.Then,the baseline conventional CT(130k V and 65 m As)scan images of the patients were checked from the PACS system.The difference in subjective image quality score of different size,location,type,area nodules was compared between the two groups.A total of 48 patients were selected for surgery,including 16 patients with central nodules,13 patients with hilar nodules,and 19 patients with peripheral nodules.The peripheral nodules were preoperatively located by the LDCT guided spring coil.Results:1.A total of 430 pulmonary nodules were found on baseline conventional CT in204 patients.425 pulmonary nodules were found on low-dose follow-up CT.The overall detection rate of pulmonary nodules on low-dose CT was 98.84%.2.Group with average diameter ≤4mm and 4mm<average diameter≤10mm,the sensitivity of low-dose CT detection was 97.04% and 100%,respectively.There was no significant difference in the sensitivity of conventional and low-dose CT in detecting pulmonary nodules between the two groups(P>0.05).However,the average diameter of5 misdiagnosed pulmonary nodules and 1 misdiagnosed pulmonary nodules on low-dose CT was ≤4mm.3.The sensitivity of low-dose CT was 100%,100% and 98.45% in the hilar group,central group and peripheral group,respectively.There was no significant difference in the sensitivity of conventional and low-dose CT in detecting pulmonary nodules among the three groups(P>0.05).There was significant difference between conventional and low-dose CT image quality scores in peripheral area group(P<0.05).There was no significant difference between the conventional and low-dose CT image quality scores in the central region and the hilar region(P>0.05).All the 5 missed and 1 misdiagnosed pulmonary nodules on low-dose CT were peripheral nodules.4.The sensitivity of low dose CT detection was 98.05%,100% and 98.79% in the solid,mixed and pure ground glass nodules group,respectively.There was no significant difference in the sensitivity of conventional and low-dose CT in detecting pulmonary nodules among the three groups(P>0.05).The difference of image quality scores between conventional and low-dose CT in solid nodules group was statistically significant(P<0.05).All the 5 missed and 1 misdiagnosed pulmonary nodules on low-dose CT were solid nodules.5.The sensitivity of low-dose CT detection in the right upper lobe,right middle lobe,right lower lobe,left upper lobe and left lower lobe were 99.03%,100%,97.85%,100% and 98.11%,respectively.There was no significant difference in the sensitivity of the five groups to pulmonary nodules detected by conventional and low-dose CT(P>0.05).There was no statistically significant difference between the conventional dose CT and low-dose CT image quality scores in the five groups(P>0.05).Among the 5missed and 1 misdiagnosed pulmonary nodules on low-dose CT,3 were located in the lower lobe of right lung,2 were located in the lower lobe of left lung,and 1 was located in the upper lobe of right lung.They are mostly located in the lower lobes of both lungs.6.The coincidence rate of pathological findings and imaging diagnosis was93.75%(45/48)in 48 patients with lung cancer diagnosed by low-dose CT images after surgical resection.7.Low-dose CT successfully guided 19 patients with peripheral pulmonary nodules.Spring coils were placed preoperatively for positioning.8.Pulmonary nodules adjacent to the pleura at the base of the peripheral region were scanned in prone position better than in supine position.The results of supine position were better than that of prone position for small pulmonary nodules in the base of the peripheral region adjacent to the diaphragm.Conclusion:Low-dose CT combined with iterative reconstruction technique can better display pulmonary nodules of different sizes,locations,types and regions.It showed pure ground glass pulmonary nodules,central and hilar pulmonary nodules,upper lobe and middle lobe nodules,4mm<averagediameter≤10mm were more advantageous.Low-dose spiral CT can accurately determine the benign and malignant pulmonary nodules.It provides the basis for early surgical treatment in clinic. |
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