Study Of The Detection Of Ground-glass Nodulars With Low-dose And Standard-dose Spiral CT Scans

Objective:1.To explore the ability of low-dose and standard-dose 128 slice spiral CT with different construction slice thickness in detection of ground-glass nodules(GGN).2.To explore the feature of borderline,interior characteristics and neighboring structures of the ground-glass nodules detected at the low-dose and standard-dose 128 slice spiral CT with different construction slice thickness. Materials and Methods:1.Patient data: fifty-six patients with ground-glass nodules(GGNs) found at standard-dose(200m As) spiral CT with 5mm slice thickness in Shandong tumor hospital between July,2011 and December 1,2012, including 27 males and 29 females. The mean age was 60 years(28-70 years).2. CT scanning method: all the patients were scanned with a 128 slice spiral CT( Philips). Patient took a supine and head first position with arms lifted above head. Scan range cover from the apex of the lung to the bottom of the lung. When a GGN is detected at standard-dose CT scan, a low-does CT scan was performed after getting informed consent from the patient. Parameters of standard-dose scanning was as follows: 120 KV, 200 m As,slice thickness 5mm,slice spacing1 mm,pitch 1.5;parameters of low-dose scanning: 120 KV, 300 m As, slice thickness 5mm, slice spacing 1mm, pitch 1.5. At the same time, standard-dose and low-dose CT images of 2mm and 1mm of slice thickness were reconstructed from the original data using i Dose technique.3.Items of observation: number, size, shape, internal structure(pulmonary cavity and air bronchogram) and neighboring structures(vessel convergence sign and pleural indentation sign) of the GGNs. The longest diameter of GGNs was measured on the workstation. The images obtained were divided into three groups according to the longest diameter: <5mm、5-10mm、>10mm.4. Statistical analysis:SPSS 17.0 software was used for data calculation.The number of the GGNs detected at the low-dose and standard-dose spiral CT in the different construction slice thickness was compare using “Wilcoxon or X2” text, P<0.05 was considered to be statistically significant. The feature of borderline, interior characteristics and neighboring structures of the ground-glass nodules detected at the low-dose and standard-dose spiral CT in the different construction slice thickness was compared by using “Fisher or X2” text, P<0.05 was considered to be statistically significant. Results:1.The number of GGNs detected at the low-dose and standard-dose spiral CT scan with 5mm、2mm 、1mm construction slice thickness had no differences between any pair of groups.2. In standard-dose spiral CT scan,the number of GGNs detected at different slice thickness had no differences between each pair of groups. In low-dose spiral CT scan,the number of GGNs in 5mm and 2mm construction slice thickness had significant difference;but the number of GGNs in 5mm and 1mm 、2mm and 1mm construction slice thickness to compare each other had no differences.3.The feature of borderline,interior characteristics and neighboring structures of the GGNs detected at the low-dose and standard-dose 128 slice spiral CT in the 5mm 2mm 1mm construction slice thickness had no difference.4.In standard-dose spiral CT scan,the feature of borderline,interior characteristics and neighboring structures of GGNs in different construction slice thickness to compare each other no differences. In low-dose spiral CT scan,the feature of GGN in 5mm and 2mm construction slice thickness had significant differences;but the feature of borderline,interior characteristics and neighboring structures of GGNs in 5mm and 1mm、2mm and 1mm slice thickness to compare each other have no differences. Conclusion: Low-dose scan(30m A)on 128 slice CT with 2mm slice thickness reconstruction has advantages in detection of GGNs and depicting border and internal characteristics over 5mm and 1mm reconstruction and deserves to be popularized in general health survey.