Significance Of Intra-nodular Vessel Sign In Subsolid Nodules With A Diameter Of ≤10mm For Differentiating Pathological Subtypes Of Lung Adenocarcinoma

Objective: To compare and analyze the correlation between the imaging morphological features of subsolid nodules ≤10 mm(sub-centimeter)in diameter size and the pathological subtypes of lung adenocarcinoma in order to improve the diagnosis of sub-solid nodules of sub-centimeter size;to explore the significance of vascular signs in differentiating the pathological subtypes of lung adenocarcinoma and to assess their value in the treatment options of sub-solid nodules.Methods: The clinical and CT imaging data of 103 pathologically confirmed subsolid nodules with a mean diameter ≤10 mm with ≥1 preoperative CT follow-up between January2015 and December 2021 at our institution were retrospectively analyzed.They were divided into 3 groups according to the pathological staging criteria of the WHO Lung Adenocarcinoma 2021(5th edition): glandular precursor lesion group(n=31);microinvasive adenocarcinoma group(MIA)(n=33);and invasive adenocarcinoma group(IAC)(n=39).The clinical characteristics(gender,age),imaging morphological features including(i)external features: nodule site,nodule size,nodule morphology,nodule-lung interface,lobar sign,burr sign,vacuolation sign,distended bronchus sign,pleural distraction sign;(ii)internal features:nodule type(partially solid nodules and pure ground glass nodules),vascular signs,were statistically analyzed.Multiplanar reorganization(MPR)and volumetric reproduction(VR)image display techniques were performed for the vessels in the lesion areas with partial enhancement CT scan results,and the vascular signs were observed on the cross-sectional raw images and post-processed reconstructed images,and the relationship between subsolid nodules and vascular signs was categorized into four types,type I: vessels do not cross the pulmonary nodules(can be close or far away)(Figure 2a);type II: vessels cross the pulmonary nodules Type III: vessels cross the nodule and are twisted and dilated without an increase in the number of vessels(Figure 3a);Type IV: the vascular signs are complicated by the presence of two or more vessels entering the lesion,which may form branches,sometimes with interbranch connections and irregularly dilated and distorted vessel diameters(Figure2d).One-way ANOVA and chi-square tests were used to statistically analyze the relationship between the different pathological groupings and the clinical features,the imaging morphological features of subsolid nodules and the types of vascular signs of the patients.Results:(1)statistically significant differences in clinical characteristics(gender,age)were observed among the glandular precursor lesion group,microinvasive adenocarcinoma group,and invasive adenocarcinoma group in patients with subsolid nodules(P < 0.05);(2)statistically significant differences in nodule size,irregular morphology,and marginal features(lobar sign,burr sign,pleural pulling sign)in the appearance of subsolid nodules among different pathological subgroups were observed among the 3 groups(P < 0.05);the differences in nodule site,marginal features(vacuolar sign,pulling bronchial dilatation sign)and nodule-lung interface were not statistically significant among the 3 groups(P > 0.05);(3)nodule type and vascular signs among the internal features of subsolid nodules in different pathological groups were significantly different among the 3 groups(P < 0.01),with type I and type II vascular signs being more common in the group of glandular precursor lesions Further analysis of the vascular signs in the microinvasive and invasive adenocarcinoma groups showed that there was no significant difference in the proportion of type II vascular signs between the two groups,while type III vascular signs were more common in the microinvasive adenocarcinoma group and type IV vascular signs were more common in the invasive adenocarcinoma group with statistically significant differences(P < 0.05).Conclusions:(1)Subsolid nodular adenocarcinoma of the lung(≤10 mm in diameter)is more common in female patients,and the malignancy of subsolid nodules increases with patient age and nodule diameter.(2)Partially solid nodules with irregular morphology with positive lobar signs and pleural traction signs combined with type III or IV vascular signs may suggest adenocarcinoma.(3)Pathological subtypes of subsolid nodules with glandular precursor lesions mainly show type I and II vascular signs,while microinfiltrative and infiltrative adenocarcinoma mainly show type III and IV vascular signs.The typing by observing vascular signs can help distinguish pathological subtypes of subsolid nodular adenocarcinoma of subcentimeter size,which may help guide clinicians to determine the surgical subsolid nodular adenocarcinoma of the lung(≤10 mm in diameter)nodes and provide a reliable basis for timely treatment.