Exploration Of The Regularity Of Anatomic Variations From The Perspective Of Dominant And Inferior Lung Segments

Background The existence of anatomical variation often brings challenges to pulmonary surgery.The traditional statistical methods of pulmonary segment anatomical structure mainly describe the occurrence frequency of the types of vascular anatomic variation in pulmonary segment,but do not report the occurrence regularity of vascular variation.As a result,we only know the cause,but do not know why.Meanwhile,we also found great differences in the volume distribution of lung segments in clinical work.Therefore,we proposed the hypothesis that there is a correlation between vascular variation in lung segments and differences in lung segment volume distribution,and systematically explored the morphologic regularity of anatomical variation in lung segments by studying the anatomical characteristics of lung segments in a large sample of Chinese.Methods In this study,the thin-slice enhanced CT data of our center were used for 3D reconstruction,and 800 cases were eventually included in the study model.Digitalized 3D virtual lung segment segmentation was carried out,and then the definition and naming of the dominant and inferior lung segments of both upper lobes and the regularity of anatomical variation were explored.Results In the changing process of the dominant and inferior segments,we found the corresponding regularity of the occurrence of anatomical variation,as follows: Right upper lobe: In the process of increasing volume of the anterior segment of the right upper lobe,the occurrence rate of the bifurcated type of bronchus(B1+2,B3)and the "Central vein type" gradually increased.And,the incidence of trunk inferior(Tr.inf)and ascending artery(A.asc)involved in anterior segment blood supply gradually increased.In the process of the continuous enlargement of the posterior segment of the right upper lobe,proportion of artery from trunk superior(A.sup)and recurrent artery(A.rec)participating in the blood supply of the posterior segment increased gradually.The incidence of "Anterior vein type" gradually increased.During the gradual increase in the volume of the apex segment of the right upper lobe,the occurrence rate of B1-deficient bronchus increased gradually.Left upper lobe: As the volume of apicoposterior segment of the left upper lobe grows,the proportion of the arteries of the bifurcated type(A1+2a+b,A1+2c)and the trifurcated type(A1+2a,A1+2b and A1+2c)gradually increased.As the volume of the lingular segment gradually increases,we can see: The proportion of mediastinal lingual artery increased gradually while that of interlobar lingual artery decreased gradually.The co-trunk type vein(V4+5)was more inclined to appear in the inferior lingual segment,and the bifid type vein(V4/5)was more inclined to appear in the dominant lingual segment.Conclusion This study is the first to clearly define the concept of dominant and inferior lung segments and fill in the blank of anatomical studies on lung segments.At the same time,we proposed that "dominant and inferior lung segments and anatomical variations are complementary to each other".This discovery,from the perspective of dominant and inferior lung segments,deeply analyzed the occurrence regularities of anatomical variation,and provided the first morphological explanation for the numerous and complex anatomical variation phenomena.Therefore,it is conducive to a deeper understanding and mastery of the anatomical variation of the segments to ensure the accuracy and safety of pulmonary segmentectomy.