Study On Anatomy And Variation Of Right Inferior Pulmonary Vein With Multi-Slice CT

ObjectiveTo investigate the distribution and confluence pattern classification of the right inferior pulmonary vein branch by systematic analysis of the right lower lobe vein using multi-slice spiral CT angiography(MSCTA)images combined with reprocessing techniques,and to discuss the related of clinical value application.Materials and methodsThe imaging data of 100 healthy adults who underwent MSCTA examination in the Affiliated Hospital of Taishan Medical University from March 2017 to July 2018 were retrospectively analyzed,including 54 males and 46 females with the age of 24-86(58.9 ±13.54)years.The raw data of images were transmitted to the post-processing station for volume rendering(VR)and multiplanar reformation(MPR).The VR images of pulmonary veins were observed from different angles and directions,and the number,distribution and confluence of the branches of right inferior pulmonary vein were observed on the MSCTA images,then were named and typed.ResultsThe whole convergence patterns of the right inferior pulmonary veins include RLL type Ⅰ(2 stems),RLL type Ⅱ(3 stems),RLL type Ⅲ(4 stems),accounting for 67%(67/100),28%(28/100)and 5%(5/100)respectively.Type Ⅰwas the most common pattern,with 2 ways of confluence patterns and 5 subtypes.According to the lengths of the right inferior pulmonary vein and the common basal vein were divided into RLL Ⅰ a(37%),RLL Ⅰ b(28%),RLL Ⅰ c(2%)and RLL Ⅰ a1(27%),RLL Ⅰ a2(10%),RLL Ⅰ b1(16%),RLL Ⅰ b2(12%).Whereas Type Ⅱ was the most complex pattern,with 6 ways of confluence patterns and 7 subtypes,i.e.type Ⅱ a+Ⅱ B b(19%),type Ⅱ c(3%),type Ⅱ d(2%),type Ⅱ e(2%),type Ⅱ f(1%)and type Ⅱ g(1%).Type Ⅲ was rare,with 4 ways of confluence patterns and 4 subtypes,namely,type Ⅲ a(2%),type Ⅲ b(1%),type Ⅲ c(1%)and type Ⅲ d(1%).However,there were some other rare variations: the ectopic middle lobe vein(ectopic V4,ectopic V4+V5)and the ectopic superior pulmonary vein(ectopic V2),accounting for 7%(7/100)and 4%(4/100),respectively.Moreover,Superior segmental vein(V6)was divided into single-stem type and two-stem type,accounting for 88%(88/100)and 12%(12/100)respectively.Mediobasal segmental vein(V7)was the smallest basal vein,the confluence patterns of which were irregular,and a total of 10 patterns were counted.Ventrobasal,laterobasal,and dorsobasal segmental veins(V8,V9,V10)had bifurcation,trifurcation and quadrifurcation types,accounting for 95%(95/100),4%(4/100)and 1%(1/100)respectively.The simple bifurcation type was divided into two drainage subtypes,V8+V9 and V10,V8 and V9+V10,accounting for 56%(56/100)and17%(17/100)respectively;and the split type also was divided into two drainage subtypes,V8+V9+V10 and V10,V8+V9 and V9+V10,accounting for 12%(12/100)and 10%(10/100)respectively.ConclusionThe drainage and confluence patterns of the right inferior pulmonary veins are complex and variable,MSCTA combined with post-processing technique can clearly show the anatomy and variation of the right inferior pulmonary vein branches.And the distribution of pulmonary vein branches can be clearly observed before operation,which provides safety guarantee for thoracoscopic anatomical segmentectomy.