Inter-multisegmental veins (IMSVs): a new positional indication for pulmonary segmentectomy.

Background: Positional indications for sublobar resection have been increasingly focused by clinical surgeons while the surgical strategies for cases involving inter-multisegmental veins (IMSVs) remain underreported. We want to further clarify the positional indications for sublobar resection in patients with clinical T1a-bN0 non-small cell lung cancer (NSCLC).

Methods: The clinical data of 686 patients from August 2021 to July 2022 were retrospectively analyzed. In the three-dimensional (3D) reconstruction images, we analyzed the prevalence and drainage patterns of typical IMSVs, specifically focusing on the lateral vein (Vl) in the upper lobes and the branches of the superior segmental vein (V⁶b) in the lower lobes. The potential association between lesion locations and surgical strategy was also analyzed.

Results: The prevalence of Vl, V⁶b2, and V⁶b3 was 58.5% (231/395), 98.3% (286/291), and 25.1% (73/291), respectively. Vl mainly drained into V²a+b (70/110, 63.6%) on the right and into V¹⁺²b+c (72/121, 59.5%) on the left. V⁶b2 and V⁶b3 mainly converged with other branches of the superior segmental vein. Limited resection was more feasible when the 2 cm simulated cutting margin of nodules did not involve IMSVs, or when lesions were located in the outer region. Multivariable logistic regression analyses identified four independent predictors for surgical procedure selection: (I) whether the 2 cm simulated cutting margin involves IMSVs; (II) diameter; (III) consolidation-to-tumour ratio (CTR); and (IV) depth ratio.

Conclusions: IMSVs exhibited high prevalences, with Vl showing diverse drainage patterns, while V⁶b2 and V⁶b3 displayed little variation. Depth ratio and the lesion's relative location to the IMSVs were identified as longitudinal and transverse positional indications, respectively, for sublobar resection in patients with clinical T1a-bN0 NSCLC.