Preoperative Computed Tomography Colonography‐Angiography for Vascular Mapping to Guide and Standardize <scp>D3</scp> Lymphadenectomy in Right‐Sided and Transverse Colon Cancer

ABSTRACT Background In right hemicolectomy (RHC) and left‐sided transverse colectomy (TC), D3 lymph node dissection is oncologically significant but technically demanding because of marked vascular variability. Standardization requires reliable preoperative anatomical assessment. We evaluated colic vascular anatomy and quantified D3 dissection distance using computed tomography colonography‐angiography (CTC‐A). Methods We retrospectively analyzed 591 patients with primary right or transverse colon cancer who underwent preoperative CTC‐A during 2014–2023. Arterial origins, venous drainage, and positional relationships around the superior mesenteric artery (SMA) and vein (SMV) were classified. After excluding aberrant cases, branching patterns relevant to D3 dissection were categorized and D3 distances measured along the SMA centerline using curved planar reformation images. Results An accessory middle colic artery (aMCA) was present in 38.1% of patients (SMA‐derived, 76.4%). The MCA originated as a common trunk in 77.8% and as independent branches in 19.0%. The right colic artery (RCA) was observed in 41.8%. Four reproducible vascular patterns each were identified for RHC and TC. In RHC ( n = 490), independent‐origin MCA was consistently associated with shorter D3 distances (RCA‐present, 22.5 vs. 27.5 mm, p = 0.012; RCA‐absent, 16.5 vs. 20.5 mm, p &lt; 0.001). In TC ( n = 524), the aMCA originated dorsal to the pancreas in ~23%, and D3 distance was shorter in aMCAs with an independent‐origin MCA (18.0 vs. 25.0 mm, p &lt; 0.001). Conclusions High‐resolution CTC‐A yielded a single‐modality, operation‐oriented mapping integrating tumor location with mesenteric arteriovenous anatomy. Pattern‐based classification and objective D3 distance estimation may support preoperative planning and help establish standardized, safer D3 lymphadenectomy for right‐sided and transverse colon cancer.