Lymphatic and vascular anatomy define surgical principles for bowel-sparing radical treatment of ileal tumors

Abstract

Background: There is no consensus on the level of vascular ligation and the extent of lymphadenectomy in the treatment of ileal tumors. This study aims to define lymphovascular bundles of the terminal ileal artery (TIA) and subsequent ileal arteries. It also aims to extrapolate results from two distinct methodologies to define the level of arterial ligation and the dissection area for radical and bowel-sparing surgery.

Methods: Analysis of 3D-CT mesenteric vascular reconstructions of 104 operated patients. The second dataset consisted of 5 human cadavers for anatomical dissection. In one case, harvested viscera underwent the superior mesenteric artery (SMA) perfusion after ligation of the TIA.

Results: The calibers of the first three ileal arteries were: 2.67 ± 0.98 mm, 2.22 ± 0.78 mm, 2.31 ± 1.24 mm. The distances from the first three ileal arteries to the ileocolic artery (ICA) origin were: 12.45 ± 8.79 mm, 27.45 ± 13.47 mm, and 43.04 ± 16.94 mm. The SMA trifurcated in 61 (59%) of cases and bifurcated in 43 (41%). In 89 cases, the combined ICA + first jejunal artery caliber (6.7 ± 1.6 mm) was greater than the TIA caliber (4.84 ± 1.42 mm). The ileal artery lymphatic clearances were 0.85 mm to the preceding vessel. In the D3 volume at the ICA origin, 3-8 lymph nodes were observed. Internal calibers of the small bowel marginal artery, after selective TIA ligation and the SMA perfusion, were: proximal jejunal part 0.417 mm and distal ileal part 0.291 mm.

Conclusions: Ileal tumors are irrigated through the TIA, which can be ligated without consequences. Lymphadenectomy should encompass the adjacent vessels (1st jejunal artery, ICA) and can include the central nodes (D3 volume) at the surgeon's preference. Preserving the adjacent vessels and the marginal artery is paramount for bowel-sparing surgery.

Keywords: D3 volume; Ileal artery; Ileal tumor; Lymphatic anatomy; Operative technique.

Fig. 1

Anatomical dissection of the lymph vessels at the level of the SMA tripod. ICA ileocolic artery, JA jejunal artery, IA (IA2, i.e., second ileal artery), TIA terminal ileal artery, a terminal portion of superior mesenteric artery below ICA origin, D3 volume [21]

Fig. 2

Mimics segmentation of the perfused excisate’s paraintestinal marginal artery. SMA superior mesenteric artery, ICA ileocolic artery, JA1 first jejunal artery, IA1 first ileal artery, TIA terminal ileal artery, a terminal portion of the superior mesenteric artery below the ICA origin

Fig. 3

The D2 and D3 levels of dissection and the proposed technique of extended mesenterectomy. ICA ileocolic artery, JA jejunal artery, IAs ileal arteries, TIA terminal ileal artery, a terminal portion of Superior Mesenteric Artery below ICA origin, TIVT terminal ileal venous trunk (terminal branch of Superior Mesenteric Vein), ICV ileocolic vein, SMA superior mesenteric artery, SMV superior mesenteric vein, marginal artery paraintestinal ileal arcade, Tu tumor, GTH gastrocolic trunk of henle, MCA middle colic artery. Blue line—D2 dissection line- Lymphadenectomy should follow the ICA on one side and the 1st jejunal artery on the other, to the first arcade. Red dashed line—D3 volume dissection line

Fig. 4

Anatomical illustration of the superior mesenteric artery and vein: branching pattern and spatial relationships. Illustration on the left: ICA posterior to the SMV, TIA anterior to the TIVT. Illustration on the right: ICA anterior to the SMV, TIA posterior to the TIVT. ICA ileocolic artery, JA jejunal artery, IA ileal artery, TIA terminal ileal artery, TIVT terminal ileal venous trunk, ICV ileocolic vein, SMA superior mesenteric artery, SMV superior mesenteric vein, marginal artery paraintestinal ileal arcade, Tu tumor, GTH gastrocolic trunk of Henle, MCA middle colic artery, JV jejunal vein, SV splenic vein, IMV inferior mesenteric vein