PMC8179784_01
Initial presentation to the emergency department with diffuse abdominal pain and diarrhea. CT abdomen and pelvis with oral contrast only. Axial image (a) displays colonic mural thickening (star) and adjacent pericolonic fat stranding (arrow) most pronounced in the descending colon with ascites in the left paracolic gutter (circled). Coronal image (b) displays left hemicolon mural thickening (star) and adjacent pericolonic fat stranding (arrow) in the region of the IMA distribution. Suggestion of a prominent vascular structure is noted medial to the descending colon (arrowhead).
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fig1
Significant colonic wall thickening and pericolonic inflammatory stranding of the entire colon with sparing of the cecum, concerning for pancolitis with mild ascites, were noted on the initial CT scan (Figures 1(a) and 1(b)).
CTA of the abdomen and pelvis (early arterial phase images) 4 days after initial presentation. Maximum intensity projection (MIP) coronal image (a) displays prominent tortuous third-order branches of the IMA within the left abdomen adjacent to the descending colon (arrows). The descending colon appears thickened (star) with persistent pericolonic fat stranding. MIP coronal image (b) displays the superior rectal artery (arrowhead) leading to a tangle of vessels, the presumed nidus (arrow). MIP coronal image (c) exhibits aneurysmal dilatation of a venous outflow tract contiguous with outflow from the sigmoid territory (arrow). 3D volume rendered coronal oblique image (d) displays the prominent tortuous vascular structure in the inferior mesenteric vascular territory (arrow).
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The CTA also displayed tortuous vascular lesions in the IMA territory with early filling veins concerning for AVMs (Figures 2(a)-2(d)).
MRA of the abdomen with and without gadolinium 7 weeks after initial presentation. Coronal T1-weighted fat-suppressed VIBE late arterial phase postcontrast images display (a) a prominent marginal artery connecting the middle colic artery to the left colic artery (arrow) and also reveal (b) a cluster of early draining veins in the region of the sigmoid colon mesentery (arrow).
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The MRA exhibited an inferior mesenteric artery distribution of multiple focal aneurysmal vessels in the left colonic mesentery (Figures 3(a) and 3(b)).
Mesenteric angiogram demonstrates subselection of the IMA in order of progressive filling which eventually displays three AVM niduses arising from the left colic artery, sigmoid artery, and superior rectal artery with respective dilated venous outflow tracts. Minimal opacification is seen in the presumed venous outflow tracts (a) of the AVM niduses at the sigmoid (red arrow) and superior rectal artery (arrowhead). Progressive opacification (b) is noted in the sigmoid (long arrow) and superior rectal niduses (arrowhead); opacification of the left colic nidus is demonstrated (short arrow). Ectatic venous outflow tracts of the left colic (c) (short arrow), sigmoid (long arrow), and superior rectal (arrowhead) AVM niduses are seen. Washout of the venous outflow tracts of the three AVM niduses (d) is demonstrated with similar labeling as (b).
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Arteriogram demonstrated a total of 3 AVMs, each individually supplied by branches of the IMA (Figures 4(a)-4(d)).
Intervention. (a) Coiling of left colic artery branches (arrows) prior to Onyx injection into the left colic artery (arrowhead) in order to prevent Onyx progression into the marginal artery. (b) Onyx embolization of the superior rectal artery (short arrow). Minimal filling of nontarget branches is also displayed (arrowhead). Onyx glue is seen through the AVM in the outflow vein of the left colic and superior rectal niduses. Inadvertent dissection of the IMA is demonstrated with stagnant contrast present in the IMA (long arrow). (c) Coils were deployed in two branches of the sigmoid artery to prevent Onyx filling of the marginal artery (arrows).
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The left colic artery was divided into two distal omental branches, which were coil embolized prior to Onyx liquid embolic instillation of the left colic artery (Figure 5(a)). The superior rectal artery was divided into two distal branches; both of which supplied the largest of the three AVMs, which was embolized with Onyx injection into the superior rectal artery proximal to both of the aforementioned branches (Figure 5(b)). The sigmoid artery, similar to the left colic, had two distal omental branches that were coil embolized before Onyx liquid embolic instillation (Figure 5(c)).