PMC5774732_01
Abdominal CT angiography of a cat with congenital absence of the portal vein. (a) Oblique transverse multiplanar reformatted image through the porta hepatis. The portal vein, normally located dorsal to the hepatic artery branches, is absent and the hepatic artery (HA) is enlarged. There is patchy enhancement of the liver parenchyma and intrahepatic portal vein branches are absent. Contrast fills the intrahepatic caudal vena cava (CdVC). (b) Oblique transverse multiplanar reformatted image through the porta hepatis of a normal cat. The large-diameter terminal portal vein (PV) is seen ventral and slightly to the left of the CdVC. The PV spirals ventrally and to the right before dividing conspicuously into the lobar left and right portal vein branches (green arrowheads). The hepatic parenchyma enhances homogeneously
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There was no portal vein at the level of the porta hepatis and intrahepatic portal branches were not recognised (Figure 1).
Abdominal CT angiography of a cat with congenital absence of the portal vein. (a) Oblique parasagittal multiplanar reformatted image at the level of the left kidney showing communications between portal tributaries and systemic veins and the prehepatic caudal vena cava (CdVC). The coeliac artery (Ca) is increased in diameter compared with the cranial mesenteric artery (CMa). An aberrant segmented paracaval vessel (A) lies to the left of the CdVC and ventral to the aorta (Ao). The cranial mesenteric vein (green arrowhead) enters the paracaval vessel cranially where it merges with the CdVC. The splenic vein (blue arrowhead) is tortuous and enters the ventrocaudal aspect of the aberrant paracaval vessel immediately ventral to the termination of the left renal vein (LRv) in the same vessel. The left gonadal vein (Gv) enters the most caudal aspect of the paracaval vessel. Yellow arrowhead - left adrenal. (b) Dorsal multiplanar reformatted image. Note the aneurysmal paracaval vessel (A) to the left midline and the segmental dilation of the prehepatic CdVC cranial to the point at which the paracaval vessel merges with the CdVC. The LRv and left Gv terminate in the caudolateral and caudal aspect of the paracaval vessel, respectively. Asterisks indicate the adrenals. Cv = colic vein. (c) Transverse oblique multiplanar reformatted image. The cranial mesenteric vein (Mv) remains paired with the CMa to the mesenteric root and enters the paracaval vessel (A) on the left where it merges with the CdVC. The phrenicoabdominal vein (yellow arrowhead) is enlarged and varicose and courses ventral to the left adrenal (asterisk) before entering the mid-segment of the paracaval vessel ventrally on the left. Sv = splenic vein
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It entered the cranial aspect of the paracaval vessel (Figures 2 and 3).
(a) Volume-rendered three-dimensional reformatted image from a left lateral perspective of a cat with congenital absence of the portal vein demonstrates enlargement of the coeliac artery (CA) vs the cranial mesenteric artery (CMa). The cranial mesenteric vein (red arrowhead) enters the left side of the paracaval vessel and caudal vena cava (CdVC) immediately caudal to the CMa. A cranial left adrenal artery branch (+) arises from the CA, communicating with the varicose left phrenicoabdominal vein (PAv). The PAv extends ventral to the left adrenal (asterisk) entering the mid-segment of the paracaval vessel on the left. The tortuous splenic vein (SV) terminates on the caudal margin of the paracaval vessel. A segment of the aorta (Ao) has been removed from the reconstruction to visualise the vessels terminating in the paracaval aneurysm better. (b) Volume-rendered three-dimensional reformatted image from a ventral perspective shows the tortuous splenic vein (blue arrowheads and SV) entering the left caudal aspect of the paracaval vessel ventral to the termination of the left renal vein (LRV). The left gonadal vein (Gv) terminates in the most caudal aspect of the paracaval vessel. The anatomy of the cranial mesenteric artery and vein (CM a&v) is abnormal. The vessels remain paired both returning to the mesenteric root. Sa = splenic artery
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It entered the cranial aspect of the paracaval vessel (Figures 2 and 3).