Straight line sign: appearance and significance during CT portography.

Abstract

The computed tomographic (CT) angiograms of 44 patients who were being evaluated for possible hepatic surgery were studied. All patients were imaged with CT arterial portography (CTAP), delayed CT of the liver, and magnetic resonance (MR) imaging. All CTAP studies were evaluated for a "straight line," a linear variation in contrast within the liver. Sixteen patients (36%) demonstrated the straight line sign. All 16 had a mass at the proximal portion of the defect. Nine of 16 had defects that clearly correlated with portal venous distribution seen at limited digital angiography. Fourteen of the 16 patients showed loss of the straight line sign at delayed CT and/or MR imaging of the liver. These defects are thought to be due to vascular obstruction. The straight line sign will probably be seen more frequently as CTAP is more commonly used. Recognition of the sign is important in the evaluation of primary liver carcinomas, since it signifies that the tumor may be inoperable. Also, if metastatic disease is present, it alerts the surgeon to the proximity of the portal vein to the neoplasm.

Homogeneous enhancement of hepatic parenchyma: MR imaging during arterial portography versus CT during arterial portography

“…We excluded rounded, well-delineated areas of low attenuation and signal intensity diagnosed as the focal hepatic masses (Fig. 1) and defects limited peripherally by a straight line ending at the liver edge that was caused by decreased portal blood flow adjacent to the tumor [10] (Fig. 2).…”

Hepatocellular carcinoma: Findings on spiral CT during arterial portography

“…The presence of a straight-line sign [12], intra-or extrahepatic bile duct dilatation, hepatic parenchymal changes, vascular invasion, and extrahepatic spread were also determined. In addition, the presence or absence of opacified portosystemic collateral vessels was noted.…”

“…Several reports have described the CT features of HCC [2][3][4][5][6][7][8], but to our knowledge CT during arterial portography (CTAP) features of this tumor have received little attention in the radiologic literature. In most published papers, the goal of the study was focused on tumor detection [6,7,9], and in other studies HCCs were included in the different tumors studied and not treated with a particular emphasis [10][11][12]. Therefore, to date, a description of the CTAP findings of HCC is lacking in the radiologic literature.…”

Correlation of perfusion abnormalities on CTAP and immediate postintravenous gadolinium-enhanced gradient echo MRI

“…Large and segmental perfusion defects on CT arterial portography are attributed to the presence of a proximal obstruction to portal venous flow [1]. As contrast delivery on CTAP studies is delivered exclusively by portal veins, perfusion defects are consistent with regions of diminished or absent portal venous supply.…”

“…The presence of wedge-shaped perfusion defects on CT arterial portograms (CTAP) are a common occurrence, being reported in 15 -36% of studies [1,2]. Large and segmental perfusion defects on CT arterial portography are attributed to the presence of a proximal obstruction to portal venous flow [1].…”