Ultrasonic Study of the Normal and Dilated Biliary Tree

Abstract

With the advent of real time scanners, segments of the normal biliary tree can now be seen regularly. Normally, the biliary junction is narrower than the portal vein or the portal division. With early dilatation of the bile ducts the diameters of the two systems tend to equalize. Thus, the presence of two parallel ducts with similar diameters is pathologic. As the dilatation of the biliary tree progresses, the portal system may become flattened, thus reversing the initial proportion between the diameter of the biliary junction and that of the biliary tree.

Role of US in the Detection, Characterization, and Staging of Cholangiocarcinoma

“…True intrahepatic ductal dilatation is always a significant finding at US, particularly when the "shotgun" ("parallel channel") sign is seen ( Fig 6) (13,14). This sign represents a dilated duct in n Scientific Exhibit Volume 19 Number 5 association with a portal vein branch within a peripheral portal triad.…”

Sonographic differentiation of enlarged hepatic arteries from dilated intrahepatic bile ducts

“…3) This appearance has been referred to as the double-barrel sign, parallel-channel sign, and the shotgun sign [5][6][7].…”

“…When the intrahepatic ducts are markedly dilated, the "too-many-tubes" sign is easily recognized [4]. Milder dilatation of the intrahepatic ducts has been described as the "doublebarrel" appearance [5], the "shotgun" sign [6], and the "parallel-channel" sign [7]. Despite its potential clinical importance, two parallel tubular structures may be identified within the substance of the liver in patients without intrahepatic bile duct dilatation.…”

Sonographically visible intrahepatic bile ducts in healthy elderly

“…1 The sonographic observation of intrahepatic bile duct dilatation in a few asymptomatic elderly people prompted me to study 179 men in a nursing home near Tehran, Iran. Abdominal sonography was performed using a Picker Type LS2400 ultrasound scanner (Picker International, Munich, Germany) with a 3.5-MHz linear-array transducer, with subjects in a fasting state.…”