The utility of image‐directed Doppler ultrasound in the evaluation of the “parallel channel” sign

Abstract

Ultrasound has been shown to be an excellent modality in the evaluation of the jaundiced patient, proving extremely valuable in differentiating surgical (obstructive) from medical jaundice based on the presence or absence of ductal dilatation.1 The sonographic finding of intrahepatic dilatation has been termed the “double barrel,”2 “shotgun,”3, or “parallel channel”4 sign. This refers to visualization of dilated intrahepatic bile ducts with the normally visualized portal venous radicles. Subsequent to its initial description, this sign has also been observed in patients with increased hepatic arterial flow.5,6 In these patients, one of the components of the parallel channel sign represents the prominent intrahepatic artery. In the following case report, we demonstrate the use of pulsed Doppler to help make this distinction.

Percutaneous transhepatic biliary drainage guided by color doppler echography

“…Pulsed Doppler ultrasound has been used to overcome this limitation of gray scale B-mode image in identifying the small vessels. Berland et al [5] and Levy et al [6] differentiated the bile ducts from the intrahepatic vessels by the presence of the pulsed Doppler spectrum. McGahan et al [7] safely performed aspiration liver biopsy with the pulsed Doppler technique.…”

Color Doppler sonography avoids misinterpretation of the ?parallel channel sign? in the sonographic diagnosis of cholestasis

“…Enlarged hepatic artery branches have been associated with alcoholic liver disease and liver cirrhosis. [6][7][8][9][10] Color Doppler sonography is a reliable, noninvasive method to detect blood flow in intraabdominal vessels and vessel-like structures. 10 This modality can distinguish between bile ducts (without blood flow) and small intrahepatic vessels that may be misinterpreted as bile ducts on gray-scale sonograms.…”