For that reason, it is the most common first-line imaging modality used when obstructive jaundice is suspected clinically [32]. US is used to determine the presence of obstructive jaundice by depicting dilated bile ducts, with reported sensitivities ranging from 32% to 100% and specificities of 71% to 97% [20-25]. The cause of the obstruction (benign or malignant) is less often definitively seen on US, particularly in the distal CBD, with reported sensitivity for Jaundice detection of a distal CBD stone ranging from to 22.5% to 75% [20-22]. False-negative US studies are typically due either to the inability to visualize the extrahepatic biliary tree (often from interposed bowel gas or large body habitus) or to the absence of biliary dilation in the presence of acute obstruction. US is less accurate than either CT or MRCP for determining the site and the cause of obstruction [20,22,34-36,76]. MRI Abdomen MRI is an advanced noninvasive imaging technique that uses powerful magnets to obtain high-contrast images of the abdomen; it is more time consuming (typically requiring imaging acquisitions of 30 minutes) than either CT or US but offers improved contrast resolution over other modalities. MRI can accurately demonstrate both the site and cause of biliary obstruction [34,46]. MRI can be performed with a variety of specific sequences, one of which is a heavily T2-weighted fluid-sensitive 3-D sequence, which is acquired over a 3- to 5-minute period in the coronal plane using respiratory triggering or diaphragmatic gating, also called MRCP [47]. Source images from a 3-D MRCP sequence have been shown to be useful in depicting the 3-D anatomy of the biliary and pancreatic ducts [48,49]. For detection of ductal calculi, MRI (with or without MRCP sequences) is more sensitive than CT or US [26,34,50-52].
Jaundice. For that reason, it is the most common first-line imaging modality used when obstructive jaundice is suspected clinically [32]. US is used to determine the presence of obstructive jaundice by depicting dilated bile ducts, with reported sensitivities ranging from 32% to 100% and specificities of 71% to 97% [20-25]. The cause of the obstruction (benign or malignant) is less often definitively seen on US, particularly in the distal CBD, with reported sensitivity for Jaundice detection of a distal CBD stone ranging from to 22.5% to 75% [20-22]. False-negative US studies are typically due either to the inability to visualize the extrahepatic biliary tree (often from interposed bowel gas or large body habitus) or to the absence of biliary dilation in the presence of acute obstruction. US is less accurate than either CT or MRCP for determining the site and the cause of obstruction [20,22,34-36,76]. MRI Abdomen MRI is an advanced noninvasive imaging technique that uses powerful magnets to obtain high-contrast images of the abdomen; it is more time consuming (typically requiring imaging acquisitions of 30 minutes) than either CT or US but offers improved contrast resolution over other modalities. MRI can accurately demonstrate both the site and cause of biliary obstruction [34,46]. MRI can be performed with a variety of specific sequences, one of which is a heavily T2-weighted fluid-sensitive 3-D sequence, which is acquired over a 3- to 5-minute period in the coronal plane using respiratory triggering or diaphragmatic gating, also called MRCP [47]. Source images from a 3-D MRCP sequence have been shown to be useful in depicting the 3-D anatomy of the biliary and pancreatic ducts [48,49]. For detection of ductal calculi, MRI (with or without MRCP sequences) is more sensitive than CT or US [26,34,50-52].