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cbd diameter radiology

When endoscopy is nondiagnostic, patients often proceed to CT or fluoroscopic angiography. CT angiography (CTA) allows for evaluation of both the arterial anatomy and hepatobiliary parenchyma and is useful in planning endovascular interventions. Direct findings of hemobilia include contrast extravasation into the biliary tract or liver parenchyma. 34 Indirect findings may also help localize the bleeding, such as high attenuation hemorrhagic bile or thrombus within bile ducts or gallbladder, pseudoaneurysms, arteriovenous fistulas, vascular malformations, hepatic tumors, or evidence of blunt liver injury.

Hemobilia is a rare cause of upper gastrointestinal bleeding which results from a fistulous connection between the hepatic vasculature and biliary ductal system. Most cases develop as a complication of diagnostic or therapeutic hepatobiliary interventions (percutaneous transhepatic biliary drain (PTBD) placement, percutaneous and transjugular liver biopsy, transjugular intrahepatic portosystemic shunt, ERCP, and hepatobiliary surgery). 34 Hepatobiliary neoplasms account for the majority of noniatrogenic hemobilia. 35 Other etiologies include liver trauma, vascular malformations, inflammatory conditions, calculus disease, hemorrhagic cholecystitis and underlying blood dyscrasias. These patients generally receive an upper gastrointestinal bleeding workup with endoscopy. Visualization of blood arising from the ampulla or the presence of fresh blood in the second portion of the duodenum may indicate a biliary etiology.

Biliary tract injury is a rare complication of abdominal trauma, with a reported prevalence of 2.8–7.4% in patients sustaining blunt hepatic injury. 17,18 Injuries to the extrahepatic bile ducts usually result from acute deceleration and tend to occur at sites of anatomic fixation, such as the intrapancreatic portion of the CBD. Injuries to the intrahepatic bile ducts may be seen in the setting of parenchymal liver injury.

MRI imaging characteristics of ascending cholangitis include central intrahepatic biliary dilation with smooth ductal wall thickening and enhancement. Associated parenchymal inflammatory changes include patchy or peribiliary parenchymal enhancement (most apparent on arterial phase postcontrast imaging) and geographic, wedge-shape T2-hyperintense segments of inflamed tissue around the involved bile ducts (Figure 3). In acute suppurative cholangitis, dilated bile ducts filled with echogenic purulent material are observed on ultrasound; dense biliary contents are seen on CT. 10 Biliary contents will appear low signal relative to liver on T2-weighted MRI and intermediate signal on T1-weighted MRI. 15 A uni- or multiloculated collection with capsular or rim enhancement is characteristic for abscess formation on CT and MRI; coalescence of adjacent abscesses may result in a cluster sign. 16

Biliary leaks after liver transplant

CT is often the first-line imaging modality in the setting of trauma. Findings of bile duct injury are relatively nonspecific, and diagnosis often requires a high level of suspicion on the part of the radiologist. Secondary findings such as liver lacerations, focal peri- or intrahepatic fluid collections, ascites, and associated solid organ injuries may be the only indicators of bile duct injury at initial imaging. Follow-up imaging is often helpful; progressive growth of a well-circumscribed, low-attenuation perihepatic or intraparenchymal fluid collection suggests a biloma; persistent or increasing low-attenuation intraperitoneal fluid raises concern for bile leakage; peritoneal thickening and hyperenhancement may indicate biliary peritonitis 20

The problem with biliary obstruction is that the decreased biliary flow allows ascent of bacteria from the duodenum. Biliary obstruction may also lead to hepatovenous reflux and subsequent bacteremia. 13,14 Ascending cholangitis is associated with high mortality and requires emergent biliary decompression. Imaging in suspected ascending cholangitis helps confirm the presence, level and cause of obstruction and to identify potential complications such as suppurative cholangitis, parenchymal abscess, portal vein thrombosis, and biliary peritonitis. 3

Biliary complications remain a major source of morbidity after liver transplant, with an incidence of 5-15%, and are usually observed within the early postoperative period (≤3 months after surgery). 27,37,38 Potential complications include anastomotic and non-anastomotic strictures, leaks, stones, ampullary dysfunction, biliary necrosis, and cholangitis.

Hemobilia

Bile leaks typically manifest within one week of surgery, but may not become apparent for up to one month. CT and US may demonstrate free or loculated fluid but cannot reliably distinguish between bile leaks and other postoperative collections. As in the post-traumatic setting, hepatobiliary scintigraphy can provide functional information and demonstrate the presence of free or contained bile leakage. Delayed MRI imaging with hepatobiliary contrast agents may indicate the site of bile leak and help distinguish between fluid collections of biliary and nonbiliary origin by demonstrating contrast accumulation and communication with the biliary tree. MRI/MRCP may also delineate other postoperative complications, such as biliary strictures or retained stones.

Ultrasound is primarily utilized for follow-up of findings such as bilomas, but can be used to screen for the presence or absence of perihepatic and intrahepatic fluid collections, and ascites. 19,21

Cbd diameter radiology

Nuclear medicine imaging with scintigraphy and with SPECT/CT can be used to dynamically assess the gallbladder. Technicium-99 labeled mebrofenin is administered and taken up by bile producing cells and subsequently excreted into the biliary system. The patient is typically imaged at 1 h and at 4 h post-administration of radioisotope. A normal gallbladder will be well delineated as it fills with radioactive bile. In cases of cholecystitis or gallbladder obstruction due to an impacted stone in the cystic duct, the gallbladder will not be visualised as the radioactive will not accumulate within the gallbladder. If the gallbladder is not visualised, morphine analogues can be given to induce sphincter of Oddi contraction and aid gallbladder filling. Cholescintigraphy for acute cholecystitis has a sensitivity of 97% and a specificity of 94% [14]. This is actually superior to ultrasound; however, this technique is more expensive and time consuming and also confers a radiation dose to the patient and staff and thus is generally not a first-line investigation (Fig. 6).

Axial (a), coronal (b) and sagittal (c) contrast-enhanced CT of the abdomen. There is gallbladder wall thickening and pericholecystic fluid consistent with acute cholecystitis. There is marked expansion and oedema surrounding the falciform ligament (arrows). Appearances are due to thrombophlebitis of a recanalised umbilical vein

Imaging in gallstone-related disease

On CT, a high percentage of cholesterol stones are hypoattenuating relative to bile (Fig. 3) and calcified stones are hyperattenuating relative to bile (Fig. 4); however, a significant proportion of stones are iso-attenuating relative to surrounding bile and may be radiologically occult on CT. Dual-energy CT has been shown to improve detection of gallstones with low KV imaging and base substance imaging, such as calcium-based and lipid-based imaging, which is more sensitive at detecting gallstones than traditional higher KV imaging. Despite these imaging advances, CT remains inferior to ultrasound at assessing the gallbladder and results in a significant radiation dose to the patient. As such, ultrasound is the imaging modality of choice for initial assessment of suspected gallbladder pathology. CT however can be very effective at assessing extra-biliary gallstone pathology and complications arising from gallstone pancreatitis and cholecystitis [8, 10].

Gallbladder

The broad spectrum of gallstone-related disease can be broken down based on the anatomical locations in which they occur (Fig. 8).