Jaundice





Anatomy, embryology, pathophysiology





  • Jaundice refers to the clinical sign of hyperbilirubinemia (>2.5 mg/dL), often manifesting with yellowing of the cutaneous surfaces, sclerae conjunctiva, and oral mucosa.



  • Largely subdivided into nonobstructive (prehepatic and hepatic etiologies) and obstructive (posthepatic etiologies).



  • Prehepatic causes:




    • Hemolytic anemia.



    • Hypersplenism.



    • Artificial heart valves.



    • Sepsis and low perfusional states.




  • Hepatic causes:




    • Hepatocellular injury (e.g., viral hepatitis, drug-induced hepatitis, cirrhosis).



    • Infiltrative disease (malignancy, steatohepatitis).



    • Inherited conditions (e.g., Gilbert syndrome, Crigler-Najjar syndrome, etc.).




  • Posthepatic or obstructive jaundice:




    • Benign causes:




      • Choledocholithiasis.



      • Biliary stricturing (infectious/inflammatory/iatrogenic causes, such as primary sclerosing cholangitis, posttrauma, postsurgical).



      • Extrabiliary compression (e.g., Mirrizzi syndrome, fluid collections, pancreatic pseudocysts).




    • Malignant causes:




      • Pancreatic, gallbladder, hepatocellular, and biliary malignancies.



      • Portal lymphadenopathy (metastatic, infectious, or primary lymphoproliferative disorder).





Techniques


Ultrasound





  • Ultrasound (US) is the preferred initial diagnostic modality for the assessment of the hepatobiliary system, particularly in the setting of acute right upper quadrant pain.



  • US has a sensitivity of 48% to 100% and specificity of 64% to 100% for acute cholecystitis.



  • The sensitivity of US in detecting gallstones is excellent (sensitivity >95%).



  • The sensitivity of US in detection of biliary dilatation is 55% to 91%, demonstrating improved sensitivity with higher serum bilirubin and longer duration of jaundice.




    • Common hepatic duct: Measured inner-inner wall, should measure less than 7 mm in patients under 60 years of age and less than 10 mm in patients older than 60 years of age.



    • Common bile duct (CBD): In patients in their 40s, the normal value is about 4 mm, with the normal mean diameter increasing 1 mm per decade. The upper normal limit is 8.5 mm (or 10 mm postcholecystectomy).




  • US has similar sensitivity to computed tomography (CT) for detecting choledocholithiasis (75% in the dilated ducts, 50% in the nondilated ducts).



  • US can be used for hepatocellular disease screening (such as hepatocellular carcinoma [HCC] screening, performed every 3–6 months).



Computed tomography/computed tomography-cholangiography





  • Routine CT abdomen pelvis can evaluate the hepatobiliary system with a large field of view, with highly precise imaging during 3+ phases of hepatic enhancement.



  • Optimal acquisition timing, in conjunction with thinner collimation, allows for improved lesion detection, lesion characterization and careful staging of various malignant etiologies (e.g., pancreatic malignancy, hepatic metastases, etc.).



  • Routine contrast enhanced CT is moderately sensitive for the detection of choledocholithiasis (sensitivity 65%–88%).



  • Routine contrast enhanced CT offers rapid and accurate staging.



  • CT cholangiography:




    • Biliary tree imaging for evaluation of postoperative bile leaks, strictures, choledocholithiasis, obstructing lesions and delineation of the biliary anatomy.



    • Uses oral or intravenous (IV) cholangiographic contrast agents (e.g., IV meglumine iotroxate/Biliscopin).



    • Contraindicated in severe hepatic, thyroid or renal dysfunctions, bilirubin less than 30 mmol/L, or iodinated-contrast allergies; radiation exposure.




Magnetic resonance cholangiopancreatography ( fig. 19.1 )





  • Noninvasive way to visualize intra-/extrahepatic biliary system and pancreatic duct.



  • Performed on a 1.5 T or higher magnetic resonance imaging (MRI) scanner, using phased-array body coils.



  • Requires 4 hours of fasting before the examination to reduce gastrointestinal secretions, minimize gallbladder motility/motion artifact and optimize gallbladder filling.



  • Other modified techniques include:




    • Secretin-stimulated magnetic resonance cholangiopancreatography (MRCP): Allows temporary dilation of the pancreatic duct, thus improving exocrine pancreatic reserve assessment and enhancing diagnostic capabilities of MRCP in pancreatic disorders.



    • Functional MRCP: Improves anatomic delineation and enhancing of abnormal pancreaticobiliary variations and evaluation of pancreatic exocrine function.





Fig. 19.1


Conventional magnetic resonance cholangiopancreatography pancreaticobiliary anatomy. The common bile duct and the pancreatic duct most commonly drain into the major papilla.


Protocols





  • Evaluation of GB anatomy:




    • Axial and coronal breath-hold steady state fast spin echo (SE) T2-weighted images.



    • Axial respiratory-triggered fat-suppressed T2-weighted imaging.



    • Axial T1-weighted gradient-echo breath-hold in phase and out of phase.




  • MR cholecystography.




    • Oblique radial steady state fast SE T2 weighted.



    • Oblique right and left anterior steady state fast SE.



    • Three-dimensional fat-saturated MRCP.




  • Contrast enhanced MR cholecystography.




    • 0.05 to 0.1 mL/kg of gadolinium injected over 1 to 2 min at 2 mL/s.




  • Dynamic contrast enhanced study.




    • 0.1 mmol/kg of gadolinium based contrast agent, at 2 mL/s, to cover the liver (run before, at 25 s, 60 to 70 s and 120 s after bolus administration).




Specific disease processes


Choledocholithiasis



Jun 13, 2021 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Jaundice
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