imaging in obstrucctive biliopathy .pptx

Imaging in Obstructive Biliopathy

1. IMAGING APPROACH TO OBSTRUCTIVE BILIOPATHY DR. KEZIA TYAGI

2. NORMAL ANATOMY

3. Pathophysiology B lockage of the bile duct system- impaired bile flow from the liver into the intestinal tract occur anywhere along the path- hepatic dysfunction, renal failure, nutritional deficiencies, bleeding problems, and infections ↑ bilirubin and alkaline phosphatase levels J aundice and P ruritis . C onjugated bilirubin is excreted- dark colour urine I nability of bilirubin to reach the intestinal tract - pale colour ed stools. 

4. GOAL OF IMAGING

5. Causes

6. IMAGING MODALITIES

7. ULTRASOUND Initial modality Advantages: Cheap, Non-invasive, Easily available, No radiation and Dynamic evaluation

8. TECHNIQUE a Subcostal view in suspended inspiration proximal common bile duct and porta hepatis are best seen on a subcostal view distal common bile duct is best evaluated by using the epigastric window An impacted calculus can be detected by slight rotation of the transducer L imitations – Excessive bowel gas and body habitus

9. CT

10. Goal of imaging in malignancy- resectability In malignant hilar block- Proximal extent Patency of portal vein Presence of secondaries Lower obstruction (due to periampullary or pancreatic carcinoma) tumor size, vascular involvement, lymph node and hepatic metastasis higher accuracy than ultrasound and MRI in diagnosis and determination of resectability does not have similar accuracy in assessing resectability of cholangiocarcinomas , limited in detecting small peritoneal deposits, secondaries in normal sized nodes and the intraductal extent of tumor

11. Calculi Partially calcified Bilirubinate in a sufficient quantity- hyperattenuation Insensitive to cholesterol calculi Seen as soft tissue density or a ring like density surrounded by lower density bile Non-contrast CT Thin sections with a collimation <2.5 mm and tube kvp at 140 kv not the preferred modality for detection of biliary calculi. reported sensitivity of 96–100% in detection of obstruction and level of obstruction is identified in nearly all cases whereas cause is identified in 70% Disadvantage- radiation and use of contrast

12. CT-IV Cholangiography very limited availability of the contrast (available in a few countries only, not available in India) Contrast has certain amount of toxicity, the examination has limited indications, in some cases of live hepatic donation for transplantation, to evaluate biliary anatomy Intravenous contrast that is preferentially excreted by liver is given by slow infusion followed by CT after 30 minutes. Opacification of bile ducts is noted. The contrast used is Meglumine iotroxate ( BiliscopinTM ) which has a better safety profile, than other IV biliary agents. The technique requires normal liver function and fails in patients with elevated bilirubin levels. CT intravenous cholangiography (CT-IVC) is a functional study as there is excretion and passage of contrast into the bile ducts

13. Magnetic Resonance Cholangiopancreatography (MRCP) Primary imaging modality for evaluating the biliary ducts and pancreatic duct. C an be done in jaundiced patients unlike CT-IVC. Contrast material is not routinely required and there is no sedation required preferred modality in pregnant patients Performed on a 1.5 T or higher magnetic resonance im- aging (MRI) scanner, using phased-array body coils. 4 hours of fasting prior to reduce GI secretions, minimize gallbladder motility/motion artifact and optimize gallbladder filling. two most commonly used sequences- T2-weighted turbo spin echo sequence and 2D single shot fast spin echo (SSFSE) 3D respiratory triggered fast spin echo provides greater details with 3–4 minutes acquisition Luminal abnormalities better evaluated with thin slab images

14. 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).

15. Diagnostic pitfalls - L ocalised signal voids caused by surgical clips and intraductal gas or blood. Bile flow voids may mimic small stones ( bile flow voids centrally placed with less well-defined margins) Longer Acquisition times - more prone to motion and respiratory artefacts. Indention by an adjacent artery; usually the right hepatic artery may mimic a stricture All signal voids should be seen in at least two orthogonal planes for a confident diagnosis of calculus.

16. Sensitivity of MRI in differentiating benign and malignant stricture varies between studies (30–98%). Malignant strictures long, irregular with asymmetric dilatation of the biliary radicals and there may be presence of a mass. Benign strictures are short in length, show gradual smooth tapering with a regular border. MRI and MRCP has a higher sensitivity than CT in determining nature of hilar stricture. Lesions at the ampulla may however, be missed. The MRCP has an advantage over endoscopic retrograde cholangiopancreatography (ERCP) that it demonstrates biliary ducts above the level of stricture, which ERCP cannot useful in patients with biliary enteric reconstructions Biggest drawback - no therapeutic intervention is possible. MRCP has a reported accuracy of 96–100% for level and 90% for cause of obstruction

17. CONTRAST-ENHANCED MAGNETIC RESONANCE CHOLANGIOGRAPHY T1W imaging done after (IV) administration of contrast gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid-Gd-EOB-DTPA/Gadobenate disodium D one in the hepatobiliary phase

18. ENDOSCOPIC ULTRASOUND This is performed by combined endoscopy and ultrasound Endoscopes are introduced via transgastric or transduodenal route and using a water balloon system for acoustic coupling. Frequency range is between 7.5 MHz and 12 MHz, with a depth of penetration of 8–10 cm. D oes not use radiation, unlike ERCP, L ess invasive, C an diagnose most causes of obstructive jaundice, and Provide tissue sampling

19. N ot easily available Op erator dependence. Presence of surgical clips, stents and aerobilia may hamper visualization. T herapeutic option is not possible at the same time unlike in ERCP U seful in detecting small biliary calculi, especially within non dilated ducts. It is equal to MRCP/ERCP in detection of calculi. Used in detection of pancreaticobiliary malignancies and in obtaining biopsy.

20. higher sensitivity in the diagnosis of pancreatic tumors U seful in small (<3 cm) pancreatic tumours sensitivity of 92% in T stage, 82% for N staging in pancreatic malignancy. more accurate than CT and angiography in detecting invasion of portal vein, splenic vein and of the confluence similar sensitivity as dual phase CT in detection of pancreatic malignancy; however it is better in lesions <15 mm sensitivity of 97% and a specificity of 88% in determining the cause of extrahepatic obstruction

21. FUNCTIONAL IMAGING Scintigraphy-99mTc hydroxyiminodiacetic acid (HIDA) is the radiotracer used as it is excreted in bile. It is not a sensitive modality in assessing the level or cause of obstruction T racer may not be excreted in patients with high bilirubin level N ot routinely used as MRCP/CT have higher resolution and provide comprehensive evaluation.

22. DIRECT CHOLANGIOGRAPHY E ndoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiogram Both are invasive Reported sensitivity of 100% in the detection of obstruction G old standard for the evaluatio n, of biliary leaks and for subtle luminal changes N o extraluminal information can be obtained with either ERCP is done after cannulation of the ampulla after a duodenoscope is introduced Contrast is i ntroduced in both biliary and pancreatic ducts

23. ERCP has a sensitivity of 90–96% and specificity of 98% in the detection of calculi Reduced sensitivity in detection of small stones in a dilated bile duct. Air bubbles may be misinterpreted as calculi. Treatment in the form of sphincterotomy, balloon and basket removal of stones can be done via the same route

24. D iagnosis and management of pancreaticobiliary tumors M alignant stricture: Long strictures with irregular margins asymmetric dilatation and presence of mass point Endoscopic tissue sampling like brush cytology, fine needle aspiration and forceps biopsy. Palliation of malignant obstruction can be done using a plastic or metal stent.

25. Limitations: significant morbidity (10%-pancreatitis) and a 0.4% mortality. The other drawbacks include cost of equipment, availability of trained personnel, need for conscious sedation. It is not possible to visualize ducts proximal to the obstruction. ERCP is now used for treatment and not for primary diagnosis.

26. ERCP MRCP

27. Percutaneous Transhepatic Cholangiography Completely replaced by MRCP/ERCP now used in transhepatic biliary intervention as a route for biliary decompression L iver punctured with a 22 gauge Chiba needle to enter an intrahepatic biliary duct after checking the coagulation profile. Contrast then injected to visualize site of obstruction.

28. Success dependent on the ducts being dilated, almost 100% in dilated ducts , 75% in nondilated complication rate <5%- biliary leaks, bile peritonitis, hemobilia , sepsis, etc. F or patients with failed ERCP or palliation in unresectable hilar tumors .

29. PET-CT I ndex SUV (standardized uptake value) max measures glucose uptake shows a significant difference of value between benign and malignant causes of obstructive jaundice Pancreatic cancer has a high uptake of the tracer I nfiltrating cholangiocarcinoma show low uptake. PET with conventional imaging like CT, MRI- Increases the sensitivity and accuracy

30. INTRADUCTAL ULTRASOUND done using a flexible, thin (2 mm) probe which is introduced via the endoscope into the pancreatic and biliary duct. The ducts are filled with fluid to provide acoustic coupling frequencies - 12 MHz to 30 MHz (high resolution but limited penetration) superior to EUS in evaluation of proximal biliary ducts increases ability of ERCP in distinguishing benign from malignant Malignancy- sessile tumor , size of tumor >10 mm interrupted wall structure Heterogeneous and irregular bile duct thickening invasion of vessels

31. Drawbacks Lack of availability, operator expertise, low penetration

32. IMAGING ALGORITHM IN OBSTRUCTIVE JAUNDICE The American College of Radiology (ACR) has categorized patients with jaundice into three categories: 1. High likelihood of mechanical obstruction. Benign malignant 2 . Low likelihood of obstruction 3. Intermediate likelihood.

33. Imaging pathway in a case of jaundice with suspected biliary colic.

34. Imaging pathway in a case of jaundice with suspected malignancy.

35. Imaging pathway in a case of jaundice with no features of obstruction on ultrasound.

36. REFERENCES Gupta, Pankaj & Gupta, Jyoti & Kumar-M, Praveen. (2020). Imaging in Obstructive Jaundice: What a Radiologist Needs to Know before Doing a Percutaneous Transhepatic Biliary Drainage. Journal of Clinical Interventional Radiology ISVIR. 4. 10.1055/s-0039-3401327. https://www.researchgate.net/figure/Percutaneous-transhepatic-cholangiography-PTC-a-d-Liver-puncture-was-done-through_fig1_349979856 Lalani T, Couto CA, Rosen MP, Baker ME, Blake MA, Cash BD, Fidler JL, Greene FL, Hindman NM, Katz DS, Kaur H, Miller FH, Qayyum A, Small WC, Sudakoff GS, Yaghmai V, Yarmish GM, Yee J. ACR appropriateness criteria jaundice. J Am Coll Radiol . 2013 Jun;10(6):402-9. doi : 10.1016/j.jacr.2013.02.020. Epub 2013 Apr 28. PMID: 23632132. AIIMS-MAMC-PGI’s Comprehensive Textbook of Diagnostic Radiology, Third Edition (Volumes 1 to 4) / Arun Kumar Gupta, Anju Garg, Manavjit Singh Sandhu Grainger & Allison's Diagnostic Radiology 7th Edition - June 8, 2020 Authors: Andy Adam, Adrian K. Dixon, Jonathan H Gillard, Cornelia Schaefer-Prokop