1. Hepatobiliary Anatomy and Pathology
By Zach Krahn MS4

2. Anatomy Review
The liver is one of two organs in the body with a dual blood supply; the portal vein supplies ~2/3 of the total blood with the hepatic artery supplying the rest.
The major function of the liver is to filter the blood of toxins although it is also very important in protein synthesis and metabolism.
The gallbladder is the storage unit for bile, a substance that aids in fat metabolism

3. CT Basics
CT images are constructed based upon the differing density of substances in the body.
Dense substances (e.g. bone or metal) appear bright {hyperdense}
Low density substances (e.g. organ tissue or fat) appear less bright {hypodense}
Hounsfield units are used to describe the relative brightness of a substance on CT
Contrast, either oral or IV, can be given to better delineate anatomic structures

4. 50 Shades of Gray
Hounsfield units
White
Shades
of gray
Black

5. Hepatobiliary CT Gallbladder SMV Liver SMA IVC R Kidney Desc Colon
Aorta
R renal artery
L Kidney

6. Case #1 Which is normal? What is abnormal?
Hyperdense material in gallbladder (biliary sludge, blood or contrast) with thickened wall
Which is normal? What is abnormal?
The white “stuff” is contrast in the bowel
Without contrast, the bowel appears black (air)

7. Case #1: Cholecystitis
Presentation: colicky pain (comes and goes), nausea, and fever.
Risks: Obesity, gallstones, prolonged fasting
Treatment is usually surgical plus antibiotics

8. Case #2 Where is the abnormality? What structure is it in?
Irregular soft tissue within the duct suggests malignancy. Dilation due to cystic common bile duct
Where is the abnormality?
What structure is it in?
Common Bile Duct

9. Case #2: Cholangiocarcinoma
Cholangiocarcinoma is a cancer of the bile duct system
Symptoms include RUQ pain and intermittent jaundice
Risk factors: Clonorchis sinensis infection, toluene/benzene exposure, cysts within bile duct
Treatment: Surgical +/- adjuvant chemotherapy; poor prognosis

10. Case #3 Where is the abnormality? What structure is it in?
Note calcifications
Liver

11. Case #3: Hepatocellular Carcinoma
Imaging demonstrates large hypodense area within liver parenchyma, calcifications are present.
Common presentation: male between ages of 40-60, often vague symptoms including jaundice, RUQ pain, fever, weight loss
Risk factors: Cirrhosis, Hepatitis B (more so than Hepatitis C), hemochromatosis
Treatment: Resection, liver transplant, radiofrequency ablation.

12. Case #4 What is abnormal? What could it be?
Blood (hemorrhage), pus (abscess), water (cyst)
Fluid around liver could also be blood, pus, or water

13. Case #4: Hepatic Abscess
CT imaging shows an area of necrosis surrounded by inflammation (heterogeneous density)
Common presentation: May be subtle. RUQ pain and fever may be present
Risk factors: Biliary tract disease, pancreatic disease, can be idiopathic
Treatment: Drainage and antibiotics

14. Case #5 What is abnormal? How do you know?
Spleen is normally about the same density as liver
Liver is less dense than spleen, suggests problem

15. Case #5: Steatohepatitis
Fat deposition in liver parenchyma
Presentation: Often asymptomatic. May have RUQ pain, muscle pain, jaundice, liver enzyme elevations
Risk Factors: Obesity, excessive alcohol, extensive weight loss (bariatric surgery)
Treatment: Lifestyle interventions

16. Describe the difference.
Case #6
Abnormality?
Describe the difference.
The edges of the liver should be smooth in appearance
This liver has a rough surface with many nodules

17. Case #6: Cirrhosis
Scarring of liver parenchyma due to chronic inflammation
Presentation: Fatigue, weight loss, jaundice, spider angioma, gynecomastia
Risk Factors: Alcoholism, Hepatitis C or B, history of blood transfusion before (before Hep C routinely tested), hemochromatosis
Treatment: Liver transplant, cease alcohol use, vaccinate against Hepatitis A, treat underlying condition

18. Take Home Points
Learning the anatomy now will help you better understand pathology and radiology in the future.
When looking at imaging studies, it is useful to know what “normal” looks like
CT imaging relies on the differing density of tissues whatever surrounds those tissues (air, water, fat)

19. References
Case in Point. American College of Radiology. Multiple topics: cholangiocarcinoma, cholecystitis, hepatocellular carcinoma
Dynamed. Topics: Cirrhosis, steatohepatitis, hepatic abscess
Images obtained from Case in Point at American College of Radiology, Imaging Consult, Radiopaedia