Hepatic arterial variants according to Michels

type Ⅰ Conventional anatomy: proper HA arising from common HA and then giving rise to right and left HAs as the sole supply of arterial blood to liver


type Ⅱ Replaced left HA arising from LGA


type Ⅲ Replaced right HA arising from SMA


type Ⅳ Both replaced left and right HAs as described for types Ⅱ and Ⅲ


type Ⅴ Accessory left HA arising from LGA


type Ⅵ Accessory right HA arising from SMA


type Ⅶ Accessory right HA arising from SMA and accessory left HA arising from left gastric artery


type Ⅷ Replaced right HA and accessory left HA or replaced left HA and accessory right HA


type Ⅸ Entire hepatic trunk arising from SMA


type Ⅹ Entire hepatic trunk arising from LGA

pancreas : uncus head body tail

Congenital biliary dilatation

<Todani classification>

Type I: Most common variety (77-87%) involving saccular or fusiform dilatation of a portion or entire common bile duct (CBD) with normal intrahepatic duct.


Type II: Isolated diverticulum protruding from the CBD(1.2-3%).


Type III or Choledochocele: Arise from dilatation of duodenal portion of CBD or where pancreatic duct meets(1.4-6%).


Type IVa: Characterized by multiple dilatations of the intrahepatic and extrahepatic biliary tree(19%).
Type IVb: Multiple dilatations involving only the extrahepatic bile ducts(rare).


Type V or Caroli's disease: Cystic dilatation of intra hepatic biliary ducts(rare).

Hepatic and portal anatomy on CT

ACR BI-RADS MRI Category

Category 0 : need additional imaging evaluation

Category 1 : negative

Category 2 : benign findings

Category 3 : probably benign finding - short interval follow up suggested ( <2%)

Category 4 : suspicious abnormality - biopsy should be considered
　　　　　　　　4A (2～32%)
　　　　　　　　4B (33～66%)
　　　　　　　　4C (67～94%)

Category 5 : highly suggestive of malignancy - appropriate action should be taken ( >95%)

Category 6 : known biopsy-proven malignancy - appropriate action should be taken (100%)


( possibility of malignancy )