Anatomical Variations of Cystic Ducts in Magnetic Resonance Cholangiopancreatography and Clinical Implications

Abstract

Background. Anatomical variations of cystic duct (CD) are frequently unrecognized. It is important to be aware of these variations prior to any surgical, percutaneous, or endoscopic intervention procedures. Objectives. The purpose of our study was to demonstrate the imaging features of CD and its variants using magnetic resonance cholangiopancreatography (MRCP) and document their prevalence in our population. Materials and Methods. This study included 198 patients who underwent MRCP due to different indications. Images were evaluated in picture archiving communication system (PACS) and variations of CD were documented. Results. Normal lateral insertion of CD at middle third of common hepatic duct was seen in 51% of cases. Medial insertion was seen in 16% of cases, of which 4% were low medial insertions. Low insertion of CD was noted in 9% of cases. Parallel course of CD was present in 7.5% of cases. High insertion was noted in 6% and short CD in 1% of cases. In 1 case, CD was draining into right hepatic duct. Congenital cystic dilation of CD was noted in one case with evidence of type IV choledochal cyst. Conclusion. Cystic duct variations are common and MRCP is an optimal imaging modality for demonstration of cystic duct anatomy.

Figure 1

Coronal oblique 3D MR cholangiopancreatography shows normal insertion of cystic duct at middle 3rd of common hepatic duct from lateral aspect (arrow).

Figure 2

Coronal oblique 3D MR cholangiopancreatography shows spiral course of cystic duct (white arrow) with medial insertion with CHD. GB: gall bladder.

Figure 3

Coronal oblique 3D MR cholangiopancreatography shows low medial insertion of cystic duct where cystic duct (arrow) drains at lower 3rd of CHD from left side.

Figure 4

Coronal oblique 3D MR cholangiopancreatography shows parallel course of cystic duct (white arrow) and CHD (white arrowhead). Also note medial insertion of cystic duct (red arrow). GB: gall bladder.

Figure 5

Coronal oblique 3D MR cholangiopancreatography shows high insertion of cystic duct at upper 3rd of CHD from lateral aspect.

Figure 6

(a) Coronal oblique 3D MR cholangiopancreatography. (b) SSH SPAIR transverse image shows short cystic duct with anterior insertion (arrow) into the CHD (arrowhead). GB: gall bladder.

Figure 7

Coronal oblique 3D MR cholangiopancreatography shows aberrant insertion of cystic duct (red arrow) into the right hepatic duct (white arrow) and low union of right and left hepatic duct (blue arrow). Also note multiple calculi (black arrow) in common bile duct (white arrowhead). A: right anterior sectoral duct, P: right posterior sectoral duct, RHD: right hepatic duct, LHD: left hepatic duct, CD: cystic duct, and GB: gall bladder.

Figure 8

Coronal oblique 3D MR cholangiopancreatography shows aberrant union of right segmental bile duct (red arrow) into the cystic duct (white arrow). Cystic duct (white arrow) unites laterally to form CBD. LHD: left hepatic duct.

Figure 9

42-year-old female with choledochal cyst involving the cystic duct. (a) Coronal oblique 3D MR cholangiopancreatography shows marked fusiform dilatation of the extrahepatic bile duct (white arrowhead) with abrupt tapering at distal part (white arrow). The cystic duct is elongated and tortuous and showing cystic dilatation at its distal end with wide communication with the CHD. Also note that there was fusiform dilatation of left hepatic duct. (b) Coronal oblique 3D MR cholangiopancreatography shows abnormal union of pancreatobiliary duct with long common channel. ∗: choledochal cyst. GB: gall bladder and CD: cystic duct.