Analysis Of Extrahepatic Bile Duct Stones Missed At MSCT And MRI

Part one Extrahepatic Bile Duct Stones Missed at MSCT:Features and CountermeasuresObjective: To investigate the features of missed extrahepatic bile duct stones by multi-slice computed tomography(MSCT) retrospectively, and analyze the causes of missed and misdiagnosis.Materials and Methods: 43 patients with extrahepatic bile duct stones that were confirmed by ERCP underwent both MSCT and MRI. The results were cotrol with ERCP.Results: The stones of density less than 40 HU and silt stones were all missed on MSCT. The missed rates is 100%, and obviously higher than other two groups(χ~2=58.973,P<0.001).In the density of 40~60HU stones group, missed and misdiagnosis rates of the long diameter less than 0.5cm, 0.5~1.0 cm and more than 1.0cm stones were 100%, 40% and 11% respectively. In this group, the missed rate of the long diameter less than 0.5cm stones is obviously higher than other two diameter groups(χ~2=11.441,P=0.003).In the density of more than 60 HU stones group, missed and misdiagnosis rates of the long diameter less than 0.5cm, 0.5~1.0 cm and more than 1.0cm stones were 25%, 20% and 14% respectively. In this group, missed and misdiagnosis rates are no difference in different diameter stones(χ~2=4.273,P=0.403).In the density of 40~60HU stones group, missed and misdiagnosis rates of patients with and without choledochectasia were 60%, 100% respectively. There is no difference between the groups(χ~2=1.200,P=0.549). In the density of more than 60 HU stones group, missed and misdiagnosis rates of patients with and without choledochectasia were 22%, 50% respectively. There is no difference between the groups(χ~2=2.568,P=0.277).Conclusion: The missed and misdiagnosis of extrahepatic bile duct stones were concluded by multiple factors: density, size, location, and choledochectasia. Part two Extrahepatic Bile Duct Stones Missed at 3.0T MRI:Features and CountermeasuresObjective: To investigate the features of missed extrahepatic bile duct stones by 3.0T MRI(MRCP) retrospectively, and analyze the missed causes.Materials and Methods: 43 patients with extrahepatic bile duct stones confirmed by ERCP underwent MRI(MRCP), the results were cotrol with ERCP.Results: The missed diagnosis rate of MRCP in the diagnosis of extrahepatic bile duct stones was 30.23%. This study defined stones with long diameters >5 mm as large stones, and ≤5 mm as small stones, The remaining stones similar to fluid were classified as silt stones. The missed diagnosis rate of silt stones, small stones and large stones were 100%, 30.77% and 12.5%, respectively. There are obviously differences in the three groups(χ~2=15.938,P=0.0001). With increase of long diameter of extrahepatic bile duct stones, the missed diagnosis rate of MRCP declined. The missed diagnosis rate of patients with and without choledochectasia were 20%, 53.85%, respectively. There is obviously difference in the two groups(χ~2=4.926,P=0.026).The missed diagnosis rate of patients with choledochectasia is higher than in patients without choledochectasia.Conclusion: The missed diagnosis of MRCP in extrahepatic bile duct stones were concluded by multiple factors: size, location, and choledochectasia.