_______________________________________________________________________________________
The objective of our study was to evaluate whether CT or MRCP compared to abdominal ultrasound was more appropriate in evaluation of pancreatobiliary and hepatic disease. In both the emergency department and inpatient setting, it is important to diagnose and treat in a timely and efficient manner. Evaluating costs relating to services performed, such as imaging and length of stay, are of concern in healthcare today, making this a relevant topic of investigation.
Patients often undergo multiple imaging modalities in developing a diagnosis. Abdominal ultrasound is considered to be a better initial imaging modality in imaging patients with suspected biliary disease [1]. Abdominal ultrasound is relatively quick and costeffective but CT may also be used to diagnose acute hepatic and pancreatobiliary disease with higher sensitivity and specificity, although these results are not always conclusive [2]. Magnetic resonance imaging is known to have superior soft-tissue and contrast resolution compared to other noninvasive tests, such as CT and ultrasound [3].
_______________________________________________________________________________________
Institutional review board approval was obtained for this retrospective study, and informed patient consent was waived. This study was compliant with HIPAA.
We performed a retrospective analysis over an 18-month period to compare patients who had MRCP, CT of the abdomen and pelvis and abdominal ultrasound performed within five days of each other during the same hospital encounter (inpatient or emergency room) for evaluation of pancreatobiliary and hepatic disease. Thirty-five patients with positive findings had MRCP,
CT abdomen and pelvis and abdominal ultrasound performed. Positive findings for inclusion in this study included acute and chronic pancreatitis, acute cholecystitis, choledocholithiasis, common duct dilatation, cholelithiasis, gallbladder wall thickening, gallbladder wall polyps, pancreatic intraductal papillary mucinous neoplasms, hepatic metastatic disease and cirrhosis.
MRCP sequences performed were axial FIESTA fat saturated, coronal FIESTA fat saturated, thick slab, axial diffusion weighted imaging and coronal 3D MRCP centered on the pancreatobiliary system.
_______________________________________________________________________________________
Comparing MRCP with abdominal ultrasound, only MRCP demonstrated choledocholithiasis in 9 of 35 patients. Only MRCP showed cirrhosis in 1 of 35 patients. Only MRCP illustrated acute pancreatitis in 3 of 35 patients. Both MRCP and abdominal ultrasound demonstrated common bile duct dilatation, cholelithiasis, chronic pancreatitis, hepatic metastasis and pancreatic tumors in 20 of 35 patients. MRCP failed to demonstrate gallbladder wall thickening and a 3mm polyp in 2 of 35 cases due to patient motion and respiratory artifacts.
Comparing MRCP with CT of the abdomen and pelvis, only MRCP demonstrated choledocholithiasis in 3 of 35 patients. Only
MRCP demonstrated common bile duct dilatation and gallstones in 1 of 35 patients. Only MRCP demonstrated acute cholecystitis in 2 of 35 patients. Both MRCP and CT demonstrated cirrhosis, pancreatic intraductal papillary mucinous neoplasms, dilated common bile duct, acute pancreatitis and gallstones in 29 of 35 patients.
Abdominal ultrasound shows dilatation of the common bile duct.
Photograph from ERCP shows a stone that has been removed from the common bile duct following sphincterotomy.
MRCP shows a choledocholith.
Coronal FIESTA fat saturated MRI shows a choledocholith.
CT shows acute pancreatitis and cholelithiasis.
_______________________________________________________________________________________
In our analysis, MRCP had higher accuracy than abdominal ultrasound in diagnosing choledocholithiasis (n=9), cirrhosis (n=1) and acute pancreatitis (n=3). MRCP had higher accuracy than CT in diagnosing choledocholithiasis
(n=3), common bile duct dilatation (n=1), gallstones (n=1) and acute cholecystitis (n=2).
Both MRCP and abdominal ultrasound play a role in detecting common bile duct dilatation, cholelithiasis, chronic pancreatitis, hepatic metastasis and pancreatic intraductal mucinous neoplasms. Both MRCP and CT play a role in detecting cirrhosis and pancreatic intraductal mucinous neoplasms. Limitations of MRCP are influenced by patient motion and respiratory artifacts.
Abdominal ultrasound could be considered as an initial modality for patients in the emergency room and inpatient setting for evaluation of acute right upper quadrant pain. Abdominal ultrasound is more readily available and has no ionizing radiation. Sonographically-equivocal cases of choledocholithiasis and common duct dilatation should prompt the clinician to consider MRCP instead of CT in order to provide a more timely, accurate diagnosis without excess imaging, unnecessary radiation and increased medical spending. MRCP should also be considered for evaluating complicated cases of pancreatobiliary and hepatic disease.
_______________________________________________________________________________________
MRCP is a more appropriate modality compared to CT and abdominal ultrasound for diagnosing choledocholithiasis and common duct dilatation as seen with our limited evaluation of 35 patients. Abdominal ultrasound is the preferred initial modality in evaluation of right upper quadrant pain. CT can provide a more timely and accurate diagnosis of cirrhosis, pancreatic neoplasms, acute pancreatitis and gallstones. Further research could be completed in an larger academic center to include a more substantial patient base and to strengthen the statistical significance of the results.
_______________________________________________________________________________________
1. Harvey, RT, Miller WT Jr., Acute biliary disease: initial CT and follow-up US versus initial US and follow-up CT. Radiology
December 1999; Volume 213:831-836.
2. Watanabe, Y, Nagayama, M, Okumura, A, et al. MR Imaging of acute biliary disorders. Radiographics March 2007; Volume 27,
Number 2:477-495.
3. Sainani, NI, Saokar, A, Deshpande, V, et al. Comparative performance of MDCT and MRI with MR cholangiopancreatography in characterizing small pancreatic cysts. AJR 2009; 193:722-731.