|Year : 2017 | Volume
| Issue : 3 | Page : 162-168
Comparative study of multidetector computed tomography and magnetic resonance cholangiopancreatography in obstructive jaundice
Shoibam Subhaschandra Singh, Farooq Shafi, Nongthombam Roshan Singh
Department of Radiodiagnosis, Regional Institute of Medical Sciences, Imphal, Manipur, India
|Date of Web Publication||17-Aug-2017|
Department of Radiodiagnosis, Regional Institute of Medical Sciences, Imphal, Manipur
Source of Support: None, Conflict of Interest: None
Background: Accurate diagnosis of the cause is crucial in the management of obstructive jaundice. Multidetector computed tomography (MDCT) and magnetic resonance cholangiopancreatography (MRCP) play the pivotal roles in the diagnosis.
Objective: The objective of this study is to evaluate the diagnostic accuracy of MDCT in determining the level and cause of biliary obstruction in patients with obstructive jaundice and correlates MDCT findings with that of MRCP.
Materials and Methods: This cross-sectional study was conducted in the Department of Radiodiagnosis of a tertiary hospital in Manipur after obtaining the Institutional Ethical Committee approval. Fifty-seven patients with obstructive jaundice, age ranging 20–80 years, were subjected to MDCT and MRCP. Final definite diagnosis was made from operative or histopathological findings. Data and findings of MDCT and MRCP were correlated and statistically analyzed.
Results: Maximum numbers of cases were seen to occur in the fourth to sixth decades. The female-to-male ratio was 1.4:1. Both MDCT and MRCP could correctly determine the level of obstruction in all the cases. The most common level of obstruction was at the suprapancreatic level. The most common cause of obstruction was choledocholithiasis (45.61%). Benign causes constituted 68% and malignant causes constituted 32%. MDCT could correctly determine the cause in 85.96% of cases, compared to 75.44% by MRCP. Kappa statistics showed fair agreement between MDCT and MRCP in diagnosing the cause of biliary obstruction. MDCT showed comparable sensitivity, specificity, and positive and negative predictive value, in diagnosing the causes of obstruction.
Conclusion: Overall performance of the MDCT was comparable or better than that of MRCP.
Keywords: Magnetic resonance cholangiopancreatography, multidetector computed tomography, obstructive jaundice
|How to cite this article:|
Singh SS, Shafi F, Singh NR. Comparative study of multidetector computed tomography and magnetic resonance cholangiopancreatography in obstructive jaundice. J Med Soc 2017;31:162-8
|How to cite this URL:|
Singh SS, Shafi F, Singh NR. Comparative study of multidetector computed tomography and magnetic resonance cholangiopancreatography in obstructive jaundice. J Med Soc [serial online] 2017 [cited 2018 Jan 21];31:162-8. Available from: http://www.jmedsoc.org/text.asp?2017/31/3/162/211103
| Introduction|| |
The word jaundice is derived from the French word jaune, meaning yellow. Jaundice or icterus is not only a disease but also rather a sign of number of different disease conditions. It is the yellow discoloration of tissues occurring due to the deposition of excess bilirubin, which in turn occurs due to imbalance between production and clearance of bilirubin. Clinically, jaundice is detectable when the serum bilirubin concentration is more than 2.0–2.5 mg/dL. There are three stages of bilirubin metabolism, namely, pre-, intra-, and post-hepatic. Jaundice occurs when there is (a) bilirubin production in excess to that which liver can metabolize like patients with hemolytic anemia. (b) Abnormal hepatic bilirubin conjugation or defective bile secretion. (c) Obstruction to the biliary flow due to calculus, benign, or malignant stricture. The last entity, obstructive jaundice, is also called surgical jaundice as these cases are managed surgically.
Surgical jaundice can be caused by the obstruction of the bile duct as with common bile duct (CBD) stones, strictures, malignancy, such as cholangiocarcinoma, periampullary carcinoma, carcinoma gallbladder, and carcinoma head of the pancreas. In patients with suspected biliary obstruction, the diagnosis is important for treatment planning, and radiological imaging is the cornerstone of diagnosis.
Magnetic resonance cholangiopancreatography (MRCP) has recently become a well-established noninvasive diagnostic tool for assessing the biliary tree which also allows evaluation of surrounding structures, and has been reported can replace direct cholangiography in many instances. However, it is not widely available and is expensive,, and contraindications – including patients with cardiac pacemakers, cerebral aneurysm clips, or claustrophobia and those who cannot endure the long examination – limit its use.
Computed tomography (CT) scanning technology has improved significantly over the past two decades. The revolution has proceeded through several stages, from conventional CT to helical (or spiral) CT to new multidetector CT (MDCT), in which ultrafast detector rotation and collimation can be combined to yield high-resolution image reconstructions of the liver, pancreas, and related structures. MDCT's ability to obtain volume dataset with submillimeter spatial resolution allows the optimal display of bile duct using multiplanar reconstruction (MPR) and minimal intensity projection (MinIP) without compromising image quality. The combined use of MPR and MinIP techniques significantly improves the images of the biliary ducts and their site of confluence compared with those obtained by axial CT.,, These recent advances make MDCT often sufficient for evaluating obstructive jaundice. To the best of our knowledge, however, there are only few studies comparing the accuracy of MDCT and magnetic resonance imaging (MRI) in assessment of cause and level of obstruction in obstructive jaundice.
Upadhyaya et al. conducted a study to compare the diagnostic accuracy of ultrasonography, CT, endoscopic retrograde cholangiopancreatography (ERCP)/percutaneous transhepatic cholangiography (PTC), and MRCP in assessing the level and cause of obstruction in patients with obstructive jaundice. The overall diagnostic accuracy for detection of level of obstruction with CT was 85.71%. For assessing the cause, accuracy of CT scan was 85.71%.
Ahmetoglu et al. conducted a study on MDCT cholangiography with volume rendering for the assessment of patients with biliary obstruction. The findings on MDCT cholangiography were compared with those ERCP, PTC, biopsy, or surgery. For the diagnosis of biliary stone, sensitivity and specificity of MDCT cholangiography were 93% and 89%, respectively. For the diagnosis of malignant obstruction, sensitivity and specificity were both 94%. The accuracy of the technique for the diagnosis of biliary obstruction was 83.3%.
Ishimaru et al. compared the diagnostic accuracy of MDCT with MPR images with MRCP for evaluating obstructive jaundice and concluded that MDCT with MPR images was as accurate as MRI/MRCP for evaluating the biliary duct obstruction level and had high diagnostic accuracy in evaluating the cause of jaundice.
This study evaluates the diagnostic accuracy of MDCT in determining the level and cause of biliary obstruction in patients with obstructive jaundice and correlates MDCT findings with that of MRCP.
| Materials and Methods|| |
This is a cross-sectional study conducted in the Department of Radiodiagnosis of a tertiary care hospital in Imphal, Manipur, India, for 2 years from October 2013 to September 2015. Approval of the Hospital Ethical Committee and informed consent from all the participating patients were obtained. Patients with suspected obstructive jaundice attending the Department of Surgery of the same hospital and referred to the Department of Radiodiagnosis during the study were included in the study. The cases were randomly selected with clinical suspicion or biochemical abnormalities suggestive of obstructive jaundice. Patients in whom MRI or CT is contraindicated as with those with metallic implants in their bodies, prosthetic heart valves, or pacemaker, patients with suspected metallic foreign body in any organ of the body, pregnant women, and patients in whom intravenous (IV) contrast administration is contraindicated such as renal failure, thyroid dysfunction, and contrast hypersensitivity were excluded from the study. This study was performed using (1) Philips Brilliance 64-slice CT and (2) Siemens 1.0T Harmony. Oral contrast for MDCT – diatrizoate meglumine and diatrizoate sodium (urografin 76%) and IV contrast for MDCT – iohexol 350 mgI/mL (Omnipaque) was given. Light and low residue diet was advised for at least 2 days before the examination. They were kept nil orally for 8 h before the examination. MDCT abdomen with contrast was followed by MRCP for the assessment of the cause and level of biliary obstruction. MDCT protocol followed were: collimation - 64 × 0.625, pitch - 0.798, rotation time - 0.5 s, field of view (FOV) - 350 mm, kVp - 120, mAs/slice - 230, and reconstruction slice interval - 0.8 mm. Orally administered contrast material (20 ml of urografin in 2 L of water) was used and the waiting period was 1–1½ h to delineate the entire gastrointestinal tract. Then, noncontrast CT scan of the whole abdomen was done starting from above the domes of diaphragm up to the pelvis. The noncontrast scans were followed by contrast studies taken 40–60 s after IV bolus injection of 80 ml of iohexol. Delayed scans after 10–15 min were taken whenever deemed necessary.
For MRCP, localizer images were obtained in the coronal and transverse planes using a spoiled gradient-recalled sequence with 130/1.7 (repetition time ms/echo time ms), flip angle of 90°, FOV of 24–36 cm, section thickness of 10 mm with no gap, matrix size of 256 × 128, and one acquisition. It was followed by conventional T1 (TR - 110 ms, TE - 4.7 ms, FOV of 200–400, slice thickness of 6 mm with no gap, flip angle of 70°, and matrix size of 154 × 256) and T2 (TR - 4000 ms, TE - 103 ms, FOV - 350, flip angle - 150°, matrix size of 154 × 256, and slice thickness of 6 mm) images obtained in the axial plane, followed by T2 HASTE (TR - 1000 ms, TE - 85 ms, FOV - 350, slice thickness 3 mm, and flip angle 150°) images in the axial and oblique coronal planes at an angle of 20°–35° to the coronal plane. Subsequently, single thick-section images were obtained with an echo time of 755 ms FOV - 280, slice thickness of 40 mm, and flip angle - 180° in the coronal, lateral, and left and right 15°, 30°, and 45° oblique planes (eight images were obtained). Finally, thin-section 3D T2 - fast spin echo images were obtained with an effective echo time of 66–100 ms, FOV of 320 cm, and section thickness of 5 mm with no gap. IV contrast agents were not used.
The digitally stored images were analyzed at the end of data collection by two radiologists. First, the MDCT images were read randomly. MRCP images were later randomly read after a gap of 4 weeks to avoid review bias. MDCT images were interpreted in Philips Brilliance Extended Workstation. Curved MPR image was obtained interactively by tracing a curved path through the imaging volume along the course of the pancreaticobiliary duct. The MinIP technique was performed using different slab thicknesses based on the dilatation of the pancreaticobiliary duct. The presence, the site, and the various etiologies of biliary obstruction were classified. Intrahepatic bile duct caliber of more than 2 mm or more than 40% of the diameter of the accompanying portal vein was considered abnormal. Dilated extrahepatic bile duct (CBD), caliber of common hepatic duct ≥8 mm (equivocal = 6–7 mm, maximum upper normal value in elderly patients = 8 mm, and in postoperative cholecystectomy patients, the maximum caliber considered as normal is 10 mm). Dilated pancreatic duct is considered if there is loss of parallel nature of the walls of the duct and caliber of more than 3 mm in the head, >2 mm in the body, and >1.6 mm in the tail. Level of obstruction was classified as obstruction at porta hepatis, suprapancreatic, and intrapancreatic. Statistical analysis entered and analyzed using SPSS software, version 21 for Windows (IBM Corporation, IL, USA). Descriptive statistics was presented as mean and standard deviation for variables like age and in terms of proportions (percentage) for nominal data such as sex, level of obstruction, and cause of obstruction. Sensitivity, specificity, accuracy, positive and negative predictive value for MDCT and MRCP were calculated separately for choledocholithiasis, benign, and malignant causes. Kappa statistics was calculated to determine the degree of agreement between MDCT and MRCP findings for the cause of obstruction.
| Results|| |
Age of occurrence of obstructive jaundice was maximum in the fourth to sixth decades and mean age of 48.7 with standard deviation of 13. The youngest patient in this study was 22-year-old, and the oldest patient was 80-year-old. Majority of the patients in the present study were females (59.65%), outnumbering males at 40.35%. The female-to-male ratio was 1.48:1. The extrahepatic ductal diameter was more than 8 mm, with mean, median, and mode of 15 mm. No patient with normal caliber duct was found.
Both MDCT and MRCP could identify the level of obstruction in all the patients correctly. The highest number of cases (28) were seen at the level of the suprapancreatic portion of the duct and accounted for 49.12% of the total. Next was the porta hepatis part at 31.57%.
The most common cause of obstruction was found to be calculi of the CBD [Figure 1] and [Figure 2]. Choledocholithiasis was found in 26 of the total 57 cases and constituted 45.61% of the total cases. The next leading cause of obstructive jaundice was found to be carcinoma of gallbladder invading into the porta hepatis and benign stricture each of which constituted 14.03% of the total. Cholangiocarcinoma [Figure 3] and [Figure 4] constituted 12.2%, followed by choledochal cyst constituting 5.2%.
|Figure 1: Choledocholithiasis: minimal intensity projection oblique coronal multiplanar reconstruction image from the multidetector computed tomography scan showing hyperdense lesion with a Lucent core in the distal common bile duct (white arrow) with upstream dilation of biliary tree. Incidentally detected focal nodular hyperplasia is also seen in the image (black arrow)|
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|Figure 2: Choledocholithiasis: Magnetic resonance cholangiopancreatography image showing signal void area (arrow) in the distal common bile duct with moderate dilatation of the biliary tract|
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|Figure 3: Cholangiocarcinoma: Minimal intensity projection oblique coronal multiplanar reconstruction image of the delayed phase multidetector computed tomography scan showing delayed enhancing mass (arrow) distal to the confluence of dilated hepatic ducts|
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|Figure 4: Cholangiocarcinoma: Magnetic resonance cholangiopancreatography image showing abrupt narrowing (white arrow) of the suprapancreatic common bile duct, with proximal dilatation of biliary tract. Distal common bile duct (black arrow) is seen with normal caliber|
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The number of benign causes of obstruction was more than the number of malignant causes [Table 1]. Benign cause accounted for 68% of the total number of cases, outnumbering the malignant cases at 31.5%. Choledocholithiasis was the major cause constituting 66.67% of all benign cases. Other benign causes we encountered in our study are Mirizzi syndrome [Figure 5], choledochal cyst, benign strictures, and biliary helminths. Gallbladder carcinoma with local infiltration was the most common malignant cause of obstructive jaundice constituting 44.44% of the malignant cases in our study. Cholangiocarcinoma constituted 38.89% of the malignant cases, followed by periampullary carcinoma [Figure 6] and [Figure 7] and carcinoma head of the pancreas [Figure 8].
|Table 1: Cause of obstruction as determined on magnetic resonance cholangiopancreatography and multidetector computed tomography|
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|Figure 5: Mirizzi syndrome: Magnetic resonance cholangiopancreatography image showing gallbladder neck calculus (arrow) causing biliary obstruction|
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|Figure 6: Periampullary carcinoma: Minimal intensity projection oblique coronal multiplanar reconstruction image showing relatively hypoenhancing periampullary mass (white arrow) with upstream dilation of biliary tract and main pancreatic duct - double duct sign (black arrows)|
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|Figure 7: Periampullary carcinoma: Magnetic resonance cholangiopancreatography image showing double duct sign (arrows) with nonvisualization of confluence of common bile duct and pancreatic duct|
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|Figure 8: Carcinoma head of the pancreas: Minimal intensity projection oblique coronal multiplanar reconstruction image from the multidetector computed tomography scan showing heterogeneously enhancing mass in the head of the pancreas (white arrow) with dilated biliary tract and main pancreatic duct (black arrows) (double duct sign)|
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For determination of the level of obstruction, both MRCP and MDCT were equally accurate in all the cases. As shown in [Table 1], it was observed that the cause of obstruction to the biliary ducts diagnosed on MDCT was correct in 49 of the 57 patients comprising 85.96% of the total cases as compared to MRCP (75.44%). For the benign causes, both modalities had almost similar results. For malignant causes, the MDCT (89.7%) had a better number of correct diagnosis compared to MRCP (44.4%). As shown in [Table 2], both MDCT and MRCP had high sensitivity and specificity for diagnosis of choledocholithiasis. The accuracy of MDCT was same as that of MRCP. MDCT showed equal sensitivity and better specificity and accuracy in diagnosing benign as well as malignant obstruction. There was fair agreement between MDCT and MRCP on overall diagnosis of cause of obstruction. All the cases showed extrahepatic CBD diameter more than 8 mm with a mean, median, and mode of 15 mm.
|Table 2: Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of multidetector computed tomography and magnetic resonance cholangiopancreatography in diagnosis of biliary obstruction|
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| Discussion|| |
Accurate diagnosis of the cause and level of obstruction in obstructive jaundice is important for the proper treatment planning, and MRCP has been well-established modality for the same. Recent improvements in the MDCT technologies have enabled it to be a potential noninvasive diagnostic tool in the evaluation of biliary obstruction.
In the present study, for the identification of the level of biliary obstruction, both MDCT and MRCP showed high and comparable accuracy. MDCT could accurately diagnose the cause of obstruction in 49 (85.96%) in comparison to MRCP (75.44%). Fair agreement was noted between MDCT and MRCP in overall diagnosis of the cause of biliary obstruction with a kappa value of 0.448.
Choledocholithiasis was the most common cause of obstruction, constituting 45.67% of total cases, correlating with the findings by most of other similar studies.,,,, Majority of the cases with CBD stones in the present study were correctly diagnosed by both MDCT and MRCP showing that MDCT and MRCP are equally accurate in the diagnosis of choledocholithiasis. However, MDCT is known to be less sensitive in diagnosis of stones compared to MRCP because majority of biliary calculi are radiolucent and not detected on CT. Surprisingly, in this study, all except one radiolucent stone was correctly diagnosed. The diagnosis was made by ruling out other causes of obstruction.
The present study shows, for benign obstruction accuracy of MDCT (94.2%) is correlating with or slightly better than that of MRCP (91.2%) comparable with the study by Ferrari et al. who found accuracy for MDCT and MRCP as 92.6% and 93.13%, respectively.
For the diagnosis of malignant obstruction, accuracy of MDCT (94.2%) is comparable with or slightly better than that of MRCP (91.2%) correlating with the study by Ferrari et al. and Ishimaru et al. Accurately diagnosing malignant strictures require high spatial resolution as the lesion behind the malignant stricture is usually small. Thin collimation of the MDCT enables the acquisition of large volume of data, which in turn enable multiplanar images with high Z-axis resolution.
Our experience showed MPR images of high spatial resolution are the reason behind the better performance of MDCT in diagnoses of malignant strictures and also the comparable performance of MDCT to MRCP in overall evaluation of obstructive jaundice with respect to the level and cause of obstruction.
| Conclusion|| |
In the evaluation of obstructive jaundice, MDCT due to its high spatial resolution provided exact information for determination of obstruction level and also had high diagnostic accuracy for determining the cause of obstruction. MDCT findings were comparable with that of MRCP in determination of level of obstruction, diagnosis of choledocholithiasis, and differentiating benign from malignant biliary obstruction. For diagnosis of individual causes of biliary obstruction, MDCT performance was better than that of MRCP. Thus, MDCT may be used as the initial imaging modality to evaluate obstructive jaundice.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
[Table 1], [Table 2]