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Nasreen Naz and Ummme Aymen
Department of Radiology, Civil Hospital and Dow University
of Health Sciences, Karachi, Pakistan.
Correspondence: Dr. Nasreen Naz, Department of Radiology,
Civil Hospital and Dow University of Health Sciences,
Karachi, Pakistan.
Email: nasreenradiologist@gmail.com
INTRODUCTION
Obstructive Jaundice is a common clinical problem
but needs confirmation by imaging1.The detection of
jaundice is based on clinical and laboratory findings
but to identify the cause of obstruction it requires
different imaging modalities1. Intrahepatic ducts carries
bile from liver to gallbladder and from gallbladder it
is drained into duodenum. Mechanical blockage of
biliary pathway at any level from liver to gallbladder
and to 2nd part of duodenum can cause obstruction and
leads to obstructive jaundice and cholestasis. There
are several causes of obstruction at both intrahepatic
and extrahepatic level2. The most common intraductal
cause of obstruction is calculi / calculus, other causes
are benign and malignant biliary strictures, neoplasms
like cholangiocarcinoma, parasites and primary
sclerosing cholangitis. Extraductal causes are
compression of biliary channels by periampullary
masses, pancreatitis, pseudopancreatic cyst and
mucocele1. The frequency of common bile duct stones
is around 10% with high morbidity rates3. The Magnetic
Resonance Cholangio-pancreatography (MRCP) has
high accuracy rate in the detection of biliary duct calculi
in obstructive jaundiced patients. Furthermore it is
multiplannar, non-ionizing and non-invasive imaging
modality4-8.
Diagnostic Accuracy of Magnetic Resonance Cholangio-
Pancreatography in Choledocholithiasis
ORIGINAL ARTICLE
Journal of the Dow University of Health Sciences Karachi 2016, Vol. 10 (3): 77-81
ABSTRACT
Objectives: To estimate the diagnostic accuracy of MRCP in the detection of bile duct calculi in patients with
obstructive jaundice using ERCP as gold standard.
Study Design: This is a cross sectional study. The study was conducted at Department of Diagnostic Radiology
and Imaging Civil Hospital Karachi, from 01-08-2013 to 31-12-2014.
Materials & Methods: This study comprises 249 cases of clinically observed obstructive jaundice which
were referred by hospital consultants or by general practitioner to the Radiology Department for Magnetic
Resonance Cholangio-Pancreatography (MRCP). Inclusion criteria were Patients of either gender between 26-
70 years of age with obstructive jaundice, raised direct bilirubin levels of 3 mg/dl and above, raised alkaline
phosphatase levels and abdominal ultrasound showed suspicion of stone in dilated or non-dilated common bile
duct. Previously Diagnosed cases of Choledocholithiasis, patients of chronic liver disease and those for which
MRI is contraindicated such as those with surgical clips, braces were excluded from the study. Standard MRI
technique carried out for evaluation of bile duct calculi in obstructive jaundice patients. Its features were carefully
evaluated in terms of presence and absence of calculus / calculi, dilatation of CBD and pancreatic duct and
presence of intrahepatic cholestasis by the consultant radiologist. Data entered and Statistical analyses were
carried out by using SPSS version 17. Sensitivity, specificity, diagnostic accuracy positive and negative predictable
values were calculated. Mean and frequency distribution for ages and gender was calculated respectively.
Results: Mean age of the patients was 45.54 ±11.352 years. Gender distribution shows, 42 patients (17%)
were male while remaining 207 patients (83%) were female. True positive cases for stones were 145 (58%)
and false positive cases were 80 (32%). Positive predictive value was 91.77%, negative predictive value
87.91% with sensitivity 92.95%, specificity 86.02% and Diagnostic accuracy were found to be 90.36%.
Conclusion: It is conclude that Magnetic Resonance Cholangio-Pancreatography (MRCP) is a safe, precise,
relatively fast, with no ionizing radiation and non-invasive imaging modality for the assessment of common
bile duct stones in patients of obstructive jaundice. The result of this study recommends that MR Imaging
showed high Sensitivity and positive predictive values in the detection of bile duct calculi.
Key words: Bile duct calculi, choledodholithiasis, ERCP, MRI, MRCP, obstructive jaundice positive predictive
value, negative predictive value.
How to cite this article: Naz N, Aymen U. Diagnostic accuracy of magnetic resonance cholangio-pancreatography in
choledocholithiasis. J Dow Uni Health Sci 2016; 10(3): 77-81.
77
For assessment of obstructive jaundice many studies
were carried out with different imaging techniques,
but previously most of the techniques were invasive
and ionizing radiation were used, with the invention
of Magnetic Resonance Imaging it became safe,
accurate and non-invasive .
The gold standard for examination of the hepatobiliary
and pancreatic channel is Endoscopic retrograde
cholangio-pancreatography (ERCP)9,10. This is widely
used for the diagnostic as well as therapeutic purposes.
ERCP is an invasive direct cholangiopraphy technique
and thus may contain risks of biliary infection and
other complications9. Therefore, there is a strong
requirement for a less / noninvasive, safe and highly
sensitive diagnostic technique for patients with suspected
hepatobiliary ductal or pancreatic duct abnormalities10.
Magnetic resonance cholangiopancreatography (MRCP)
is an abdominal heavily weighted T2 weighted MR
imaging method that requires no contrast administration
for visualization of the biliary and pancreatic ducts. It
has 88.9% sensitivity and 100% specificity for
diagnosing biliary stone disease. Its positive predictive
value (PPV), negative predictive value (NPV) and
accuracy rates were 100%, 99.2% and 99.2%,
respectively11.
Internationally data is available on this topic but
available statistics from our part of the World is limited.
One study was done locally but there is an issue on
sample sizes. All these studies had sample size of less
than 100 cases, therefore the present study designed
with an appropriate sample size so that true diagnostic
accuracy of MRCP could be assessed and decision
could be taken for its usage in obstructive jaundice
patients in future.
The objective of this study is to determine the diagnostic
accuracy of MRCP in revealing the cause of obstructive
jaundice which helps in early and prompt treatment
and usage of endoscopic retrograde cholangio-
pancreatography (ERCP) is limited as a management
option
MATERIALS & METHODS
This was a cross sectional study carried out in the
department of Radiology, DMC / Civil Hospital Karachi
from 01/08/ 2013 to 31 /12/ 2014.. It is estimated as
249 Patients using 95% confidence level with an
expected percentage of sensitivity 87.5%, specificity
96.5% and desired precision 12% for sensitivity and
2% for specificity. The sampling technique was non
probability consecutive. Inclusion criteria were Patients
of either gender between 26 - 70 years of age with
obstructive jaundice and level of direct bilirubin 3
mg/dl or above 3mg/dl, raised alkaline phosphatase
levels, on abdominal U/S findings of echogenic foci
in dilated and non-dilated CBD. Previously diagnosed
cases of Choledocholithiasis, patients of chronic liver
disease and those patients in which MRI is not indicated
such as those with surgical clips and braces were
excluded from the study.
Operational Definitions: Presence of stone in common
bile duct is known as Choledocholithiasis.
Findings of Choledocholithiasis on MRCP: Presence
of hypointense, well circumscribed area in common
bile duct on MRCP was labeled as cholidocholithiasis.
Findings of Choledocholithiasis on ERCP: Presence
of a filling defect in common bile duct on ERCP were
labeled as cholidocholithiasis.
True Positive: Cases with MRCP findings were positive
for Choledocholithiasis and confirmed by ERCP.
False Positive: Cases with MRCP findings were
positive for Choledocholithiasis but not found to have
Choledocholithiasis by ERCP.
False Negative: Cases with MRCP findings were
negative for Choledocholithiasis but cholidocholithiasis
were positive on ERCP.
True Negative: Cases with MRCP findings were
negative for Choledocholithiasis and confirmed by
ERCP.
All the patients who fulfilling the above mentioned
inclusion criteria were selected, referred from surgical
wards and outpatient department for MRCP to the
Department of Radiology DMC / Civil Hospital
Karachi. Procedure was explained to the patient and
written consent was taken, then patient transferred /
carried to MRI suite of the Radiology Department.
The patient MRCP was conducted on the state of art
1.5 tesla GE machine. Standard protocol for MRCP
was followed. The patient was lying in supine position,
TORSO PA coils were used in an oblique plane. FOV
32 cm, frequency 256 MHz, NEX1, bandwidth 31.25
and auto frequency of water were used. FRFSE-XL
(Fast Recovery Fast Spin Echo-Accelerated) 90 pulse
sequence was used and images were obtained in 3D
mode. Upper abdomens MRI were included whenever
needed. After the MRCP the patient was then sent back
to the ward and ERCP was performed within 48 hours
of the MRCP by a surgeon or senior consultant
(qualified fellow gastroenterologist with at least three
years post-degree experience) at Surgical Unit IV of
Civil Hospital Karachi. MRCP images were assessed
on the viewing console by senior consultant / radiologist
to the findings of the ERCP. Its features will be
Journal of the Dow University of Health Sciences Karachi 2016, Vol. 10 (3): 77-81
78
Nasreen Naz, Ummme Aymen
carefully evaluated in terms of cause of obstruction,
intra / extrahepatic cholestasis, dilatation of CBD and
pancreatic duct by the consultant radiologist having at
least five years of experience in both MRCP and
ultrasound.
Data so collected were entered on SPSS version17.0.
Mean and standard deviation were calculated for age.
Frequency and percentages were calculated for
qualitative variable like gender and presence of stone
on MRCP and ERCP. Sensitivity, specificity, PPV and
NPV and diagnostic accuracy were calculated by taking
ERCP as gold standard. Effect modifiers were reported
for age and gender to see the effect of these on
outcomes. Post stratification chi-square tests were
applied taken p = 0.05 as significant.
All procedures followed were in accordance with the
ethical standards of the responsible committee on
human experimentation (institutional and national) and
with the Helsinki Declaration of 1975, as revised in
2008. Informed consent was obtained from all patients
for being included in the study.
RESULTS
In this study two hundred and forty-nine (249) patients
were enrolled to assess the diagnostic accuracy of the
Magnetic Resonance Cholangio- pancreatography
(MRCP) for detection of bile duct calculi in patients of
obstructive jaundice using ERCP as gold standard.
Mean age of the patient was 44.5years with the standard
deviation of ±11.3years, Similarly, Out of total 249
patients, 42 (17%) patients male while 207 (83%) patients
were female and female to male ratio were 1:4.9.
True positive cases for stone were 156 and true negative
cases 80. In non-calculus cases strictre were the cause
of obstruction both benign and malignant. Overall
diagnostic accuracy of MRI is shown in Table 1 & 2.
Sensitivity and Specificity was found to be 92.95 and
86.02% respectively. Positive predictive value was
found to 91.77% and negative predictive value was
87.91%, and over all accuracy found 90.36%.Image
of MRCP showing calculus at distal CBD as shown in
Figure 1.
DISCUSSION
The purpose of this research study was to determine
the diagnostic accuracy of Magnetic Resonance
Cholangio - Pancreatography (MRCP) in patients of
obstructive jaundice to find out whether stone is a
cause of obstruction, by keeping ERCP as gold standard.
We evaluated diagnostic accuracy on the basis of
sensitivity, specificity, positive predictive and negative
predictive values. If these values were suitable for
MRCP, then the ERCP could be proposed as the
examination of choice for bile duct abnormalities and
could be reserved for therapeutic intervention. There
are different hepatobiliary imaging methods available
like US, CT, MRI, MRCP, ERCP and PTC.
Ultrasound is the initial imaging investigation in patients
suffering from obstructive jaundice. Now days the
pattern of diagnostic approach in hepatobiliary system
has been completely revolutionized. However despite
the development of high tech imaging modalities,
ultrasound is still considered the initial choice in the
diagnosis of choledocholithiasis as it is readily available.
The sensitivity of ultrasound in choledocholithias varies
between 20– 80%12. On the other hand distal CBD
stones are usually missed on ultrasound due to overlying
duodenal gases of the patient12. Also the diagnostic
value of ultrasound in common bile duct is inconstant
and limited, as it depends on operator’s experience and
patient’s preparations. Hence these complications have
indirectly led to the growing popularity of MRCP.
MRCP is a noninvasive and non–ionizing imaging
modality whereas ERCP is ionizing and invasive,
associated with 1-7% of morbidity13,14. With the
continuous progression and improvement of high
resolution equipment, scanning procedure and
Journal of the Dow University of Health Sciences Karachi 2016, Vol. 10 (3): 77-81
Table 1: Diagnostic accuracy of MRCP in detection of bile duct
calculi keeping ERCP as gold standard (n=249)
MRCP (Positive)
MRCP (Negative)
Total
Positive
145
11
156
Negative
13
80
93
ERCPRESULTS OF
MRCP
Table: 2: Diagnostic accuracy of MRCP in detection of bile duct
calculi keeping ERCP as gold standard (n=249)
Sensitivity
Specificity
PPV
NPV
Diagnostic Accuracy
%
92.95
86.02
91.77
87.91
90.36
Figure 1. MRCP: Multiple stones in distal CBD
with proximal Cholestasis
79
Diagnostic accuracy of magnetic resonance cholangio-pancreatography in choledocholithiasis
interpretive skills, there are high levels of diagnostic
achievements to determine the specific cause of biliary
tract or common bile duct obstruction15,16. The
radiological diagnostic accuracy when combined with
clinical data is approaching 98 percent17. Liang CA,
Mao HE18 reported that sensitivity of MRCP is 85%
in the diagnosis of common bile duct stones which are
the most common cause of hepatic obstruction19. The
sensitivity of MRCP was raised to 88% in the other
two studies20,21. This systematic review shows evidence
that MRCP stands up well to comparisons with
diagnostic ERCP, for the diagnosis of many hepatbiliary
channel abnormalities. It appears that ERCP is an
adequate reference standard for choledocholithiasis
with sensitivities and specificities above 89%, however
the results for malignancy were much less reliable.
The evidence on patient satisfaction shows that patients
prefer MRCP over diagnostic ERCP. The results of
our review are similar to those found by Romagnuoloet
al14 who in their meta-analysis showed high levels of
sensitivity and specificity for demonstrating the level
and presence of biliary obstruction.
In our study the mean age of the patients was
44.54±11.352years. According to the study of Khurram
SE, Qasim AI15, the mean age of the patients was
48.54±9.86years, which is close to the results of our
study. Furthermore in the present study there were 83%
female patients and 17% male patients. This gender
distribution is comparable with the study of Mehmet
BN, HuseyinTK,et al16 where there were 19% male
and 81% female patients.
In this study, the positive predictive value of MRCP
was 91.77%, diagnostic accuracy was 90.36% with
sensitivity 92.95% and specificity 86.02%. In another
study conducted by Hina GL, Sameer WD22, the
reported sensitivity was 93.5% and specificity 85.6%
of MRCP with diagnostic accuracy of 88.78%, which
is much more alike & comparable with our conducted
research study. On the light of above discussion, it is
concluded that MRCP proved high diagnostic accuracy
in the detection of bile duct calculi in patients with
obstructive jaundice taking ERCP as gold standard.
Our study has a few limitations; it is a single center
study and it was conducted with an urban environment
therefore the results might not be generalizable to larger
populations.
CONCLUSION
It is concluded from this study that MRCP is a
comparable diagnostic investigation in contrast to
ERCP for diagnosing bile duct calculi. MRCP is non-
ionizing, easily available and a non-invasive imaging
modality. MRCP is much better in determining the
extent of the disease and its complications. It is also
concluded from the results of this study that MRCP
proved high diagnostic accuracy as well as positive
predictive value in the detection of choledocholithiasis
and has the potential to replace diagnostic ERCP.
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