ORIGINAL RESEARCH ARTICLE
Comparative Analysis of Hepatobiliary and Pancreatic Pathologies on Sonography and Magnetic Resonance Cholangiopancreatography
Corresponding Author: Niveditha Basappa, Department of Radiodiagnosis, Government Medical College, Amritsar, Punjab, India, Phone: +91 9901931723, e-mail: email@example.com
How to cite this article Singh A, Basappa N, Singh J. Comparative Analysis of Hepatobiliary and Pancreatic Pathologies on Sonography and Magnetic Resonance Cholangiopancreatography. AMEI’s Curr Trends Diagn Treat 2019;3(2):45–55.
Source of support: Nil
Conflict of interest: None
Background: The pancreaticobiliary pathologies are one of the most common routinely encountered disorders. The evaluation of a suspected pancreaticobiliary pathology is a common radiological problem and is routinely diagnosed by a variety of imaging modalities including ultrasonography (USG), computed radiography, and magnetic resonance cholangiopancreatography (MRCP).
Objectives: To study and compare the radiological features in pancreatic and biliary system pathology using USG and MRCP, and to compare the findings with histopathology results wherever available.
Materials and methods: The prospective study was carried out on 50 patients with suspected pancreaticobiliary pathologies who underwent both USG and MRCP.
Results: In our study of 50 cases, there were 34 (68%) female cases and 16 (32%) male cases with hepatobiliary pathologies. The female to male ratio was 2.1:1. The maximum number of 15 (30%) cases were between the age range of 41 years and 50 years. The dilatation of the biliary system was seen in 40 (80%) cases, cholelithiasis in 22 (44%), isolated choledocholithiasis in 16 (32%), cholecystitis in 3 (6%), pancreatic divisum in 3 (6%), choledochal cyst in 3 (6%), acute pancreatitis in 2 (4%) chronic pancreatitis in 4 (8%), and common bile duct (CBD) stricture in 2 (4%) cases; these are the most common pancreaticobiliary pathologies identified on MRCP. Ultrasonography was equally good in comparison to MRCP in identifying intrahepatic biliary radical dilatation, gallbladder distension, and cholelithiasis in 100% cases. However, the sensitivity and specificity of USG in detecting choledocholithiasis was low.
Conclusion: Though USG provides a good information about the presence of biliary obstruction, it does not suggest the possible cause in many cases. Hence, USG is regarded as an initial guide to select the patients for MRI examination. Magnetic resonance cholangiopancreatography is a highly sensitive noninvasive modality in the detection of the level and cause of the biliary obstruction.
Keywords: Magnetic resonance cholangiopancreatography, Pancreaticobiliary pathologies, Sonography.
The pancreaticobiliary pathologies are one of the most common, routinely encountered disorders in daily clinical practice. The evaluation of a suspected pancreaticobiliary pathology is a common radiological problem and is routinely diagnosed by a variety of imaging modalities including ultrasonography (USG), computed radiography, magnetic resonance cholangiography, and endoscopic retrograde cholangiopancreatography (ERCP).
The role of a radiologist is to accurately access the etiology, location, severity, and extent of the disease and to guide the clinician to choose the appropriate mode of treatment based on clinical, laboratory, and imaging findings.
Plan: Ultrasonography is the first-line imaging modality for most pancreatic and biliary pathologies due to its accuracy, safety, and noninvasiveness. It is helpful in detecting bile duct morphology, and the sensitivity and specificity of USG in pancreatic and biliary pathology is 61.63 and 83.3%, respectively.1
Magnetic resonance cholangiopancreatography (MRCP) is a radiologic technique that produces images of the pancreaticobiliary tree that are similar in appearance to those obtained by invasive radiographic methods, such as ERCP. Magnetic resonance cholangiopancreatography takes advantage of the inherent contrast-related properties of fluid in the biliary and pancreatic ducts. Currently, the diagnostic accuracy of MRCP is considered to be equivalent to that of ERCP for a broad spectrum of benign and malignant pancreatic and biliary ductal diseases.2
Magnetic resonance cholangiopancreatography makes use of heavily T2-weighted pulse sequences, thus exploiting the inherent differences in the T2-weighted contrast between stationary fluid-filled structures in the abdomen (which have a long T2 relaxation time) and the adjacent soft tissue (which has a much shorter T2 relaxation time). Static or slow-moving fluids within the biliary tree and the pancreatic duct appear of high-signal intensity on MRCP, while the surrounding tissue is of reduced signal intensity.3,4
AIMS and OBJECTIVES
- To study the radiological features in pancreatic and biliary system pathology using USG and MRCP.
- To compare the findings of USG with MRCP in hepatobiliary pathologies.
- To compare the findings of MRCP with histopathological results wherever available.
MATERIALS AND METHODS
This prospective study was conducted in the Department of Radiodiagnosis, Guru Nanak Dev Medical College and Hospital, Amritsar, Punjab, from May 2017 to November 2019. A total of 50 patients with signs and symptoms related to biliary and pancreatic pathologies underwent USG, MRCP, and CT wherever needed for evaluation of biliary and pancreatic pathology. In all cases, a written informed consent was taken from them/guardian before conducting the study.
Sonographic imaging was done with the MINDRAY DC-8 machine using the curvilinear and superficial probe. Magnetic resonance cholangiopancreatography was done with the SIEMENS MAGNETOM AERA 1.5 TESLA MRI machine.
Technique of Examination
The investigations were done after fasting for 4 hours prior to the examination to reduce the motility to eliminate motion artifacts and to promote distension of the gallbladder (GB).
Transabdominal USG was performed on all 50 patients with suspected pancreaticobiliary pathologies with a convex probe (2–5 MHz), focusing mainly on the details of the GB, pancreas, and the biliary system. The findings were recorded in a proforma for comparisons. Magnetic resonance cholangiopancreatography is performed on a 1.5-T or superior MRI system, using a phased-array body coil. All protocols obtain heavily T2-weighted sequences. The most commonly obtained sequences were rapid acquisition and relaxation enhancement (RARE), fast-recovery fast spin-echo (FRFSE) coronal oblique 3D respiratory triggered, and half-Fourier acquisition single shot turbo spin echo HASTE axial 2D breath hold sequence which provide superior images and can be performed in single breath hold (%3C;20 seconds) and a fat-suppressed sequence, additional sequence that can be acquired to evaluate duct wall is a fat-suppressed T1-GRE sequence. For optimum visualization of ducts, acquired images are reformatted in different planes using multiplanar reconstruction (MPR) and maximum intensity projection (MIP). The advantage of FRFSE, as a 3D technique, is the ability to perform MPRs.4
In our study of 50 cases, there were 34 (68%) female cases and 16 (32%) male cases with hepatobiliary pathologies. The male to female ratio was 1:2.1 (Table 1).
The maximum number of 15 (30%) cases were between the age range of 41 years and 50 years, followed by 13 (26%) cases between the age range of 51 years and 60 years, 8 (16%) cases between 31 years and 40 years, 7 (14%) cases between 61 years and 70 years, 3 (6%) cases each between 21 years and 30 years and %3E;70 years, respectively, and only one (2%) case between 11 years and 20 years (Table 2).
|Gender||No. of patients||Percentage|
The cholelithiasis was the most common finding in 25 (50%) patients with 19 (38%) females and 6 (12%) males. The second most common finding was choledocholithiasis seen in 16 (32%) patients with 10 (20%) females and 6 (12%) males. There were 10 (20%) cases of GB mass with 8 (16%) females and 2 (4%) males. The other pathologies include acute pancreatitis 4 (8%), atrophic pancreatitis 4 (8%), choledochal cyst 2 (4%), pancreatic lipomatosis 1 (2%), pancreatic mass 1 (2%), common bile duct (CBD) stricture 1 (2%), abnormal cystic duct 2 (4%), and cholangiocarcinoma 5 (10%) cases. The intrahepatic biliary dilatation was seen in 40 (80%) cases in both USG and MRCP (Table 3).
On sonography, the GB distension was seen in 43 (86%) cases while on MRCP it was seen in 44 (88%) cases. On sonography, GB was contracted in 6 (12%) cases while on MRCP it was seen in 5 (10%) cases. Both USG and MRCP showed GB wall mass in 10 (20%) cases. The contracted GB was seen in 6 (12%) cases on USG, and on MRCP it was seen in 5 (10%) cases. Ultrasonography showed intraluminal GB contents in 31 (62%) cases, while MRCP showed it in 30 (60%) cases. The GB calculi were seen in 22 (44%) cases on both USG and MRCP. The GB sludge was also seen 2 (4%) cases on both USG and MRCP.
On USG, the CBD was dilated in 31 (62%) cases with obscuration of lumen in 1 (2%) case. The MRCP showed dilatation in 32 (64%) cases indicating that it is a better modality for CBD dilatation. The CBD calculi were seen in 16 (32%) cases on sonography while MRCP showed it in 17 (34%) cases. One case showed a calculus in the cystic duct stump on MRCP, which was missed on sonography. The CBD mass was seen in 5 (10%) cases on sonography and in 7 (14%) cases on MRCP. One case was that of multifocal CBD masses. The CBD sludge was equally seen in 6 (12%) cases on both the modalities.
In our study of 50 cases, the pancreas was normal in 42 (84%) cases, with the pancreatic abnormalities seen in 8 (16%) cases. The pancreas appeared atrophic in three (6%) cases on sonography and in four (8%) cases on MRCP. The pancreatic enlargement was seen in two (4%) cases with one case of pancreatic lipomatosis and one case of pancreatic tail cyst. On sonography, one (2%) case was poorly visualized due to the overlying bowel gas due to inherent disadvantage of ringing down artefacts.
The main pancreatic duct (MPD) was normal in 43 (86%) cases on sonography and dilated in 7 (14%) cases. The MRCP showed normal MPD in 40 (80%) cases with dilated in 10 (20%) cases, indicating that MRCP is a better modality for assessment of MPD.
|Age in years||Gender||Total (%)|
|Female (%)||Male (%)|
|11–20||1 (2)||–||1 (2)|
|21–30||2 (4)||1 (2)||3 (6)|
|31–40||8 (16)||–||8 (16)|
|41–50||9 (18)||6 (12)||15 (30)|
|51–60||9 (18)||4 (8)||13 (26)|
|61–70||3 (6)||4 (8)||7 (14)|
|>70||2 (4)||1 (2)||3 (6)|
|Total||34 (68)||16 (32)||50 (100)|
|Diagnosis||Female (n = 34)||Male (n = 16)||Total (n = 50)|
|GB stump calculus||0||0||1||2||1||2|
|Abnormal cystic duct||1||2||1||2||2||4|
The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of USG compared to MRCP were calculated in assessment of intrahepatic biliary radicles (IHBR), GB, CBD, and pancreatic pathologies Table 4).
Two noninvasive modalities, USG and MRCP, are compared in the detection of various pancreaticobiliary pathologies. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of USG are calculated (Table 5).
The pancreaticobiliary pathologies are evaluated using several imaging techniques; USG, computed tomography (CT), and MRCP are the most commonly used noninvasive modalities. The percutaneous transhepatic cholangiography (PTC) and the ERCP are the most commonly used invasive techniques (Figs 1 to 9).
In the present study, 50 patients with pancreaticobiliary pathologies were evaluated primarily by using the two noninvasive imaging modalities, i.e., USG and MRCP. The results of USG were compared with that of MRCP in pancreaticobiliary pathologies and histopathology wherever the results were available.
In our study of 50 patients, 34 (68%) were females and 16 (32%) were males. There was a female preponderance with male:female ratio of 1:2.1. The mean age of the study population was 45.6 years. Håkansson et al.5 studied 85 patients, out of which 43 (51%) were males and 42 (49%) were females. Ferrari et al.6 studied 131 patients, and the distribution of male patients was 47% while that of females was 53%. Upadhyaya et al.7 studied 100 patients, out of which 46% were males and 54% were females.
Kushwah et al. studied 50 patients, out of which 20 (40%) were males and 30 (50 %) were females. In our study of 50 patients, 32% were males and 68% were female patients, which closely matches with Kushwah et al.8
In our study, the maximum number of 15 (30%) cases were between the age range of 41 years and 50 years, followed by 13 (26%) cases between the age range of 51 years and 60 years, 8 (16%) cases between 31years and 40 years, 7 (14%) cases between 61 years and 70 years, 3 (6%) cases each between 21 years and 30 years and >70 years, respectively, and only 1 (2%) case between 11 years and 20 years. The youngest patient in our study was 18 years old and the oldest was 75 years old. These findings are comparable to study conducted by Kaur et al.9
|USG vs MRCP||Observation||Correlation|
* p < 0.001, significant
|USG vs MRCP||Observation||Correlation|
* p < 0.001, significant
The cholelithiasis was the most common pathology identified in 22 (44%) patients both on USG and MRCP, and similarly cholecystitis was seen in 4 (8%) cases on both USG and MRCP.
The choledocholithiasis was identified in 16 (32%) patients on USG and 17 (14%) patients on MRCP. In one patient, the echogenic sludge was noted on USG; however, on MRCP a small calculus was noted. The sensitivity of USG and MRCP in the detection of choledocholithiasis was 81.2 and 100%, respectively. Similarly, a study done by Kaur et al.9 showed sensitivity in detection of choledocholithiasis on USG and MRCP as 63 and 100%, respectively. In a study conducted by Attri et al.,10 the sensitivity and specificity of MRCP in the detection of choledocholithiasis was 85–100%, which is comparable to our study.
In our study, the CBD stricture was detected in 1 (2%) patient on MRCP, which was missed in USG. Shadan et al.11 reported benign strictures in 4% cases. In a study conducted by Kaur et al., the benign stricture was noted in 5 (10%) cases9 and in the study conducted by Bhatt et al.12 the benign stricture was seen in 2% patients, which is same as in our study.
The choledochal cyst was identified in two (4%) patients on MRCP in our study, which yielded 100% diagnostic information in identifying the choledochal cyst. However, on USG, the choledochal cyst was not identified due to the distal location and misdiagnosed as other cystic lesion. In the study conducted by Bhatt et al.,12 choledochal cysts were noted in five patients, which is similar to our study. Upadhayaya et al.7 reported the choledochal cyst in 3% of cases in his study, which is comparable with our study.
In our study of 50 patients, the abnormal cystic duct was observed in 2 (4%) patients on MRCP, which was not initially diagnosed on USG. In a study by Sarawagi et al.,13 it was reported that low insertion of the cystic duct was seen in 18 (9%) cases and 8 (4%) cases had a lower medial insertion. Taourel et al. showed a low cystic duct insertion in 11 (9%) cases and a medical cystic duct insertion in 22 (17%) cases.14
Magnetic resonance cholangiopancreatography is highly accurate in the diagnosis of anatomic variants of the biliary tree that may increase the risk of bile duct injury during laparoscopic cholecystectomy.14
The acute pancreatitis was identified in two (4%) patients on USG and MRCP. The chronic atrophic pancreatitis was identified in three (6%) patients on USG and in four (8%) patients on MRCP. In one case, there were no features of acute pancreatitis on USG; however, peripancreatic edema was identified on MRI and hence acute on chronic pancreatitis diagnosis was made. The ductal dilatation was identified in two patients with pancreatitis on USG and in all cases of pancreatitis on MRCP. Shadan et al.11 reported chronic pancreatitis in 10% cases, which nearly matches our study.
In our study of 50 patients, cholangiocarcinoma was identified in five (10%) patients on ultrasound and seven (14%) patients on MRCP and the results were confirmed in five (10%) patients on histopathology. Only one case of Kaltskin’s tumor was detected. Two cases were wrongly diagnosed on USG; one was reported as calculus and other as obscured CBD due to poor echo window. Shadan et al.11 reported cholangiocarcinoma in 4% cases, Bhatt et al.12 reported Klatskin’s tumor in 12% cases and Reinhold et al.15 reported cholangiocarcinoma in 2.3% cases. In a study conducted by Kaur et al.,9 cholangiocarcinoma was noted in 10% cases, which is nearly same as in our study.
In our study, the sensitivity, specificity, and accuracy of USG in the detection of cholangiocarcinoma was 70, 100, and 94%, respectively. In a study by Attri et al.,10 the overall sensitivity was 83.3%, specificity was 100%, and accuracy was 98.0% for cholangiocarcinoma on MRCP, which is comparable with our study.
The GB carcinoma was identified in 10 (20%) patient on both USG and MRCP, which was confirmed on histopathology. Shadan et al.11 reported carcinoma GB in 4% cases, while Bhatt et al.12 reported it in 2% cases. The sensitivity and specificity, of both USG and MRCP was 100%. This is comparable with the previous study conducted by Attri et al.10 where MRCP was highly diagnostic with sensitivity, specificity and accuracy of 100% each. All the cases diagnosed as GB mass in our study were diagnosed as adenocarcinoma on histopathologic evaluation.
It was noted that the percentage distribution of cholangiocarcinoma in our study closely matches with a study done by Soto et al.16 The percentage distribution of the carcinoma of the pancreas in our study is low compared to the other studies. The overall of the sensitivity and specificity of USG and MRCP in the diagnosis of pancreatic mass were 100%. In the study conducted by Kaur et al.,9 the sensitivity of USG in diagnosing carcinoma pancreas was 75% because of obscuration of the head of the pancreas by bowel gas shadows. The sensitivity and diagnostic accuracy of MRCP is 100%, which is same as our study.
In our study, a case of hydatid cyst of the liver was noted on MRCP, i.e., one (2%) patient, which was misdiagnosed as a simple hepatic cyst on USG, which is comparable to the study conducted by Shadan et al.,11 which showed one (2%) case of the hydatid cyst.
There was one case of hepatocholecystic fistula, which was accurately diagnosed on MRCP whereas it was missed on USG. Similarly, a case of cystic duct stump calculus was accurately diagnosed on MRCP, which was not detected on USG. Hence, MRCP plays a major role in complicated cases of hepatobiliary pathologies.17
Tamura et al.18 reported that overall sensitivity and specificity values of MRCP for delineating pathologic pancreatic changes were 88 and 98%, respectively. In our study, the cases of chronic atrophic pancreatitis were detected with a sensitivity of 75% and specificities of 100% on USG compared to MRCP.
Overall, the pathologies causing obstructive biliopathy included both benign and malignant lesions. The benign lesions constituted 55% (22/40) cases, and malignant lesions constituted 45% (18/40) cases. The most common benign cause was calculus. The accuracy, sensitivity, and specificity of USG compared to MRCP in the diagnosis of being 81, 91, and 88%, respectively. The most common cause of obstruction in malignant pathology was cholangiocarcinoma. The sensitivity, specificity, and accuracy of USG in the diagnosis of malignant diseases were 70, 100, and 94%, respectively, compared to MRCP.
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