Back
Year : 2015 | Volume : 3 | Issue : 2 | Page : 142 - 146  


Original Articles
Ultrasound and magnetic resonance cholangio-pancreatography correlation in biliary disorders

Siva Prasad A 1, Sandeep J2

1Assistant Professor, Department of Radio Diagnosis, Malla Reddy Institute of Medical Sciences, Hyderabad

2Associate Professor, Department of Radio Diagnosis, Malla Reddy Institute of Medical Sciences, Hyderabad

Corresponding Author:

Dr. Siva Prasad A.

Email: dravulasivaprasad@gmail.com

Abstract:

Biliary strictures can also be visualized with sufficient anatomic detail to determine the level of obstruction and in some instances, differentiate benign from malignant causes. MRCP has potentially two major advantages in neoplastic pancreatico biliary obstruction. Firstly, MRCP can directly reveal extraductal tumor whereas ERCP depicts only the duct lumen. Second, MRCP lacks the major complication rate of approximately 3% associated with ERCP such as sepsis, bleeding, bile leak and death. Overall the purpose of this study will be to prospectively assess the accuracy of MR imaging. A cross sectional study was carried out comprising of fifty unselected patients of different age groups in whom there was clinical suspicion of the biliary diseases. This was a prospective study carried out in the Department of Radio diagnosis, Bharati Vidyapeeth Medical College and Hospital, Pune. Each patient was separately studied by using Ultrasonography and MRCP and compared both studies with other modalities and some cases were followed up & compared with post operative findings. In the present study the cases of Duct calculi predominated and was seen in 16 patients (32%) followed by congenital (choledochal cysts) in 12 (24 %) and Gall bladder masses in 6 (12%). In our study, patients of biliary pathology especially stricture and mass lesions in lower part of CBD were better evaluated by MRCP. In patients with Klatskin tumor, in which hepatic ducts were more involved were better evaluated by MRCP. Strictures were better diagnosed by MRCP. ERCP, histopathological reports and post-operative findings were compared. MRCP was 98% accurate in diagnosis of diseases. False negative result in one patient was due to technical problem. In this patient MRCP diagnosis was mass lesion in 2nd part of duodenum, but per operation mass was in the head of pancreas.

Key words: Ultrasound, Magnetic Resonance, Biliary Disorders

INTRODUCTION:

Evaluation of suspected biliary obstruction has traditionally involved a variety of imaging modalities including Ultrasonography (US), Computed Tomography (CT) and invasive cholangiography. These techniques have limitations because of poor visualization of intraductal stones on US and CT and the need for invasive procedures like Endoscopic Retrograde Cholangio-Pancreatography (ERCP) arid Percutaneous Transhepatic Cholangiography (PTC). Magnetic Resonance Cholangio-Pancreatography (MRCP) is a non-invasive imaging modality that provides good visualization of the hepato- biliary system [1].

Currently the non-invasive diagnosis of bile duct obstruction mainly relies on US and CT. However the accuracy of these techniques is limited because of low sensitivity for the diagnosis of stones in Common Bile Duct (CBD) when compared with that of ERCP. However ERCP is a very operator dependent and invasive procedure and it is associated with 1-7% related morbidity and 0.2%-1 % mortality [2].

Ultrasound is the initial screening tool that is used in evaluating patients presenting with biliary diseases and is mainly supplemented with CT. Ultrasonography has limitations especially in the evaluation of the distal CBD where bowel gas, debris, fluid in the duodenum and obesity can degrade the image quality. CT scan also has its share of limitations, especially in demonstrating two important pathologies, biliary stones and biliary strictures. CT has a sensitivity of only 90% for detecting biliary stones [3, 4].

Stones which have high cholesterol content may be missed as their attenuation resembles fluid; as a result they are difficult to separate from bile. Mixed stones also may be difficult to detect on CT as they present as soft tissue density; this soft tissue density may merge with the pancreatic parenchyma thereby decreasing the sensitivity of CT.

Biliary strictures are not directly visualized on CT. As CT is a cross sectional imaging modality, limited to axial plane, strictures are not demonstrated in a coronal or projectional plane. CT therefore detects strictures only by a process of exclusion, an abrupt cut off of dilated bile ducts without mass lesion. The length and extent of the stricture is difficult to determine on CT. It is very important from a management point of view to be able to visualize the length and extent of strictures. For these reasons cholangiographic modalities like Intravenous Cholangiography (IVC), PTC and ERCP are required. IVC has limitations, in 30-40% of cases there is incomplete opacification of the biliary system [4, 5] PTC has the same diagnostic and therapeutic role as ERCP but is more invasive and risky. Incidence of sepsis is around 1-4% [6].

Neoplasms of the bile and pancreatic ducts present major challenge both for diagnosis and treatment. These tumors may arise primarily from the ducts or may involve the pancreatico-biliary tree secondarily by extension from metastatic tumors of the liver, gall bladder, pancreas or adjacent lymph nodes. Before definite therapy, knowledge of the level of obstruction and its cause is essential [7].

In view of limitation of US and CT and invasiveness of PTC, IVC and ERCP there is need for an imaging modality which is non invasive and provides high resolution projection images of the biliary and pancreatic duct.

MRI plays a vital role in diagnosing many conditions of the biliary tract. On MRI primary sclerosing cholangitis shows several characteristic features including bile duct abnormalities and increased enhancement of liver parenchyma. Wall thickening and enhancement of extra hepatic bile duct are also common MRI findings in patients with primary sclerosing cholangitis [8].

MRI can depict the extent of gall bladder carcinomas and can contribute to the staging of this disease [9]. It is a non-invasive, non-ionizing imaging modality and is unaffected by bowel gas shadow as in ultrasound. With the development of higher magnetic field strength and newer pulse sequences, MRCP with its inherent high contrast resolution, rapidity, multi planar capability and virtually artifact free display of anatomy and pathology in this region is proving to be examination of choice in patients with Biliary diseases [10].  

Since its introduction by Wallner et al in 1991 MRCP has undergone tremendous technical changes essentially in the search for an optional imaging sequence. This imaging technique is able to create projectional type images similar in detail and appearance to direct cholangiography. It avoids the use of Intravenous (LV) contrast and ionizing radiation and is relatively operator independent. Several recent studies have demonstrated that MRCP is able to accurately identify common bile duct stones with sensitivity of 81-100 %.

Biliary strictures can also be visualized with sufficient anatomic detail to determine the level of obstruction and in some instances, differentiate benign from malignant causes. MRCP has potentially two major advantages in neoplastic   pancreatico-biliary obstruction. Firstly, MRCP can directly reveal extraductal tumor whereas ERCP depicts only the duct lumen. Second, MRCP lacks the major complication rate of approximately 3% associated with ERCP such as sepsis, bleeding, bile leak and death [10]. Overall the purpose of this study will be to prospectively assess the accuracy of MR imaging.

 

MATERIAL AND METHODS

 

STUDY DESIGN: A cross sectional study

Patient Selection & Sample Size:

This study comprised of fifty unselected patients of different age groups in whom there was clinical suspicion of the biliary diseases. This was a prospective study carried out in the Department of Radio diagnosis, Bharati Vidyapeeth medical college and Hospital, Pune.

Each patient was separately studied by using Ultrasonography and MRCP and compared both studies with other modalities and some cases were followed up & compared with post operative findings.

Inclusion criteria;-

All cases of biliary pathology attending Bharati Hospital, Bharati Vidyapeeth University, Pune were included.

Exclusion criteria:-

Patients having cardiac pacemakers, prosthetic heart valves, cochlear implants or any metallic orthopedic implants.

Statistical analysis:-

Once patient agrees to participate in the study ,information is obtained as per the Performa.

INSTRUMENTATION:-

For MRCP: MACHINE: Siemens Magnetom C MRI System

SPECIFICATION: Permanent magnet with field strength 0.35T. Magnet homogeneity      

MRI SCAN PARAMETERS

The following scan parameters were used for the patients..

SCANNING TECHNIQUES :-

Localizer………………   0.21sec.

T2 _tras………………..   4.54sec.

T2_cor_thic_slab……… 0.16sec.

T2_haste_cor_thin_slab.   0.20sec.

T2_tse 3D_rst_cor_trig.. 4.40sec.

Breath-hold SSFSE

  • Projectional slabs (40 mm) slabs (40 mm)
  • Coronal / axial multi-isection acq. (3 mm) Coronal / axial Optional
  • •Non breath-hold 3D FRFSE
  • •Functional MRC. M:Biliary enteric anastomosis.
  • •Kinematic MRCMRC

—Non visualization of distal CBD

Follow-up:- Few cases were followed up clinically, biochemically and radiologically as indicated. The radiological diagnosis was correlated with ERCP, surgical findings and histopathology correlation.

 

RESULTS:

 

Table 1: Sex wise distribution in the biliary diseases

 

Sex

No. Of cases

Percentage %

Males

17

34%

 

Females

 

33

 

66%

 

 

~

Total

50

100%

In the present study there is female preponderance, Male: female ratio being 1:1.9

 

Table 2: Age wise distribution in biliary diseases

 

 

AGE (YEARS)

 

NO.OF PATIENTS

 

PERCENTAGE (%)

 

0-18

 

03

 

06

 

19 - 40

 

16

 

32

 

> 40

 

31

 

62

 

TOTAL

 

50

 

100 %

 

In the present study the peak incidence of Biliary diseases is seen in the age group of >40 years (62%) and least in age group of 0-18 Years i.e. (6%).

 

 

Table 3: Number of patients showing various diseases

 

Diagnosis

No.of cases

Usg dx accuracy

Mrcp dx accuracy

 

1) congenital

 

Choledochal cyst

12

 

12

100 %

 

100%

100%

 

100%

 

2) DUCT CALCULI

 

IN LOWER END OF CBD

IN THE MID PART CBD

CHD

 

 

16

 

08

05

03

 

 

 

25%

70%

100%

 

 

 

100%

100%

100%

 

3) STICTURE

 

BENIGN

MALIGNANT

 

06

 

02

04

 

 

 

20%

40%

 

 

 

100%

100%

 

4) MASS LESION

 

KLATSKIN TUMOUR

PERIAMPULLARY MASS

GB MASS

 

16

 

05

05

06

 

 

 

83%

50%

100%

 

 

 

100%

50%

100%

 

In the present study the cases of Duct calculi predominated and was seen in 16 patients(32%) followed by congenital (choledochal cysts) in 12 (24 %) and Gall bladder masses in 6 (12%).

In our study, patients of biliary pathology especially stricture and mass lesions in lower part of CBD were better evaluated by MRCP. In patients with Klatskin tumor, in which hepatic ducts were more involved were better evaluated by MRCP. Strictures were better diagnosed by MRCP.

ERCP, histopathological reports and pre and post-operative findings were compared. MRCP was 98% accurate in diagnosis of diseases. False negative result in one patient was due to technical problem. In this patient MRCP diagnosis was mass lesion in 2nd part of duodenum, but per operation mass was in the head of pancreas.

 

DISCUSSION:

Evaluation of suspected biliary obstruction has traditionally involved a variety of imaging modalities including ultrasonography (US), computed tomography (CT) and invasive cholangiography. These techniques have limitations because of poor visualization of intraductal stones on US and CT and the need for invasive procedures like ERCP and PTC. MRCP is a non-invasive imaging modality that provides good visualization of the hepato biliary system [11].

Two noninvasive, non radiating modalities for evaluation of biliary pathology are USG & MRCP. Magnetic resonance cholangio pancratography (MRCP) is a radiologic technique that produces images of the pancreatico biliary tree that are similar in appearance to those obtained by invasive radiographic methods, such as endoscopic retrograde Cholangio-Pancreatography (ERCP).

The basic principle underlying MRCP is that body fluids, such as bile secretions, have high signal intensity on heavily T2-weighted magnetic resonance sequences (i.e., they appear white), whereas background tissues generate little signal (i.e., they appear dark) [12].

Since its introduction by Wallner et al in 1991 [13], MRCP has undergone tremendous technical changes essentially in the search for an optional imaging sequence. In 1991 - Wallner BK et al [13] introduced MRCP used a breath hold two dimensional, T-2 gradient echo sequence using steady state Free Precession (SSFP) [13].

Marimoto improved image quality by introducing - 3D SSFP sequences. Modified FSE sequences were introduced recently. These are the RARE (Rapid Acquisition with Rapid Enhancement sequence) and HASTE (half fourier acquisition single shot turbo spin echo sequences). So, now HASTE & RARE sequence used and ideal cholangiography sequence for MRCP are a combination of HASTE & RARE takes only 10 minutes imaging time.

Currently, diagnostic accuracy of MRCP is considered to be equivalent to ERCP for a broad spectrum of benign and malignant pancreatic & biliary diseases. Ultrasonography has limitation especially in the evaluation of distal CBD where bowel gas, debris/ fluid in the duodenum and obesity can degrade the image quality. Other imaging modalities are invasive; hence MRCP is an excellent modality for evaluation of biliary diseases.

Meta-analysis including 67 patients study shows that MRCP is 97% sensitive & 98% specific for defining the biliary tract obstruction. The overall sensitivity, specificity and accuracy of MRCP in the detection of bile duct lesions were 97%, 98% and 97%, respectively.

5 cases of cholangio carcinoma (Klatskin tumor) were evaluated. In one case of cholangio carcinoma diagnosed by MRI there was infiltration into the gallbladder and minimal local spread. Per operative findings were those of carcinoma of gallbladder. This is a known limiting factor on imaging when both, the gall bladder and bile duct are involved. MRI helped in defining the level, extent and staging of the disease in the pre surgical evaluation. Guibaud et al [14], Barish M A and Soto [15] and Pavone et al [16] who concluded their studies with sensitivities ranging from 80-86% and specificities of 96-98%and diagnostic accuracies of 91-100% for level of obstruction. In 5 cases of periampullary carcinoma, MRI was able to delineate the extent, level and local infiltration and helped in staging of the lesion. The assessment of the periampullary lesions was difficult on ultrasound in obese patients and bowel gas, shadows was also a limiting factor. Sugita et al in his study of 25 cases of periampullary tumors reported a sensitivity 88%, specificity 100% and diagnostic accuracy of 96% [17].  

In our study of 6 cases of carcinoma of gall bladder, MRI can be used for investigative tool and the staging will be very accurate. MRI detected all 6 cases and detecting subtle lesions in liver and local spread and helped in pre-surgical staging. Ultrasound can be used as a primary investigative tool and cannot be used for staging purpose of carcinoma gall bladder. The diagnostic accuracy for staging was very low.

In our study of 12 cases of congenital lesions (choledochal cysts), both MRI and USG has 100% sensitivity and specificity. Results of studies show clearly that USG is not able to diagnose cases of stricture, mass lesion, calculi in lower end of CBD.

 

CONCLUSION:

The introduction of MRCP now readily permits the study of anatomy and pathology of the biliary tree very easily. Based on the results of our study the following conclusions can be made:

  1. MRI serves as an accurate and non invasive, non ionizing imaging method for evaluation of Biliary anatomy and pathology.
  2. Ultrasound still remains the primary investigative modality of choice.
  3. Combination of MRI and MRCP allows safe surgical management decisions.
  4. Potentially useful in patients undergoing biliary enteric anastomosis for knowing the level and extent of strictures.
  5. Very useful tool in case of obese patients and children.
  6. High spatial tissue resolution.
  7. All in one approach (Parenchyma, Ducts, Vessels)
  8. Direct multi planar modality

Drawbacks -

  1. a) Claustrophobia
  2. b) No therapeutic and interventional procedures can be carried out
  3. c) Breath holding is not possible in elderly, children and debilitated patients
  4. d) Time consuming
  5. e) Cost & availability
  6. f) More limited spatial resolution
  7. g) Poor sensitivity for detecting scattered calcification

There is now enough evidence to suggest that the efficacy of MRI and MRCP is at par with that of ERCP and can be considered as the gold standard for evaluation of the Biliary system. In the patients of suspected biliary pathology, USG is the primary imaging modality of choice, but it has very less diagnostic accuracy in evaluation of benign, malignant stricture of lower end of CBD, mass lesion and calculi in lower end of CBD.

So, MRCP based on heavily T-2 weighted images (HASTE & RARE sequences) produces remarkable increased contrast between stagnant fluid (bile) and background (abdominal fat, hepatic, pancreatic parenchyma) has almost 100% diagnostic accuracy.

So, all patients having biliary pathology, not clearly diagnosed by USG must be evaluated by MRCP for diagnostic accuracy.

 

REFERENCES:

 

  1. Magnuson T H, Bender JS, Duncan MD. Utility of Magnetic Resonance Cholangiography in the evaluation of biliary obstruction. J Am Coil Surg 1999; 189: 63-
  2. Reinhold C, Taorel P,Bret P et al .Choledocholithiasis: Evaluation of MR Cholangiography for diagnosis. Radiology1998; 209:435-442.
  3. Baron RL: Common Bile Duct Stones. Reassessment criteria for CT Diagnosis. Radiology 1987; 162:419-424.
  4. Dawson P, Adam A, Benjamin IS. Intravenous Cholangiography revisited. Clinical Radiology 1993; 47:223-225.
  5. Patel JC, Me Cinnis, Bagely OS et al .The role of Intravenous cholangiography in pre operative assessment for laparoscopic cholecystectomy . Br J Radiology 1993; 66:1125-1127.
  6. Wallener B K, Schumacher KA, Weidenmaier W et al. Dilated Biliary tract: Evaluation with MR Cholangiography with a T2 weighted contrast enhanced fast: sequence, Radiology 1991; 181:805-808.
  7. Schwartz L, H, Coakely FV, Sun V et al. Neoplastic pancreatico biliary duct obstruction: Evaluation with breath hold MR Cholangiography . AJR 1998; 170:1491-1495.
  8. Katsuoyshi, Donald MO, Primary Sclerosing Cholangitis: MR imaging. Features. AJR 1999;172:1527-1533.
  9. Tadashi S, Satoshi N, Juniji K et al. Gallbladder Carcinoma: Evaluation with MR imaging. Radiology 1990; 174: 131-136.
  10. David, Reinhold C, Wang L, Kaplan R et al: Pitfalls in the interpretation of MR Cholangio-Pancreatography. AJR 1998; 170:1055-1059.
  11. Wiedmeyer DA, Stewart ET, Taylor AJ. Radiologic evaluation of structure and function of the sphincter of Oddi. Gastrointest Endosc Clin N Am 1993; 3:13-40.
  12. Matthew A Barish, E. Kent Yucel and Joseph T. ferrucci, Magnetic Resonance Cholangio-Pancreatography. The New England J Of Medicine July 22 1999;341:258-264.
  13. Wallner BK, Schumacher K.A. Weidenmaier W. Fariedrich jm (1991) Dilated biliary tract: evaluation with MR Cholangiography with a T2 weighted contrast-enhanced fast sequence. Radiology 181:805-808.
  14. Guibaud L, Bret PM, Reinhold C, Atri M, Barkun AN. Bile duct obstruction and choledocholithiasis: Diagnosis with MR cholangiography. Radiology 1995; 197:109-115.
  15. M A Barish, J Soto. MRCP Techniques and Clinical applications. AJR 1997; 169:1295-1303.
  16. Lomas DJ, Bearcroft, PW, Gimson AE. MRCP: Prospective comparison of a breath-hold 2D projection technique with diagnostic ERCP. European Radiology1999; 9 (7): 1411-1417.
  17. Sugita R, Furuta A,lto K, Fujita N, Ichinohasama R, Takahashi S.Periampullary tumors: High Spatial MR Imaging and Histopathologic Findings in Ampullary Region Specimens. Radiology 2004; 231:767-774.




img

Important links

adv apply rec

Open Access Journal

MRIMS Journal of Health Sciences is an open access journal which means that all content is freely available without charge to the user or his/her institution. Users are allowed to read, download, copy, distribute, print, search, or link to the full texts of the articles in this journal without asking prior permission from the publisher of the author. This is in accordance with the BOAI definition of open access.

Visitor Count


407728
© 2019 Chandramma Education society . All Rights Reserved.