Optimal MR cholangiopancreatographic sequence and its clinical application

Single-Breath-Hold MRI-SPACE Cholangiopancreatography with Compressed Sensing versus Conventional Respiratory-Triggered MRI-SPACE Cholangiopancreatography at 3Tesla: Comparison of Image Quality and Diagnostic Confidence

To compare two magnetic resonance cholangiopancreatography (MRCP) sequences at 3 Tesla (3T): the conventional 3D Respiratory-Triggered SPACE sequence (RT-MRCP) and a prototype 3D Compressed-Sensing Breath-Hold SPACE sequence (CS-BH-MRCP), in terms of qualitative and quantitative image quality and radiologist's diagnostic confidence for detecting common bile duct (CBD) lithiasis, biliary anastomosis stenosis in liver-transplant recipients, and communication of pancreatic cyst with the main pancreatic duct (MPD). Sixty-eight patients with suspicion of choledocholithiasis or biliary anastomosis stenosis after liver transplant, or branch-duct intraductal papillary mucinous neoplasm of the pancreas (BD-IPMN), were included. The relative CBD to peri-biliary tissues (PBT) contrast ratio (CR) was assessed. Overall image quality, presence of artefacts, background noise suppression and the visualization of 12 separated segments of the pancreatic and bile ducts were evaluated by two observers working independently on a five-point scale. Diagnostic confidence was scored on a 1-3 scale. The CS-BH-MRCP presented significantly better CRs (p < 0.0001), image quality (p = 0.004), background noise suppression (p = 0.011), fewer artefacts (p = 0.004) and better visualization of pancreatic and bile ducts segments with the exception of the proximal CBD (p = 0.054), cystic duct confluence (p = 0.459), the four secondary intrahepatic bile ducts, and central part of the MPD (p = 0.885) for which no significant differences were found. Overall, diagnostic confidence was significantly better with the CS-BH-MRCP sequence for both readers (p = 0.038 and p = 0.038, respectively). This study shows that the CS-BH-MRCP sequence presents overall better image quality and bile and pancreatic ducts visualization compared to the conventional RT-MRCP sequence at 3T.

Optimized Breath-Hold Compressed-Sensing 3D MR Cholangiopancreatography at 3T: Image Quality Analysis and Clinical Feasibility Assessment

Magnetic resonance cholangiopancreatography (MRCP) has been widely used in clinical practice, and recently developed compressed-sensing accelerated MRCP (CS-MRCP) has shown great potential in shortening the acquisition time. The purpose of this prospective study was to evaluate the clinical feasibility and image quality of optimized breath-hold CS-MRCP (BH-CS-MRCP) and conventional navigator-triggered MRCP. Data from 124 consecutive patients with suspected pancreaticobiliary diseases were analyzed by two radiologists using a five-point Likert-type scale. Communication between a cyst and the pancreatic duct (PD) was analyzed. Signal-to-noise ratio (SNR) of the common bile duct (CBD), contrast ratio between the CBD and periductal tissue, and contrast-to-noise ratio (CNR) of the CBD and liver were measured. Optimized BH-CS-MRCP showed significantly fewer artifacts with better background suppression and overall image quality. Optimized BH-CS-MRCP demonstrated communication between a cyst and the PD better than conventional MRCP (96.7% vs. 76.7%, p = 0.048). SNR, contrast ratio, and CNR were significantly higher with optimized BH-CS-MRCP (p < 0.001). Optimized BH-CS-MRCP showed comparable or even better image quality than conventional MRCP, with improved visualization of communication between a cyst and the PD.

Breath-hold compressed-sensing 3D MR cholangiopancreatography compared to free-breathing 3D MR cholangiopancreatography: prospective study of image quality and diagnostic performance in pancreatic disorders

PURPOSE

To compare image quality and diagnostic performance of three magnetic resonance cholangiopancreatography (MRCP) protocols in patients with suspected pancreatic abnormalities: free-breathing standard 3D-MRCP (STD), free-breathing compressed sensing 3D-MRCP (CS), and CS 3D-MRCP with acquisition during a single breath-hold > 20 s (BH-CS).

METHODS

Informed consent was obtained. We performed 57 MRCPs in 56 prospectively included patients (29 men, median age 59 years). The three protocols were performed in random order. Acquisition time was recorded. Two radiologists blinded to the protocols used 5-point scales to assess image quality parameters (overall image quality, amount of artifacts, background suppression, bile and pancreatic duct visualization) and diagnostic performance (anatomical variants, duct abnormalities, cystic lesions).

RESULTS

Acquisition time was 279 s with STD, 176 s with CS (-37%), and 22 s with BH-CS (-93%). STD and BH-CS were not significantly different for overall image quality, artifacts, or background suppression. The BH-CS group had fewer non-diagnostic scans (3% vs. 19% with STD and 21% with CS, p < 0.05), higher-quality scans (78% vs. 66% with STD and 58% with CS, p < 0.05), and milder artifacts (2% vs. 18% with STD and 16% with CS, p < 0.05). The main pancreatic duct was better visualized with BH-CS compared to STD (p = 0.015) and CS (p < 0.001). Diagnostic performance did not differ across the three protocols. There were fewer indeterminate scans in the BH-CS group.

CONCLUSION

3T BH-CS is reliable, saves time, and is not associated with decreases in image quality or diagnostic performance compared to STD and CS.

The clinical value of secretin-enhanced MRCP in the functional and morphological assessment of pancreatic diseases

Secretin-enhanced magnetic resonance cholangiopancreatography (S-MRCP) provides a non-invasive way, with which, to evaluate pancreatic duct (PD) anatomy and exocrine pancreatic function. S-MRCP can be added to the routine pancreas MR examination in equivocal cases. Moreover, it can detect subtle PD involvement, allowing diagnosis of early, rather than end-stage, pancreatic diseases. Although S-MRCP is a valuable non-invasive diagnostic method, it is only performed in a few centres due to relative high cost. Furthermore, less familiarity with its indications, the examination technique, and image interpretation also contribute to its limited use. Thus, the purpose of this article is to explain secretin's mechanism of action, the examination technique, the clinically relevant indications, the advantages, and limitations. Finally, we will focus on image analysis and its role in achieving an early and accurate diagnosis of specific pancreatic and PD diseases.

Imaging of Cholangiocarcinoma

Cholangiocarcinoma (CC) is the second most common primary hepatobiliary tumour, and it is increasing in incidence. Imaging characteristics, behaviour, and therapeutic strategies in CC differ significantly, depending on the morphology and location of the tumour. In cross-sectional imaging, CCs can be classified according to the growth pattern (mass-forming, periductal infiltrating, intraductal) and the location (intrahepatic, perihilar, extrahepatic/distal). The prognosis of CC is unfavourable and surgical resection is the only curative treatment option; thus, early diagnosis (also in recurrent disease) and accurate staging including the evaluation of lymph node involvement and vascular infiltration is crucial. However, the diagnostic evaluation of CC is challenging due to the heterogeneous nature of the tumour. Diagnostic modalities used in the imaging of CC include transabdominal ultrasound, endosonography, computed tomography, magnetic resonance imaging with cholangiopancreatography, and hybrid imaging such as positron emission tomography/computed tomography. In this review, the potential of cross-sectional imaging modalities in primary staging, treatment monitoring, and detection of recurrent disease will be discussed.

Balanced MR cholangiopancreatography with motion-sensitised driven-equilibrium (MSDE) preparation: feasibility of Gd-EOB-DTPA-enhanced biliary examination

AIM

To evaluate the effectiveness of motion-sensitised driven-equilibrium (MSDE)-prepared balanced magnetic resonance cholangiopancreatography (MRCP) in a gadolinium ethoxybenzyl diethylene triamine pentaacetic acid (Gd-EOB-DTPA)-enhanced study compared to conventional T2-weighted MRCP.

MATERIALS AND METHODS

Fifteen patients (seven male and eight female patients) prospectively underwent conventional three-dimensional turbo spin-echo T2-weighted MRCP and MSDE-balanced MRCP using a 1.5 T MRI system after hepatobiliary phase image acquisition. For quantitative evaluation, the contrast-to-noise ratio (CNR) of the common hepatic duct to liver tissue was calculated. For qualitative analysis, two radiologists evaluated the depiction of the biliary system and main pancreatic duct (MPD) using a scoring system. Signal suppression of the portal vein (PV) and hepatic vein (HV) on MSDE-balanced MRCP was also scored.

RESULTS

MSDE-balanced MRCP showed significantly higher CNR than T2-weighted MRCP. For all biliary structures, the mean depiction scores of MSDE-balanced MRCP were significantly higher than those of T2-weighted MRCP, whereas the mean depiction score of MPD with MSDE-balanced MRCP was significantly lower than that of T2-weighted MRCP. Signal suppression of the PV and HV was thought to be clinically sufficient.

CONCLUSIONS

MSDE-balanced MRCP more clearly depicted biliary structures compared with T2-weighted MRCP in a Gd-EOB-DTPA-enhanced study. This sequence may be utilised for routine MRCP on Gd-EOB-DTPA-enhanced MRI.

Mucin-producing carcinoma of the gallbladder: evaluation by magnetic resonance cholangiopancreatography in three cases

We report three cases of mucin-producing carcinoma of the gallbladder, along with the magnetic resonance (MR) findings, especially the findings on a MR cholangiopancreatography. In our cases, linear or curvilinear streaks were detected running along the long axis of an enlarged gallbladder (mucus thread sign). When such findings were seen, a mucin-producing carcinoma of the gallbladder should be included as a differential diagnosis. Thus, gadolinium-enhanced MR imaging is mandatory for the precise diagnosis of the mucin-producing carcinoma of the gallbladder.

Contrast-enhanced MR cholangiography: comparison of Gd-EOB-DTPA and Mn-DPDP in healthy volunteers

OBJECTIVE

The purpose of this study was to compare the biliary enhancement dynamics of gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid (Gd-EOB-DTPA) and mangafodipir trisodium (Mn-DPDP) for contrast-enhanced MR cholangiography (MRC) in healthy subjects.

METHODS

15 healthy volunteers underwent MRI at 1.5 T with volumetric interpolated breath-hold examination sequence. Each volunteer was scanned once for each contrast agent. The signal-to-noise ratio (SNR) of the liver parenchyma and common hepatic duct (CHD) and the contrast-to-noise ratio (CNR) of CHD to liver parenchyma were evaluated and compared before and at several time points (5, 15, 30, 45, 60, 90, and 120 min) after injection of each agent.

RESULTS

SNR was significantly higher for Gd-EOB-DTPA than for Mn-DPDP in liver parenchyma after 5 min and in CHD after 15 min (p<0.05). CNR of CHD to liver parenchyma using Gd-EOB-DTPA showed an initial decrease at 5 min post-injection followed by a steep increase to a peak at 15 min post-injection. CNR using Mn-DPDP showed a steady increase to a peak at 15 min post-injection without an initial decrease. At 15 min, the value of CNR was significantly higher for Gd-EOB-DTPA than for Mn-DPDP (p<0.05).

CONCLUSION

For both contrast agents, CNR reached a peak at 15 min after contrast injection. At this time point, CNR of Gd-EOB-DTPA was significantly higher than that of Mn-DPDP. Therefore, Gd-EOB-DTPA may provide better contrast-enhanced MRC than Mn-DPDP at 15 min after contrast administration.

Optimal fast T2-weighted magnetic resonance microscopy imaging of the eye and its clinical application

PURPOSE

To compare a half-Fourier single-shot rapid acquisition with relaxation enhancement (RARE) sequence with a balanced steady-state free precession (b-SSFP) sequence in the evaluation of the eye using magnetic resonance (MR) microscopy imaging and to clarify the usefulness of RARE microscopy imaging in evaluating nonoperative glaucoma patients and patients who have undergone surgery for glaucoma or cataract.

MATERIALS AND METHODS

One-mm and 2-mm slice thickness images of RARE sequence and b-SSFP sequence using a 1.5 T MR unit and a 23-mm microscopy coil were obtained in eight healthy volunteers. The signal-to-noise (S/N) ratio of aqueous humor in the anterior chamber was measured quantitatively and visualization of the anterior chamber anatomy was assessed qualitatively. Furthermore, we evaluated 21 glaucoma patients (including six postoperative patients) and four patients after cataract surgery with 2-mm slice thickness RARE MRI.

RESULTS

The 2-mm slice thickness RARE imaging had a significantly greater S/N ratio than the 1-mm slice thickness RARE imaging (P < 0.05) and acquired the best image quality among the four types of images (P < 0.01). Additionally, 2-mm slice thickness RARE microscopy imaging could depict anterior chamber anatomy of glaucoma eyes and eyes after cataract surgery.

CONCLUSION

We believe that optimal fast T2-weighted MR microimaging might become a useful ophthalmologic examination technique.

Comparison of different MRCP techniques for the depiction of biliary complications after liver transplantation

OBJECTIVE

Biliary strictures after liver transplantation are common. We aimed to compare different magnetic resonance cholangiopancreatography (MRCP) sequences with regard to their diagnostic accuracy in depicting anastomotic stenoses (AST), ischaemic-type biliary lesions (ITBL) and cholelithiasis.

METHODS

In patients with clinically suspected biliary obstruction after liver transplantation, MRCP was performed at 1.5 T using two-dimensional (2D) single-shot RARE, 2D T2-weighted (T2w) HASTE, 2D TrueFISP and 3D T2w TSE RESTORE sequences. The presence and localisation of lesions were assessed for each sequence independently and all sequences together. Endoscopic retrograde cholangiopancreatography (ERCP) served as the "gold standard".

RESULTS

Biliary strictures were detected with a sensitivity of 96% by MRCP and most accurately depicted when all sequences were analysed together. AST was visualised with highest sensitivity on TrueFISP and 3D T2w TSE sequences (79%). For ITBL highest sensitivity was found with the HASTE sequence (81%). Highest sensitivity for filling defects was revealed by the 3D T2w TSE sequence (54%). Receiver operating characteristic (ROC) curve/area under the curve (AUC) analysis revealed the best results for the 3D T2w TSE sequence.

CONCLUSION

Our results underline the value of different MRCP sequence types for the depiction of biliary lesions. A clinical protocol consisting of different sequences may be helpful depending on the clinical question and the likely underlying abnormality.

Common bile duct stones - their presentation, diagnosis and management

Common Bile duct stones (CBD) continue to pose a significant problem both to the patient and the Surgeon. They increase the morbidity of a patient undergoing Cholecystectomy from less than 5% to as much as 20% and almost zero mortality to as high as 30%. Recent times have thrown up a fair share of controversy in the management of this condition both due to technological innovations and costreduction-pressures. The aim in CBD stone disease, as in any benign disease is to discover a therapeutic algorithm with minimal morbidity, no mortality and at reasonable cost. This can be achieved only by a thorough understanding of the disease and also the available diagnostic and treatment modalities.This article dicusses the diagnosis, investigation and therapy of Common Bile Duct Stones (CBD) and gives a therapeutic algorithm.

Morphine- and glucagon-augmented magnetic resonance cholangiopancreatography to evaluate living liver donors

The purpose of this study was to investigate the effectiveness of the combined use of intravenous morphine and intramuscular glucagon in improving magnetic resonance cholangiopancreatography (MRCP) image quality in donors for living-related liver transplantation. Sixteen healthy donor candidates underwent an MRCP study. Coronal, single-shot, fast spin-echo, heavily T2-weighted dynamic MRCP images were obtained before and 3 minutes after the intravenous administration of morphine HCl with a dose of 0.04 mg/kg. Thirty minutes after the injection of morphine, intramuscular glucagon was used. Another MRCP image of the same pulse sequence was generated 15 minutes after the injection of glucagon with a dose of 1 mg. The diameter, signal intensity, and number of branches of bile ducts in MRCP images taken immediately before and after the injection of morphine and after the injection of glucagon (plus delayed morphine effects) were compared and analyzed. In all 16 donor candidates, the diameters of the right and left hepatic ducts, common bile duct, and main pancreatic duct were significantly increased (P < 0.05) in the MRCP images taken 3 minutes after the injection of morphine and 15 minutes after the injection of glucagon (plus delayed morphine effects) in comparison with MRCP images taken before any drug administration. The qualitative grading scores of the signal intensity and order of branches of bile ducts revealed improvements in the MRCP images after the injection of glucagon (plus delayed morphine effects; P < 0.05). In conclusion, combining the intravenous administration of low-dose morphine and the intramuscular use of glucagon before MRCP examination improves the visualization of the nondilated biliary ductal anatomy, which is important for the preoperative biliary evaluation of donor candidates for living-related liver transplantation.

Orally administered lemon/orange juice improved MRCP imaging of pancreatic ducts

BACKGROUND

The aim of this study was to determine the effectiveness of oral administration of lemon/orange juice in improving the visualization of pancreatic ducts on MRCP.

MATERIALS AND METHODS

MRCP images were generated before and at every 15 min for 90 min after oral administration of lemon/orange juice in a dose of 2 ml/kg in 20 volunteers and 26 patients. The pre- and post-administration images were compared and analyzed qualitatively and quantitatively.

RESULTS

In 20 volunteers and 26 patients, the visualization at pancreatic duct of head, body, tail, accessory pancreatic duct, and branch duct was improved after juice administration. The diameter of pancreatic ducts was augmented, and the differences in the mean values before and after oral juice were highly significant at both sites in volunteers and patients (P < 0.01). In 20 volunteers and 26 patients, after juice administration, the best visualization of the pancreatic duct was achieved at (58.98 +/- 14.96) min and (59.41 +/- 13.79) min, respectively, and the overlap imaging of oral juice was especially observed at (42.86 +/- 10.92) min and (41.63 +/- 9.32) min, respectively.

CONCLUSIONS

Orally lemon/orange juice is an effective method to improve MRCP imaging of pancreatic ducts. The lemon/orange juice should be administered at 60 min prior to MRCP.

Calibrated magnetic resonance hydrometry to quantify pancreatic juice: a preliminary study

PURPOSE

To investigate the effectiveness of the calibrated MR hydrometry (CMRH) method for accurately measuring pancreatic secretion.

MATERIALS AND METHODS

All studies were performed on a 1.5-T MR system using a fat-suppressed, single-shot half-Fourier fast spin-echo sequence with a standard body coil. A certain volume (20 mL) of saline solution was employed as an extrabody calibrator. The validity of the CMRH method was tested both in vitro and in vivo, and actual and calculated volumes were compared.

RESULTS

The in vitro study yielded a high correlation (r = 0.99; P < 0.0001) between the actual volume of saline solution in the imaging field and the calculated volume. In the in vivo study, for all volunteers, there was a very strong and significant positive correlation between the measured signal intensities or calculated volumes and actual volumes (correlation coefficient range: 0.94-0.99; P < 0.0001).

CONCLUSION

This preliminary study shows that CMRH is an effective tool to measure the amount of pancreatic fluid secretion.

Computed tomography and magnetic resonance cholangiography

In patients with biliary obstruction, determining the level and the cause of the obstruction is essential because it can be a key factor for the next step in diagnostic or therapeutic intervention. Noninvasive cholangiography, such as computed tomography (CT) cholangiography or magnetic resonance (MR) cholangiography, allows the diagnosis of cause and level of biliary disease with minimal risk. Traditional magnetic resonance cholangiopancreatography (MRCP) is an established and effective noninvasive diagnostic modality particularly for extrahepatic biliary tract evaluation. Intrahepatic biliary duct evaluation and functional MR, including evaluating for leaks and gallbladder dyskinesia and outlet obstruction, are evolving diagnostic techniques that show promising results. CT cholangiography techniques are especially useful when MRI is not available or contraindicated or when the quality of MRCP images is suboptimal. CT cholangiography is particularly useful as an adjunct to surgery or postsurgical cases. The primary limitation of cholangiographic contrast-enhanced CT cholangiography (the most prevalent type of CT cholangiography) is its hindrance by poor liver function and/or high-grade biliary obstruction. In this setting MRCP is clearly superior. There are different types of CT cholangiography and MRCP. This article discusses the types of CT cholangiography and MRCP techniques and their clinical applications.

Magnetic resonance cholangiopancreatography: current use and future applications

Magnetic resonance pancreatography (MRCP) is now established as a robust noninvasive tool for the evaluation of biliary and pancreatic pathology. Its diagnostic performance is comparable with endoscopic retrograde cholangiopancreatography without the associated risks. This article aims to familiarize the reader with the technique, clinical indications, and limitations of the investigation. Common pitfalls in interpretation also are addressed. Emerging applications and techniques are discussed that include recent advances in technology and the development of functional imaging.

Visualization of the biliary tract using gadobenate dimeglumine: preliminary findings

OBJECTIVE

To compare contrast-enhanced magnetic resonance (MR) cholangiography (CE-MRC) performed with gadobenate dimeglumine with T2-weighted MRC (T2-MRC) for visualization of the bile ducts in nondilated biliary systems.

MATERIALS AND METHODS

Twenty consecutive patients who underwent MR imaging (MRI) of the liver and pancreas with nondilated intrahepatic ducts were included in this retrospective study. T2-weighted MRC was performed using a multislice, high-resolution fat-suppressed half-Fourier acquisition turbo spin-echo sequence. Contrast-enhanced MR cholangiography was performed using a fat-suppressed 3-dimensional fast low-angle shot sequence acquired 1 to 1.5 hour after intravenous administration of gadobenate dimeglumine. For image interpretation, the biliary system was divided into 8 segments. Two readers graded visualization of each segment on T2-MRC and CE-MRC using a 5-point scale (0, nonvisualization; 4, excellent visualization). Final opinion for each sequence was rendered by consensus. Superiority of visualization was assessed using the McNemar test and comparing adequately (visualization scores 3 and 4) and inadequately (visualization scores 0, 1, and 2) visualized segments of the ducts on both sequences. Interobserver variability was assessed with kappa statistics.

RESULTS

Overall and segment-based evaluation revealed superior visualization of biliary segments with CE-MRC compared with T2-MRC. We also found a statistically significant difference between the 2 sequences for overall and for right hepatic duct and cystic channel visualization (P < 0.05). A high concordance between readers 1 and 2 both for T2-MRC and CE-MRC was achieved (85.8% and 89.4%, respectively).

CONCLUSIONS

Gadobenate dimeglumine can be used as an alternative intrabiliary contrast agent for contrast-enhanced MR cholangiography in nondilated biliary systems in patients with normal excretory liver function tests.

Differentiation of intraductal papillary mucinous neoplasms from other pancreatic cystic masses: comparison of multirow-detector CT and MR imaging using ROC analysis

PURPOSE

To compare the diagnostic performance of multirow-detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the differentiation of intraductal papillary mucinous neoplasms (IPMNs) from other pancreatic cystic masses.

MATERIALS AND METHODS

A total of 53 patients with pathologically proven pancreatic cystic lesions who had undergone MDCT and MRI were included in this study. Two radiologists analyzed the morphologic features of the lesions and graded the lesion conspicuity on each examination. The readers assigned their confidence level regarding the differentiation of IPMN from other lesions and predicting ductal communication of the lesion. The radiologists' diagnostic confidence was compared using receiver operating characteristic (ROC) analysis.

RESULTS

The Az values for each observer for predicting ductal communication of the lesion and differentiating IPMN from other lesions were as follows: For MRI they were respectively 0.949 and 0.995 for reader 1, and 0.916 and 0.932 for reader 2. For MDCT they were respectively 0.790 and 0.875 for reader 1, and 0.774 and 0.850 for reader 2. In addition, for differentiating IPMNs from other lesions, MRI was significantly more accurate than MDCT (P < 0.05) for one observer, but for the other observer there was no significant difference between the two examinations (P = 0.059). For predicting ductal communication of the cystic lesions for both observers, MRI was significantly more accurate than MDCT (P < 0.05). The weighted kappa values indicate good agreement (kappa = 0.61) between observers for MDCT, and excellent agreement (kappa = 0.82) for MRI.

CONCLUSION

Pancreatic MRI shows better diagnostic performance than MDCT for differentiating IPMNs from other cystic lesions of the pancreas.

Collateral branches IPMTs: secretin-enhanced MRCP

Recently, the fantastic evolution of imaging modalities (especially MR, MDCT, EUS) has raised many issues regarding the correct classification of smaller and smaller lesions, their preoperative evaluations, and indications of most appropriate treatment. However, it is still debated which technique should be employed for the diagnosis and the follow-up of intraductal papillary mucinous tumours (IPMTs). Despite the superb spatial resolution of MDCT, nowadays most of the authors agree on considering MR with magnetic resonance cholangiopancreatography (MRCP) the imaging modality of choice in studying IPMTs. In particular, MRCP is rapid, non-invasive, and accurate in detecting, localizing, and correctly classifying IPMT. The diagnostic performance of MRCP is even improved after the introduction of secretin stimulation. In fact, dynamic MRCP studies after secretin administration, besides facilitating the depiction of the structural characteristics of the lesions, make easier the detection of the communicating duct of branch duct IPMTs with the main pancreatic duct, especially if the newest high resolution 3D heavily T2-weighted sequences are utilized. Secretin stimulation is also useful in the demonstration of early changes of associated chronic pancreatitis. Consequently, we believe that secretin-enhanced MRCP is the most suitable imaging modality in the diagnosis and follow-up of IPMTs of the collateral branches.

Magnetic resonance cholangiopancreatography: A useful tool in the evaluation of pancreatic and biliary disorders

Magnetic resonance cholangiopancreatography (MRCP) is being used with increasing frequency as a noninvasive alternative to diagnostic retrograde cholangiopancreatography (ERCP). The aim of this pictorial review is to demonstrate the usefulness of MRCP in the evaluation of pancreatic and biliary system disorders. Because the recently developed techniques allows improved spatial resolution and permits imaging of the entire pancreaticobiliary tract during a single breath hold, MRCP is of proven utility in a variety of pancreatic and biliary disorders. It uses MR imaging to visualize fluid in the biliary and pancreatic ducts as high signal intensity on T2 weighted sequences and is the newest modality for pancreatic and biliary duct imaging. Herein, we present the clinical applications of MRCP in a variety of pancreaticobiliary system disorders and conclude that it is an important diagnostic tool in terms of imaging of the pancreaticobiliary ductal system.

Gallbladder adenomyomatosis: imaging findings

In this pictorial essay, we describe the imaging findings of adenomyomatosis of the gallbladder and emphasize high-resolution ultrasound and magnetic resonance cholangiopancreatography in its diagnosis.

Gadobenate dimeglumine as an intrabiliary contrast agent: comparison with mangafodipir trisodium with respect to non-dilated biliary tree depiction

OBJECTIVE

To compare the efficacy of Mangafodipir trisodium (Mn-DPDP)-enhanced MR cholangiogrphy (MRC) and Gadobenate dimeglumine (Gd-BOPTA)-enhanced MRC in visualizing a non-dilated biliary system.

MATERIALS AND METHODS

Eighty-eight healthy liver donor candidates underwent contrast-enhanced T1-weighted MRC. Mn-DPDP and Gd-BOPTA was used in 36 and 52 patients, respectively. Two radiologists reviewed the MR images and rated the visualization of the common duct, the right and left hepatic ducts, and the second-order branches using a 4-point scale. The contrast-to-noise ratio (CNR) of the common duct to the liver in the two groups was also compared.

RESULTS

Mn-DPDP MRC and Gd-BOPTA MRC both showed similar visualization grades in the common duct (p=.380, Mann-Whitney U test). In the case of the proximal bile ducts, the median visualization grade was significantly higher with Gd-BOPTA MRC than with Mn-DPDP MRC (right hepatic duct: p=0.016, left hepatic duct: p=0.014, right secondary order branches: p=0.006, left secondary order branches, p=0.003). The common duct-to-liver CNR of the Gd-BOPTA MRC group was significantly higher (38.90+/-24.50) than that of the Mn-DPDP MRC group (24.14+/-17.98) (p=.003, Student's t test).

CONCLUSION

Gd-BOPTA, as a biliary contrast agent, is a potential substitute for Mn-DPDP.

Three-dimensional fast-recovery fast spin-echo MRCP: comparison with two-dimensional single-shot fast spin-echo techniques

PURPOSE

To retrospectively evaluate the technical quality of and the visibility of the biliary tree and pancreatic duct on magnetic resonance (MR) cholangiopancreatographic (MRCP) images obtained with a single-breath-hold three-dimensional (3D) fast-recovery fast spin-echo (FRFSE) sequence in comparison with conventional two-dimensional (2D) single-shot fast spin-echo (SSFSE) thin-section and thick-slab sequences.

MATERIALS AND METHODS

Institutional review board approval was obtained; informed consent was not required for this HIPAA-compliant study. MRCP was performed at 1.5 T in 53 consecutive patients (25 men and 28 women, aged 23-84 years). A single-breath-hold volume acquisition was performed by using the 3D FRFSE sequence and the conventional 2D SSFSE sequences. Two radiologists graded studies obtained with each sequence in a blinded fashion, and the paired Student t test was used to assess differences in technical quality, visibility of eight individual ductal segments of the biliary tree and pancreatic duct, and number of ductal segments visualized per patient.

RESULTS

Studies obtained with 3D FRFSE were of significantly higher technical quality than those obtained with thin-section 2D SSFSE (P < .02 for both readers). The 3D FRFSE maximum intensity projection reconstruction and 2D SSFSE thick-slab sequence proved statistically equivalent with regard to the overall visibility of the biliary tree and pancreatic duct and the number of ductal segments visualized per patient. In comparison with 2D SSFSE thin-section imaging, however, 3D FRFSE imaging produced an improved overall duct segment visibility grade of 0.45 on a three-point visibility scale (P < .001), with a corresponding average per-patient improvement of 1.9 out of eight possible fully visualized duct segments (P < .001).

CONCLUSION

The 3D FRFSE sequence shows promise for improved visibility of the pancreatic duct and biliary tree, compared with the conventional 2D SSFSE thin-section and thick-slab approach, while permitting the entire MRCP examination to be performed in a single breath hold.

Intraductal papillary mucinous neoplasm of pancreas: multi-detector row CT with 2D curved reformations--correlation with MRCP

PURPOSE

To retrospectively compare accuracy of multi-detector row computed tomography (CT), combined with two-dimensional (2D) curved reformations, and that of magnetic resonance (MR) cholangiopancreatography (MRCP) for characterization of intraductal papillary mucinous neoplasm (IPMN) as malignant, with pathologic examination as reference standard.

MATERIALS AND METHODS

Institutional review board approval was obtained, informed consent was waived, and study was HIPAA compliant. Twenty-five patients (12 women, 13 men; age range, 44-88 years) with pathologically proved IPMN were examined with dual-phase CT with 1.25-mm-thick sections for pancreatic phase; 2D curved reformations along main pancreatic duct (MPD) were generated. T2-weighted MRCP included thick- and thin-slab single-shot fast spin-echo imaging and transverse fast spin-echo imaging. Two radiologists, blinded to surgical and pathologic findings, evaluated images for lesion location, septa, mural nodules, communication with MPD, extent and diameter of MPD dilatation, calcifications, and vascular encasement. Malignancy was suspected when one of the following was present: MPD diameter larger than 10 mm, mural nodules, vascular encasement, peripancreatic lymphadenopathy, or metastases. Sensitivity and specificity values for prediction of malignancy were calculated for CT and MRCP. Interobserver variability was determined (kappa analysis).

RESULTS

Excellent correlation between modalities was observed. Cyst communication was seen in 20 and 21 of 24 branch pancreatic duct (BPD) IPMNs with CT and MRCP, respectively. Sensitivity, specificity, and accuracy for detection of malignancy were 70%, 87%, and 76% (CT) and 70%, 92%, and 80% (MRCP), respectively. Interobserver agreement was good to perfect for both readers in all comparisons (overall, kappa = 0.70-1.00).

CONCLUSION

CT combined with 2D curved reformation can provide imaging details of IPMN, including communication of BPD IPMN with MPD, that are almost equivalent to those provided at MRCP. Presence of mural nodules, dilated MPD (>10-mm diameter), or thick septa at CT or MRCP may be used as independent predictors of malignancy.

Fentanyl-augmented MRCP

BACKGROUND

Drugs such as secretin and morphine have been used to augment the visualization of magnetic resonance cholangiopancreatography (MRCP). This study investigated the effectiveness of intravenous administration of a synthetic opioid, fentanyl, in improving the MRCP image quality.

METHODS

Thirty consecutive patients with a provisional diagnosis of benign biliary and/or pancreatic disease underwent MRCP. Coronal single-shot fast spin-echo heavily T2-weighted dynamic MRCP images were generated before and at every minute for 10 min after intravenous administration of fentanyl citrate at a dose of 1.0 mug/kg. Pre- and postinjection images were compared and analyzed qualitatively and quantitatively.

RESULTS

Qualitatively, visualization of intrahepatic bile ducts, common bile duct, and main pancreatic duct improved after fentanyl injection in five (16%), 11 (37%), and 19 (63%) patients, respectively. The pancreatobiliary junction and common channel were visualized better after fentanyl injection in eight of the 18 patients (44%). Quantitatively, signal intensity and diameters of the intrahepatic ducts, common bile duct, and main pancreatic duct measured at corresponding points on pre- and postinjection images showed an increase above preinjection values in 28 (93%), 27 (90%), and 21 (70%) and in 18 (60%), 26 (86%), and 22 (73%), respectively, and these changes were highly significant at all sites (p < 0.001).

CONCLUSIONS

Intravenous administration of fentanyl before MRCP improves qualitative and quantitative visualization of the ductal system anatomy that may be of value in clinical diagnosis and management.

Chronic pancreatitis: MRCP versus ERCP for quantitative caliber measurement and qualitative evaluation

PURPOSE

To retrospectively compare-in patients with chronic pancreatitis-magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERCP) for measurement of main pancreatic duct (MPD) diameter by using area intensity measurement (AIM) at MRCP and full width at half maximum (FWHM) at ERCP and to retrospectively determine the accuracy of MRCP for depiction of pathologic changes by using ERCP as the reference standard.

MATERIALS AND METHODS

The institutional review board approved this study and waived the need to obtain informed consent. Both MRCP and ERCP were performed in 24 patients with chronic pancreatitis (21 men, three women; mean age, 54 years +/- 14 [standard deviation]). The diameter of the MPD was determined by using both methods at the same sites in the head, body, and tail of the pancreas. MRCP and ERCP measurements involved AIM and FWHM techniques, respectively. For qualitative evaluation, visualization of the MPD and pathologic findings was also examined by using both methods. Paired t and Wilcoxon matched-pair signed rank tests were performed for the quantitative and qualitative evaluations, respectively.

RESULTS

The mean diameter of the MPD at ERCP was 1.5 times larger, on average, than that at MRCP; differences were statistically significant for each segment, as well as for the entire duct system. For qualitative evaluation, MRCP tended to be superior to ERCP for delineation of the MPD. Overall sensitivity, specificity, and accuracy values of MRCP for delineating pathologic pancreatic changes were 88% (87 of 99), 98% (44 of 45), and 91% (131 of 144), respectively.

CONCLUSION

Use of ERCP tends to result in overestimation of the caliber of the MPD. MRCP can enable accurate evaluation of the condition of the pancreatic duct and its changes in patients with chronic pancreatitis.

Complementary role of helical CT cholangiography to MR cholangiography in the evaluation of biliary function and kinetics

To explore the potential role of computed tomographic cholangiography (CTC) in relation to magnetic resonance cholangiography (MRC) in cases in which knowledge of biliary kinetics and functional information are important for therapeutic decisions, 31 patients (14 men and 17 women) underwent MRC followed by CTC. We examined nine post-cholecystectomy cases with right upper quadrant abdominal pain, six cases with a previous biliary-enteric anastomosis and clinical evidence of cholangitis, eight biliary strictures with pain or symptoms of cholangitis, four cases with strong clinical evidence of sclerosing cholangitis, three cases with suspected post-laparoscopic cholecystectomy bile leakage, and one case with chronic pancreatitis and a common bile duct stent associated with cholangitis. In relation to MRC, CTC provided additional biliary functional information as follows: abnormal biliary drainage through the ampulla in 7/9 cholecystectomy cases, impaired drainage in 3/6 biliary-enteric anastomoses, and complete obstruction in 2/8 biliary strictures. CTC diagnosed early sclerosing cholangitis in 4/4 cases and confirmed suspected bile leakage in 1/3 post-laparoscopic cholecystectomy patients, and the patency of the biliary stent in the patient with chronic pancreatitis. Thus, CTC provides clinically important information about the function and kinetics of bile and complements findings obtained by MRC.

Utility of three dimension fast asymmetric spin-echo (3D-FASE) sequences in MR sialographic sequences: model and volunteer studies

OBJECTIVES

To evaluate the utility of 3D-FASE for the visualization of salivary gland ducts for use in MR sialographic sequences.

METHODS

We compared MR sialographic images and virtual endoscopic views from 3D-FASE with those from three kinds of sequences described by previous reports in a 3D parotid gland duct model and volunteer. The four sequences were two-dimension fast spin-echo (2D-FSE), three-dimension fast spin-echo (3D-FSE), two-dimension fast asymmetric spin-echo (2D-FASE), and three-dimension fast asymmetric spin-echo (3D-FASE).

RESULTS

In the 3D parotid gland duct model, image visibility on visual score was clearest with 3D-FSE, followed by 3D-FASE (P = 0.028). In the volunteers, the visualization of images improved in the following order: 3D-FASE > 3D-FSE > 2D-FSE > 2D-FASE.

CONCLUSIONS

The technique of 3D-FASE sequencing is more suitable and useful for MR sialography with an appropriate acquisition time.

Gallbladder wall thickening: MR imaging and pathologic correlation with emphasis on layered pattern

The aim of this study was to correlate MR findings of gallbladder wall thickening with pathologic findings on the basis of the layered pattern and to evaluate the diagnostic value of MR imaging in gallbladder disease. We retrospectively evaluated the source images of HASTE sequences for MR cholangiography in 144 patients with gallbladder wall thickening. The layered pattern of thickened wall was classified into four patterns. Type 1 shows two layers with a thin hypointense inner layer and thick hyperintense outer layer. Type 2 has two layers of ill-defined margin. Type 3 shows multiple hyperintense cystic spaces in the wall. Type 4 shows diffuse nodular thickening without layering. MR findings of a layered pattern of thickened gallbladder were well correlated with histopathology. Chronic cholecystitis matched to type 1, acute cholecystitis corresponded to type 2, adenomyomatosis showed type 3, and the gallbladder carcinomas showed type 4. All four layered patterns were associated with PPV of 73% or greater, sensitivity of 92% or greater and specificity of 95% or greater. Our results indicate that MR findings of gallbladder wall thickening are characteristic in each entity and correlate well with pathologic findings. The classification of the layered pattern may be valuable for interpreting thickened gallbladder wall.

Magnetic resonance cholangiopancreatography

The current imaging technique and clinical application of MR cholangiopancreatography (MRCP) is reviewed. MRCP has evolved into a feasible method of non-invasively evaluating the pancreaticobiliary system and has considerable clinical utility. If endoscopic retrograde cholangiopancreatography (ERCP) is incomplete or has failed, or in patients with biliary and gastrointestinal surgical procedures, MRCP is a useful alternative modality. In the near future, MRCP may supplant diagnostic ERCP such that ERCP is reserved primarily for therapeutic interventions. Furthermore, when MRCP is performed in conjunction with abdominal MR and MR angiography, the 'all-in-one' examination can evaluate the solid organs and vessels of the abdomen as well as the ductal systems.

The utility of MRCP in preoperative mapping of biliary anatomy in adult-to-adult living related liver transplant donors

PURPOSE

To assess the utility of magnetic resonance cholangiopancreatography (MRCP) in preoperative mapping of biliary anatomy in adult-to-adult living related liver transplant (LRLT) donors.

MATERIALS AND METHODS

From 57 potential donors with preoperative MRCP, 27 cases (16 men, 11 women, age range 22-51 years, mean 37.2 years) underwent right lobe resection and had intraoperative cholangiography (IOC) for comparison. The MRCP and IOC reports were retrospectively reviewed in all 27 cases. The MRCP was performed on 1.5 Tesla MR magnets using breath-hold heavily T2-weighted sequences in axial/coronal thin sections, and variable-thickness rotating slabs. The accuracy of preoperative MRCP for biliary mapping in potential LRLT donors was analyzed compared to the IOC findings.

RESULTS

Of 27 donors, 26 (96.3%) had MRCP which showed adequate information of central intrahepatic biliary anatomy. Of these, 19 had normal bifurcation confirmed by IOC, and single biliary anastomosis was created in the recipient at transplantation. MRCP correctly predicted 17 of 19 normal cases (sensitivity for normals: 89.5%). In seven donors with variant biliary anatomy, two separate biliary anastomoses were performed in the recipient. MRCP correctly predicted five of seven variants (sensitivity for variants: 71.4%). Overall, MRCP had an accuracy 84.6% (22/26).

CONCLUSIONS

MRCP has potential in the preoperative assessment of nondilated bile ducts in LRLT donors, however further improvements are desired to increase its quality and accuracy.

Imaging diagnosis of pancreato-biliary diseases: A control study

AIM: To evaluate the clinical value of various imageological methods in diagnosing the pancreato-biliary diseases and to seek the optimal procedure.

METHODS: Eighty-two cases of pancreato-biliary diseases confirmed by surgery and pathology were analyzed. There were 38 cases of cholelithiasis, 34 cases of pancreato-biliary tumors and 10 other cases. The imageological methods included B-US, CT, ERCP, PTC, cross-sectional MRI and MR cholangiopancreatography (MRCP).

RESULTS: The accuracy rate of MRCP in detecting the location of pancreato-biliary obstruction was 100%. In differentiating malignant from benign obstruction, the sensitivity of the combination of MRCP and cross-sectional MRI was 82.3%, the specificity was 93.8%, and the accuracy rate was 89.0%. The accuracy rate for determining the nature of obstruction was 87.8%, which was superior to that of B-US (P = 0.0000) and CT (P = 0.0330), but there was no significant difference between direct cholangiopancreatography and the combination of MRCP and conventional MRI (P = 0.6666).

CONCLUSION: In most cases, MRCP can substitute direct cholangiopancreatography for diagnosis. The combination of MRCP and cross-sectional MRI should be considered as an important means in diagnosing the pancreato-biliary diseases, pre-operative assessment and post-operative follow-ups.

Intraductal papillary mucinous tumors of the pancreas. Comparison of helical CT and MR imaging

PURPOSE

To compare the effectiveness of thin-section helical CT and MR imaging with gadolinium-enhanced dynamic technique and MR cholangiopancreatography (MRCP) in the examination of patients with intraductal papillary mucinous tumors.

MATERIAL AND METHODS

Helical CT, dynamic MR imaging, and MRCP of 25 intraductal papillary mucinous tumors were compared with ERCP and surgical findings.

RESULTS

The duodenal papilla was identified by helical CT and dynamic MR imaging in 11 (44%) and 20 (80%) of the 25 patients, respectively (p<0.05). The main pancreatic duct was visualized on helical CT, dynamic MR imaging, and MRCP in all patients (100%): 25 (96.2%), 24 (92.3%), and 26 (100%) cystic lesions were depicted, respectively. A communicating duct between the main pancreatic duct and the cystic lesion was visualized on helical CT, dynamic MR imaging, and MRCP in 14 (53.8%), 11 (42.3%), and 15 (55.7%) lesions, respectively. The papillary projections corresponding to 3 mm or larger papillary neoplasms were depicted on helical CT and MR imaging in 7 patients (25%).

CONCLUSION

MR imaging was equal or slightly superior to thin-section helical CT in the evaluation of intraductal papillary mucinous tumors.

The pearl necklace sign: an imaging sign of adenomyomatosis of the gallbladder at MR cholangiopancreatography

PURPOSE

To evaluate the demonstration of the pearl necklace sign at magnetic resonance (MR) cholangiopancreatography (MRCP) in patients with proven adenomyomatosis and carcinoma of the gallbladder.

MATERIALS AND METHODS

MRCP findings and those of a combination of unenhanced and arterial phase computed tomography (CT) and arterial phase MR imaging were retrospectively compared in 29 patients who were pathologically proven to have adenomyomatosis of the gallbladder and in 18 patients with pathologically proven gallbladder carcinoma. Receiver operating characteristic (ROC) analysis was used with a five-point confidence scale. The relative sensitivity, specificity, and accuracy of each imaging modality were also calculated. The pearl necklace sign was defined on MRCP images as small round foci, with the same markedly high signal intensity as bile, within the thickened wall of the gallbladder.

RESULTS

The mean area under the ROC curve of MRCP alone and that of the combination of MRCP and arterial phase MR imaging was significantly higher than that of combined CT (unenhanced and arterial phase) and arterial phase MR imaging alone (P <.01). The relative sensitivities in the diagnosis of adenomyomatosis of the gallbladder were 24% for the combined CT, 29% for arterial phase MR imaging, 62% for MRCP, and 57% for the combination of MRCP and arterial phase MR imaging. The mean relative sensitivity, specificity, and accuracy of the pearl necklace sign on MRCP images were 62%, 92%, and 74%, respectively. In eight (28%) of 29 patients with adenomyomatosis of the gallbladder, the pearl necklace sign was not identified by all three readers on the MRCP images.

CONCLUSION

The pearl necklace sign, which indicates the presence of Rokitansky-Aschoff sinuses within the thickened gallbladder wall, was specifically detected at MRCP for adenomyomatosis of the gallbladder.

MR cholangiopancreatography: evaluation of common pancreatic diseases

In the evaluation of common pancreatic diseases, MRCP is a noninvasive alternative to ERCP. Ductal anatomy can be ascertained without risk of complications. MRCP is valuable in defining common anatomic variants, determining the state of the pancreatic duct in pancreatitis, and characterizing neoplasms, especially combined with other MR imaging sequences. With the advent of MRCP, techniques requiring endoscopy and percutaneous access are largely reserved for histologic diagnosis and treatment, or for cases in which MRCP fails to establish a diagnosis.

MR cholangiopancreatography

In summary, over the past decade, MRCP has evolved not only as a feasible means of noninvasively evaluating the pancreaticobiliary tract but also as a technique with documented clinical utility. With the evolution of MRCP, there has been, by necessity, an evolution of ERCP. In fact, at some institutions MRCP has replaced diagnostic ERCP such that ERCP is reserved primarily for therapeutic interventions. When MRCP is performed in conjunction with abdominal MR and MRA, a comprehensive examination results that permits evaluation of the solid organs and vessels of the abdomen as well as the ductal systems.

Cystic pancreatic neoplasms evaluation by CT and magnetic resonance cholangiopancreatography

CT provides limited assistance in the differentiation between serous and mucinous neoplasms. Because of the variability in the radiographic appearance of serous cystadenomas and overlap in CT characteristics with mucinous neoplasms, most serous neoplasms still require ancillary testing such as biopsy to reach a definitive diagnosis. MRCP is useful in differentiating benign and malignant mucinous tumors including IPMT of the pancreas. The presence of mural nodules is suggestive of malignancy; however, the absence of mural nodules does not indicate that the tumor is benign. A maximum main pancreatic duct diameter of greater than 15 mm and diffuse dilatation of the main pancreatic duct are suggestive of malignancy in main duct-type tumors. Among branch duct-type tumors, malignant tumors tend to be larger than benign tumors; however, this finding is variable. The presence of main pancreatic duct dilatation may be helpful in determining malignancy of branch duct-type tumors.