MR cholangiopancreatography versus endoscopic sonography in suspected common bile duct lithiasis: a prospective, comparative study

Magnetic resonance cholangiopancreatography versus endoscopic ultrasound for diagnosis of choledocholithiasis: an updated systematic review and meta-analysis

INTRODUCTION

Both endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP) are used for the diagnosis of choledocholithiasis (CDL). Previous studies have shown conflicting results regarding the optimal diagnostic strategy for suspected CDL; hence, this meta-analysis was conducted.

METHODS

A comprehensive search of literature from 1990 till April 2022 was done of three databases for studies comparing EUS and MRCP to diagnose CDL.

RESULTS

A total of 12 studies were identified. The pooled sensitivity and specificity for EUS were 0.96 [95% confidence interval (CI) 0.92-0.98], and 0.92 (95% CI 0.85-0.96), respectively. The pooled sensitivity and specificity for MRCP were 0.85 (95% CI 0.78-0.90) and 0.90 (95% CI 0.79-0.96), respectively. EUS had a higher relative sensitivity [Relative risk (RR) 1.12, 95% CI 1.05-1.19], a higher diagnostic accuracy (Odds ratio 1.98, 95% CI 1.35-2.90) but comparable specificity (RR 1.02, 95% CI 0.96-1.08) with MRCP.

CONCLUSION

There is little difference concerning specificity, although EUS likely provides a higher sensitivity and accuracy for diagnosing CDL, compared to MRCP.

Role of endoscopic ultrasound in evaluation of patients with missed common bile duct stones

BACKGROUND

Choledocholithiasis develops in up to 20% of patients with gall bladder stones. The challenge in diagnosis usually occurs with small stones that may be missed by magnetic resonance cholangiopancreatography (MRCP). Endoscopic ultrasound (EUS) is accurate in detecting common bile duct (CBD) stones missed by MRCP, especially the small ones or those impacted at the distal CBD or the papillary region.

AIM

To evaluate the accuracy of EUS in detecting CBD stones missed by MRCP.

METHODS

Patients with an intermediate likelihood of choledocholithiasis according to ESGE guidelines and those with acute pancreatitis of undetermined cause were included. The presence of choledocholithiasis was evaluated by MRCP and EUS, and then results were confirmed by endoscopic retrograde cholangiopancreatography (ERCP). The sensitivity and specificity of EUS and MRCP were compared regarding the presence of stones, the size, and the number of detected stones.

RESULTS

Ninety out of 100 involved patients had choledocholithiasis, while ten patients were excluded as they had pancreatic or gall bladder masses during EUS examination. In choledocholithiasis patients, the mean age was 52.37 ± 14.64 years, and 52.2% were males. Most patients had biliary obstruction (74.4%), while only 23 (25.6%) patients had unexplained pancreatitis. The overall prevalence of choledocholithiasis was 83.3% by EUS, 41.1% by MRCP, and 74.4% by ERCP. Also, the number and size of CBD stones could be detected accurately in 78.2% and 75.6% by EUS and 41.1% and 70.3% by MRCP, respectively. The sensitivity of EUS was higher than that of MRCP (98.51% vs 55.22%), and their predictive value was statistically different (P < 0.001). Combination of both tools raised the sensitivity to 97.22% and specificity to 100%.

CONCLUSION

EUS could be a useful tool in assessing patients with suspected choledocholithiasis especially if combined with MRCP. However, its usefulness depends on its availability and the experience of the local centers.

Endoscopic ultrasound versus magnetic resonance cholangiopancreatography for the diagnosis of computed tomography-negative common bile duct stone: Prospective randomized controlled trial

OBJECTIVES

For suspected common bile duct stone (CBDS) missed on computed tomography (CT), there is no clear evidence on whether endoscopic ultrasound (EUS) or magnetic resonance cholangiopancreatography (MRCP) is the better diagnostic tool. We aimed to compare the diagnostic accuracy of EUS and MRCP for cases of missed CBDS on CT.

METHODS

Patients suspected of having CBDS were enrolled and randomly allocated to the EUS or MRCP group. Upon the initial examination, those having CBDS or sludge formation underwent endoscopic retrograde cholangiopancreatography (ERCP), while those who were CBDS-negative underwent a second examination with either MRCP or EUS, which was distinct from the initial diagnostic procedure. The primary outcome was diagnostic accuracy, and the secondary outcomes were diagnostic ability, detection rate and characteristics of CBDS in the second examination, and the frequency of adverse events.

RESULTS

Between April 2019 and January 2021, 50 patients were enrolled in the study. The accuracy was 92.3% for EUS and 68.4% for MRCP (P = 0.055). EUS showed 100% sensitivity, 88.2% specificity, 81.8% positive predictive value, and 100% negative predictive value, and MRCP showed 33.3% sensitivity, 84.6% specificity, 50% positive predictive value, and 73.3% negative predictive value. The CBDS detection rate in the second examination was 0% for MRCP after a negative EUS and 35.7% for EUS after a negative MRCP (P = 0.041). No adverse events occurred in any of the patients.

CONCLUSIONS

Endoscopic ultrasound may be a superior diagnostic tool compared to MRCP for the detection of CBDS that are undetected on CT. (UMIN000036357).

ACR Appropriateness Criteria® Jaundice

Jaundice is the end result of myriad causes, which makes the role of imaging in this setting particularly challenging. In the United States, the most common causes of all types of jaundice fall into four categories including hepatitis, alcoholic liver disease, blockage of the common bile duct by a gallstone or tumor, and toxic reaction to a drug or medicinal herb. Clinically, differentiating between the various potential etiologies of jaundice requires a detailed history, targeted physical examination, and pertinent laboratory studies, the results of which allow the physician to categorize the type of jaundice into mechanical or nonmechanical causes. Imaging modalities used to evaluate the jaundiced patient (all etiologies) include abdominal ultrasound (US), CT, MR cholangiopancreatography, endoscopic retrograde cholangiopancreatography and endoscopic US. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Rapid 3D navigator-triggered MR cholangiopancreatography with SPACE sequence at 3T: only one-third acquisition time of conventional 3D SPACE navigator-triggered MRCP

PURPOSE

The purpose of this study was to compare the proposed rapid NT-MRCP protocol and the conventional NT-MRCP protocol with respect to image quality as well as the acquisition time.

MATERIALS AND METHODS

Between January 2019 and May 2019, a total number of 67 consecutive patients with suspected pancreaticobiliary diseases were included in this prospective study and underwent 3D rapid MRCP and 3D conventional MRCP sequences. Both acquisition protocols were set from the same navigator-triggered 3D SPACE sequence. The acquisition time was recorded. Two blinded radiologists performed qualitative analyses with respect to overall image quality, motion artifacts, and CBD visibility using a four-point scale. Quantitative evaluation included the contrast, signal-noise ratio (SNR), and contrast-noise ratio (CNR) between the common bile duct (CBD) and periductal tissues. A paired t test was used to assess differences in the qualitative and quantitative evaluations between the two acquisition methods.

RESULTS

All MRCP studies were completed successfully. The mean acquisition time of rapid NT-MRCP (96.64 ± 30.55 s) was significantly lower than that of the conventional NT-MRCP (271.42 ± 61.63 s; p < 0.001).The contrast ratio, SNR, and CNR of the CBD were significantly higher for conventional NT-MRCP than with rapid NT-MRCP images (0.95 ± 0.02 vs. 0.93 ± 0.03, p < 0.001; 10.36 ± 4.63 vs. 8.90 ± 4.71, p = 0.011; 14.01 ± 6.02 vs. 12.22 ± 6.36, p = 0.020, respectively). The rapid MRCP depicted the overall image quality, artifacts, CBD visibility, right and left hepatic duct, segment 2 branch, main pancreatic duct, and cystic duct significantly better compared with conventional MRCP (p < 0.05). There were no statistically significant differences between the two methods regarding visibility of anterior, posterior, and segment 3 branches (p > 0.05).

CONCLUSIONS

In conclusion, the proposed rapid MRCP protocol yielded significantly higher overall image quality and better visualization of the pancreaticobiliary tree with a significantly reduced imaging time without deterioration of image quality compared with the conventional MRCP at 3T.

Diagnostic performance of the current risk-stratified approach with computed tomography for suspected choledocholithiasis and its options when negative finding

BACKGROUND

Several studies evaluated the current guideline of the American Society for Gastrointestinal Endoscopy (ASGE) and reported only suboptimal accuracy. This study evaluated the diagnostic performance of the ASGE guideline based on computed tomography (CT) and role of endoscopic ultrasonography (EUS) and magnetic resonance cholangiopancreatography (MRCP) in patients with suspected choledocholithiasis but negative CT finding.

METHODS

Patients with suspected choledocholithiasis undergoing ERCP between January 2016 and January 2017 were retrospectively analyzed. All patients underwent CT to detect choledocholithiasis. EUS or MRCP was performed when the CT scan showed negative findings. Patients were classified into the high and intermediate-risk groups, based on predictors from the ASGE criteria.

RESULTS

Of 583 patients with suspected choledocholithiasis, 340 (58.3%) had stones on ERCP (65.9% in the high-risk group and 40.6% in the intermediate-risk group). The accuracy of ASGE guideline for CT was 63.98% (79.12% sensitivity, 42.80% specificity) and 36.02% (20.88% sensitivity, 57.20% specificity) in the high-risk and intermediate-risk groups, respectively. In 103 patients in the high-risk group underwent both CT and US, the accuracy of CT was higher than that of US for detecting choledocholithiasis (78.64% vs. 53.40%), with a significant difference in area under the curve (AUC) (0.78 vs. 0.59, P < 0.001). Of 339 with negative CT finding, the accuracy of EUS was higher than that of MRCP (90.91% vs. 82.76%), but with no significant difference in AUC (0.91 vs. 0.83, P = 0.347).

CONCLUSIONS

CT-based ASGE guideline showed superior diagnostic performance than US for predicting choledocholithiasis. The diagnostic options, EUS or MRCP, with negative CT finding showed comparable performance. Therefore, the diagnostic modality should be selected based on availability, experience, cost, and contraindications.

ASGE guideline on the role of endoscopy in the evaluation and management of choledocholithiasis

Each year choledocholithiasis results in biliary obstruction, cholangitis, and pancreatitis in a significant number of patients. The primary treatment, ERCP, is minimally invasive but associated with adverse events in 6% to 15%. This American Society for Gastrointestinal Endoscopy (ASGE) Standard of Practice (SOP) Guideline provides evidence-based recommendations for the endoscopic evaluation and treatment of choledocholithiasis. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework was used to rigorously review and synthesize the contemporary literature regarding the following topics: EUS versus MRCP for diagnosis, the role of early ERCP in gallstone pancreatitis, endoscopic papillary dilation after sphincterotomy versus sphincterotomy alone for large bile duct stones, and impact of ERCP-guided intraductal therapy for large and difficult choledocholithiasis. Comprehensive systematic reviews were also performed to assess the following: same-admission cholecystectomy for gallstone pancreatitis, clinical predictors of choledocholithiasis, optimal timing of ERCP vis-à-vis cholecystectomy, management of Mirizzi syndrome and hepatolithiasis, and biliary stent therapy for choledocholithiasis. Core clinical questions were derived using an iterative process by the ASGE SOP Committee. This body developed all recommendations founded on the certainty of the evidence, balance of risks and harms, consideration of stakeholder preferences, resource utilization, and cost-effectiveness.

Long term outcome of EUS-based strategy for suspected choledocholithiasis but negative CT finding

OBJECTIVES

The American Society for Gastrointestinal Endoscopy (ASGE) guidelines offered the risk-stratified approach in suspected choledocholithiasis. Previous studies have raised concern about the insufficient accuracy of the guideline, especially in high probability group. The purposes of this study were to authenticate the stratification and clinical predictors of the guidelines for suspected choledocholithiasis with no visible choledocholithiasis on computed tomography (CT) and to make clear the clinical strategy of endoscopic ultrasonography (EUS).

MATERIALS AND METHODS

We carried out the retrospective single-center study of 156 patients with suspected choledocholithiasis but negative findings on CT who underwent EUS for about 8 years at Samsung Medical Center. We assessed the clinical predictors of the ASGE guidelines in predicting the presence of choledocholithiasis and the outcome of the EUS.

RESULTS

Fifty-three of the 156 patients had positive findings on EUS that included choledocholithiasis (n = 43, 27.6%) or obstructive papillitis (n = 10, 6.4%). Among the 53 patients, 51 (96.2%) had choledocholithiasis or obstructive papillitis on ERCP. The 101 patients of 103 patients with negative finding on EUS did not show biliary events during follow-up period. EUS accuracy was 98.7% (sensitivity 100%; specificity 98.1%). Among the 49 patients with high probability, 21 (42.9%) had choledocholithiasis on ERCP. In 107 patients who were classified as intermediate probability, 30 (27.3%) had choledocholithiasis. There were no complications related to EUS.

CONCLUSIONS

Not only intermediate probability group but also high probability group without definite acute cholangitis may require EUS. Application of EUS for suspected choledocholithiasis is highly accurate, safe and reduces unnecessary invasive ERCP in 57.1% of patients with high probability group.

Diagnostic accuracy of EUS compared with MRCP in detecting choledocholithiasis: a meta-analysis of diagnostic test accuracy in head-to-head studies

BACKGROUND AND AIMS

There is a wide range of reported sensitivity and specificity for EUS and MRCP in the diagnosis of choledocholithiasis, with lack of a proper meta-analysis of diagnostic test accuracy by using head-to-head comparison. Here, we aimed to compare the diagnostic accuracy of EUS and MRCP in detecting choledocholithiasis by using appropriate methodology recommended by the Cochrane Collaboration.

METHODS

A comprehensive electronic literature search up to January 2017 was done by 2 reviewers for prospective cohort studies comparing EUS and MRCP to a reference standard for detecting choledocholithiasis. The acceptable reference standards were considered ERCP, intraoperative cholangiography, or clinical follow-up >3 months for negative cases. Quality of the included studies was measured by using the QUADAS-2 tool. A bivariate hierarchical model was used to perform the meta-analysis of diagnostic test accuracy. Summary receiver operating characteristics were developed and the area under the curve was calculated.

RESULTS

A total of 5 of 32 studies were included. No study presented a high risk of bias. The pooled sensitivity and specificity were 0.97 (range, 0.91-0.99) and 0.90 (range, 0.83-0.94) for EUS and 0.87 (range, 0.80-0.93) and 0.92 (range, 0.87-0.96) for MRCP. The overall diagnostic odds ratio of EUS was significantly higher than the one with MRCP (162.5 vs 79.0, respectively; P = .008). Further analysis showed that this was mainly due to the significantly higher sensitivity of EUS as compared with that of MRCP (P = .006). The specificity was not significantly different between 2 modalities (P = .42).

CONCLUSION

Both EUS and MRCP provide good diagnostic accuracy, with EUS providing statically better diagnostic accuracy and sensitivity, with comparable specificity. EUS should be incorporated in the diagnostic algorithm in patients suspected of choledocholithiasis whenever appropriate.

Contrast-Enhanced Magnetic Resonance Cholangiography: Practical Tips and Clinical Indications for Biliary Disease Management

Since its introduction, MRCP has been improved over the years due to the introduction of several technical advances and innovations. It consists of a noninvasive method for biliary tree representation, based on heavily T2-weighted images. Conventionally, its protocol includes two-dimensional single-shot fast spin-echo images, acquired with thin sections or with multiple thick slabs. In recent years, three-dimensional T2-weighted fast-recovery fast spin-echo images have been added to the conventional protocol, increasing the possibility of biliary anatomy demonstration and leading to a significant benefit over conventional 2D imaging. A significant innovation has been reached with the introduction of hepatobiliary contrasts, represented by gadoxetic acid and gadobenate dimeglumine: they are excreted into the bile canaliculi, allowing the opacification of the biliary tree. Recently, 3D interpolated T1-weighted spoiled gradient echo images have been proposed for the evaluation of the biliary tree, obtaining images after hepatobiliary contrast agent administration. Thus, the acquisition of these excretory phases improves the diagnostic capability of conventional MRCP—based on T2 acquisitions. In this paper, technical features of contrast-enhanced magnetic resonance cholangiography are briefly discussed; main diagnostic tips of hepatobiliary phase are showed, emphasizing the benefit of enhanced cholangiography in comparison with conventional MRCP.

Sensitivity and Specificity of Magnetic Resonance Cholangiopancreatography versus Endoscopic Ultrasonography against Endoscopic Retrograde Cholangiopancreatography in Diagnosing Choledocholithiasis: The Indonesian Experience

BACKGROUND/AIMS

Biliary stone disease is one of the most common conditions leading to hospitalization. In addition to endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasonography (EUS) and magnetic resonance cholangiopancreatography (MRCP) are required in diagnosing choledocholithiasis. This study aimed to compare the sensitivity and specificity of EUS and MRCP against ERCP in diagnosing choledocholithiasis.

METHODS

This retrospective study was conducted after prospective collection of data involving 62 suspected choledocholithiasis patients who underwent ERCP from June 2013 to August 2014. Patients were divided into two groups. The first group (31 patients) underwent EUS and the second group (31 patients) underwent MRCP. Then, ERCP was performed in both groups. Sensitivity, specificity, and diagnostic accuracy of EUS and MRCP were determined by comparing them to ERCP, which is the gold standard.

RESULTS

The male to female ratio was 3:2. The mean ages were 47.25 years in the first group and 52.9 years in the second group. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for EUS were 96%, 57%, 87%, 88%, and 80% respectively, and for MRCP were 81%, 40%, 68%, 74%, and 50%, respectively.

CONCLUSIONS

EUS is a better diagnostic tool than MRCP for diagnosing choledocholithiasis.

Management of suspected common bile duct stone: diagnostic yield of current guidelines

BACKGROUND

The American Society for Gastrointestinal Endoscopy (ASGE) has recently published a guideline for suspected CBDS with the intention of reducing unnecessary ERCP and thereby complications. The aim of this study was to assess the diagnostic efficacy of the ASGE guideline.

METHODS

Data of patients who underwent ERCP with suspected CBDS were analyzed retrospectively. Patients were classified into high, intermediate and low risk groups based on predictors that have been suggested by the ASGE. Very strong predictors of the presence of ductal stones included: CBDS on transabdominal ultrasonography (US), clinical ascending cholangitis or total bilirubin (TBIL) >4 mg/dL). Strong predictors included dilated CBD >6 mm on US with gallbladder in situ and TBIL level of 1.8-4.0 mg/dL whereas moderate predictor included abnormal liver biochemical test other than bilirubin, age more than 55 years and clinical findings of biliary pancreatitis.

RESULTS

Of 888 enrolled patients, 704 had CBDS demonstrated by ERCP and the remainder did not. All very strong and strong predictors were found to be significantly higher among patients who had CBDS. Detection of CBDS by ultrasonography and a dilated common biliary duct were observed to be independent risk factors associated with the existence of CBDS. The high risk group had a high (86.7%) positive predictive value (PPV), however, sensitivity and specificity were observed to be moderate (67.8% and 60.3% respectively). PPV was 67.9% in the intermediate risk group and the sensitivity and specificity were very low (31.9% and 42.3%).

DISCUSSION

The probability of CBDS was observed to be high in the intermediate and high risk groups. However due to low sensitivity and specificity values, the ASGE guideline needs additional or different predictors.

Endoscopic ultrasound versus magnetic resonance cholangiopancreatography in suspected choledocholithiasis: A systematic review

BACKGROUND AND OBJECTIVES

There is a lack of consensus about the optimal noninvasive strategy for patients with suspected choledocholithiasis. Two previous systematic reviews used different methodologies not based on pretest probabilities that demonstrated no statistically significant difference between Endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP) for the detection of choledocholithiasis. In this article, we made a comparison of the diagnostic ability of EUS and MRCP to detect choledocholithiasis in suspected patients.

METHODS

We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations with all published randomized prospective trials. We performed the systemic review using MedLine, EMBASE, Cochrane, LILACS, and Scopus reviews through May 2015. We identified eight randomized, prospective, blinded trials comparing EUS and MRCP. All the patients were submitted to a gold standard method. We calculated the study-specific variables and performed analyses using aggregated variables such as sensitivity, specificity, prevalence, positive predictive value (PPV) and negative predictive value (NPV), and accuracy.

RESULTS

Five hundred and thirty eight patients were included in the analysis. The pretest probability for choledocholithiasis was 38.7. The mean sensitivity of EUS and MRCP for detection of choledocholithiasis was 93.7 and 83.5, respectively; the specificity was 88.5 and 91.5, respectively. Regarding EUS and MRCP, PPV was 89 and 87.8, respectively, and NPV was 96.9 and 87.8, respectively. The accuracy of EUS and MRCP was 93.3 and 89.7, respectively.

CONCLUSIONS

For the same pretest probability of choledocholithiasis, EUS has higher posttest probability when the result is positive and a lower posttest probability when the result is negative compared with MRCP.

Biliary strictures and masses: an expanded differential diagnosis

Biliary strictures and masses are commonly a result of cholangiocarcinoma. However, there are several congenital, infectious, inflammatory, autoimmune, iatrogenic, and neoplastic etiologies that should also be considered in the differential diagnosis. Knowledge of the key imaging and clinical findings will aid in facilitating the diagnosis and treatment.

Use of advanced imaging techniques during visits to emergency departments--implications, costs, patient benefits/risks

25 years ago, on a Friday evening at 9 pm, the emergency department (ED) was full of patients with a wide range of clinical problems. Their investigations included plain radiographs, but no other imaging was included until the next working day. At present, many patients are receiving advanced imaging such as ultrasound, CT and MRI, often delivered out of hours--an obvious advance for patients or sometimes an unnecessary development? In this article, we will consider how to assess patient benefits and whether increased use of advanced imaging is an overall advance for patients. We will address the general implications for healthcare services which come with greater use of advanced imaging. We will then address the effect of advanced imaging on individual fictional ED patients with a variety of complaints.

The efficacy of endoscopic papillary balloon dilation for patients with acute biliary pancreatitis

Background. No study investigated the efficacy and safety of endoscopic papillary balloon dilation (EPBD) for the treatment of acute biliary pancreatitis (ABP). Method. We retrospectively reviewed the effects of EPBD on patients with ABP from February 2003 to December 2012. The general data, findings of image studies, details of the procedure, and outcomes after EPBD were analyzed. Result. Total 183 patients (male/female: 110/73) were enrolled. The mean age was 65.9 years. Among them, 155 patients had mild pancreatitis. The meantime from admission to EPBD was 3.3 days. Cholangiogram revealed filling defects inside the common bile duct (CBD) in 149 patients. The mean dilating balloon size was 10.5 mm and mean duration of the dilating procedure was 4.3 minutes. Overall, 124 patients had gross stones retrieved from CBD. Four (2.2%) adverse events and 2 (1.1%) intraprocedure bleeding incidents but no procedure-related mortality were noted. Bilirubin and amylase levels significantly decreased after EPBD. On average, patients resumed oral intake within 1.4 days. The clinical parameters and outcomes were similar in patients with different severity of pancreatitis. Conclusion. EPBD can be effective and safe for the treatment of ABP, even in patients presenting with severe disease.

Endoscopic ultrasound versus magnetic resonance cholangiopancreatography for common bile duct stones

BACKGROUND

Endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP) are tests used in the diagnosis of common bile duct stones in patients suspected of having common bile duct stones prior to undergoing invasive treatment. There has been no systematic review of the accuracy of EUS and MRCP in the diagnosis of common bile duct stones using appropriate reference standards.

OBJECTIVES

To determine and compare the accuracy of EUS and MRCP for the diagnosis of common bile duct stones.

SEARCH METHODS

We searched MEDLINE, EMBASE, Science Citation Index Expanded, BIOSIS, and Clinicaltrials.gov until September 2012. We searched the references of included studies to identify further studies and of systematic reviews identified from various databases (Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment (HTA), Medion, and ARIF (Aggressive Research Intelligence Facility)). We did not restrict studies based on language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included studies that provided the number of true positives, false positives, false negatives, and true negatives for EUS or MRCP. We only accepted studies that confirmed the presence of common bile duct stones by extraction of the stones (irrespective of whether this was done by surgical or endoscopic methods) for a positive test, and absence of common bile duct stones by surgical or endoscopic negative exploration of the common bile duct or symptom free follow-up for at least six months for a negative test, as the reference standard in people suspected of having common bile duct stones. We included participants with or without prior diagnosis of cholelithiasis; with or without symptoms and complications of common bile duct stones, with or without prior treatment for common bile duct stones; and before or after cholecystectomy. At least two authors independently screened abstracts and selected studies for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently collected the data from each study. We used the bivariate model to obtain pooled estimates of sensitivity and specificity.

MAIN RESULTS

We included a total of 18 studies involving 2366 participants (976 participants with common bile duct stones and 1390 participants without common bile duct stones). Eleven studies evaluated EUS alone, and five studies evaluated MRCP alone. Two studies evaluated both tests. Most studies included patients who were suspected of having common bile duct stones based on abnormal liver function tests; abnormal transabdominal ultrasound; symptoms such as obstructive jaundice, cholangitis, or pancreatitis; or a combination of the above. The proportion of participants who had undergone cholecystectomy varied across studies. Not one of the studies was of high methodological quality. For EUS, the sensitivities ranged between 0.75 and 1.00 and the specificities ranged between 0.85 and 1.00. The summary sensitivity (95% confidence interval (CI)) and specificity (95% CI) of the 13 studies that evaluated EUS (1537 participants; 686 cases and 851 participants without common bile duct stones) were 0.95 (95% CI 0.91 to 0.97) and 0.97 (95% CI 0.94 to 0.99). For MRCP, the sensitivities ranged between 0.77 and 1.00 and the specificities ranged between 0.73 and 0.99. The summary sensitivity and specificity of the seven studies that evaluated MRCP (996 participants; 361 cases and 635 participants without common bile duct stones) were 0.93 (95% CI 0.87 to 0.96) and 0.96 (95% CI 0.90 to 0.98). There was no evidence of a difference in sensitivity or specificity between EUS and MRCP (P value = 0.5). From the included studies, at the median pre-test probability of common bile duct stones of 41% the post-test probabilities (with 95% CI) associated with positive and negative EUS test results were 0.96 (95% CI 0.92 to 0.98) and 0.03 (95% CI 0.02 to 0.06). At the same pre-test probability, the post-test probabilities associated with positive and negative MRCP test results were 0.94 (95% CI 0.87 to 0.97) and 0.05 (95% CI 0.03 to 0.09).

AUTHORS' CONCLUSIONS

Both EUS and MRCP have high diagnostic accuracy for detection of common bile duct stones. People with positive EUS or MRCP should undergo endoscopic or surgical extraction of common bile duct stones and those with negative EUS or MRCP do not need further invasive tests. However, if the symptoms persist, further investigations will be indicated. The two tests are similar in terms of diagnostic accuracy and the choice of which test to use will be informed by availability and contra-indications to each test. However, it should be noted that the results are based on studies of poor methodological quality and so the results should be interpreted with caution. Further studies that are of high methodological quality are necessary to determine the diagnostic accuracy of EUS and MRCP for the diagnosis of common bile duct stones.

Evidence-Based Management of Common Gallstone-Related Emergencies

Gallstone-related disease is among the most common clinical problems encountered worldwide. The manifestations of cholelithiasis vary greatly, ranging from mild biliary colic to life-threatening gallstone pancreatitis and cholangitis. The vast majority of gallstone-related diseases encountered in an acute setting can be categorized as biliary colic, cholecystitis, choledocholithiasis, and pancreatitis, although these diagnoses can overlap. The management of these diseases is uniquely multidisciplinary, involving many specialties and treatment options. Thus, care may be compromised due to redundant tests, treatment delays, or inconsistent management. This review outlines the evidence for initial evaluation, diagnostic workup, and treatment for the most common gallstone-related emergencies. Key principles include initial risk stratification of patients to aid in triage and timing of interventions, early initiation of appropriate antibiotics for patients with evidence of cholecystitis or cholangitis, patient selection for endoscopic biliary decompression, and growing evidence in favor of early laparoscopic cholecystectomy for clinically stable patients.

MR imaging of the biliary system

Although ultrasound, computed tomography, and cholescintigraphy play essential roles in the evaluation of suspected biliary abnormalities, magnetic resonance (MR) imaging and MR cholangiopancreatography can be used to evaluate inconclusive findings and provide a comprehensive noninvasive assessment of the biliary tract and gallbladder. This article reviews standard MR and MR cholangiopancreatography techniques, clinical applications, and pitfalls. Normal biliary anatomy and variants are discussed, particularly as they pertain to preoperative planning. A spectrum of benign and malignant biliary processes is reviewed, emphasizing MR findings that aid in characterization.

Role of endoscopic ultrasonography in patients with intermediate probability of choledocholithiasis but a negative CT scan

BACKGROUND/GOALS

Despite the increased role of endoscopic ultrasonography (EUS) in diagnosis, few studies have evaluated its impact on the management of choledocholithiasis in a clinical setting for patients for whom computed tomography (CT) was conducted initially. Our aim in this study was to evaluate the role of EUS in patients with a diagnosis of intermediate probability of choledocholithiasis with a negative CT scan result.

STUDY

A total of 98 patients who were diagnosed with symptomatic cholelithiasis with intermediate probability of choledocholithiasis were evaluated prospectively. Twenty-six of the 98 patients (26.5%) were diagnosed with choledocholithiasis by CT scans. The remaining 72 patients underwent EUS.

RESULTS

Twenty-five of the 72 patients were shown to have choledocholithiasis (n=20/72, 27.8%) or papillitis with biliary outflow obstruction (n=5/72, 6.9%) on EUS. These 25 patients with positive EUS findings underwent endoscopic sphincterotomy, and choledocholithiasis was endoscopically confirmed in 23 of the 25 patients (92.0%). Postendoscopic retrograde cholangiopancreatography (ERCP) pancreatitis occurred in 3 patients (12.0% of the 25 patients who received ERCP, 4.2% of all 72 patients). Forty-seven patients with no evidence of choledocholithiasis on EUS were followed-up for a median period of 340 days (range, 185 to 755 d), and no recurrent biliary events occurred in these patients during this period. The sensitivity and specificity of EUS for choledocholithiasis was 87.0% and 100%, respectively.

CONCLUSIONS

An EUS-first strategy in patients with intermediate probability of choledocholithiasis but a negative CT scan is very useful and can reduce the need to perform invasive ERCP.

Consecutive versus separate sessions of endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) for symptomatic choledocholithiasis

BACKGROUND

Common bile duct (CBD) stones are a potentially life-threatening medical condition. Patients with proven CBD stones should undergo stone extraction. The aim of this study was to evaluate whether performing endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) for symptomatic CBD stones in a single session reduces complications related to postponing treatment due to separate EUS and ERCP sessions, and to assess the safety in both options.

METHODS

A total of 151 patients with EUS-proven CBD stones, with subsequent ERCP, treated in our department between January 2005 and December 2011 were included. Complications related to the procedures or sedation and complications due to the CBD stones when EUS and ERCP were not performed in a single session were assessed and compared to complications when the two procedures were performed in one session.

RESULTS

In total, 149 patients of the 151 (98.7 %) had a successful ERCP. Four (5 %) patients in the separate-session group (B) had a major complication compared to none in the single-session group (A) (p > 0.05). Group B received 14 % more midazolam during ERCP than group A (p < 0.05). No sedation-related complications were noted in either group. Eleven of the 80 patients in group B (13.8 %) experienced complications while waiting for ERCP compared to none in group A (p = 0.001, OR = 2.17, CI = 1.06-4.

CONCLUSIONS

EUS and ERCP done in a single session proved to be safe, with no increase in sedation- or procedure-related complications. Postponing treatment for symptomatic CBD stones exposes the patient to biliary complications, especially cholangitis.

Gallbladder patterns in acute pancreatitis: an MRI study

RATIONALE AND OBJECTIVES

The aim of this study was to assess the gallbladder patterns on magnetic resonance imaging (MRI) associated with acute pancreatitis (AP).

MATERIALS AND METHODS

There were 197 patients with AP, all of whom had undergone abdominal MRI. AP was categorized as either edematous or necrotizing according to its findings on MRI and graded as mild (0-3 points), moderate (4-6 points), or severe (7-10 points) according to the magnetic resonance severity index. The changes to the walls and dimensions of the gallbladder and common bile duct, in addition to the presence of biliary stones and pericholecystic fluid, were noted and compared with the severity of AP on the basis of the magnetic resonance severity index.

RESULTS

Of the 197 patients with AP, 81% were classified as edematous and 19% as necrotizing on MRI. There were 35%, 59%, and 6% of patients with mild, moderate, and severe AP according to the magnetic resonance severity index, respectively. Seventy-six percent of patients had at least one gallbladder abnormality on MRI, including a thickened gallbladder wall (42%), pericholecystic fluid (38%), gallbladder stones (35%), an enlarged gallbladder (24%), dilatation of the common bile duct (16%), and subserosal edema (15%). Eighty-nine percent of patients (34 of 38) with necrotizing AP had gallbladder abnormalities, which was significantly higher than the 72% of patients (115 of 159) with edematous AP (P < .05). The prevalence of gallbladder abnormalities was 64% in patients with mild AP, 81% in those with moderate AP, and 91% in those with severe AP (P < .05 among the three groups).

CONCLUSIONS

Most patients with AP have gallbladder abnormalities on MRI, including a thickened gallbladder wall and pericholecystic fluid. The prevalence of gallbladder abnormalities has a positive correlation with the severity of AP on MRI.

EUS in exploring the etiology of mild acute biliary pancreatitis with a negative finding of biliary origin by conventional radiological methods

BACKGROUND AND AIM

Conventional radiological methods, including transcutaneous ultrasonography (US), computed tomography (CT), and magnetic resonance cholangiopancreatography (MRCP) are non-invasive and recommended for the detection of etiologies of acute biliary pancreatitis (ABP). There are still, however, a number of patients whose etiologies cannot be found by these methods. The value of endoscopic ultrasound (EUS) for this population is still unknown. The aim of the present study was to evaluate the role of EUS in exploring the unknown etiology of mild ABP.

METHODS

The data from patients with mild ABP admitted to Changhai Hospital, Shanghai, China, from June 2006 to December 2009 were retrospectively collected, and the results of the imaging methods in detecting biliary disorders were analyzed.

RESULTS

A total of 223 patients with mild ABP underwent both US and CT. Of these, 106 underwent additional MRCP. There were still 37 patients with unknown biliary etiologies, even after the use of the conventional methods mentioned earlier. EUS was conducted in 33 of these patients. Abnormalities associated with the etiology of mild ABP were found in 14 cases (42.4%) confirmed by subsequent endoscopic retrograde cholangiopancreatography, with biliary stones in 11 cases, biliary sludge in two cases, and ampullary adenocarcinoma in one case.

CONCLUSION

The results suggest that EUS is helpful in the identification of the etiology of mild biliary pancreatitis when conventional radiological imaging is negative or equivocal.

Cost-effective treatment of patients with symptomatic cholelithiasis and possible common bile duct stones

BACKGROUND

Clinicians must choose a treatment strategy for patients with symptomatic cholelithiasis without knowing whether common bile duct (CBD) stones are present. The purpose of this study was to determine the most cost-effective treatment strategy for patients with symptomatic cholelithiasis and possible CBD stones.

STUDY DESIGN

Our decision model included 5 treatment strategies: laparoscopic cholecystectomy (LC) alone followed by expectant management; preoperative endoscopic retrograde cholangiopancreatography (ERCP) followed by LC; LC with intraoperative cholangiography (IOC) ± common bile duct exploration (CBDE); LC followed by postoperative ERCP; and LC with IOC ± postoperative ERCP. The rates of successful completion of diagnostic testing and therapeutic intervention, test characteristics (sensitivity and specificity), morbidity, and mortality for all procedures are from current literature. Hospitalization costs and lengths of stay are from the 2006 National Centers for Medicare and Medicaid Services data. The probability of CBD stones was varied from 0% to 100% and the most cost-effective strategy was determined at each probability.

RESULTS

Across the CBD stone probability range of 4% to 100%, LC with IOC ± ERCP was the most cost-effective. If the probability was 0%, LC alone was the most cost-effective. Our model was sensitive to 1 health input: specificity of IOC, and 3 costs: cost of hospitalization for LC with CBDE, cost of hospitalization for LC without CBDE, and cost of LC with IOC.

CONCLUSIONS

The most cost-effective treatment strategy for the majority of patients with symptomatic cholelithiasis is LC with routine IOC. If stones are detected, CBDE should be forgone and the patient referred for ERCP.

Comparison of three-dimensional negative-contrast CT cholangiopancreatography with three-dimensional MR cholangiopancreatography for the diagnosis of obstructive biliary diseases

PURPOSE

The purpose of our study was to compare three-dimensional (3D) negative-contrast CT cholangiopancreatography (3D-nCTCP) with 3D MR cholangiopancreatography (3D-MRCP) for the diagnosis of obstructive biliary diseases.

MATERIALS AND METHODS

3D-nCTCP and 3D-MRCP were performed on seventy clinically documented obstructive biliary diseases patients. The accuracy of each technique in determining the location and cause of biliary obstruction was evaluated compared with the final clinical diagnoses.

RESULTS

Both methods achieved 100% of accuracy in the diagnosis of the presence and location of biliary obstruction, and had a similar sensitivity, specificity, accuracy in differentiating benign from malignant biliary obstruction or calculous from noncalculous biliary obstruction (p>0.05). At 3D-nCTCP, six patients with stones were misinterpreted as cholangitis (N=2), papillitis (N=3), or bile duct adenocarcinoma (N=1); two metastases were mistaken as acute pancreatitis or pancreatic head carcinomas, and one intrahepatic cholangiocarcinoma was misled as bile duct adenoma. At 3D-MRCP, one small stone, one ampullary adenoma, and one intrahepatic cholangiocarcinoma were mistaken as cholangitis, ampullary stone, and intrahepatic bile duct stone, respectively, and three gallbladder carcinomas and another intrahepatic cholangiocarcinoma were misdiagnosed as hilar cholangiocarcinoma (N=3) or common hepatic duct stone (N=1); four metastases were mistaken as pancreatic head carcinomas (N=3) or distal cholangiocarcinoma (N=1). The overall accuracy in making specific diagnosis of the cause of biliary obstruction was 87.1% for 3D-nCTCP and 84.3% for 3D-MRCP, respectively, (p>0.05).

CONCLUSION

3D-nCTCP has the similar effects as 3D-MRCP for the diagnosis of biliary obstruction and, the location and the cause of biliary obstruction. In view of selected cases contraindications for MRI, 3D-nCTCP is a potential substitute.

Prospective comparison of endoscopic ultrasonography and magnetic resonance cholangiopancreatography in the etiological diagnosis of "idiopathic" acute pancreatitis

OBJECTIVES

The objectives of the study were to compare endoscopic ultrasonography (EUS) and magnetic resonance cholangiopancreatography (MRCP) in the etiological diagnosis of patients initially diagnosed with idiopathic acute pancreatitis and to determine the clinical and analytical factors related to the end result of these techniques.

METHODS

Forty-nine patients, initially diagnosed with idiopathic acute pancreatitis, were evaluated prospectively with EUS and MRCP. Diagnoses were compared between the 2 procedures. The clinical-evolutionary characteristics of these patients with regard to the results obtained with these techniques were compared.

RESULTS

In twenty-eight patients (57%), EUS and/or MRCP diagnosed at least 1 possible cause of acute pancreatitis. The diagnostic yield of EUS was higher than that of MRCP (51% vs 20%; P = 0.001). Cholelithiasis and biliary sludge (24%) were the most frequent EUS diagnoses, and pancreas divisum (8%) was the most frequent MRCP diagnosis. Only in 3 cases (6%) did MRCP identify additional features in patients etiologically undiagnosed using EUS. The EUS yield was lower in patients who had a previous cholecystectomy (11% vs 60%; P = 0.008).

CONCLUSIONS

Endoscopic ultrasonography and MRCP are useful techniques in the etiological diagnosis of acute pancreatitis of nonestablished cause. Endoscopic ultrasonography should be preferred for establishing a possible biliary etiology in patients who have not had a cholecystectomy.

Biliary, pancreatic, and hepatic imaging for the general surgeon

Technologic advancements have allowed imaging modalities to become more useful in the diagnosis of hepatobiliary and pancreatic disorders. Computed tomography scanners now use multidetector row technology with contrast-delayed imaging for quicker and more accurate imaging. Magnetic resonance imaging with cholangiopancreatography can more clearly delineate liver lesions and the biliary and pancreatic ducts, and can diagnose pathologic conditions early in their course. Newer technologies, such as single-operator cholangioscopy and endoscopic ultrasonography, have sometimes shown superiority to traditional modalities. This article addresses the literature regarding available imaging techniques in the diagnosis and treatment of common surgical hepatobiliary and pancreatic diseases.

Role of intra operative cholangiogram in current day practice

The role of Intra Operative Cholangiogram during laparoscopic cholecystectomy remains controversial. This review discusses the modalities used in the pre- and peri-operative assessment of Common Bile Duct. It also discusses the advantages and disadvantages of selective and routine IOC. In this review we explore the role of Intra Operative Cholangiogram in current day practice.

Alanine transaminase rather than abdominal ultrasound alone is an important investigation to justify cholecystectomy in patients presenting with acute pancreatitis

OBJECTIVES

The aims of this study were to investigate the predictive value of an elevated level of alanine transaminase (ALT) for biliary acute pancreatitis (AP) and to reconsider the role of abdominal ultrasound (AUS).

METHODS

All patients admitted to Christchurch Public Hospital with AP between July 2005 and December 2008 were identified from a prospectively collected database. Peak ALT within 48 h of presentation was recorded. Aetiology was determined on the basis of history, AUS and other relevant investigations.

RESULTS

A total of 543 patients met the inclusion criteria. Patients with biliary AP had significantly higher median (range) ALT than those with non-biliary causes (200 units/l [63-421 units/l] vs. 33 units/l [18-84 units/l]; P < 0.001). An ALT level of >300 units/l had a sensitivity of 36%, specificity of 94%, positive predictive value of 87% and positive likelihood ratio of 5.6 for gallstones. An elevated ALT and negative AUS had a probability of 21-80% for gallstones.

CONCLUSIONS

An elevated ALT strongly supports a diagnosis of gallstones in AP. Abdominal ultrasound effectively confirms this diagnosis; however, a negative ultrasound in the presence of a raised ALT does not exclude gallstones. In some patients consideration could be given to proceeding to laparoscopic cholecystectomy based on ALT alone.

Magnetic resonance cholangiopancreatography and contrast-enhanced magnetic resonance cholangiopancreatography versus endoscopic ultrasonography in the diagnosis of extrahepatic biliary pathology

PURPOSE

This study compared the diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasonography (EUS) in evaluating the cause of extrahepatic bile duct dilatation.

MATERIALS AND METHODS

Forty-five patients (26 men, mean age 57 years) with extrahepatic biliary dilatation, as shown by transabdominal ultrasound, with or without elevated biliary and pancreatic serum indices, were prospectively studied with MRCP and EUS between September 2007 and October 2008. EUS and MRCP were performed within no more than 24 h of each other to reduce the possibility of changes due to stone migration. Image analysis was carried out in a double-blind fashion.

RESULTS

MRCP had 88.9% diagnostic accuracy, 91.9% sensitivity and 75% specificity, with 94.4% positive predictive value and 66.7% negative predictive value. EUS had 93.3% diagnostic accuracy, 97.3% sensitivity and 75% specificity; the positive and negative predictive values were 94.7% and 85.7%, respectively.

CONCLUSIONS

MRCP and EUS do not show significant statistical differences in diagnostic accuracy. MRCP is an accurate, noninvasive modality in the study of extrahepatic biliary pathology. EUS is especially reliable in patients with extrahepatic biliary obstruction caused by endoluminal sludge.

Evaluation of the biliary and pancreatic system with 2D SSFSE, breathhold 3D FRFSE and respiratory-triggered 3D FRFSE sequences

PURPOSE

The authors compared biliary and pancreatic imaging obtained through 2D single-shot fast spin-echo (SSFSE), breath-hold 3D fast recovery fast spin-echo (FRFSE) and respiratory-triggered 3D FRFSE sequences.

MATERIALS AND METHODS

A total of 106 magnetic resonance cholangiopancreatography (MRCP) examinations performed between December 2007 and September 2008 were evaluated with a comparison of 2D SSFSE (thin section and thick slab), breath-hold 3D FRFSE and respiratory-triggered 3D FRFSE sequences. The biliary tract was divided into seven segments: right hepatic duct, left hepatic duct, common hepatic duct, cystic duct, common bile duct, cystic duct junction and biliary-pancreatic confluence. The main pancreatic duct was divided into three segments (head, body and tail). Visualisation of biliary variants was also compared. Two blinded radiologists evaluated segment visibility using a quantitative scale. The Student's t test for paired samples was used for statistical analysis.

RESULTS

Compared with 2D SSFSE, respiratory-triggered 3D FRFSE sequences showed better visibility of the right hepatic duct (p=0.0277), the cystic duct (p=0.0081), the cystic duct junction (p=0.0010), the biliary-pancreatic confluence (p=0.0334) and biliary variants (p=0.0198). In the comparison between breath-hold 3D FRFSE and 2D SSFSE, a significant statistical difference was found in visualisation of the cystic duct (p=0.027), the cystic duct junction (p=0.020), the biliary-pancreatic confluence (p=0.0338) and biliary variants (p=0.0311).

CONCLUSIONS

Three-dimensional FRFSE offers a significant benefit over conventional 2D imaging.

Endoscopic ultrasound: what is it and when should it be used?

Endoscopic ultrasound (EUS) is an increasingly available diagnostic and therapeutic tool used within the U.K. it has wide applications both in the gastrointestinal tract and mediastinum with its current main uses being in the staging of luminal malignancies and assessment of pancreatic and subepithelial lesions. The emergence of linear EUS has opened up new therapeutic avenues with fine needle aspiration, trucut biopsies, coeliac plexus blocks and transmural pseudocyst drainage all now possible. Future developments include localised brachytherapy/chemotherapy and alcohol ablation of unresectable pancreatic malignancies and EUS-guided endoscopic surgery.

Tissue harmonic sonography in the diagnosis of common bile duct stones: a comparison with endoscopic retrograde cholangiography

PURPOSE

To revisit the diagnostic accuracy of sonography in the detection of choledocholithiasis using modern equipment with tissue harmonic imaging (THI) and endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy as the gold standard.

METHODS

A total of 107 patients with clinically suspected choledocholithiasis were examined with THI before undergoing ERCP. The sonographic findings that were prospectively evaluated included the presence of choledocholithiasis, size of common bile duct, sonographic view and patient position that best visualized the stone(s), visualization of the distal common duct, and duration of examination. The accuracy of sonography compared with ERCP and sphincterotomy was calculated.

RESULTS

Sonography correctly detected stones in 65 of 76 patients (sensitivity of 86%). The specificity and the overall accuracy were 87% and 86%, respectively. The sensitivity of sonography was higher with dilated extrahepatic duct (44% in patients with common bile duct measuring less than 6 mm in diameter, 82% between 6 and 10 mm, and 100% with common bile duct larger than 10 mm). The lateral approach with the patient in left lateral decubitus position of the patient was the most effective in 47% of the cases.

CONCLUSION

Sonography with THI is an accurate technique for the detection of choledocholithiasis that may be used as the first-choice technique to avoid unnecessary procedures in a high percentage of patients, especially those with dilated biliary tree.

Imaging patients with acute abdominal pain

Acute abdominal pain may be caused by a myriad of diagnoses, including acute appendicitis, diverticulitis, and cholecystitis. Imaging plays an important role in the treatment management of patients because clinical evaluation results can be inaccurate. Performing computed tomography (CT) is most important because it facilitates an accurate and reproducible diagnosis in urgent conditions. Also, CT findings have been demonstrated to have a marked effect on the management of acute abdominal pain. The cost-effectiveness of CT in the setting of acute appendicitis was studied, and CT proved to be cost-effective. CT can therefore be considered the primary technique for the diagnosis of acute abdominal pain, except in patients clinically suspected of having acute cholecystitis. In these patients, ultrasonography (US) is the primary imaging technique of choice. When costs and ionizing radiation exposure are primary concerns, a possible strategy is to perform US as the initial technique in all patients with acute abdominal pain, with CT performed in all cases of nondiagnostic US. The use of conventional radiography has been surpassed; this examination has only a possible role in the setting of bowel obstruction. However, CT is more accurate and more informative in this setting as well. In cases of bowel perforation, CT is the most sensitive technique for depicting free intraperitoneal air and is valuable for determining the cause of the perforation. Imaging is less useful in cases of bowel ischemia, although some CT signs are highly specific. Magnetic resonance (MR) imaging is a promising alternative to CT in the evaluation of acute abdominal pain and does not involve the use of ionizing radiation exposure. However, data on the use of MR imaging for this indication are still sparse.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/content/253/1/31/suppl/DC1.

High spatial resolution 3D MR cholangiography with high sampling efficiency technique (SPACE): comparison of 3T vs. 1.5T

PURPOSE

The aim of this study was to evaluate image quality of 3D MR cholangiography (MRC) using high sampling efficiency technique (SPACE) at 3T compared with 1.5T.

METHODS AND MATERIALS

An IRB approved prospective study was performed with 17 healthy volunteers using both 3 and 1.5T MR scanners. MRC images were obtained with free-breathing navigator-triggered 3D T2-weighted turbo spin-echo sequence with SPACE (TR, >2700ms; TE, 780ms at 3T and 801ms at 1.5T; echo-train length, 121; voxel size, 1.1mmx1.0mmx0.84mm). The common bile duct (CBD) to liver contrast-to-noise ratios (CNRs) were compared between 3 and 1.5T. A five-point scale was used to compare overall image quality and visualization of the third branches of bile duct (B2, B6, and B8). The depiction of cystic duct insertion and the highest order of bile duct visible were also compared. The results were compared using the Wilcoxon signed-ranks test.

RESULTS

CNR between the CBD and liver was significantly higher at 3T than 1.5T (p=0.0006). MRC at 3T showed a significantly higher overall image quality (p=0.0215) and clearer visualization of B2 (p=0.0183) and B6 (p=0.0106) than at 1.5T. In all analyses of duct visibility, 3T showed higher scores than 1.5T.

CONCLUSION

3T MRC using SPACE offered better image quality than 1.5T. SPACE technique facilitated high-resolution 3D MRC with excellent image quality at 3T.

Magnetic resonance imaging and the acute abdomen

Work in progress

When should abdominal magnetic resonance imaging be used?

When assessing the use of an imaging study, historically 2 criteria were used, diagnostic accuracy and cost of the study. However, as the awareness of risk for radiation-induced cancer in the general population increases as a direct result of more computed tomography (CT) studies being performed, reevaluation of the approach to imaging studies is necessary. The new imaging paradigm considers patient safety as an important aspect of assessing the role of an imaging modality. The primary goals of the new imaging paradigm should be diagnostic accuracy and patient safety, with the secondary goal being more affordable cost of study. In formulating a plan for when to use body magnetic resonance imaging (MRI), one has to consider all of these criteria and should also consider the question of when CT has unmatched diagnostic accuracy. The advantages of the spatial resolution of CT are mainly realized when there is great contrast between what is being looked for and background tissue; examples include small lung nodules and renal calculi. The greater intrinsic soft tissue contrast resolution and greater sensitivity for the presence or absence of intravenous contrast are appreciated in MRI studies, circumstances in which lesions occur within an organ without altering its exterior contour. This is well-shown for liver lesions. Adding patient safety into the equation, MRI should be indicated in exams in which there is no greater difference in diagnostic accuracy between CT and MRI, in patients with greater concern for radiation safety such as pediatric patients, and in cases of multiple or serial exams.