Current role and future potential of magnetic resonance cholangiopancreatography with an emphasis on incidental findings

ACR Appropriateness Criteria® Workup of Pleural Effusion or Pleural Disease

Pleural effusions are categorized as transudative or exudative, with transudative effusions usually reflecting the sequala of a systemic etiology and exudative effusions usually resulting from a process localized to the pleura. Common causes of transudative pleural effusions include congestive heart failure, cirrhosis, and renal failure, whereas exudative effusions are typically due to infection, malignancy, or autoimmune disorders. This document summarizes appropriateness guidelines for imaging in four common clinical scenarios in patients with known or suspected pleural effusion or pleural disease. 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 process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Global Prevalence of Pancreatic Cystic Lesions in the General Population on Magnetic Resonance Imaging: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Understanding the burden of pancreatic cystic lesions (PCLs) in the general population is important for clinicians and policymakers. In this systematic review, we sought to estimate the global prevalence of PCLs using magnetic resonance imaging (MRI) and to investigate factors that contribute to its variation.

METHODS

We searched MEDLINE, EMBASE, and Cochrane Central, from database inception through February 2023. We included full-text articles that reported the prevalence of PCLs using MRI in the general population. A proportional meta-analysis was performed, and the prevalence of PCLs was pooled using a random-effects model.

RESULTS

Fifteen studies with 65,607 subjects were identified. The pooled prevalence of PCLs was 16% (95% confidence interval [CI], 13%-18%; I2 = 99%), most of which were under 10 mm. Age-specific prevalence of PCLs increased from 9% (95% CI, 7%-12%) at 50 to 59 years, to 18% (95% CI, 14%-22%) at 60 to 69 years, 26% (95% CI, 20%-33%) at 70 to 79 years, and 38% at 80 years and above (95% CI, 25%-52%). There was no difference in prevalence between sexes. Subgroup analysis showed higher PCL prevalence when imaging findings were confirmed by independent radiologist(s) (25%; 95% CI, 16%-33%) than when chart review alone was used (5%; 95% CI, 4%-7%; P < .01). There was no independent association of PCL prevalence with geographic location (Europe, North America, or Asia), MRI indication (screening vs evaluation of non-pancreatic pathology), enrollment period, sample size, magnet strength (1.5 vs 3 tesla), and MRI sequence (magnetic resonance cholangiopancreatography vs no magnetic resonance cholangiopancreatography).

CONCLUSION

In this systematic review, the global prevalence of PCLs using a highly sensitive noninvasive imaging modality ranged between 13% and 18%.

Noninvasive prediction of insufficient biochemical response after ursodeoxycholic acid treatment in patients with primary biliary cholangitis based on pretreatment nonenhanced MRI

OBJECTIVES

To explore the feasibility of pretreatment nonenhanced magnetic resonance imaging (MRI) in predicting insufficient biochemical response to ursodeoxycholic acid (UDCA) in patients with primary biliary cholangitis (PBC).

METHODS

From January 2009 to April 2022, consecutive PBC patients who were treated with UDCA and underwent nonenhanced MRI within 30 days before treatment were retrospectively enrolled. All MR images were independently evaluated by two blinded radiologists. Uni- and multivariable logistic regression analyses were performed to develop a predictive model for 12-month insufficient biochemical response. Model performances were evaluated by computing the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity.

RESULTS

A total of 74 patients (50.6 ± 11.9 years; 62 females) were included. Three pretreatment MRI features, including hepatomegaly (odds ratio [OR]: 4.580; p = 0.011), periportal hyperintensity on T2-weighted imaging (T2WI) (OR: 4.795, p = 0.008), and narrowing of the bile ducts (OR: 3.491; p = 0.027) were associated with 12-month insufficient biochemical response in the multivariable analysis. A predictive model based on the above indicators had an AUC of 0.781, sensitivity of 85.4%, and specificity of 61.5% for predicting insufficient biochemical response.

CONCLUSIONS

A noninvasive model based on three pretreatment MRI features could accurately predict 12-month insufficient biochemical response to UDCA in patients with PBC. Early identification of PBC patients at increased risk for insufficient response can facilitate the timely initiation of additional treatment.

CLINICAL RELEVANCE STATEMENT

A noninvasive predictive model constructed by incorporating three pretreatment MRI features may help identify patients with primary biliary cholangitis at high risk of insufficient biochemical response to ursodeoxycholic acid and facilitate the timely initiation of additional treatment.

KEY POINTS

• Noninvasive imaging features based on nonenhanced pretreatment MRI may predict an insufficient biochemical response to UDCA in PBC patients. • A combined model based on three MRI features (hepatomegaly, periportal hyperintensity on T2-weighted imaging, and narrowing of the bile ducts) further improved the predictive efficacy for an insufficient biochemical response to UDCA in PBC patients, with high sensitivity and specificity. • The nomogram of the combined model showed good calibration and predictive efficacy for an insufficient biochemical response to UDCA in PBC patients. In particular, the calibration curve visualised the clinical applicability of the prediction model.

Ultrasound-guided transhepatic computed tomography cholecystography in beagle dogs

This study was performed to evaluate the feasibility of ultrasound-guided computed tomography (CT) cholecystography and to establish an optimal protocol. In 8 healthy beagles, CT cholecystography was conducted using four contrast formulas; two dilution ratios (1:1 vs. 1:3) and two total volumes (8 mL vs. 16 mL) of 300 mgI/kg iohexol after ultrasound-guided percutaneous contrast injection into the gallbladder. CT images were obtained at 3, 10, and 30 min after injection and assessed qualitatively and quantitatively. For all contrast formulas, CT cholecystography showed the gallbladder and the intra- and extrahepatic bile ducts. The volume of the gallbladder and size of bile duct were significantly larger when using a volume of 16 mL iohexol than an 8 mL volume regardless of the dilution ratio. The distinction between the common bile duct and duodenum, the filling of the gallbladder, and the patency of bile duct were effectively assessed using a 16 mL volume of contrast agent with either dilution ratio. Beam-hardening artifacts deteriorated CT image quality for visualizing the biliary system when using the dilution ratio of 1:1. Patency of the bile tract could be easily evaluated using a curvilinear planar reconstruction. There was no significant difference in CT scan time among the different conditions. Minor leakage of contrast agent temporarily occurred after contrast injection in 30% of 32 sets of CT cholecystography. Ultrasound-guided percutaneous cholecystography can visualize both gallbladder and biliary tract with minimal artifacts using a contrast agent volume of 16 mL with a 1:3 dilution ratio.

Systematic review and meta-analysis: Prevalence of incidentally detected pancreatic cystic lesions in asymptomatic individuals

BACKGROUND & AIMS

Pancreatic cystic lesions (PCLs) are frequent incidental findings. As most PCLs require costly diagnostic evaluation and active surveillance, it is important to clarify their prevalence in asymptomatic individuals. We therefore aimed at performing a systematic review and meta-analysis to determine it.

METHODS

a systematic search was conducted and studies meeting inclusion criteria were included. The prevalence of PCLs was pooled across studies. A random effect model was used with assessment of heterogeneity.

RESULTS

17 studies, with 48,860 patients, were included. Only 3 were prospective; 5 studies were conducted in the US, 7 in Europe, 4 in Asia and 1 in Brazil. The pooled prevalence of PCLs was 8% (95% CI 4-14) with considerable heterogeneity (I² = 99.5%). This prevalence was higher in studies of higher quality, examining older subjects, smaller cohorts, and employing MRCP (24.8% vs 2.7% with CT-scan). The pooled rate of PCLs was four times higher in studies conducted in the US than in Asia (12.6% vs 3.1%). 7 studies reported the prevalence of mucinous lesions, with a pooled rate of 4.3% (95% CI 2-10; I² = 99.2%), but of 0.7% only for worrisome features or high risk stigmata.

CONCLUSION

The rate of incidentally detected PCLs is of 8%. Mucinous lesions are the most common incidentally detected PCLs, although they rarely present with potential indication for surgery. The observed different rates in the US and other geographic Areas suggest that different protocols might be necessary to help balancing costs and effectiveness of follow-up investigations in asymptomatic subjects.

Accuracy of magnetic resonance cholangiography compared to operative endoscopy in detecting biliary stones, a single center experience and review of literature

AIM: To compare diagnostic sensitivity, specificity and accuracy of magnetic resonance cholangiopancreatography (MRCP) without contrast medium and endoscopic ultrasound (EUS)/endoscopic retrograde cholangiopancreatography (ERCP) for biliary calculi.

METHODS: From January 2012 to December 2013, two-hundred-sixty-three patients underwent MRCP at our institution, all MRCP procedure were performed with the same machinery. In two-hundred MRCP was done for pure hepatobiliary symptoms and these patients are the subjects of this study. Among these two-hundred patients, one-hundred-eleven (55.5%) underwent ERCP after MRCP. The retrospective study design consisted in the systematic revision of all images from MRCP and EUS/ERCP performed by two radiologist with a long experience in biliary imaging, an experienced endoscopist and a senior consultant in Hepatobiliopancreatic surgery. A false positive was defined an MRCP showing calculi with no findings at EUS/ERCP; a true positive was defined as a concordance between MRCP and EUS/ERCP findings; a false negative was defined as the absence of images suggesting calculi at MRCP with calculi localization/extraction at EUS/ERCP and a true negative was defined as a patient with no calculi at MRCP ad at least 6 mo of asymptomatic follow-up. Biliary tree dilatation was defined as a common bile duct diameter larger than 6 mm in a patient who had an in situ gallbladder. A third blinded radiologist who examined the MRCP and ERCP data reviewed misdiagnosed cases. Once obtained overall data on sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) we divided patients in two groups composed of those having concordant MRCP and EUS/ERCP (Group A, 72 patients) and those having discordant MRCP and EUS/ERCP (Group B, 20 patients). Dataset comparisons had been made by the Student’s t-test and χ² when appropriate.

RESULTS: Two-hundred patients (91 men, 109 women, mean age 67.6 years, and range 25-98 years) underwent MRCP. All patients attended regular follow-up for at least 6 mo. Morbidity and mortality related to MRCP were null. MRCP was the only exam performed in 89 patients because it did show only calculi into the gallbladder with no signs of the presence of calculi into the bile duct and symptoms resolved within a few days or after colecistectomy. The patients remained asymptomatic for at least 6 mo, and we assumed they were true negatives. One hundred eleven (53 men, 58 women, mean age 69 years, range 25-98 years) underwent ERCP following MRCP. We did not find any difference between the two groups in terms of race, age, and sex. The overall median interval between MRCP and ERCP was 9 d. In detecting biliary stones MRCP Sensitivity was 77.4%, Specificity 100% and Accuracy 80.5% with a PPV of 100% and NPV of 85%; EUS showed 95% sensitivity, 100% specificity, 95.5% accuracy with 100% PPV and 57.1% NPV. The association of EUS with ERCP performed at 100% in all the evaluated parameters. When comparing the two groups, we did not find any statistically significant difference regarding age, sex, and race. Similarly, we did not find any differences regarding the number of extracted stones: 116 stones in Group A (median 2, range 1 to 9) and 27 in Group B (median 2, range 1 to 4). When we compared the size of the extracted stones we found that the patients in Group B had significantly smaller stones: 14.16 ± 8.11 mm in Group A and 5.15 ± 2.09 mm in Group B; 95% confidence interval = 5.89-12.13, standard error = 1.577; P < 0.05. We also found that in Group B there was a significantly higher incidence of stones smaller than 5 mm: 36 in Group A and 18 in Group B, P < 0.05.

CONCLUSION: Major finding of the present study is that choledocholithiasis is still under-diagnosed in MRCP. Smaller stones (< 5 mm diameter) are hardly visualized on MRCP.