Comparison of respiratory-triggered 3-D fast spin-echo and single-shot fast spin-echo radial slab MR cholangiopancreatography images in children

Comparison of quantitative 3D magnetic resonance cholangiography measurements obtained using three different image acquisition methods

PURPOSE

To compare quantitative biliary measurements obtained with three different magnetic resonance cholangiopancreatography (MRCP) acquisition methods.

METHODS

This retrospective study was IRB-approved. Patients with combinations of clinically indicated 3D FSE MRCP with sensitivity encoding (SENSE), 3D FSE SENSE MRCP with compressed sensing (CS-FSE; acceleration factor 8), and 3D gradient and spin-echo (GRASE) MRCP, acquired between October 2018 and March 2020, were included. The MRCP + Tuning Threshold algorithm (Perspectum Ltd., Oxford, UK) was used to segment 3D biliary models from MRCP data, with multiple metrics quantified from the models. Single measure, two-way, mixed-effects intra-class correlations, Bland-Altman analyses, and Wilcoxon signed-rank tests were used to compare quantitative measurements.

RESULTS

From 160 MRCP datasets (25 3D FSE, 67 3D CS-FSE, 68 3D GRASE) in 69 patients, 48 datasets (7 [28%] 3D FSE, 14 [21%] 3D CS-FSE, 27 [40%] 3D GRASE) failed post-processing due to motion artifacts. The remaining 112 MRCP datasets (18 3D FSE, 53 3D CS-FSE, 41 3D GRASE) from 60 patients were included in the analysis. There was good to excellent agreement between 3D FSE and 3D CS-FSE MRCP for diameter of the left and right hepatic ducts, biliary volume, number and length of ducts, and total length of dilations (ICC: 0.83-0.93). The only metrics that exhibited good agreement between 3D FSE and 3D GRASE MRCP were biliary volume (ICC: 0.75) and total number of dilations (ICC: 0.77).

CONCLUSION

3D CS-FSE MRCP produces comparable biliary diameter metrics and global duct quantification to 3D FSE MRCP at a significantly reduced acquisition time.

Current State of Imaging of Pediatric Pancreatitis: AJR Expert Panel Narrative Review

Pancreatitis is as common in children as it is in adults, though causes and accepted imaging strategies differ in children. In this narrative review we discuss the epidemiology of childhood pancreatitis and key imaging features for pediatric acute, acute recurrent, and chronic pancreatitis. We rely heavily on our collective experience in discussing advantages and disadvantages of different imaging modalities; practical tips for optimization of ultrasound, CT, and MRI with MRCP in children; and image interpretation pearls. Challenges and considerations unique to imaging pediatric pancreatitis are discussed, including timing of imaging, role of secretin-enhanced MRCP, utility of urgent MRI, severity prediction, autoimmune pancreatitis, and best methods for serial imaging. We suggest a methodical approach to pancreatic MRI interpretation in children and have included a sample structured report, and we provide consensus statements according to our experience imaging children with pancreatitis.

Magnetic resonance cholangiopancreatography at 3T in a single breath-hold: comparative effectiveness between three-dimensional (3D) gradient- and spin-echo and two-dimensional (2D) thick-slab fast spin-echo acquisitions

Background

To compare the depiction conspicuity of three-dimensional (3D) magnetic resonance cholangiopancreatography (MRCP) based on gradient- and spin-echo (GRASE) and two-dimensional (2D) thick-slab MRCP using fast spin-echo (FSE) in different segments of hepatic and pancreatic ducts at 3T.

Methods

Both 3D GRASE and 2D thick-slab FSE MRCP, with parameters adjusted under the constraints of specific absorption rate and scan time within single breath-hold, were performed for 95 subjects (M/F =49:46; age range, 25-75) at 3T. Conspicuity of eight ductal segments was graded by two experienced raters using a 4-point score. Situations where one technique is superior or inferior to the other were recorded.

Results

3D GRASE MRCP outperformed 2D thick-slab FSE MRCP in the common bile duct and common hepatic ducts (both with P<0.001), but compared inferiorly in the right hepatic ducts (P<0.001), right posterior hepatic ducts (P<0.005) and pancreatic duct distal (P<0.05). Performing both 3D and 2D MRCP would reduce the number of non-diagnostic readings in the left hepatic duct to 10 remaining (5.3%), compared with 31 (16.3%) or 21 (11.1%) out of 190 readings if using 3D GRASE or 2D thick-slab FSE alone, respectively.

Conclusions

Although 3D GRASE MRCP is preferential to visualize the common bile duct and common hepatic duct within one single breath-hold, the complementary role of 2D thick-slab FSE MRCP in smaller hepatic and pancreatic ducts makes it a useful adjunct if performed additionally.

Magnetic Resonance Cholangiopancreatography Severity Predicts Disease Outcomes in Pediatric Primary Sclerosing Cholangitis: A Reliability and Validity Study

Magnetic resonance cholangiopancreatography (MRCP) has not been assessed as a surrogate biomarker in pediatrics. We aimed to determine the inter‐rater reliability, prognostic utility, and construct validity of the modified Majoie endoscopic retrograde cholangiopancreatography classification applied to MRCP in a pediatric primary sclerosing cholangitis (PSC) cohort. This single‐center, retrospective, cohort study included children with PSC undergoing diagnostic MRCP between 2008 and 2016. Six variations of the Majoie classification were examined: 1) intrahepatic duct (IHD) score, 2) extrahepatic duct (EHD) score (representing the worst intrahepatic and extrahepatic regions, respectively), 3) sum IHD‐EHD score, 4) average IHD score, 5) average EHD score, and 6) sum average IHD‐EHD score. Inter‐rater reliability was assessed using weighted kappas and intraclass correlation coefficients (ICCs). Ability to predict time to PSC‐related complications (ascites, esophageal varices, variceal bleed, liver transplant [LT], or cholangiocarcinoma) (primary outcome) and LT (secondary outcome) was assessed with Harrell’s concordance statistic (c‐statistic) and univariate/multivariable survival analysis. Construct validity was further assessed with Spearman correlations. Forty‐five children were included (67% boys; median, 13.6 years). The inter‐rater reliability of MRCP scores was substantial to excellent (kappas/ICCs, 0.78‐0.82). The sum IHD‐EHD score had the best predictive ability for time to PSC complication and LT (c‐statistic, 0.80 and SE, 0.06; and c‐statistic, 0.97 and SE, 0.01, respectively). Higher MRCP scores were independently associated with a higher rate of PSC‐related complications, even after adjusting for the PSC Mayo risk score (hazard ratio, 1.74; 95% confidence interval, 1.14‐2.). MRCP sum scores correlated significantly with METAVIR fibrosis stage, total bilirubin, and platelets (r = 0.42, r = 0.33, r = −0.31, respectively; P < 0.05). Conclusion: An MRCP score incorporating the worst affected intrahepatic and extrahepatic regions is reliable and predicts meaningful outcomes in pediatric PSC. Next steps include prospective validation and responsiveness assessment.

Magnetic resonance imaging of pancreaticobiliary diseases in children: from technique to practice

Magnetic resonance imaging is useful for evaluating pancreaticobiliary diseases in children after initial sonography, obviating the use of ionizing radiation or invasive procedures such as endoscopic retrograde cholangiopancreatography (ERCP) or transhepatic biliary procedures. Advanced MRI applications have improved depiction of pediatric pancreaticobiliary anatomy and have greatly impacted management of biliary and pancreatic diseases in children. In this article, we review current MRI and magnetic resonance cholangiopancreatography (MRCP) techniques and discuss their role in the assessment of common pancreatic and biliary disorders in children.

[Modern magnetic resonance imaging of the liver]

Magnetic resonance imaging (MRI) of the liver has become an essential tool in the radiological diagnostics of both focal and diffuse diseases of the liver and is subject to constant change due to technological progress. Recently, important improvements could be achieved by innovations regarding MR hardware, sequences and postprocessing methods. The diagnostic spectrum of MRI could be broadened particularly due to new examination sequences, while at the same time scanning time could be shortened and image quality has been improved. The aim of this article is to explain both the technological background and the clinical application of recent MR sequence developments and to present the scope of a modern MRI protocol for the liver.

Reference values of MRI measurements of the common bile duct and pancreatic duct in children

BACKGROUND

Magnetic resonance imaging/cholangiopancreatography (MRI/MRCP) is now an essential imaging modality for the evaluation of biliary and pancreatic pathology in children, but there are no data depicting the normal diameters of the common bile duct (CBD) and pancreatic duct. Recognition of abnormal duct size is important and the increasing use of MRCP necessitates normal MRI measurements.

OBJECTIVE

To present normal MRI measurements for the common bile duct and pancreatic duct in children.

MATERIALS AND METHODS

In this retrospective study we searched all children ages birth to 10 years in our MR urography (MRU) database from 2006 until 2013. We excluded children with a history of hepatobiliary or pancreatic surgery. We stratified 204 children into five age groups and retrospectively measured the CBD and the pancreatic duct on 2-D axial and 3-D coronal T2-weighted sequences. We performed statistical analysis, using logistic and linear regressions to detect the age association of the visibility and size of the duct measurements. We used non-parametric tests to detect gender and imaging plane differences.

RESULTS

Our study included 204 children, 106 (52%) boys and 98 (48%) girls, with a median age of 33 months (range 0-119 months). The children were distributed into five age groups. The common bile duct was visible in all children in all age groups. The pancreatic duct was significantly less visible in the youngest children, group 1 (54/67, 80.5%; P = 0.003) than in the oldest children, group 5 (22/22, 100%). In group 2 the pancreatic duct was seen in 19/21 (90.4%), in group 3 52/55 (94.5%), and in group 4 39/39 (100%). All duct measurements increased with age (P < 0.001; r-value > 0.423), and the incremental differences between ages were significant. The measurement variations between the axial and coronal planes were statistically significant (P < 0.001); however these differences were fractions of millimeters. For example, in group 1 the mean coronal measurement of the CBD was 2.1 mm and the axial measurement was 2.0 mm; the mean coronal measurement of the pancreatic duct was 0.9 mm and the axial measurement was 0.8 mm.

CONCLUSION

Our study provides normative measurements for the common bile duct and pancreatic duct for children up to age 10 years. The upper limits of the CBD and pancreatic duct increase with age, and the values range 1.1-4.0 mm for the CBD and 0.6-1.9 mm for the pancreatic duct.

Characteristics of Pediatric Pancreatitis on Magnetic Resonance Cholangiopancreatography

Pediatric pancreatitis is not uncommon and results in considerable morbidity and mortality in the affected children. Unlike adults, pediatric pancreatitis is more frequently associated with underlying structural abnormalities, trauma, and drugs rather than an idiopathic etiology. Magnetic resonance cholangiopancreatography (MRCP) is a good imaging modality for evaluating pancreatitis and determining etiology without exposure to radiation. This article focuses on MRCP findings associated with various causes of pancreatitis in children, particularly structural abnormalities of the pancreaticobiliary system, as well as describing the feasibility, limitations, and solutions associated with pediatric MRCP.