Magnetic resonance imaging of the pediatric pancreaticobiliary system

Magnetic resonance imaging glossary of findings of pediatric pancreatitis and the revised Atlanta classification

While still uncommon, the incidence of acute pancreatitis in children has been increasing over the last two decades. The Atlanta classification for acute pancreatitis, developed for adults, stratifies cases of acute pancreatitis based on imaging and clinical criteria. This classification scheme allows for standardized use of terminology to facilitate treatment and prognostication. Although US and CT should be used in critical or unstable patients, MRI is an ideal imaging modality in pediatric patients with acute pancreatitis because of its ability to characterize tissue without ionizing radiation. We review MRI examples specific to Atlanta classification terminology in pediatric patients. Chronic pancreatitis has also been increasingly diagnosed in children, and imaging plays a key role in the diagnosis and management of this insidious disease. MRI with magnetic resonance cholangiopancreatography is the optimal modality for assessing the pancreas in a child with known or suspected chronic pancreatitis because it provides tissue characterization and high-contrast imaging of the pancreatic duct without the use of invasive instrumentation or ionizing radiation. We also review and demonstrate accepted MRI findings of chronic pancreatitis.

Patient- and Examination-Related Predictors of 3D MRCP Image Quality in Children

Background: MRCP provides noninvasive imaging of the biliary tree and pancreatic duct. In our experience, MRCP image quality is commonly suboptimal in children. Objective: To characterize the frequency of nondiagnostic 3D fast spin echo (FSE) MRCP acquisitions and determine predictors of nondiagnostic MRCP image quality in children. Methods: This retrospective study included 200 randomly selected pediatric patients (mean age, 11.7 years; 101 female, 99 male) who underwent MRCP between January 1, 2019 and December 31, 2020. Patient and examination-related variables were recorded. Three fellowship-trained pediatric radiologists independently reviewed 3D FSE MRCP acquisitions for diagnostic quality (diagnostic vs nondiagnostic) and overall image quality score (1-5 scale; 1=worst image quality imaginable, 5=best image quality imaginable). After computing interreader agreement, analyses used readers' most common diagnostic quality assessment and mean image quality score. Multivariable logistic regression and linear regression analyses were used to identify predictor variables of a diagnostic examination and higher image quality score. Results: Interreader agreement for an MRCP acquisition being diagnostic, expressed as kappa, was 0.53-0.71; interreader agreement for image quality score, expressed as intraclass correlation coefficient, was 0.37-0.57. A total of 36/200 (18%) MRCP acquisitions were nondiagnostic; mean image quality score was 3.5 ± 1.1. Multivariable predictors of a diagnostic MRCP acquisition included greater body mass index (OR=1.11 [95% CI: 1.02-1.21], p=.02), scanner field strength of 1.5 T (OR=2.87 [95% CI: 1.23-6.68], p=.01), and presence of acute pancreatitis (OR=4.91 [95% CI: 1.53-15.77], p=.008). Multivariable predictors of a higher image quality score (β=0.05-0.94) included older age (p=.01), imaging under sedation/general anesthesia (p<.001), presence of biliary dilation (p=.004), and inpatient status (p=.02). A lower image quality score was predicted by a scanner field strength of 3 T (β=-0.61, p<.001). A greater amount of time between the start of the MRI examination and the MRCP acquisition exhibited a nonsignificant association with a decrease in image quality score (p=.06). Conclusion: Pediatric MRCP acquisitions are commonly nondiagnostic. Patient-specific and technical factors systematically impact MRCP image quality in children. Clinical Impact: Recognition of image quality predictors that are potentially modifiable and amendable to proactive intervention can guide efforts to optimize MRCP image quality in children.

Advanced imaging techniques in pediatric body MRI

While there are many challenges specific to pediatric abdomino-pelvic MRI, many recent advances are addressing these challenges. It is therefore essential for radiologists to be familiar with the latest advances in MR imaging. Laudable efforts have also recently been implemented in many centers to improve the overall experience of pediatric patients, including the use of dedicated radiology child life specialists, MRI video goggles, and improved MR suite environments. These efforts have allowed a larger number of children to be scanned while awake, with fewer studies being done under sedation or anesthesia; this has resulted in additional challenges from patient motion and difficulties with breath-holding and tolerating longer scan times. In this review, we highlight common challenges faced in imaging the pediatric abdomen and pelvis and discuss the application of the newest techniques to address these challenges. Additionally, we highlight the newest advances in quantified imaging techniques, specifically in MR liver iron quantification. The techniques described in this review are all commercially available and can be readily implemented.

Pediatric cholangiopathies: diseases of the gallbladder and biliary tract

Pediatric gallbladder and bile duct disease encompasses a broad spectrum of processes, from congenital to developmental to neoplastic. We describe normal pediatric biliary anatomy and summarize the most common pathologic entities, with a focus on non-invasive imaging techniques and findings. Ultrasound is the first-line imaging modality in children with suspected biliary pathology based on its widespread availability, cost effectiveness, and lack of ionizing radiation. MRI and MRCP are often used for further evaluation in cases of diagnostic uncertainty and for surgical planning.

Pediatric Body Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a radiation-free imaging modality with excellent contrast resolution and multiplanar capabilities. Since ionizing radiation is an important concern in the pediatric population, MRI serves as a useful alternative to computed tomography (CT) and also provides additional clues to diagnosis, not discernible on other investigations. Magnetic resonance cholangiopancreatography (MRCP), urography, angiography, enterography, dynamic multiphasic imaging and diffusion-weighted imaging provide wealth of information. The main limitations include, long scan time, need for sedation/anesthesia, cost and lack of widespread availability. With the emergence of newer sequences and variety of contrast agents, MRI has become a robust modality and may serve as a one-stop shop for both anatomical and functional information.

Acute Pancreatitis in Pediatric Patients: Demographics, Etiology, and Diagnostic Imaging

OBJECTIVE

The objective of this article is to provide updates on acute pancreatitis in children regarding the imaging findings, causes, and complications based on a review of the current studies in the pediatrics literature. We discuss the epidemiology of acute pancreatitis, the role of imaging and imaging findings in the diagnosis of acute pancreatitis, and the causes and complications of acute pancreatitis.

CONCLUSION

The incidence of acute pancreatitis is increasing in children. Imaging plays an important role in the diagnosis of acute pancreatitis because imaging findings can be used to establish the cause of acute pancreatitis, evaluate for complications of acute pancreatitis, and possibly predict the course of the disease.

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.

Comparative analysis of spherical and fusiform choledochal cyst based on three-dimensional magnetic resonance cholangiopancreatography, biliary amylase, and histopathological examination

Aims:

The aim was to compare biliary amylase, common channel, and gall bladder/liver histopathology between spherical and fusiform choledochal cysts.

Materials and Methods:

Children undergoing cyst excision with Roux-en-Y hepatico-jejunostomy over a 17 months period were prospectively studied. The common channel was assessed by three-dimensional (3D) magnetic resonance cholangiopancreatography (MRCP).

Results:

Among 22 patients (spherical = 10, fusiform = 12), there was a higher incidence of spherical cysts in infants (5/7-71.4%) and fusiform cysts in older children (10/15-66.7%) (P = 0.09). Common channel identified in 14 (64%) cases was long (>10 mm) in 5 (38.2%) (one spherical, four fusiform [P = 0.5]) with associated high biliary amylase levels (>500 IU/L) in four (one spherical, three fusiform) (P = 0.05). Exact point of junction of common bile duct with pancreatic duct was visible with coronal half-Fourier-acquisition single-shot turbo spin-echo and 3D sampling perfection with application with optimize contrast using different flip angle evolution sequence using a reformatted plane of axis, particularly coronal, and coronal oblique orientation. Biliary amylase was raised (>100 IU/L) in 4 (40%) in the spherical group, compared to 8 (67%) in the fusiform group. Mean biliary amylase was similar in gallbladder and cyst in spherical but higher in gallbladder in fusiform cysts. Mean biliary amylase was <500 IU/L in 85.7% infants. Five out of 7 infants had liver fibrosis or cirrhosis on histopathology (P = 0.05). There were no dysplastic changes in the gallbladder epithelium.

Conclusion:

Three-dimensional MRCP delineated the common channel in two-third cases especially in coronal and coronal oblique orientation. The long common channel may have an etiological role in fusiform cysts. Spherical cysts, especially in infants, have a higher incidence of obstructive cholangiopathy.

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.