Imaging makes advances in pancreatic diseases

This analysis is based on imaging findings from our own database of pediatric pancreatic pathology. We performed ultrasound in all cases and CT and/or MRI when ultrasound was inconclusive. MR cholangiopancreatography (MRCP) was used to study the pancreatic ducts. The pancreas is a nonencapsulated, multilobar gland that extends from the second portion of the duodenum to the splenic hilum.1 It forms embryologically from a ventral anlage that becomes the inferior pancreatic head and uncinate process, and a dorsal anlage that becomes the superior pancreatic head, body, and tail. The two anlagen fuse at seven weeks' gestation, and, in over 90% of cases, the ducts also fuse.2 The size of the pancreas varies according to the child's age. The duct of Wirsung ends at the second portion of the duodenum at the major papilla, together with the common bile duct. An accessory pancreatic duct draining through the minor ampulla is present in 44% of individuals.2 Ultrasound is the modality of choice for initial evaluation of suspected pancreatic disease in children,2 due to their lack of fat, the prominence of their left hepatic lobe, and the modality's lack of ionizing radiation or need for sedation. No special preparation is necessary other than six to eight hours of fasting (three hours for neonates). The investigation is generally performed with a 5or 7.5-MHz sector transducer, although a 3.5-MHz sector transducer can be used in older children. Transverse and longitudinal scanning of the entire pancreas is performed. Each portion of the organ should be measured and its echogenicity compared with that of the liver. A systematic scan of the entire superior abdomen should also be performed (Figure 1A). Pancreatic MRI is indicated in cases of suboptimal or equivocal ultrasound findings with a high clinical suspicion of pathology.3,4 Specific indications include evaluation of acute and chronic pancreatitis and characterization of complex peripancreatic fluid collections. Complete evaluation of pancreatic disease generally requires fat-suppressed T1-weighted sequences before and after contrast, as well as T2-weighted sequences, but the choice of sequences will depend on the scanner. MRCP is a noninvasive technique for imaging the pancreaticobiliary tract.2 The pancreas has a higher T1 signal intensity on fat-suppressed sequences than any other intra-abdominal organ. Signal intensity is higher than that of the liver on the arterial-capillary phase of gadolinium-enhanced images and is similar to liver on delayed images. T2 signal intensity of the normal pancreas varies; it can be isotense to liver or as high as abdominal fat (Figure 1B). CT is not recommended as the primary modality for pediatric pancreatic imaging, but it is useful when ultrasound findings are nondiagnostic and MRI is not available.5 CT may be used for diagnostic and therapeutic procedures such as aspiration biopsy or drainage. Patients undergoing CT should receive adequate intravenous contrast and oral contrast when possible. We vary the slice thickness, pitch, and reconstruction interval according to patient age, keeping dose to a minimum. CT attenuation of the pancreas is normally similar to that of the liver. CONGENITAL ANOMALIES True epithelial cysts of the pancreas are uncommon and are caused by anomalous development of the pancreatic ducts.1 The cysts may appear alone or in association with systemic diseases such as Von Hippel-Lindau syndrome or polycystic kidney disease.6,7 When a large number of epithelial cysts are present, distinguishing their origin can be difficult. The differential diagnosis includes mesenteric cysts, choledochal cysts, and enteric duplication cysts.6-8 Ultrasound shows a well-defined, thick-walled anechoic mass with posterior acoustic enhancement.1 CT reveals a mass with well-defined walls and central low attenuation.2 MRI shows a mass with