Gastrointestinal Imaging
Abdominal X-Ray
Abdominal X-ray is a fundamental imaging method for diagnosing pediatric digestive system disorders. It is simple, convenient, and well-tolerated by children. It is primarily used to evaluate conditions such as gastrointestinal perforation, intussusception, intestinal obstruction, abdominal masses, organ malpositions, tissue calcifications, and neonatal digestive tract anomalies including esophageal atresia and anal atresia. Depending on the clinical context and diagnostic needs, images may be obtained in supine, upright, horizontal lateral, or inverted lateral positions.
Gastrointestinal Contrast Studies
Contrast imaging techniques are used to observe morphological and functional changes in pediatric gastrointestinal diseases. They can also provide information about the range and nature of certain extra-gastrointestinal abnormalities. Contrast agents are divided into negative agents (e.g., air and oxygen) and positive agents (e.g., barium and iodine-based compounds). Barium studies include plain barium sulfate contrast, double-contrast barium studies, and air-contrast barium enemas. Iodinated contrast agents are categorized into oil-based and water-soluble types. Gastrointestinal contrast studies are widely used in pediatric clinical practice for diagnosing various gastrointestinal diseases.
Upper Gastrointestinal Contrast Studies
These are primarily performed to identify upper gastrointestinal diseases or congenital anomalies, such as esophagotracheal fistula, esophageal stricture, hiatal hernia, gastric volvulus, malrotation, congenital hypertrophic pyloric stenosis, and diaphragmatic hernia. The studies allow detailed examination of the mucosa and the filling states of various segments of the gastrointestinal tract. They can also measure the transit time of barium and assess the presence of reflux, facilitating the diagnosis of conditions such as gastric or duodenal ulcers and gastroesophageal reflux.
Barium Enema
Barium enema is mainly used to diagnose pediatric diseases such as intussusception, Hirschsprung's disease, intestinal polyps, and anorectal developmental anomalies. It can also aid in differentiating between colonic obstruction and small intestinal obstruction. For infants, solid food is withheld on the day of the procedure, and fasting is required for 3 hours before the examination; routine preparation with a cleansing enema is unnecessary. For preschool- and school-aged children, whether a cleansing enema is needed depends on the suspected diagnosis. For instance, cleansing is not required when Hirschsprung's disease is suspected.
Computed Tomography (CT)
Abdominal CT is mainly used for the diagnosis of liver and pancreatic diseases, as well as for evaluating abdominal masses, retroperitoneal tumors, small bowel conditions, and abdominal vascular abnormalities. Intravenous contrast-enhanced CT can clearly outline vascular anatomy and help differentiate tumors from normal tissue. CT enterography (CTE) can assess intra- and extra-intestinal lesions. CT imaging is faster than MRI and requires less time, but it exposes the patient to radiation, so its use in children is minimized whenever possible.
Magnetic Resonance Imaging (MRI)
MRI is particularly useful for diagnosing liver tumors such as hemangiomas and cystic lesions. It provides excellent visualization of localized fat infiltration and is also effective for diagnosing cystic fibrosis of the pancreas with fatty deposition and cyst formation. MRI offers superior vascular imaging compared to CT, especially in identifying liver vascular abnormalities through magnetic resonance angiography (MRA). MR enterography (MRE) is used for detecting intra- and extra-intestinal lesions, and MR cholangiopancreatography (MRCP) is effective for evaluating bile duct and pancreatic duct abnormalities. Since MRI does not involve radiation, it is more suitable for pediatric patients.
Abdominal Ultrasound
Ultrasound imaging utilizes the reflection of ultrasonic waves from various tissues to create images, indirectly depicting the structures of different layers of tissues in the body. Abdominal ultrasound is applicable for diagnosing conditions involving the gastrointestinal tract, liver, gallbladder, bile ducts, spleen, pancreas, and other abdominal organs. It is a simple, accurate, and non-invasive diagnostic method, making it a commonly used approach for evaluating abdominal diseases in children.
Gastrointestinal Endoscopy in Children
Gastrointestinal endoscopy is a reliable method for diagnosing and treating gastrointestinal diseases. With the widespread use of electronic endoscopes and high-performance video monitors, it allows for clear visualization of even subtle mucosal lesions in the gastrointestinal tract. Endoscopic procedures can record and preserve images in a variety of ways, making them valuable for diagnosis, consultations, and teaching. In addition to observing mucosal lesions, endoscopy can be used for histological or microbiological analysis of mucosal tissue. Currently, gastrointestinal endoscopy is widely used in pediatric practice.
Upper Gastrointestinal Endoscopy
Upper gastrointestinal endoscopy, also known as gastroscopy, provides a direct and accurate way of examining the gastrointestinal tract, with a higher detection rate of lesions compared to barium studies. Gastroscopy can reveal conditions such as inflammation, ulcers, diverticula, polyps, hemangiomas, and vascular dilation in the esophagus, stomach, and duodenum. In children, the primary indications include upper abdominal pain, hematemesis, melena, swallowing difficulties or pain, recurrent vomiting, and ingestion of foreign objects. It can also facilitate interventional treatments such as foreign object removal, esophageal dilation for strictures, hemostasis, polyp removal, or sclerotherapy for esophageal varices.
Colonoscopy
Colonoscopy is primarily used for examining diseases of the colon. In children, conditions such as colitis, vascular malformations, polyps, and diverticula are commonly evaluated. Up to 65% of lower gastrointestinal bleeding cases in pediatric populations may be caused by polyps. In conventional X-ray barium enemas, lesions smaller than 0.5 cm in diameter are easily missed. Colonoscopy allows for direct visualization of the nature, extent, and location of colonic polyps and facilitates biopsy and treatments such as high-frequency polyp removal. Colonoscopy is therefore mainly indicated for pediatric conditions such as rectal bleeding, chronic diarrhea, polyps, and inflammatory bowel diseases, as well as for interventional treatments like polyp removal, foreign object removal, dilation of strictures, and hemostasis.
Endoscopic Ultrasonography (EUS)
Endoscopic ultrasonography involves the introduction of a high-frequency miniature ultrasound probe via a gastroscope or colonoscope to scan the gastrointestinal wall and adjacent organs under endoscope-guided direct visualization. Because the ultrasound probe is positioned close to the lesion, image resolution is significantly enhanced. Intraluminal ultrasound scanning avoids the interference caused by subcutaneous fat, intestinal gas, and skeletal structures during external ultrasound imaging, allowing for clear visualization of the layers of the gastrointestinal wall and surrounding organs. In children, this technique is used to measure the thickness of the muscle layer in conditions like congenital hypertrophic pyloric stenosis and to assess the source of submucosal masses in the gastrointestinal tract.
Small Bowel Endoscopy
The small intestine, approximately 3 to 5 meters in length, is convoluted and located between the stomach and colon. Double-balloon enteroscopy is a novel method for examining small bowel diseases, providing valuable insights into deep-seated small intestinal diseases. This technique differs from standard endoscopy in that it involves two balloons—one at the tip of the endoscope and another on an external sheath. Through sequential inflation, deflation, tube advancement, traction, and other maneuvers, the endoscope is able to access deep regions of the small bowel for diagnostic purposes. It is mainly used for the evaluation and treatment of unexplained gastrointestinal bleeding, chronic diarrhea, and other chronic small bowel disorders.
Capsule Endoscopy
Capsule endoscopy, also known as wireless endoscopy, is another method for diagnosing small bowel lesions. Its advantages include being painless and non-invasive, but it does not allow for biopsy or interventional endoscopic treatments. Due to swallowing difficulties, its use in preschool-age children is limited, although recent reductions in capsule diameter allow children weighing over 10 kg to undergo the test with the aid of a gastroscope. Prior to the procedure, intestinal narrowing or obstruction must be ruled out.
Endoscopic Retrograde Cholangiopancreatography (ERCP)
Endoscopic retrograde cholangiopancreatography involves inserting a duodenoscope into the descending part of the duodenum to locate the major duodenal papilla. Through the endoscope's biopsy channel, a contrast catheter is introduced into the papilla and advanced into the bile duct or pancreatic duct, where a contrast agent is injected for X-ray imaging of the ducts. ERCP is an important minimally invasive diagnostic and therapeutic method for the biliary and pancreatic systems. In children, it is primarily used for the evaluation and treatment of diseases such as intrahepatic and extrahepatic biliary obstruction (e.g., biliary atresia, choledochal cyst), acute recurrent pancreatitis, and chronic pancreatitis.
Gastrointestinal Motility Testing
pH Monitoring
pH monitoring involves the use of pH electrodes (commonly antimony electrodes in pediatrics), which are positioned 3–5 cm above the lower esophageal sphincter and/or within the stomach to assess pH levels. By analyzing 24-hour changes in pH within the esophagus and/or stomach, this method provides a diagnostic basis for gastroesophageal reflux disease (GERD) and its differential diagnosis. It also has utility in evaluating the therapeutic efficacy of treatments for acid-related conditions.
Manometry
Gastrointestinal manometry evaluates gastrointestinal motility by measuring pressure changes due to muscle contractions in the digestive tract. High-resolution manometry is now widely used and is applicable for esophageal manometry, anorectal manometry, gastric pressure measurement, and sphincter of Oddi manometry. This method is a critical tool for diagnosing motility disorders in the gastrointestinal system.
Esophageal Impedance Measurement
Esophageal impedance measurement assesses the nature and movement of refluxate based on differences in electrical impedance of materials. This technique is often combined with pH monitoring or high-resolution esophageal manometry, referred to as 24-hour pH-MII (multichannel intraluminal impedance) and high-resolution impedance manometry (HRIM), respectively. The 24-hour pH-MII technique is used to identify the causes of GERD, while HRIM provides a comprehensive evaluation of esophageal pressure conditions, peristaltic transport of boluses, and their passage through the gastroesophageal junction into the stomach. These techniques help determine esophageal motility status from multiple perspectives.
Electrogastrography (EGG)
Electrogastrography records the electrical activity of the stomach to evaluate its motility function. This technique can aid in diagnosing conditions such as tachygastria, bradygastria, and other motility-related disorders.
Nuclear Medicine Testing
In nuclear testing, patients consume liquid or solid meals labeled with radionuclides. A gamma camera is employed to directly observe the dynamic progression of the meal through the esophagus, allowing calculation of parameters such as the emptying rate and gastric half-emptying time. This helps assess gastric emptying function, gastroesophageal reflux, and the aspiration of refluxate into the lungs.
Ultrasound Examination
B-mode real-time or three-dimensional real-time ultrasound imaging is used to observe the dynamic motion of the gastric antrum, body, pylorus, and duodenum after consuming a specific volume of liquid meal. Gastric emptying can be quantified, including determining the gastric emptying time and half-emptying time.
Breath Tests
Hydrogen Breath Test
The hydrogen breath test (HBT) measures the concentration of hydrogen (H2·) in exhaled air. It is used for diagnosing conditions such as lactose intolerance, sucrose malabsorption, small intestinal bacterial overgrowth, and assessing gastrointestinal transit time. As a non-invasive test of gastrointestinal function, it is simple, pain-free, and repeatable. However, it requires the cooperation of children capable of exhaling into the testing device.
Carbon Dioxide Breath Test
After oral administration of compounds labeled with 13C, the compound undergoes metabolic processing and is ultimately excreted as 13CO2 from the lungs. The concentration of 13CO2 in exhaled breath is measured to evaluate conditions such as fat malabsorption, lactose intolerance, small intestinal bacterial overgrowth, and liver function. The 13C-urea breath test is also used to detect Helicobacter pylori infection. Since 13C is a stable isotope and non-radioactive, it is suitable for use in children.