Pedriatic radiology

Gastrointestinal tract

 

Diseases of the abdomen and gastrointestinal (GI) tract may be unique in infants in children: they may be found only in the pediatric age group (congenital anomalies, necrotizing enterocolitis); and they have radiologic

Figure 29. Pulmonary sling. There is a characteristic soft-tissue mass (arrows) between the trachea and the esophagus. This is the oberrant left pulmonary artery seen on-end.

or imaging features unique to the child when compared with the adult (hiatus hernia, abdominal masses).

Modalities

Conventional plain films are still important in the diagnosis of gastro intestinal disease; they should be obtained prior to contrast studies or other imaging modalities. There are general guide lines for the use of gastrointestinal contrast media. Most GI examinations are performed with barium sulfate. If there is a risk of aspiration or perforation, a water-soluble, non-ionic contrast medium should be used. Water-soluble contrast is also preferred if obstruction is suspected. Hyperosmolar contrast medium is extremely dangerous and should only be used as a possible therapeutic enema for patients with meconium ileus.

Ultrasonography has become increasingly important in the evaluation of pediatric gastrointestinal disease. US allows systematic evaluation of all abdominal and pelvic organs. CT and MRI have more limited applications. Abdominal angiography is rarely performed in infants and children.

Problem-oriented pediatric GI radiology

Vomiting
Vomiting is a common phenomenon in neonates and young infants. Contrast examination is performed in severe cases and may demonstrate gastrointestinal reflux, hiatus hernia, and partial or complete obstruction of the more distal bowel. Barium is the contrast medium of choice; if symptoms are severe or there is a known risk of aspiration, water-soluble, non-ionic contrast may be used. Nuclear medicine can assess intermittent episodes of gastrointestinal reflux; US assesses other abnormalities of the abdomen.

Abdominal pain
Non-specific abdominal pain in children frequently has non-organic causes. Radiological evaluation is indicated with long-standing, severe, or intermittent symptoms. Abdominal radiography may demonstrate a stone in the urinary tract or severe constipation. US can demonstrate malrotation, hydronephrosis, or cholelithiasis. Severe, intermittent pain should be evaluated during an episode.
Some common, organic causes of abdominal pain in children include malrotation with volvulus, cholelithiasis, intussusception, and hydronephrosis. Imaging of the se abnormalities will be discussed later in this chapter.

Oesophagus

Oesophageal atresia/Tracheoesophageal fistula

Oesophageal atresia (EA) and tracheoesophageal fistula (TEF) is a complex of congenital anomalies characterized by failure of formation of the tubular oesophagus or an abnormal communication between the oesophagus and trachea. It occurs approximately 1 in 5000 births. The complex includes pure EA without a fistula; EA with a fistula that may be proximal, distal, or proximal and distal; and a TEF without oesophageal atresia. The most common abnormality (85 %) is EA with a distal fistula; the blind-ending upper pouch is distended by air and fluid (Fig. 30).

Contrast examination may be performed to verify the diagnosis of EA and demonstrate or exclude a fistula within the upper segment of the oesophagus and the trachea. Water-soluble, non-ionic iso-osmolar

Figure 30.Esophageal atresia and distal tracheoesophageal fistula. Enteric tube coils in upper esophageal pouch (arrows). Gas is seen in stomach and small bowel. [From Kirks.]

Figure 31.Tracheoesophageal fistula. 3-week-old male with cough during feeding. Fistula (arrow) is identified passing obliquely upward from the esophagus (E) to the trachea (T). [From Kirks.]

contrast media should be used. A small amount of contrast is injected through a tube; the contrast is removed as soon as the diagnosis is made. This type of pouch injection is always performed with fluoroscopy. In 2 % of patients with EA/TEF, there is a right aortic arch; surgery should be performed through a left thoracotomy. Therefore, the position of the aortic arch should always be determined pre operatively by chest radiography or US.

Coexisting anomalies may involve the cardiovascular, skeletal, gastrointestinal, genitourinary, central nervous, and other systems. If EA is present without a fistula, no gas is seen in the stomach. In these cases, the atretic segment may be quite long; end-to-end anastomosis may be difficult or impossible.

An isolated TEF may cause coughing and choking during feeding, recurrent pneumonia, failure to thrive, and gaseous abdominal distention. The fistula may be extremely difficult to visualize. If a tube examination is performed, the tip of the tube is withdrawn from the distal oesophagus to the proximal oesophagus with syringe injections of contrast material at every 1-2 cm of the entire esophagus. The fistula will be identified passing obliquely upward from the oesophagus to the trachea (Fig. 31).

Hiatus hernia/Gastroesophageal reflux
A hiatus hernia (HH) is present if the gastroesophageal junction herniates through the diaphragmatic hiatus into the chest. Gastroesophageal reflux (GER), the retrograde flow of gastric contents into the oesophagus is always abnormal. Reflux is more clinically significant if it is spontaneous, reproducible, and severe.

Although nuclear scintigraphy and US may be used to assess the gastroesophageal junction, initial radiologic evaluation in any infant with suspected HH or GER should be a UGI series for careful assessment of oesophageal peristalsis, anatomy of the gastroesophageal junction, presence or absence of reflux, and anatomy of the stomach in its outflow. A contrast study can demonstrate concomitant aspiration. It is always important to exclude obstruction of the stomach or pylorus in patients with vomiting.

It should be remembered that oesophagitis is an endoscopic, not an X-ray diagnosis. However, the sequela of oesophagitis, such as ulceration or stricture, are readily demonstrated by contrast examination. Radiologic findings of HH include high location of the gastroesophageal junction, gastric mucosal folds above the hiatus, wide hiatus with wide oesophagus above it, and large part of the stomach above the diaphragm in the chest.

Oesophageal foreign body
Children between the ages of 6 months and 3 years frequently put foreign objects in their mouths and may sometimes swallow them. Most foreign bodies that are swallowed pass through the GI tract without

Figure 32.Esophageal duplication. Soft-tissue mass (arrows) incidentally noted at cardiac catheterization for pulmonary valvular stenosis. CT confirmed a cystic mass in the middle mediastinum.

complication. Occasionally, a foreign body lodges in the oesophagus and requires removal. Oesophageal foreign bodies may lodge at the thoracic inlet (75 %), thoracic oesophagus at the level of the carina (20 %), or distal oesophagus at the gastraesophageal junction (5 %).
Radiopaque foreign bodies (some metal, glass, mineral) are seen on conventional radiographs; contrast examination is required to demonstrate nonopaque (plastic toys, vegetable material, food particles) foreign bodies. Oesophageal foreign bodies may be removed at endoscopy or by catheter with fluoroscopic control. After removal of the foreign body, a contrast examination should be performed to exclude any esophageal abnormality.

Oesophageal duplication
Oesophageal duplication is one of the causes of a mediastinal mass (Fig. 32). It usually does not extrinsically compress the oesophagus but displaces it. Rarely, there is communication between the duplication and the normal oesophageal lumen. CT or MRI demonstrate a cystic mass of the middle mediastinum.

Stomach and duodenum

Peptic ulcer disease
Peptic ulcer disease is much less common in children than in adults. Only 2- 3 cases of duodenal ulcer per year are seen in a children's hospital; gastric ulcers in children are even less frequent. Etiology of peptic ulcer disease in children is unknown, but it is thought to be related to increased acid production in response to stimulation, to abnormal mucosal protective barriers, and to emotional stress.

The criteria for radiologic diagnosis of gastric ulcer and duodenal ulcer in children are identical to those in the adult. Complications, such as perforation, gastric outlet obstruction, or fistula, are also rarer in children than adults.

Hypertrophic pyloric stenosis
Hypertrophic pyloric stenosis (HPS) is the most common disease of infancy in the United States requiring surgical therapy. Males are affected 4 times as frequently as females. Symptoms of HPS occur most frequently during the second to sixth weeks of life, with a peak incidence at 3 weeks of age. The most frequent symptom is nonbilious vomiting, beginning as simple regurgitation and progressing to projectile vomiting. Other findings may include weight loss, dehydration, and metabolic alkalosis.

HPS may be diagnosed by clinical examination, UGI series, or US. The diagnosis is based on the demonstration of a thickened pyloric muscle producing a mass. HPS by UGI series shows a long and thin pyloric lumen with muscle hypertrophy producing an impression on the gastric antrum and duodenal bulb (Fig. 33 a). The UGI is best performed after placement of an enteric tube into the stomach; this allows the injection of small amounts of barium. At the end of the UGI, any remaining contrast medium should be removed.

Muscle hypertrophy is well demonstrated by US. The findings of HPS are those of a soft-tissue mass of hypertrophied muscle that surrounds the pylorus; this muscle thickening increases the overall diameter of the pylorus, thickens the pyloric wall, and elongates the pyloric canal (Fig. 33 b). Specific findings of HPS include a pyloric diameter of more than 8mm, pyloric canal length of more than 13mm, and pyloric muscle thickness of more than 3mm.

Duodenal atresia/Duodenal stenosis
Duodenal atresia and stenosis are common causes of bowel obstruction in the neonate. There is complete obliteration of the duodenal lumen with atresia but only a partial or incomplete obstruction of the duodenal

a	Figure 33.Hypertrophic pyloric stenosis. a) UGI examination. The pylorus (*) is elongated with extrinsic compression producing a double and triple channel sign. There is extrinsic impression on the gastric antrum (arrowheads) and duodenal bulb (arrowheads). b) Ultrasound examination. Longitudinal oblique sonography shows that the pyloric muscle is elongated (I9.8mm) and thickened (7mm).
b

Figure 34.Duodenal atresia. Supine radiograph demonstrates gas in the stomach and markedly dilated duodenal bulb.

lumen with stenosis. Duodenal atresia is approximately 15 times as common as duodenal stenosis or annular pancreas with duodenal stenosis. Most intrinsic congenital obstructions are thought to represent an alteration of normal development caused by some insult during early gestation.

Abdominal radiography in duodenal atresia is usually diagnostic. Gas is present in the stomach and dilated duodenal bulb ("double bubble"), but there is no air in the distal gastrointestinal tract (Fig. 34). If the abdominal radiograph shows partial duodenal obstruction, a small amount of barium (3-5ml) is injected into the stomach.

Small bowel

Small bowel atresia and stenosis
Small bowel atresia and stenosis are important causes of neonatal intestinal obstruction. Atresia is a complete occlusion of the intestinal lumen; it accounts for 95 % of cases. Stenosis, an incomplete intraluminal occlusion, is much less frequent. Small bowel atresia and stenosis are due to an in utero vascular accident.

The diagnosis of obstruction is usually apparent on plain films of the abdomen. If obstruction is present in the jejunum, a few gas-filled loops of small bowel are present, with the remainder of the abdomen being gasless. Further radiologic studies are usually not necessary. A small amount of air may be injected for confirmation of complete or partial jejunal obstruction. The diagnosis of distal ileal atresia by plain films is more difficult. It may be difficult or impossible to distinguish dilated distal small bowel from colon. A contrast enema is frequently indicated to establish the precise diagnosis. Water-soluble, nonionic contrast material is preferred. The enema distinguishes between small and large bowel distention, determines the presence or absence of microcolon, and locates the position of the cecum in regard to possible abnormalities of intestinal rotation and fixation. Contrast opacifies a small colon, indicating that dilated loops are small bowel and complete obstruction is present.

Inresunalduplicauon
Duplications are enteric cysts. A duplication is a spherical or tubular structure that has an internal lining of intestinal epithelium, has smooth muscle in its wall, and is adherent to some portion of the intestinal tract. Duplications of the small bowel have a mesenteric location. Multiple duplications may occur anywhere from tongue to anus, most are located in the terminal ileum near the ileocecal valve. Other common sites of duplication include distal esophagus, stomach, and duodenum.

a	Figure 35.Gastric duplication cyst. a) Left upper quadrant mass (M) extrinsically compresses the stomach (arrowheads). b) Longitudinal sonography confirms that the mass (M) is cystic. The muscular rim sign is due to echogenic mucosa and mucus (white arrows) with adjacent sonolucent muscularis mucosa (black arrows). [From Kirks.]
b

Plain films usually show a soft-tissue mass within the abdomen (Fig. 35 a). Sonography may demonstrate either anechoic cystic mass, or mixed echogenic mass due to hemorrhage and inspisated material within the duplication. The muscular rim sign is highly suggestive of an enteric duplication; US demonstrates an ioner echogenic line of intestinal mucosa interfacing with mucus and is surrounded by a hypoechoic rim of muscularis mucosa in the wall of the duplication cyst (Fig. 35 b). Contrast examinations confirm that the mass is intraperitoneal in location and extrinsically affects bowel.

Malrotation with midgut volvulus
Malrotation includes a wide spectrum of anomalies of intestinal rotation and fixation. During normal development, the midgut rotates 270° counter clockwise about the superior mesenteric artery; the small bowel mesentery is attached from the left upper quadrant (duodenojejunal junction)

Figure 36.Malrotation with midgut volvulus. The duodenojejunal junction (curved arrow) overlies the spine and is inferior to the duodenal bulb. There is also an abnormal, spiral course (curved arrow) of the duodenum.

to the right lower quadrant. In malrotation, a narrow mesenteric attachment may lead to midgut volvulus or peritoneal bands (Ladd bands) may partially obstruct the bowel.

US may show an abnormal relationship between the superior mesenteric artery and vein; however, it may also be completely normal in patients with malrotation. UGI demonstrates that the duodenojejunal junction is not in its normal location to the left of the spine at the level of the bulb (Fig. 36). There may be a spiral course of the duodenum due to volvulus and the proximal small bowel may be on the right. Barium enema may be completely normal in malrotation with midgut volvulus and cannot be used to exclude the diagnosis. However, in most cases of malrotation, the cecum is high and not located in its normal position overlying the right iliac wing.

The treatment of malrotation with volvulus is a surgical emergency because of potential bowel necrosis. The accepted surgical procedure
(Ladd operation) includes reduction of volvulus, resection of nonviable bowel, transsection of abdominal peritoneal bands, exclusion of possible associated abnormalities, and placement of small bowel in the right abdomen with the colon on the left. The mesentery of the small bowel is spread smoothly from right to left with a broad attachment that eliminates the potential for recurrent volvulus.

Figure 37.Necrotizing enterocolitis. Air is seen in the wall of the descending colon (arrows). There is also a suggestion of air in the portal venous system.

Necrotizing enterocolitis
Necrotizing enterocolitis (NEC) is a disease most frequently seen in premature infants. The etiology is multifactorial: prematurity, hypoxia, stress, ischemia, early feeding, congenital heart disease, and infection. Indirect and direct bowel injury cause loss of the mucosal protective barrier with subsequent bacterial overgrowth leading to NEC.

Radiographic findings in NEC include focal bowel distention in the right lower quadrant, ileus, intramural gas, bowel-wall thickening, and portal vein gas (Fig. 37). The only absolute radiologic indication for surgical intervention is pneumoperitoneum due to bowel perforation. The cross-table, horizontal-beam radiograph is the most sensitive indicator of pneumoperitoneum. US may demonstrate air in the bowel wall, air in the portal venous system, and free gas or fluid in the peritoneal cavity.

Mortality in NEC is high, especially in infants of very low birth weight. Repeat physical examination and serial abdominal radiographs are important in following neonates with NEC. Indications for surgical intervention include perforation and clinical deterioration with shock, peritonitis, persistent metabolic acidosis and disseminated intravascular coagulation. Surgical treatment includes resection of necrotic bowel with ileostomy or colostomy. Strictures may occur following NEC; contrast studies of the excluded bowel segment are always performed prior to reestablishment of bowel continuity to exclude the possible development of a stricture. Strictures due to NEC may be treated by surgical resection or balloon dilatation.

Problems with meconium
There are at least four common problems with meconium that should be distinguished and not confused: meconium peritonitis, meconium ileus, meconium ileus equivalent, and meconium-plug syndrome. Meconium peritonitis is due to antenatal perforation of the GI tract. It may be due to meconium ileus but is not always associated with cystic fibrosis. For practical purposes, meconium ileus and meconium ileus equivalent occur only in patients with cystic fibrosis. Meconium-plug syndrome is one of several causes of functional colonic obstruction in the newborn. Meconium-plug syndrome may be the presenting syndrome of Hirschsprung disease; it is rarely due to cystic fibrosis.

Acquired small-bowel obstruction (SBO)
One of the aims of this section is to remind the reader of the differential diagnosis of acquired small-bowel obstruction in children. This aim is spelled AIIMM; the letters stand for the most common causes of acquired small-bowel obstruction in children: Adhesions from previous surgery; Appendicitis, frequently with abscess formation (See Fig. 41); Incarcerated inguinal hernia; Intussusception; Malrotation with volvulus, ladd bands, or both; and Miscellaneous (Meckel diverticulum, duplication, ingested foreign body). Intussusception is the most frequent cause of mechanical obstruction of infants and children.

Colon

Anorectal malformation
Anorectal malformation (imperforate anus) includes a group of related anomalies of the termination of the hindgut. In most patients, there is communication of the hindgut with the perineum, genital tract, or urinary system. The precise diagnosis and proper surgery are critical for preventing serious genitourinary or gastrointestinal tract damage. These patients need specialized treatment and should be referred to tertiary medical centres.

Frequency of anorectal malformations is approximately 1 in 5000 live births, with males affected usually more frequently than females. Careful

a	Figure 38.Hirschsprung disease. 3-day-oldfemale with failure to pass meconium. a) AP supine abdominal radiograph. Gaseous distention of both small bowel and colon. b) Barium enema. There is a discrepancy in calibre between the maximal diameter of the rectum (lower arrows) and the maximal diameter of the sigmoid colon (upper arrows). The narrowed rectum is aganglionic.
b

physical examination of the newborn with anorectal malformation almost always establishes the diagnosis and level of hindgut termination. There are frequently other visceral and skeletal anomalies in patients with anorectal malformations. These include abnormalities of the spine (sacral anomalies), urinary tract (neurogenic bladder), GI tract (atresia, TEF) and cardiovascular system (CHD).

Hirschsprung disease
Hirschsprung disease is a functional colonic obstruction due to an absence of ganglion cells in the distal segment of bowel; the distal colon is most commonly affected. The frequency is approximately 1/5000 births. Most patients (80%) with Hirschsprung disease present in the first 6 weeks of life with obstruction or intermittent diarrhea and constipation. Symptoms usually date from birth. There is an increased frequency in patients with Down syndrome.

Abdominal radiographs show dilatation of bowel proximal to the aganglionic segment with associated air-fluid levels (Fig. 38 a). The radiologic diagnosis of Hirschsprung disease requires a barium enema with meticulous technique; contrast enemas are performed and contrast is injected slowly through a catheter. The critical film for identifying a transition zone is a lateral film during slow injection. The transition from narrowed aganglionic colon to dilated normal bowel is clearly demonstrated (Fig. 38 b). Delayed films at 24 hours may be helpful. Patients with Hirschsprung disease show little evacuation at 24 hours; there is a lack of bolus movement of barium toward the left colon and rectum. Since children with Hirschsprung disease are at risk for the development of toxic colitis, diagnostic evaluation should be performed as soon as possible. The barium enema is highly accurate for the diagnosis of Hirschsprung disease, even in the newborn; the diagnosis is confirmed by rectal biopsy before surgical repair.

Intussusception
lntussusception is an invagination of a segment of intestine into adjacent bowel. More than 95 % of intussusceptions in children are ileocolic or ileoileocolic and have no pathologic lead point; these idiopathic cases are probably due to hypertrophy of lymphoid tissue in the terminal ileum. Pathologic lead points that may cause intussusception include Meckel diverticulum, lymphosarcoma, and polyp. Most patients with idiopathic intussusception are between 3 months and 2 years of age. Signs and symptoms include pain, vomiting, blood per rectum, and a palpable abdominal mass.

Plain film findings include normal bowel gas pattern, loss of the subhepatic angle, intraluminal soft-tissue mass, and mechanical small-bowel obstruction. lntussusception may also be diagnosed by US; a soft-tissue mass with concentric layers of echogenicity produces a target sign on transverse images or a pseudokidney sign on longitudinal images.

The only absolute contraindications to contrast enema and attempted reduction of intussusception are pneumoperitoneum and clinical peritonitis. Hydrostatic or pneumatic reduction are successful in 75-85 % of cases (Fig. 39). During hydrostatic reduction, the rule of 3s is used: 3 attempts; 3 minutes of intermittent fluoroscopy for each attempt; bag placed 3-4 feet above the tabletop. Mean pressures during air insufflation should not exceed 120 mmHg at rest.

Figure 39.Intussusception. Hydrostatic reduction of intussusception. The intussusceptum (*) is identified in the right transverse colon. Subsequently, the intussusception was readily reduced.

 

a	Figure 40. Sonography of appendicitis. 16-year-old male with right lower quadrant and pelvic pain. a) Transverse and b) Longitudinal sonographic sections demanstrate dilated appendiceal lumen (L), thickened appendiceal wall (W), and appendicalith (arrow) with distal acoustic shadowing. [From Kirks.}
b

Appendicitis
Acute appendicitis is the most frequent condition requiring abdominal surgery in children. Disease is rare in young infants but becomes more frequent during each year of childhood. In older children, the clinical findings are usually suggestive of the diagnosis. However, in young children with appendicitis, there is an increased frequency of perforation and decreased specificity of physical findings. Imaging is performed only if the clinical presentation is confusing.

Plain films of the abdomen may be completely normal in patients with acute appendicitis. An appendicolith is present in up to 2 % of cases. There are frequently signs of right lower quadrant inflammatory disease on plain films of the abdomen. These inflammatory changes include airfluid levels in the terminal ileum and cecum, thickening of the cecal wall, soft-tissue mass effect on the cecum, loss of the obturator internus fat plane in the pelvis, and fluid between the cecum and properitoneal fat line. A common manifestation of perforated appendicitis is small-bowel obstruction.

Sensitivity and specificity of US for the diagnosis of appendicitis in children is between 80 and 90%. Graded compression in patients with US shows a noncompressible appendix, an overall diameter of more than 6mm, thickening of the appendiceal wall, dilatation of the appendiceal lumen, and, occasionally, an appendicolith (Fig. 40). CT is the imaging modality of choice for evaluating patients with complicated appendicitis and possible abdominal abscess formation (Fig. 41).

Liver and biliary disease

Choledocal cyst
Choledocal cyst is a localized dilatation of the biliary ductal system. There are two broad groups of patients. The first group is neonates with choledocal cyst which is caused by stenosis or atresia of a portion of the biliary tree and is related to biliary atresia. A second group is diagnosed later in life and is frequently associated with anomalous relationship of the terminations of the common bile duct and pancreatic duct.

US and hepatobiliary nuclear scintigraphy confirm the diagnosis of choledocal cyst. US shows a cystic mass in the porta hepatis with possible dilatation of bile ducts emptying into this cystic mass. Functional hepatobiliary nuclear scintigraphy shows normal extraction of tracer by the liver accumulation and stasis within the choledocal cyst, and absent or decreased bowel excretion.

a	Figure 41. Pelvic abscess due to appendicitis. a) AP supine film shows dilated small bowel consistent with mechanical obstruction. b) CT section shows large pelvic abscess (A) containing fluid and air that impresses on the bladder (B). Note thickening of wall of sigmoid colon (S) adjacent to the abscess collection. [From Kirks.]
b

Biliary atresia/Neonatal hepatitis
Some jaundice is physiologic during the newborn period. However, if neonatal jaundice is marked or persistent, the possibility of biliary atresia, neonatal hepatitis, or choledocal cyst should be considered.

The initial imaging procedure in patients with neonatal jaundice is US to exclude choledocal cyst or dilatation of the extrahepatic biliary system. US of the hepatic parenchyma and intrahepatic bile ducts in both hepatitis and biliary atresia in the neonate is usually normal. Hepatobiliary scintigraphy, with phenobarbital enhancement, permits accurate differentiation of biliary atresia from neonatal hepatitis. In infants less than 3 months of age with biliary atresia, the hepatic extraction of tracer is good but there is no excretion into the GI tract. In neonatal hepatitis, there is poor extraction of tracer by the liver with demonstration of some tracer activity within the GI tract; operative cholangiography will demonstrate a small but patent bile duct system.

There is a spectrum from neonatal hepatitis to biliary atresia which explains intermediate cases as well as the known progression from hepatitis to post-natal occlusion of bile ducts. Liver biopsy is also helpful in the important distinction between biliary atresia and neonatal hepatitis.

Portal hypertension
Portal hypertension is caused by increased resistance to portal venous blood flow. Portal hypertension in children may be due to extrahepatic obstruction, intrahepatic obstruction, hepatic venous hypertension, or hyperkinetic hypertension. The frequency of extrahepatic portal obstruction is considerably higher in children than adults; moreover, extrahepatic obstruction due to portal vein thrombosis (cavernous transformation of the portal vein) is a more frequent cause of portal hypertension in children than is intrahepatic obstruction due to cirrhosis.
Duplex US with Doppler, and colour-flow Doppler analysis is extremely useful for assessing patients with portal hypertension. The size of the portal vein and direction of portal venous flow can be determined; portosystemic collateral circulation is identified. The earliest signs of portal hypertension are abnormal Doppler flow with subsequent reversal of flow. Severe portal hypertension causes thickening of the lesser omentum due to varices. MRI may also be extremely useful in evaluating patients with portal hypertension and end-stage liver disease. Angiography is able to determine portal venous obstruction and active GI bleeding as well as evaluating vascular hemodynamics. However, increased applications of Doppler sonography and MRI have decreased the need for angiography in pediatric patients with portal hypertension.

Gallbladder disease
Gallstones in children are uncommon but not rare; they occur more frequently than acute cholecystitis. Although cholelithiasis can occur in patients with hemolytic anemias, most cases in infants and children are still idiopathic. US is the imaging