1 Answer B. Bilious vomiting in a neonate is an emergency as it raises concern for malrotation of the bowel along with midgut volvulus. A delay in diagnosis and treatment of this entity may result in small bowel necrosis, short gut syndrome, and dependence on total parenteral nutrition (TPN). Mortality in affected newborns with malrotation and midgut volvulus is currently 3% to 5%.

Abdominal radiographs may be normal in appearance or show distention of the stomach and proximal duodenum by air, with little distal bowel gas. The radiograph of the patient in this case does not demonstrate the findings typically associated with volvulus or evidence of an obstruction. However, malrotation and midgut volvulus still must be excluded. The most sensitive test for the diagnosis of malrotation is an upper GI series with sensitivities ranging from 93% to 100%. However, the sensitivity of this exam for midgut volvulus is reported at 54%.

A contrast enema is often used to evaluate for the cause of a distal bowel obstruction but is not the most sensitive test to evaluate for malrotation and midgut volvulus. It can be helpful in assessing the location of the cecum, which is normally located in the right lower quadrant. Eighty percent of patients with malrotation have an abnormal cecal position, which a contrast enema can help demonstrate.

An abdominal ultrasound is also not the most sensitive test to evaluate for malrotation or midgut volvulus. However, in cases of malrotation with midgut volvulus, the “whirlpool sign” can be seen when the bowel wraps around the superior mesenteric artery (SMA), and the intestinal tract and the mesenteric vessels become twisted, resulting in secondary venous engorgement.

References: Applegate KE, Anderson JM, Klatte EC. Intestinal malrotation in children: a problemsolving approach to the upper gastrointestinal series. Radiographics 2006;26(5):1485-1500.

Epelman M. The whirlpool sign. Radiology 2006;241(1):83-94.

2 Answer C. The study demonstrates a “beaked” appearance of the third portion of the duodenum and only a small amount of contrast distal to the location of the beaking or obstruction (arrow). This appearance is consistent with malrotation with midgut volvulus. Other appearances of volvulus include the “corkscrew sign,” which describes the spiral appearance of the distal duodenum and proximal jejunum seen in midgut volvulus. In patients with malrotation with midgut volvulus who exhibit those findings, the duodenum and proximal jejunum do not cross the midline and instead take an inferior direction. The loops twist on a shortened small bowel mesentery resulting in a corkscrew appearance.

The normal position of the duodenojejunal junction is to the left of the leftsided pedicle of the vertebral body at the level of the duodenal bulb on frontal views. If the duodenojejunal junction is located inferior or to the right of this level, malrotation should be considered. Note however that inferior displacement of the duodenojejunal junction is common variant seen on frontal views in infants. This finding may be due to displacement of the relatively mobile ligament of Treitz by the adjacent distended stomach or bowel.

In cases where malrotation is in question, a posterior location of the duodenojejunal junction on a true lateral view, as expected for a retropritoneal structure, is reassuring. In children with malrotation, the distal course of the duodenum on the lateral view often does not reach the level of the duodenal bulb an instead turns in an anterior direction into the peritoneal cavity.

Given that the study performed in the question demonstrates findings consistent with malrotation with midgut volvulus, the patient needs to go to the operating room for further treatment. Therefore, none of the other choices are correct.

References: Applegate KE, Anderson JM, Klatte EC. Intestinal malrotation in children: a problemsolving approach to the upper gastrointestinal series. Radiographics 2006;26(5):1485-1500.

Ortiz-neira CL. The corkscrew sign: midgut volvulus. Radiology 2007;242(1):315-316.

3 Answer B. Malrotation of the bowel is a predisposing risk factor for midgut volvulus. In individuals with malrotation, the mesenteric attachment of the midgut, particularly the portion from the duodenojejunal junction to the cecum, is abnormally short. The gut is therefore prone to twist counterclockwise around the superior mesenteric artery and vein creating a volvulus. As stated above, 80% of patients with malrotation have an abnormal cecal position, which a contrast enema can help demonstrate. The superior mesenteric vein is normally located to the right of and anterior to the superior mesenteric artery on axial imaging studies, but the relative positions of the vein and artery are reversed in 60% of individuals with malrotation. Malrotation is usually diagnosed in newborns and young infants; up to 75% of symptomatic cases occur in newborns, and up to 90% of symptomatic cases occur within the first year of life.

Reference: Applegate KE, Anderson JM, Klatte EC. Intestinal malrotation in children: a problemsolving approach to the upper gastrointestinal series. Radiographics 2006;26(5):1485-1500.

4 Answer B. The clinical history and imaging findings presented in this case are concerning for hypertrophic pyloric stenosis, a common entity in young infants characterized by hypertrophy of the circular muscle and narrowing of the antropyloric canal (channel), partially caused by crowded and edematous mucosa within the lumen. This leads to a gastric outlet obstruction, which causes intractable nonbilious projectile vomiting. The age of the child at diagnosis is usually 3 weeks to 3 months of age. The male-to-female ratio is approximately 4:1, and firstborn children are more often affected than their younger siblings. Other causes of nonbilious vomiting in children are pylorospasm and gastroesophageal reflux.

The radiographs of the patient demonstrate gaseous distention of the stomach with an air-fluid level on the left lateral decubitus view. There is a paucity of bowel gas beyond the stomach. These findings are suggestive of a gastric outlet obstruction as can be seen in pyloric stenosis.

The next best step in management would be to perform a nonemergent abdominal ultrasound to confirm the diagnosis of pyloric stenosis as pyloric stenosis is not a true medical emergency. Therefore, an emergent surgical consultation is not required. Ultrasound allows direct visualization of the pyloric muscle. A contrast enema of the colon would not be helpful in making the diagnosis. A CT scan of the abdomen and pelvis would also not be helpful in making the diagnosis as realtime visualization of the pylorus over an extended period is required to make the diagnosis and would expose the child unnecessarily to ionizing radiation.

References: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

Hernanz-Schulman M. Infantile hypertrophic stenosis. Radiology 2003;227(2):319-331.

5 Answer C. The ultrasound images shown demonstrate a thickened pyloric muscle and elongated pyloric channel, which did not change over time. These findings are consistent with hypertrophic pyloric stenosis (HPS). As stated above, this condition often occurs in firstborn males. The treatment for this condition is a surgical pyloromyotomy. It is important to distinguish HPS from pylorospasm as the latter is treated medically.

On ultrasound examinations, the pyloric wall thickness should normally be <3 mm and the length of the pyloric channel should not exceed 15 mm. In the images from this case, the pyloric wall thickness measures up to 5 mm on the transverse view and the pyloric channel length measures up to 15.2 mm on the long-axis view. However, the published criteria for both of these measurements have varied. Most importantly, the pylorus should not open during the ultrasound examination. In pylorospasm, there is transient thickening of the pyloric muscle and elongation of the channel length.

However, the pylorus does eventually open in cases of pylorospasm. If the ultrasound examination demonstrates a closed pylorus with abnormal measurements of muscular thickness and channel length, it is important to extend the length of the examination by an extra 3 to 5 minutes to confirm that the pylorus remains closed and exclude pylorospasm.

In addition to the findings above, there are ancillary or secondary signs of pyloric stenosis on ultrasound including the “double-track sign.” This sign is created by the abnormally thickened muscle mass that compresses the pyloric channel into two smaller channels or tracks. In addition, thickened pyloric mucosa may indent into the antrum consistent with antral heaping.

References: Blumer SL, Zucconi WB, Cohen HL, et al. The vomiting neonate: a review of the ACR appropriateness criteria and ultrasound’s role in the work-up of such patients. Ultrasound Q 2004;20(3):79-89.

Cohen HL, Blumer SL, Zucconi WB. The sonographic double-track sign: not pathognomonic for hypertrophic pyloric stenosis; can be seen in pylorospasm. J Ultrasound Med 2004;23(5):641-646.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

6 Answer A. The images demonstrate fusiform dilatation of the common bile duct. This is best visualized on the second image to the right of the first image. The Todani classification system has been used to classify choledochal cysts. The imaging findings depicted on the MRI are consistent with a type I choledochal cyst. Note that on Figure A, the gallbladder (short arrow) is seen to the left (patient’s right) of the common bile duct (long arrow). Type I choledochal cysts are seen in 80% to 90% of patients with choledochal cysts. Note that type I cysts can be further divided into type IA, IB, and IC cysts depending upon their morphologic characteristics. A choledochocele is a type III cyst and involves only the intraduodenal portion of the common bile duct. Caroli disease or a type V cyst involves dilatation of one or several segments of the intrahepatic bile ducts. A type IVA cyst involves dilatation of the intrahepatic and extrahepatic biliary ducts.

References: Kim OH, Chung HJ, Choi BG. Imaging of the choledochal cyst. Radiographics 1995;15(1):69-88.

Mortelé KJ, Rocha TC, Streeter JL, et al. Multimodality imaging of pancreatic and biliary congenital anomalies. Radiographics 2006;26(3):715-31.

7 Answer D. The image shown in the figure demonstrates diffusely dilated loops of bowel without definite rectal bowel gas. These findings along with the patient’s clinical history are concerning for an obstruction of the distal or lower GI tract. The best way to evaluate for the etiology of such lower GI tract obstructions is to perform a contrast enema. Common causes of lower tract obstructions include Hirschprung disease, meconium plug syndrome (small left colon syndrome) (functional immaturity of the colon), ileal atresia, meconium ileus and anal atresia or anorectal malformations. An upper GI series is the test of choice to evaluate for a suspected upper or high obstruction in neonates. Common causes of upper tract obstructions include midgut volvulus/malrotation, duodenal atresia/stenosis, duodenal web, annular pancreas and jejunal atresia. A CT scan is not the appropriate initial method to evaluate suspected distal obstructions and would needlessly expose the child to ionizing radiation. An abdominal ultrasound is not an appropriate way to evaluate a neonate with a suspected distal bowel obstruction.

Reference: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

8 Answer B. Figures A and B demonstrate a contrast enema examination. In contrast enemas, it is important to evaluate the rectosigmoid ratio. The rectum should have a diameter equal to or larger than the sigmoid, which is a normal rectosigmoid ratio. Patients who have Hirschsprung disease have an abnormal rectosigmoid ratio in which the sigmoid has a larger diameter than the rectum.

The study in this case demonstrates a normal rectosigmoid ratio. In addition, the left side of the colon appears small and ahaustral. The transverse and ascending colon are dilated. There are scattered filling defects seen throughout the colon likely due to meconium plugs. These findings are consistent with functional immaturity of the colon.

Patients who have a high intestinal obstruction, or an obstruction that occurs proximal to the midileum, such as a high ileal atresia, will have a normal caliber colon. This is because there is ample proximal bowel to produce secretions that migrate distally and nourish the colon. Patients who have a low intestinal obstruction or an obstruction that occurs in the distal ileum or colon will have a microcolon or unused colon because there is not enough proximal small bowel to produce secretions to nourish the colon.

Reference: Berrocal T, Lamas M, Gutieerrez J, et al. Congenital anomalies of the small intestine, colon and rectum. Radiographics 1999;19(5):1219-1236.

9 Answer C. The initial treatment of choice for patients with functional immaturity of the colon is a contrast enema with water-soluble contrast. Sometimes, repeated enemas are needed to flush out the meconium plugs. This condition is often seen in offspring of diabetic mothers or mothers treated with magnesium sulfate for preeclampsia. Patients who have a jejunal atresia will have a normal-appearing colon as explained in the explanation for Question 8.

Reference: Berrocal T, Lamas M, Gutieerrez J, et al. Congenital anomalies of the small intestine, colon and rectum. Radiographics 1999;19(5):1219-1236.

10 Answer B. Meconium ileus occurs secondary to obstruction of the distal ileum due to the accumulation of abnormally tenacious meconium. It occurs exclusively in patients with cystic fibrosis and is the earliest clinical presentation of the disease.

Reference: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

11 Answer D. Microcolons are seen in conditions in which there is an unused colon such as distal bowel obstructions including low ileal atresia and meconium ileus. Jejunal atresias are high bowel obstructions, and there is enough proximal bowel to produce secretions to nourish the colon. Thus, a normal-caliber colon would be seen in contrast enemas performed in patients with a jejunal atresia or other proximal bowel obstructions.

References: Berrocal T, Lamas M, Gutieerrez J et al. Congenital anomalies of the small intestine, colon and rectum. Radiographics 1999;19(5):1219-1236.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

12 Answer A. The CT scan demonstrates a pancreatic pseudocyst, which is a known common late complication of acute pancreatitis, typically occurring 4 weeks after the development of a peripancreatic fluid collection. Pancreatic pseudocysts are the most common complication of pediatric pancreatitis. Pancreatitis in a young child should be suspected to be abuse related. There are many known causes of pediatric pancreatitis including pancreatitis secondary to trauma, biliary anomalies, and medication-related and autoimmune etiologies.

Reference: Restrepo R, Hegerott HE, Kulkarni S, et al. Acute pancreatitis in pediatric patients: demographics, etiology and diagnostic imaging. Am J Roentgenol 2016;206(3):632-644.

13 Answer C. The radiograph demonstrates a nonspecific bowel gas pattern with multiple calcifications throughout the abdomen. These findings are most consistent with meconium peritonitis. This entity is a result of a sterile chemical peritonitis that occurs after antenatal bowel perforation, which usually occurs after the 3rd month of gestation. The bowel perforation is a result of a bowel atresia, in utero volvulus, or meconium ileus. There is an association with polyhydramnios and not oligohydramnios. The prognosis is generally good.

References: Dähnert W. Radiology review manual, 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Saunders Elsevier, 2009.

14 Answer B. The ultrasound image of the patient in the region of the gallbladder fossa fails to demonstrate the gallbladder. The clinical presentation of neonatal jaundice and absence of the gallbladder raises concern for biliary atresia. The best way to demonstrate biliary atresia is with a Tc-99m HIDA scan. None of the other tests are helpful to make the diagnosis of biliary atresia and in the case of an upper GI series and CT scan will needlessly expose the patient to ionizing radiation.

Reference: Kirks DR, Coleman RE, et al. An imaging approach to persistent neonatal jaundice. Am J Roentgenol 1984;142(3):461-465.

15 Answer C. The images fail to demonstrate bowel activity after 6 hours. A delayed image should then be obtained after 24 hours to evaluate for possible radiotracer excretion into bowel as biliary excretion cannot be excluded at this point in the study. This patient did not appear to have a gallbladder on the ultrasound exam as can be seen in the setting of biliary atresia. Note, however, that while some patients with biliary atresia do not have a gallbladder, some affected patients have a small gallbladder and other affected patients have a normal gallbladder. This patient, however, did not have a gallbladder and therefore could not have cholecystitis. The focus of radiotracer in the pelvis is excreted radiotracer within the urinary bladder, an expected finding.

Reference: Dähnert W. Radiology review manual, 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.

16 Answer B. The image fails to demonstrate radiotracer excretion into bowel after 24 hours. Radiotracer activity is again seen in the urinary bladder, and the activity inferior to the bladder is excreted radiotracer within the diaper. Given the clinical history, the imaging findings are consistent with biliary atresia. However, these findings can also be seen in the setting of severe hepatocellular dysfunction from neonatal hepatitis, and a liver biopsy is often necessary to distinguish between these two entities. The Kasai procedure (portoenterostomy) is performed in a majority of the patients with biliary atresia and has a greater success rate when performed in children <60 days old. This is why it is imperative to make the diagnosis of biliary atresia as early as possible. Note that the Kasai procedure is often a palliative procedure as most patients will eventually need a liver transplant.

References: Bijl EJ, Bharwani KD, Houwen RHJ, et al. The long-term outcome of the Kasai operation in patients with biliary atresia: a systematic review. Neth J Med 2013;71(4):170-173.

Dähnert W. Radiology review manual, 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.

17 Answer A. In jaundiced infants in whom biliary atresia is suspected, pretreatment with phenobarbital, 5 mg/kg/d, may be given orally in two divided doses daily for a minimum of 3 to 5 days before a Tc-99m HIDA scan to enhance biliary excretion of the radiotracer and increase the specificity of the test. Phenobarbital stimulates biliary secretion by inducing hepatic enzymes, which increases conjugation and excretion of bilirubin. Morphine is given during HIDA scans to shorten the study time if there is nonvisualization of the gallbladder. This is typically injected 45 to 60 minutes after injection of radiotracer if activity is seen in the bowel. It causes contraction of the sphincter of Oddi, which raises intrabiliary pressure and can cause retrograde filling of the gallbladder. Cimetidine can be given before Meckel scans to decrease gastric secretions. CCK is a synthetic hormone that causes gallbladder contraction, but many patients with biliary atresia do not have a gallbladder.

References: Dähnert W. Radiology review manual, 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.

Majd M, Reba RC, Altman RP. Hepatobiliary scintigraphy with 99mTc-PIPIDA in the evaluation of neonatal jaundice. Pediatrics 1981;67:140-145.

18 Answer A. The lesion depicted on the ultrasound images demonstrates an anechoic cystic lesion with a wall composed of multiple layers resembling a normal bowel wall. This is characteristic of enteric duplication cysts where the cyst wall “reduplicates” the normal enteric wall. These lesions are usually attached to normal bowel but occasionally migrate into the mesentery and become a type of mesenteric cyst. Thus, these lesions are not pancreatic or renal in origin. In addition, this lesion also appears separate from the kidney and pancreas on the CT scan as there is no claw sign. Because enteric duplication cysts can contain ectopic gastric mucosa, a Meckel (Tc-99m pertechnetate) scan can be helpful in making the diagnosis.

References: Kumar R, Tripathi M, Chandrashekar N, et al. Diagnosis of ectopic gastric mucosa using 99Tcm-pertechnetate: spectrum of scintigraphic findings. Br J Radiol 2005;78(932):714-720.

Stoupis C, Ros PR, Abbit PL, et al. Bubbles in the belly: imaging of cystic mesenteric or omental masses. Radiographics 1994;14(4):729-737.

19 Answer A. Although the image presented below is a chest radiograph, there is a coarse calcification seen in the right upper quadrant (arrow). Although this calcification can be caused by multiple etiologies, a liver mass remains on the differential, and further evaluation with an ultrasound examination is indicated. An upper GI examination would not help to elucidate the etiology of a suspected hepatic calcification. Although there is a gastrojejunostomy tube seen on the radiograph, the tip has been excluded from the film, and therefore, it cannot be determined whether or not the tube is in its appropriate position. The next most appropriate step to determine whether or not the tube is in appropriate position would be to get an abdominal plain radiograph or inject the tube with contrast under fluoroscopy. Furthermore, the etiology of the suspected hepatic calcification cannot be determined with either an IR consult or abdominal radiograph.

References: Blickman JG, Parker BR, Barnes PD. Pediatric radiology: the requisites, 3rd ed. Philadelphia, PA: Elsevier/Saunders, 2009.

Chung EM, Lattin GE Jr, Cube R, et al. From the archives of the AFIP: Pediatric liver masses: radiologic-pathologic correlation part 2. Malignant tumors. Radiographics 2011;31(2):483-507.

20 Answer C. Figure A is an axial image from a contrast-enhanced CT scan of the abdomen demonstrating a large heterogeneous solid mass in the liver with a large calcification (long arrow), which may represent the calcification seen on the plain film of the abdomen seen in Question 19. There are smaller satellite lesions in the periphery of the liver (short arrow). Figure B is an axial T1 fat-saturated image after contrast enhancement, which also demonstrates a heterogeneous solid enhancing mass with smaller satellite lesions in the periphery of the liver (arrows). Given the age group and constellation of imaging findings, the most likely diagnosis is hepatoblastoma, a malignant liver mass. Ninety percent of cases of hepatoblastoma occur in children younger than 5 years of age. Hepatocellular carcinoma, which is also a malignant solid tumor, rarely occurs in children under 5 years of age. Mesenchymal hamartoma of the liver is a benign liver lesion, which often appears as a complex cystic mass and primarily affects children under 5 years of age. Focal nodular hyperplasia (FNH) is most often seen in adult women but uncommonly occurs in young children and adolescents. Because the mass is composed predominantly of hepatocytes, it appears similar to normal liver, and the lesion may be difficult to visualize. Sometimes the only clue of the presence of this lesion is its mass effect on adjacent structures. The presence of a central scar may aid identification of this lesion.

References: Chung EM, Cube R, Hall GJ, et al. From the archives of the AFIP: Pediatric liver masses: radiologic-pathologic correlation part 1. Benign tumors. Radiographics 2010;30(3):801-826.

Chung EM, Lattin GE Jr, Cube R, et al. From the archives of the AFIP: Pediatric liver masses: radiologic-pathologic correlation part 2. Malignant tumors. Radiographics 2011;31(2):483-507.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

21 Answer B. Hepatoblastoma has been associated with several syndromes, including Beckwith-Wiedemann syndrome, Gardner syndrome, familial adenomatous polyposis, type 1A glycogen storage disease, and trisomy 18. Approximately 5% of cases occur in conjunction with other congenital anomalies, commonly of the genitourinary and gastrointestinal systems. The most useful laboratory marker for hepatoblastoma is AFP. At least 90% of patients with hepatoblastoma show abnormal elevation of AFP levels. Surgical resection is the mainstay of treatment for hepatoblastoma, and the prognosis depends on the resectability of the tumor. About 40% to 60% of hepatoblastomas are unresectable at diagnosis; however, with the use of neoadjuvant chemotherapy, up to 85% of these become resectable.

Reference: Chung EM, Lattin GE Jr, Cube R, et al. From the archives of the AFIP: Pediatric liver masses: radiologic-pathologic correlation part 2. Malignant tumors. Radiographics 2011;31(2):483-507.

22 Answer D. The images provided from an upper GI series demonstrate obstruction of the proximal duodenum. In a patient, involved in recent blunt trauma, a duodenal hematoma should be suspected. The next best step in management would be an additional cross-sectional imaging study to see if the cause of the duodenal obstruction is due to a duodenal hematoma or other lesion. Abdominal radiographs would not yield any further information about the cause of the obstruction. A small bowel follow-through would not help if there is a duodenal obstruction. A gastric emptying study is used to evaluate the rate of gastric emptying into the duodenum. It would not help elucidate the cause of a duodenal obstruction.

References: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

Swischuk LE. Emergency imaging of the acutely ill or injured child, 4th ed. Philadelphia, PA: Lippincott, Williams and Wilkins, 2000.

23 Answer D. The axial images from a contrast-enhanced CT examination demonstrate an intramural lesion of heterogeneous fluid attenuation, which is likely secondary to a hematoma within the duodenum (arrows). The hematoma causes luminal narrowing. Intramural duodenal hematomas are often the result of blunt trauma that can be caused by accidental trauma as well as nonaccidental trauma. Anticoagulation can also be a cause of spontaneous intramural duodenal hematomas. These lesions are also known to occur after endoscopic biopsy.

References: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

Ghersin E, Gaitini D, Willis O, et al. Intramural duodenal hematoma mimicking an intestinal mass on sonography. J Ultrasound Med 2002;21(6):693-695.