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23205062

  1. 1. 2007 ACR Diagnostic Radiology In-Training Exam Rationales Section XII Pediatric Radiology 248. You are shown an image of the chest from a CT of a girl who is 5 years of age (Figure 1). What is the MOST LIKELY diagnosis? A. Congenital lobar emphysema B. Cystic Fibrosis C. Pulmonary Blastoma D. Cystic adenomatoid malformation RATIONALES: A. Incorrect. Typically presents as a hyperinflated lobe most often affecting the left upper lobe B. Incorrect. Cystic fibrosis affects the entire lung particularly upper lobes with bronchiectasis and bronchial thickening not thin walled cysts. C. Incorrect. Mixed solid and cystic lesions adjacent to the pleura. Usually large with mediastinal displacement. D. Correct. Multiple thin walled cysts of various sizes in the macrocystic variant. Thought to be the result of abnormal endodermal mesodermal differentiation. References: Effman E, Huhn J. Anomalies of the Lung. Ed Kuhn, Slovis, Haller. Caffey’s Pediatric diagnostic imaging 10th edition Phil PA Mosby 2004 Kim WS, Lee KS, Kim IO et al: Congenital cystic adnomatoid malformation of the lung: CT path correlation. AJR 1997:168:47 Rosado De Christenson M, Stodker JT: Congenital cystic adenomatoid malformation. Radiographics 1991;11:865.
  2. 2. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 249. You are shown a sagittal sonographic image of the pelvis of a 12-year-old girl with intermittent pelvic pain (Figure 2). What is the MOST LIKELY diagnosis? A. Rhabdomyosarcoma B. Tuboovarian abscess C. Hematometrocolpos D. Hemorrhagic ovarian cyst RATIONALES: A. Incorrect. Cystic mass with debris levels as well as age of presentation are not consistent with typical findings of sarcoma botryoides. Multicystic vaginal tumor most typically presents between 1-3 years of age B. Incorrect. Cystic mass is posterior to the bladder – this location is more consistent with a vaginal or uterine origin rather than ovarian or fallopian. Cystic mass has the typical appearance of a dilated vagina with a fluid/fluid level, capped by the uterus with a dilated cervical canal and lumen. C. Correct. The dilated fluid / debris filled structure posterior to the bladder is most consistent with a hematometrocolpos in the adolescent. D. Incorrect. Cystic mass is posterior to the bladder and low in the pelvis. The location is more consistent with vaginal or uterine origin rather than ovarian. Further, an ovarian cyst could not have the typical appearance of a dilated vagina capped by a dilated uterine cervix and body. References: Cohen H, Haller J. Abnormalities of the Female Genital Tract Ed Kuhn, Slovis, Haller. Caffey’s Pediatric diagnostic imaging 10th edition Phil PA Mosby 2004 Nussbaum A, Sanders R, Gearhart JP: Obstructed ureterovaginal anomalies: demonstration with sonography. Radiology 1991;179:79 Woodward P, Sohaey R, Wagner B: Congenital uterine malformations Curr Probl Diagn Radiol 1995;24:177.
  3. 3. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 250. You are shown a chest radiograph obtained during a contrast injection into the left central line in an infant with congenital heart disease (Figure 3). What surgical procedure is outlined by the contrast injection? A. Blalock-Hanlon B. Blalock-Taussig. C. Glenn D. Rastelli RATIONALES: A. Incorrect. Blalock-Hanlon. This term refers to an atrial septectomy, performed to promote admixture of blood at the atrial level. This procedure is not illustrated in the test case, and this answer is false. B. Incorrect. Blalock-Taussig. This operation refers to a shunt between the subclavian artery and the ipsilateral pulmonary artery in order to provide pulmonary blood flow. This is not illustrated in the test case, and this choice is incorrect C. Correct. Glenn. A Glen shunt refers to anastomosis of the superior vena cava to the pulmonary artery. A bidirectional Glen refers to a shunt in which the superior caval flow enters into both pulmonary arteries and into both lungs; a unidirectional Glen shunt refers to flow directed solely to the ipsilateral pulmonary artery and lung. The test case demonstrates injection of contrast into the superior vena cava and hence into both pulmonary arteries. This constitutes the bidirectional Glenn shunt. D. Incorrect. Rastelli. Rastelli procedure refers to a conduit between the right ventricle and the pulmonary artery. This is not shown in the test case and this choice is incorrect. References: Pelech AN, Neish SR. Sudden death in congenital heart disease. Pediatr Clin N Am 51 (2004) 1257-1271
  4. 4. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 251. You are shown a radiograph of the chest and abdomen of a newborn boy, and an ultrasound image taken along his left flank (Figures 4A and 4B). What is the MOST appropriate subsequent examination? A Intravenous pyelography (IVP) B. Non-contrast CT scan C. Gadolinium-enhanced MRI D. Voiding cystourethrography (VCUG) RATIONALES: The radiograph shows centralized gas in normal-appearing loops of bowel, distension of the flanks, and elevation of the diaphragms. These findings are typical of neonatal ascites. There is no pleural effusion or skin edema to suggest hydrops. The most likely diagnosis is urinary ascites, which in a male infant is most likely due to posterior urethral valves. The sonogram confirms the presence of ascites, and additionally shows hydroureteronephrosis, perinephric urinoma, and increased renal echogenicity with diminished corticomedullary differentiation, consistent with dysplastic changes. All these findings point towards the presence of posterior urethral valves. A. Incorrect. An IVP would necessitate administration of intravenous contrast material, in a child with compromised renal function, and would not demonstrate improved anatomic definition over the sonogram. Renal function is best quantitated with scintigraphy. However, the diagnosis of valves is made with VCUG. Option A is incorrect. B. Incorrect. CT without contrast would add unnecessary radiation, and would not demonstrate anatomy or function, nor would it demonstrate the valves. Option B is incorrect. C. Incorrect. Although MRI with gadolinium would not demonstrate the valves, and might necessitate sedation. Option C is incorrect. D. Correct. VCUG is necessary in order to confirm the presence of valves, and to assess bladder capacity and function
  5. 5. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 252. Regarding the fracture dislocation in Figure 5, which of the following fractures is present? A. Supracondylar B. Lateral condylar C. Medial epicondylar D. Intercondylar RATIONALES: A. Incorrect. A supracondylar fracture is located in the distal humeral metaphysis above (proximal to) the condyles of the distal humerus. Supracondylar fractures vary from subtle buckle fractures to complete transverse fractures with displacement. In this view, the supracondylar humerus appears intact. B. Incorrect. A lateral condylar fracture courses through the lateral condyle, which is the portion of the distal humeral metaphysis adjacent to the capitellum. Lateral condylar fractures vary from subtle fractures with minimal displacement to frankly displaced complete fractures. In this image, no fracture is seen within the lateral condyle of the distal humerus. C. Correct. This image shows a dislocation of the elbow joint. In addition, the medial epicondyle is absent from its normal location. An ossified medial epicondyle should be present, because the trochlea is ossified. The trochlea ossifies after the medial epicondyle. An additional ossific density projects within the elbow joint, adjacent to the capitellum. This fragment is a displaced medial epicondyle, avulsed from its normal location. Avulsion of the medial epicondyle is commonly seen with dislocation of the elbow in children with unfused growth plates. D. Incorrect. An intercondylar fracture is vertically oriented, passing centrally between the condyles of the distal humerus. This is not present in the test case. Such fractures are uncommon in children and are more often seen in adults. Sometimes a supracondylar fracture may have a T or Y shaped orientation with an intercondylar component. References: 1. Laor T, Jaramillo D, Oestreich AE. Musculoskeletal system. In: Kirks DR, Griscom NT, eds. Practical Pediatric Imaging, 3rd edition, Lippincott-Raven, Philadelphia, 1998, pp 327-510.
  6. 6. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 2. Harcke HT, Mandell GA, Maxfield BA. Trauma to the growing skeleton. In: Kuhn JP, Slovis TL, Haller JO, eds. Caffey’s Pediatric Diagnostic Imaging, 10th edition, Mosby, Philadelphia, 2004, pp 2269-2303. 3. Roger LF, Cox TD, Sonin A. The elbow and forerarm. In: Rogers LF, ed. Radiology of Skeletal Trauma, 3rd edition, Churchill-Livingstone, Philadelphia, 2002, pp 683-778.
  7. 7. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 253. A newborn infant has a distended abdomen. The contrast enema (Figures 6A and 6B) is consistent with what diagnosis? A. Meconium plug syndrome B. Hirschsprung’s disease C. Ileal atresia D. Meconium ileus RATIONALES: A. Incorrect. In meconium plug syndrome, the colon is of normal and uniform caliber, with a characteristic long filling defect representing the meconium plug. The colon is not of uniform or normal caliber in the test case, and this choice is therefore incorrect. B. Correct. Hirschsprung’s disease is caused by failure of development of the normal myenteric plexus due to failure of migration of neural crest cells throughout the entire length of the gastrointestinal tract. A distal segment of colon is aganglionic. A variable length of colon (and sometime small bowel) is involved; however, the transition point is most commonly near the rectosigmoid junction. The distal aganglionic segment is relatively narrow and colon proximal to the transition point dilates. Normally, the rectum should be of greater diameter than the sigmoid. If this relationship is reversed, then one should suspect Hirschsprung’s disease. In this case, there is a well defined transition point at the rectosigmoid junction and a rectum which is very narrow compared to the sigmoid, consistent with Hirschsprung’s disease. Irregular contour of the distal aganglionic segment is related to aperistaltic contractions, also a typical radiographic feature in Hirschprung’s disease. C. Incorrect. In ileal atresia, neither swallowed amniotic fluid nor succus entericus enters the colon. The colon is therefore unused, and very small in caliber, termed microcolon. The colon in this patient is not a microcolon; in fact, the colon proximal to the transition zone is dilated. Therefore, this choice is incorrect. D. Incorrect. In meconium ileus, thick meconium becomes obstructed in the distal ileum. This common presentation of an infant with cystic fibrosis. The contrast enema in these patients reflects the distal ileal obstruction, and outlines a microcolon. This is not present in this case, and this choice is therefore incorrect References: 1. Buonomo C, Taylor GA, Share JC, Kirks DR. Gastrointestinal Tract. In: Kirks DR, Griscom NT, eds. Practical Pediatric Imaging, 3rd edition, Lippincott-Raven, Philadelphia, 1998, pp 821-1007.
  8. 8. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 2. Parker BR. Colon. In: Kuhn JP, Slovis TL, Haller JO, eds. Caffey’s Pediatric Diagnostic Imaging, 10th edition, Mosby, Philadelphia, 2004, pp 1649-1690. 3. Seigel MJ, Shackelford GD, McAlister WH. The rectosigmoid index. Radiology 1981;139:497-499.
  9. 9. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 254. Concerning a kidney with a duplex collecting system, which of the following would be a typical association? A. Larger than normal kidney B. Simple ureterocele C. Upper moiety reflux D. Male urinary incontinence RATIONALES: A. Correct. Kidneys with duplicated collecting systems tend to be larger than those with non-duplicated collecting systems. B. Incorrect. Ectopic ureteroceles are associated with duplex collecting systems. Simple ureteroceles are uncommon in childhood and are associated with non-duplex systems. C. Incorrect. Although reflux can occur in either moiety in uncomplicated duplications, a complicated duplex typically demonstrates obstruction of the upper moiety, and secondary reflux in the lower moiety. D. Incorrect. The insertion of the ectopic ureter is related to the course of the embryonic mesonephric duct. Urinary incontinence is seen only in females since the ectopic ureter in girls can insert beyond the bladder sphincter, along the course of the mesonephric duct. This does not happen in boys, in whom insertion always occurs proximal to the external sphincter, again outlining the course of the embryonic mesonephric duct. References: 1) Kirks DR (Ed.) 1998. Practical Pediatric Imaging, 3rd Ed. Lippincott, Philadelphia 2) Siegel MJ, 1995. Pediatric Sonography, 2nd Ed. Raven Press, New York
  10. 10. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 255. A right aortic arch is most commonly seen in which of the following? A. Truncus arteriosus B. D- transposition of the great arteries C. Ebstein’s anomaly D. Patent ductus arteriosus RATIONALES: A. Correct. Right Aortic Arch is seen in up to 35% of cases of Truncus Arteriosus and up to 25% of cases of Tetralogy of Fallot, but is not commonly seen in any of the other listed conditions. References: 1) Kirks DR (Ed.) 1998. Practical Pediatric Imaging, 3rd Ed. Lippincott, Philadelphia 2) Spindola-Franco H, Fish BG 1985. Radiology of the Heart : Cardiac Imaging in Infants, Children, and Adults. Springer 256. Concerning Pulmonary Sling, which of the following is CORRECT? A. Left pulmonary artery crosses posterior to the esophagus B. Complete tracheal cartilaginous rings increase morbidity C. Diverticulum of Kommerell compresses the airway D. Left ligamentum arteriosum completes the vascular ring RATIONALES: B. Correct. A pulmonary sling occurs when the left pulmonary artery originates from the right pulmonary artery, crossing the mediastinum from right to left between the trachea and esophagus. A subset of patients may have associated complete tracheal rings leading to significant airway stenosis, increasing morbidity. Diverticulum of Kommerell is associated with aberrant subclavian artery and vascular ring. Pulmonary sling is not a vascular ring and is not dependent on the presence or position of the ligamentum arteriosum. References: 1) Kirks DR (Ed.) 1998. Practical Pediatric Imaging, 3rd Ed. Lippincott, Philadelphia 2) Spindola-Franco H, Fish BG 1985. Radiology of the Heart: Cardiac Imaging in Infants, Children, and Adults. Springer
  11. 11. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 257. Which of the following is TRUE concerning sacrococcygeal teratomas? A. Excision of the lower sacrum is necessary to prevent recurrence. B. Currarino triad includes sacrococcygeal teratoma, sacral defect and posterior meningolocele. C. Sacrococcygeal teratomas contain elements of all three germ cell layers. D. A type IV lesion is located below the sacrum and is visible externally. RATIONALES: A. Incorrect. Excision of the coccyx is necessary. Incomplete excision of the coccyx can result in recurrence in up to 37% of cases. B. Incorrect. Associated with anterior meningomyeloceles C. Correct. The hallmark of this tumor is that it contains elements from endoderm, mesoderm and ectoderm. D. Incorrect. Type I lesion is external; Type II lesion contains an intrapelvic component; Type III is predominantly intrapelvic with an external component; Type IV lesion is located entirely within the pelvis. References: Powell RW, Weber ED, Manci EA: Intradural extension of a sacrococcygeal teratoma. J Pediatr Surg 1993;28:770 Bloom D Tumors of the Urinary Tract Ed Kuhn, Slovis, Haller. Caffey’s Pediatric diagnostic imaging 10th edition Phil PA Mosby 2004 Sheth S, Nussbaum AR, Sanders RC et al:Prenatal diagnosis of sacrococcygeal teratoma: Sonographic pathologic correlation. Radiology 1988;169:131.
  12. 12. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 258. Which of the following is TRUE concerning tracheoesophageal fistulas? A. Prenatally the stomach is not filled with fluid in approximately 80% of patients. B. Most common presentation is a fistula from the proximal pouch to the trachea. C. The side of the aortic arch must be identified preoperatively. D. It is an isolated anomaly in most patients. RATIONALES: A. Incorrect. Majority will have some fluid in the stomach due to the distal fistula allowing fluid to course from the trachea into the distal esophageal segment. B. Incorrect. 87% present with tracheoesophageal fistula to the distal esophageal segment. C. Correct. Right arch occurs in 4% of cases. This is important in determining the side of thoracotomy for repair, on the side opposite the arch. D. Incorrect. Increased incidence of cardiac, duodenal, anorectal, renal and musculoskeletal anomalies in 50-70% of patients, and VACTERL association. References: Hertsberg BS: Sonography of the fetal gastrointestinal tract: anatomic variants, diagnostic pitsfalls, and abnormalities AJR 1994;162:1175 Quan L, Smith DW: the VACTER association: vertebral defect, anal atresia, TE fistula, radial and renal dysplasia a spectrum of associated defects. J Pediatr 1973; 82:104.
  13. 13. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 259. Which of the following is a sequela of a periventricular leukomalacia? A. Schizencephaly B. Symmetric periventricular cysts C. Basal ganglia vasculopathy D. Lissencephaly A. Incorrect. Schizencephaly is the result of an in utero event leading to cerebral clefts lined by abnormal transcerebral columns of gray matter. This is not a sequela of periventricular leukomalacia. B. Correct. Periventricular leukomalacia is a result of ischemia to the premature vascular watershed zone in the periventricular white matter, resulting in periventricular leukomalacia and multiple periventricular cysts. C. Incorrect. Lenticulostriate vasculopathy associated with many etiologies, particularly in utero TORCH infection. D. Incorrect. Lissencephaly is a migration disorder resulting in a smooth cortex with abnormal neuronal layers. In some cases it may follow CMV infection References: Rumack C, Drose J. Neonatal and infant brain imaging. Rumack, Wilson, Charboneau (ed) third edition Diagnostic Ultrasound, St Louis Elsevier Mosby 2005 Perlman JM, Rollins N: Surveillance protocol for the detection of intracranial abnormalities in premature neonates. Arch Pediatr Adol Med 2000;154:822. Bass WT, Jones MA White LE et al: Ultrasonographic differential diagnosis and neurodevelopmental outcome of cerebral white matter lesions in premature infants J Perinatol 1999;19:330
  14. 14. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 260. Which of the following ovarian masses in children is associated with abnormal sexual development? A. Cystic teratoma B. Dysgerminoma C. Granulosa cell tumor D. Endodermal sinus tumor RATIONALES: A. Incorrect. Benign ovarian lesion, also known as ovarian dermoid. B. Incorrect. Most common malignant germ cell tumor of the ovary. Usually rapidly growing can metastasize. C. Correct. Most common stromal cell tumor in children. Often associated with feminizing effects and pseudoprecocious puberty due to estrogen production D. Incorrect. Highly malignant germ cell tumor with peritoneal seeding. References: Patel MD Feldstein VA, Lipson SD et al Cystic teratomas of the ovary: Diagnostic value of sonography AJR 1998; 171: 1060 Sherman NH Rosenberh HK: Pediatric pelvic sonography in Fisher MR, Kricum ME eds): Imaging of the Pelvis Rockville, MD Aspen 1989
  15. 15. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 261. Regarding colonic abnormalities in children, which one of the following is CORRECT? A. Microcolon resolves spontaneously. B. Colonic atresia is more common than ileal atresia. C. Small left colon syndrome is part of the VACTERL association. D. Meconium ileus presents with a large plug in a normal-sized colon. RATIONALES: A. Correct. Microcolon refers to an unused colon, and is seen in infants with long- standing distal obstruction, such as is seen in ileal atresia, meconium ileus, or the distal portion of the colon in colonic atresia. Once the obstruction has been relieved, the colon returns to normal size. B. Incorrect. Colonic atresia is the least common of the intestinal atresias (other than pyloric atresia) representing only 8% of intestinal atresias in a population of 277 neonates in a published series. C. Incorrect. Anal atresia is part of the VACTERL association, along with vertebral anomalies, cardiac abnormalities, esophageal atresia/distal fistula complex, renal anomalies and limb anomalies typically affecting the radius. Colonic atresia typically occurs in isolation, or in conjunction with other GI atresias. D. Incorrect. Meconium ileus consists of particularly thick and tenacious meconium inspissated within the distal small bowel, resulting in distal small bowel obstruction and microcolon. Meconium ileus can be complicated in utero by intrauterine bowel perforation, meconium peritonitis or meconium cyst. References: 1. Dalla Vecchia et al. Intestinal atresia and stenosis. Arch Surg 1998; 133:490- 497 2. Heinen F et al. Pyloric atresia. www.thefetus.net, 1000-08-28-10
  16. 16. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 262. Regarding Tetralogy of Fallot, which one of the following is CORRECT? A. Most patients have a right-sided aortic arch. B. A normal-sized heart is a common presurgical finding on chest radiographs. C. The ventricular septal defect may close if surgery is delayed. D. The Fontan procedure is most appropriate for surgical repair. Rationales; A. Incorrect. A right-sided aortic arch is present in approximately 25% of patients with Tetralogy of Fallot. The majority of patients have a left-sided arch. B. Correct. Patients with Tetralogy of Fallot have a pressure overload on the right ventricle, resulting in right ventricular hypertrophy, but little cardiac enlargement as a result. The apex is typically elevated, with concavity at the hypoplastic pulmonary artery, leading to the typical description of “coeur en sabot” or boot- shaped heart. C. Incorrect. The ventricular septal defect in patients with Tetralogy results from a malalighment of the stenotic infundibular portion of the interventricular septum. This type of defect does not close. D. Incorrect. The Fontan procedure is performed in patients with single ventricle anatomy, which is not the case in patients with Tetralogy of Fallot. Surgical repair of these patients most often consists of enlargement of the infundibular portion of the septum via a pericardial patch.
  17. 17. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 263. Regarding the pediatric duodenum, which one of the following is CORRECT? A. Duodenal atresia results from in utero vascular accident B. Duodenal stenosis or atresia is not associated with annular pancreas. C. Malrotation with volvulus can present with a normal abdominal radiograph. D. Presurgical diagnosis of duodenal atresia requires UGI. RATIONALES A. Incorrect. Duodenal atresia, unlike small bowel and colonic atresia, is believed to results from failure of recanalization. B. Incorrect. In approximately 40% of patients with annular pancreas, there is underlying stenosis or atresia. These patients tend to present earlier, usually in the neonatal period. C. Correct. Although patients with long-standing or more severe obstruction will tend to have a distended stomach and some distension of the duodenum, with paucity of distal bowel gas, a normal radiograph does not exclude malrotation with volvulus. D. Incorrect. The diagnosis of duodenal atresia can be made on the plain film findings of double bubble, with distension of the stomach, and marked distension of the duodenum, typically ½ to 1/3 the size of the stomach. References: Hernanz-Schulman. Imaging of neonatal gastrointestinal obstruction. Radiol Clin North Am 1999; 37:1163-86
  18. 18. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 264. Regarding renal masses in children, which of the following is TRUE? A. Nephrogenic rests are associated with Beckwith-Wiedemann syndrome. B. Incidence of Wilms tumor exceeds that of renal cell carcinoma in the second decade. C. Clear cell sarcoma has a better prognosis than mesoblastic nephroma. D. Renal medullary carcinoma most commonly occurs in patients of Nordic descent. RATIONALES: A. Correct. Nephrogenic rests or nephroblastomatosis, refers to foci of metanephric blastema persistent beyond 36 weeks of gestation. Hyperplastic or neoplastic rests are grossly visible and are considered premalignant lesions. They may be classified into perilobar or intralobar types. Perilobar rests are associated with Beckwith Wiedemann syndrome and hemihypertrophy. Intralobar type is associated with DRASH syndrome and sporadic aniridia. B. False. The incidence of renal cell carcinoma and Wilms tumor is greater second decade is nearly equal. C. False. Clear cell sarcoma, also known as bone-metastasizing renal tumor of childhood, is a highly aggressive tumor with poorer prognosis than Wilms tumor. Mesoblastic nephroma, on the other hand, is a tumor typically presenting in young infants or in the neonatal period. Excision with wide margins is typically curative. D. False. Renal medullary carcinoma occurs in adolescent and young adult black patienst with SC disease or sickle cell trait. The tumor grows within the renal pelvis with satellite nodules, and has a very poor prognosis. References: Lowe LH et al. Pediatric renal masses; Wilms tumor and beyond. Radiographics; 2000; 20:1585-1603
  19. 19. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 265. Concerning enteral duplications, which of the following is CORRECT? A. Most common at the stomach B. Most communicate with the adjacent bowel C. May act as the lead point in an intussusception D. Are best delineated by a barium small bowel follow-through RATIONALES: A. Incorrect. The most common location of enteral duplications is in the distal ileum, followed by the esophagus. B. Incorrect. The majority of duplications do not communicate with the adjacent bowel. C. Correct. Duplication cysts may act as the lead point of an intussuception, particularly when located in the distal ileum. Duplication cysts may also present with inflammatory changes in cases in which gastric mucosa is present within the cyst, or with segmental volvulus from the mass effect and traction of the cyst. D. Incorrect. Although contrast studies may show mass effect on bowel by a duplication cyst, they do not typically depict the mass itself. Cross-sectional imaging will better demonstrate the mass and its cystic nature. Ultrasound is the most definitive study, as it will show the cystic nature of the mass and often demonstrate the layered appearance of the cyst wall (inner echogenic mucosa and outer hypoechoic muscle) which is characteristic although not completely specific, of a duplication cyst. References: 1. Buonomo C, Taylor GA, Share JC, Kirks DR. Gastrointestinal Tract. In: Kirks DR, Griscom NT, eds. Practical Pediatric Imaging, 3rd edition, Lippincott- Raven, Philadelphia, 1998, pp 821-1007. 2. Barr LL, Hayden CKJr, Stansberry SD, Swischuk LE. Enteric duplication cysts in children: are their ultrasonic wall characteristics diagnostic? Pediatr Radiol 1990;20:326-328. 3. Teele RL, Henschke CT, Tapper D. The radiographic and ultrasonographic evaluation of enteric duplication cysts. Pediatr Radiol 1980:10;9-14.
  20. 20. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 266. Concerning fibromatosis colli, which of the following is CORRECT? A. CT is the preferred imaging modality B. The chin points towards the opposite side C. Biopsy is required to exclude rhabdomyosarcoma D. Birth history is usually normal RATIONALES: A. Incorrect. The preferred modality for imaging fibromatosis colli is ultrasound. Both CT and MR may demonstrate the abnormality; however, neither provides additional information to ultrasound. On ultrasound, enlargement of the sternocleidomastoid muscle is clearly demonstrated and the lesion is readily distinguished from tumor. CT is less desirable due to radiation. MR is less desirable due to potential need for sedation. B. Correct. With fibromatosis colli, there is a contracture of the sternocleidomastoid muscle. The mastoid attachment of the muscle pulls down on the affected side, tilting the head down on the affected side, and pointing the chin towards the contralateral side. C. Incorrect. Particularly with the appropriate clinical history (i.e. torticollis or head tilt), the imaging findings of fibromatosis colli are diagnostic and biopsy is not needed to exclude rhabdomyosarcoma. In fibromatosis colli, the muscle is enlarged. If a discrete mass is identified distorting the muscle or outside of the muscle and displacing it, then consideration for other processes besides fibromatosis colli should be raised. D. Incorrect. In many of these patients, there is a history of complications during delivery, such as breech presentation or forceps extraction. References: 1. Effmann EL. Neck and upper airway. In: Kuhn JP, Slovis TL, Haller JO, eds. Caffey’s Pediatric Diagnostic Imaging, 3rd edition, Mosby, Philadelphia, 2004, pp 777-809. 2. Crawford SC, Harnsberger HR, Johnson L, et al. Fibromatosis colli of infancy: CT and sonographic findings. AJR 1988;151-1183-1184. 3. Chan YL, Cheng JCY, Metrewelli C. Ultrasonography of congenital muscular torticollis. Pediatr Radiol 1992;22:356-360.
  21. 21. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 267. Concerning Legg-Calve-Perthes disease, which of the following is correct? A. It occurs more commonly in girls than in boys. B. Patients usually have bilateral disease at presentation. C. Contrast-enhanced MRI is not useful in establishing a diagnosis. D. Acutely, femoral head marrow is low signal on T1-weighted MRI. RATIONALES: A. Incorrect. Legg-Calve-Perthes disease is more common in boys than girls. The boy to girl ratio is approximately 4:1. B. Incorrect. Legg-Calve-Perthes disease is usually unilateral. Approximately 85% of cases are unilateral. Bilateral disease is less common (10-15%) and is usually asynchronous at presentation. C. Incorrect. Administration of intravenous Gadolinium can help to identify viable tissue in areas of bone marrow edema. D. Correct. MR may show abnormality prior to radiographs and may diagnose Legg- Calve-Perthes disease before radiographic abnormality develops. On MR imaging, the affected femoral head will show decreased signal on T1-weighted images. Normally, the femoral head shows high signal due to fatty marrow. With Legg-Calve-Perthes disease, the femoral head bone marrow becomes edematous, decreasing its signal intensity on T1-weighted images. References: 1. Laor T, Jaramillo D, Oestreich AE. Musculoskeletal system. In: Kirks DR, Griscom NT, eds. Practical Pediatric Imaging, 3rd edition, Lippincott-Raven, Philadelphia, 1998, pp 327-510. 2. Meyer J. Dysplasia epiphysialis capitis femoris: a clinical-radiological syndrome and its relationship to Legg-Calve-Perthes disease. Acta Orthop Scand 1964;34:183-197. 3. Kramer PP. The value of MRI in early Perthes’ disease. Pediatr Radiol 1997;27:517-522. 4. Mahnken AH, Staatz G et al. MR signal intensity characteristics in Legg- Calve-Perthes Disease. Value of fat-suppressed STIR images and contrast- enhanced T1 weighted images. Acta Radiologica 2002;43:329
  22. 22. 2007 ACR Diagnostic Radiology In-Training Exam Rationales 268. Regarding skeletal dysplasias with limb shortening, which of the following is CORRECT? A. Rhizomelic – short humerus B. Mesomelic – short femur C. Acromelic – short radius D. Rhizomelic – short tibia RATIONALES: A. Correct. “Rhizomelic“means shortening of the root or proximal bone. The humerus is the proximal bone within the upper extremity. B. Incorrect. “Mesomelic” means shortening of the middle bone. The femur is not the middle bone of the lower extremity. In the lower extremity, mesomelic refers to shortening of the tibia and fibula. C. Incorrect. “Acromelic” means shortening of the distal bones. The radius is not a distal bone of the upper extremity. In the upper extremity, acromelic refers to shortening of the hand. D. Incorrect. “Rhizomelic” means shortening of the root or proximal bone. The tibia is the middle bone of the lower extremity, not the proximal bone. In the lower extremity, rhizomelic refers to shortening of the femur. References: 1. Laor T, Jaramillo D, Oestreich AE. Musculoskeletal system. In: Kirks DR, Griscom NT, eds. Practical Pediatric Imaging, 3rd edition, Lippincott-Raven, Philadelphia, 1998, pp 327-510. 2. Lachman RS. Skeletal dysplasias. In: Kuhn JP, Slovis TL, Haller JO, eds., Caffey’s Pediatric Diagnostic Imaging, 10th edition, Mosby, Philadelphia, 2004, pp 2122-2180. 3. Hall CM, Offiah. Metabolic and storage disorders; skeletal dysplasias, syndromes and reduction deformities. In: Carty H, Brunelle F, Stringer DA, Kao SCS, eds., Imaging Children, 2nd edition, Elsevier, Philadelphia, 2005, pp 379- 476.

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