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ABR Pediatric Radiology study materials
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ABR Pediatric Radiology practice questions

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Question 1Pediatric Neuroradiology

A 3-day-old preterm infant undergoes cranial ultrasound screening. A grade 1 germinal matrix hemorrhage is characterized by which finding?

  1. Intraparenchymal hemorrhage with intraventricular extension
  2. Hemorrhage extending into the lateral ventricle without ventricular dilatation
  3. Hemorrhage confined to the subependymal germinal matrix Correct answer.
  4. Hemorrhage extending into the periventricular white matter

Explanation

Grade 1 germinal matrix hemorrhage is limited to the subependymal germinal matrix, typically at the caudothalamic groove. Grade 2 extends into the ventricle without dilatation; grade 3 includes ventricular dilatation; grade 4 involves periventricular parenchymal hemorrhage.

Question 2Pediatric Neuroradiology

Which posterior fossa malformation is characterized by cystic dilatation of the fourth ventricle, hypoplasia of the cerebellar vermis, and an enlarged posterior fossa with torcular elevation?

  1. Mega cisterna magna
  2. Chiari I malformation
  3. Joubert syndrome
  4. Dandy-Walker malformation Correct answer.

Explanation

Dandy-Walker malformation consists of cystic dilatation of the fourth ventricle, vermian hypoplasia with rotation, and an enlarged posterior fossa with elevation of the torcular Herophili. Mega cisterna magna preserves the vermis and fourth ventricle; Chiari I involves tonsillar ectopia; Joubert shows the molar tooth sign.

Question 3Pediatric Neuroradiology

A 2-year-old presents with leukocoria. Which imaging feature most strongly suggests retinoblastoma rather than a simulating lesion?

  1. Intraocular calcification on CT Correct answer.
  2. Hyperintensity on T1-weighted MRI
  3. Subretinal fluid
  4. Enlargement of the globe

Explanation

Retinoblastoma is the most common intraocular malignancy in children, and calcification is seen on CT in the majority of cases, which helps distinguish it from Coats disease or persistent hyperplastic primary vitreous. Coats disease typically lacks calcification and shows subretinal exudate.

Question 4Pediatric Neuroradiology

A 7-year-old presents with headache and ataxia. MRI shows a well-circumscribed cystic cerebellar mass with an enhancing mural nodule. What is the most likely diagnosis?

  1. Medulloblastoma
  2. Pilocytic astrocytoma Correct answer.
  3. Ependymoma
  4. Atypical teratoid/rhabdoid tumor

Explanation

Pilocytic astrocytoma is the most common pediatric cerebellar tumor and classically appears as a cyst with an enhancing mural nodule. Medulloblastoma is typically a solid midline mass with restricted diffusion; ependymoma arises from the fourth ventricular floor and extends through the foramina.

Question 5Pediatric Neuroradiology

Which pattern of injury is most characteristic of hypoxic-ischemic injury in the preterm infant?

  1. Watershed infarcts
  2. Diffuse cortical necrosis
  3. Periventricular leukomalacia Correct answer.
  4. Basal ganglia and thalamic injury

Explanation

Preterm infants are prone to periventricular leukomalacia because the periventricular white matter is a watershed zone and developing oligodendrocytes are vulnerable. Term infants more commonly show basal ganglia/thalamic or watershed cortical injury.

Question 6Pediatric Neuroradiology

The normal conus medullaris terminates at or above which vertebral level in children older than 2 months?

  1. L2-L3 Correct answer.
  2. S1-S2
  3. S3-S4
  4. L4-L5

Explanation

The normal conus medullaris terminates at or above the L2-L3 disc space after early infancy. A conus below L2-L3 suggests tethered cord, especially with a thickened filum terminale.

Question 7Pediatric Neuroradiology

Which finding is most strongly associated with Chiari II malformation?

  1. Isolated tonsillar herniation
  2. Syringomyelia
  3. Cerebellar tonsillar ectopia
  4. Myelomeningocele Correct answer.

Explanation

Chiari II malformation is almost always associated with open neural tube defects, particularly myelomeningocele. It includes hindbrain herniation, tectal beaking, and a small posterior fossa.

Question 8Pediatric Neuroradiology

A 6-year-old presents with growth failure and visual field deficits. CT shows a calcified suprasellar mass. What is the most likely diagnosis?

  1. Optic pathway glioma
  2. Pituitary macroadenoma
  3. Rathke cleft cyst
  4. Craniopharyngioma Correct answer.

Explanation

Adamantinomatous craniopharyngioma is the most common pediatric suprasellar mass and characteristically shows calcification on CT. Pituitary adenomas are rare in children and usually do not calcify; Rathke cleft cysts are noncalcified.

Question 9Pediatric Neuroradiology

A 5-year-old with headache and vomiting has a midline fourth ventricular mass that restricts diffusion. Which diagnosis is most likely?

  1. Ependymoma
  2. Pilocytic astrocytoma
  3. Medulloblastoma Correct answer.
  4. Choroid plexus papilloma

Explanation

Medulloblastoma typically arises from the cerebellar vermis, is a solid mass, and shows restricted diffusion due to high cellularity. Ependymoma arises from the fourth ventricular floor and extends through the foramina of Luschka or Magendie; pilocytic astrocytoma is usually cystic with a mural nodule.

Question 10Pediatric Neuroradiology

A child with seizures and ash-leaf spots has MRI showing multiple subependymal nodules along the lateral ventricular walls. Which additional finding is most characteristic of tuberous sclerosis?

  1. Tram-track calcifications
  2. Cortical tubers Correct answer.
  3. Optic pathway glioma
  4. Subdural effusions

Explanation

Tuberous sclerosis is characterized by cortical tubers, subependymal nodules, and subependymal giant cell astrocytomas. Optic pathway gliomas are associated with NF1; tram-track calcifications with Sturge-Weber.

Question 11Pediatric Neuroradiology

A 4-year-old with café-au-lait macules and axillary freckling has bilateral optic nerve thickening on MRI. What is the most likely diagnosis?

  1. Neurofibromatosis type 1 with optic pathway glioma Correct answer.
  2. Neurofibromatosis type 2 with meningioma
  3. Sturge-Weber syndrome with choroidal hemangioma
  4. Tuberous sclerosis with retinal hamartoma

Explanation

Optic pathway glioma is a common CNS manifestation of NF1 and often presents as bilateral optic nerve enlargement. NF2 is associated with bilateral vestibular schwannomas and meningiomas; Sturge-Weber shows leptomeningeal angiomatosis.

Question 12Pediatric Neuroradiology

A child with a facial port-wine stain has seizures. CT shows gyriform calcification in the occipital lobe. What is the diagnosis?

  1. Wyburn-Mason syndrome
  2. Tuberous sclerosis
  3. Neurofibromatosis type 1
  4. Sturge-Weber syndrome Correct answer.

Explanation

Sturge-Weber syndrome consists of a facial port-wine stain, leptomeningeal angiomatosis, and gyriform tram-track calcification, most often in the posterior parietal and occipital lobes. Wyburn-Mason syndrome has arteriovenous malformations of the retina and brain.

Question 13Pediatric Neuroradiology

A term neonate with a history of a sentinel event presents with seizures. MRI shows bilateral symmetric hyperintensity in the basal ganglia and thalami. What pattern of injury is this?

  1. Acute profound hypoxic-ischemic injury Correct answer.
  2. Prolonged partial hypoxia-ischemia
  3. Periventricular leukomalacia
  4. Neonatal stroke

Explanation

Acute profound asphyxia in a term infant preferentially injures the deep gray matter, especially the basal ganglia and thalami. Prolonged partial asphyxia tends to produce watershed cortical injury; periventricular leukomalacia is a preterm pattern.

Question 14Pediatric Neuroradiology

An infant has an abnormal head shape. MRI shows absence of the corpus callosum with parallel lateral ventricles and colpocephaly. Which finding is most consistent with this condition?

  1. Colpocephaly with enlarged occipital horns Correct answer.
  2. Thickened corpus callosum
  3. Enlarged frontal horns
  4. Normal ventricular morphology

Explanation

Agenesis of the corpus callosum leads to parallel lateral ventricles and colpocephaly, which is disproportionate enlargement of the occipital horns. The frontal horns may be narrow and the third ventricle may be high-riding.

Question 15Pediatric Neuroradiology

A newborn with hypotelorism and a midline facial cleft has MRI showing a single monoventricle and fused thalami. What is the diagnosis?

  1. Schizencephaly
  2. Hydranencephaly
  3. Septo-optic dysplasia
  4. Alobar holoprosencephaly Correct answer.

Explanation

Alobar holoprosencephaly is the most severe form, with a single monoventricle, fused thalami, and absence of midline structures, often accompanied by facial anomalies. Septo-optic dysplasia includes absent septum pellucidum and optic nerve hypoplasia but not fused thalami.

Question 16Pediatric Neuroradiology

A neonate presents with heart failure and a cranial bruit. MRI shows a large midline vascular structure draining into the torcular. What is the diagnosis?

  1. Cavernous malformation
  2. Dural arteriovenous fistula
  3. Arteriovenous malformation of the cerebellum
  4. Vein of Galen malformation Correct answer.

Explanation

Vein of Galen malformation is a choroidal arteriovenous fistula that shunts blood into the median prosencephalic vein, causing high-output cardiac failure in neonates. It is midline and drains to the torcular.

Question 17Pediatric Neuroradiology

A 6-year-old with progressive ataxia and cranial nerve palsies has an expansile, T2-hyperintense pontine mass without enhancement. What is the most likely diagnosis?

  1. Brainstem cavernoma
  2. Medulloblastoma
  3. Diffuse intrinsic pontine glioma Correct answer.
  4. Focal tectal glioma

Explanation

Diffuse intrinsic pontine glioma (DIPG) typically presents in children with an expansile pontine mass that is T2-hyperintense and often non-enhancing, causing cranial nerve palsies and long tract signs. Focal tectal gliomas cause hydrocephalus.

Question 18Pediatric Neuroradiology

An incidental finding in a healthy child is a well-defined extra-axial cystic lesion in the middle cranial fossa that follows CSF signal on all MRI sequences and does not enhance. What is the diagnosis?

  1. Pilocytic astrocytoma
  2. Epidermoid cyst
  3. Arachnoid cyst Correct answer.
  4. Porencephalic cyst

Explanation

Arachnoid cysts are extra-axial collections of CSF that follow CSF signal, do not enhance, and are most common in the middle cranial fossa. Epidermoid cysts restrict diffusion; porencephalic cysts communicate with the ventricle.

Question 19Pediatric Neuroradiology

A child with developmental delay and seizures has MRI showing a smooth brain surface with thickened cortex and loss of sulci. What is the diagnosis?

  1. Polymicrogyria
  2. Schizencephaly
  3. Lissencephaly Correct answer.
  4. Holoprosencephaly

Explanation

Lissencephaly (agyria-pachygyria) is characterized by a smooth brain surface, thickened cortex, and reduced white matter. Polymicrogyria shows an irregular cortical surface with many small gyri.

Question 20Pediatric Neuroradiology

A 5-year-old develops ataxia and encephalopathy 2 weeks after a viral infection. MRI shows multiple poorly marginated T2-hyperintense white matter lesions. What is the most likely diagnosis?

  1. Multiple sclerosis
  2. Acute disseminated encephalomyelitis Correct answer.
  3. Metachromatic leukodystrophy
  4. Alexander disease

Explanation

ADEM typically follows a viral infection or vaccination and presents with multifocal white matter lesions that are poorly marginated. Multiple sclerosis is rare in young children and usually has well-defined periventricular lesions.

Question 21Pediatric Neuroradiology

A child with recurrent strokes has MR angiography showing narrowing of the distal internal carotid arteries with a puff of smoke of collateral vessels at the base of the brain. What is the diagnosis?

  1. Fibromuscular dysplasia
  2. Reversible cerebral vasoconstriction syndrome
  3. Primary angiitis of the central nervous system
  4. Moyamoya disease Correct answer.

Explanation

Moyamoya disease is a progressive steno-occlusive arteriopathy of the distal internal carotid arteries with compensatory lenticulostriate collaterals that appear as a puff of smoke on angiography. It can be idiopathic or associated with conditions such as sickle cell disease or NF1.

Question 22Pediatric Neuroradiology

A child with mastoiditis develops headache and papilledema. Contrast-enhanced MRI shows a triangular filling defect in the superior sagittal sinus with enhancement of the dural margins. What is the diagnosis?

  1. Arachnoid granulation
  2. Subdural empyema
  3. Cerebral venous sinus thrombosis Correct answer.
  4. Meningioma

Explanation

The empty delta sign refers to a central filling defect in a dural sinus on contrast-enhanced imaging, representing thrombus with enhancing collateral dural venous channels. Arachnoid granulations can mimic small filling defects but are typically round and located in the lateral sinus.

Question 23Pediatric Neuroradiology

A child with a congenital heart defect and fever has a ring-enhancing brain lesion. Diffusion-weighted imaging shows marked central restriction. What is the most likely diagnosis?

  1. Glioblastoma
  2. Radiation necrosis
  3. Brain abscess Correct answer.
  4. Metastasis

Explanation

Brain abscess typically shows central restricted diffusion due to purulent material, which helps differentiate it from necrotic tumors where the central cavity usually does not restrict as strongly. The clinical setting of fever and cyanotic heart disease supports abscess.

Question 24Pediatric Neuroradiology

A term infant with prolonged partial asphyxia is most likely to show injury in which distribution?

  1. Watershed cortex Correct answer.
  2. Cerebellar vermis
  3. Periventricular white matter
  4. Basal ganglia and thalami

Explanation

Prolonged partial asphyxia in a term infant produces watershed parasagittal cortical injury because the hypotensive insult affects the border zones between major arterial territories. Acute profound asphyxia instead injures the deep gray matter.

Question 25Pediatric Neuroradiology

Which statement best distinguishes Chiari I from Chiari II malformation?

  1. Chiari I typically presents in adolescence with tonsillar herniation and syringomyelia, whereas Chiari II is associated with myelomeningocele. Correct answer.
  2. Chiari I includes a small posterior fossa with tectal beaking.
  3. Chiari I is associated with myelomeningocele, whereas Chiari II is an isolated tonsillar herniation.
  4. Chiari II is usually asymptomatic and discovered incidentally.

Explanation

Chiari I malformation is defined by cerebellar tonsillar herniation below the foramen magnum in an otherwise normal hindbrain and often presents in adolescence or adulthood with syringomyelia. Chiari II is a complex malformation with hindbrain herniation, tectal beaking, and an open neural tube defect.

Question 26Pediatric Neuroradiology

A healthy full-term neonate undergoes brain MRI on the second day of life. Which structure normally demonstrates T1 hyperintensity from early myelination?

  1. Periventricular white matter
  2. Posterior limb of the internal capsule Correct answer.
  3. Cerebellar cortex
  4. Frontal lobe white matter

Explanation

At birth, myelination is most evident on T1-weighted images in the posterior limb of the internal capsule, ventrolateral thalamus, and dorsal brainstem. The posterior limb of the internal capsule is a reliable landmark because its normal T1 hyperintensity is present in term neonates. Loss of this normal signal can be a sign of hypoxic-ischemic injury.

Question 27Pediatric Neuroradiology

A 3-day-old preterm infant has cranial ultrasound showing hemorrhage confined to the germinal matrix with extension into the lateral ventricle and adjacent intraparenchymal hemorrhage. What grade of germinal matrix hemorrhage is this?

  1. Grade IV Correct answer.
  2. Grade III
  3. Grade I
  4. Grade II

Explanation

The standard grading system assigns grade I to hemorrhage confined to the germinal matrix, grade II to intraventricular hemorrhage without ventricular dilation, grade III to intraventricular hemorrhage with ventricular dilation, and grade IV to hemorrhage extending into the brain parenchyma. The presence of intraparenchymal hemorrhage therefore makes this grade IV.

Question 28Pediatric Neuroradiology

An infant with an enlarging head circumference has MRI showing dilated lateral ventricles and a rim of T2 hyperintensity surrounding the ventricles. What does this periventricular T2 hyperintensity most likely represent?

  1. Cortical dysplasia
  2. Transependymal cerebrospinal fluid flow Correct answer.
  3. Subependymal nodules
  4. Demyelination

Explanation

Acute hydrocephalus raises ventricular pressure, allowing cerebrospinal fluid to seep across the ependyma into the periventricular white matter. This interstitial edema appears as smooth periventricular T2 hyperintensity, often called transependymal flow.

Question 29Pediatric Neuroradiology

An infant has a large posterior fossa cyst that communicates with a hypoplastic fourth ventricle, cerebellar vermian hypoplasia, and elevation of the torcular Herophili. Which diagnosis is most likely?

  1. Dandy-Walker malformation Correct answer.
  2. Arachnoid cyst
  3. Chiari I malformation
  4. Blake pouch cyst

Explanation

Dandy-Walker malformation consists of cystic dilation of the fourth ventricle, hypoplasia or agenesis of the cerebellar vermis, and an enlarged posterior fossa with a high torcular Herophili. The communication with the fourth ventricle helps distinguish it from an extra-axial arachnoid cyst.

Question 30Pediatric Neuroradiology

A 7-year-old with headache and ataxia has MRI showing a well-circumscribed cystic cerebellar mass with an enhancing mural nodule. Which tumor is most likely?

  1. Atypical teratoid/rhabdoid tumor
  2. Pilocytic astrocytoma Correct answer.
  3. Medulloblastoma
  4. Ependymoma

Explanation

In children, a cystic cerebellar mass with an enhancing mural nodule is classically a pilocytic astrocytoma, a low-grade glioma. Medulloblastoma and atypical teratoid/rhabdoid tumor are typically solid, aggressive masses, and ependymoma usually arises from the fourth ventricular floor.

Question 31Pediatric Neuroradiology

A 3-year-old with vomiting has a fourth ventricular tumor that extends through the foramina of Luschka and Magendie. Which diagnosis is most consistent with this growth pattern?

  1. Pilocytic astrocytoma
  2. Choroid plexus papilloma
  3. Craniopharyngioma
  4. Ependymoma Correct answer.

Explanation

Ependymomas arise from the ventricular lining and characteristically squeeze through the fourth ventricular outlets, a pattern sometimes called a plastic ependymoma. This growth through the foramina of Luschka and Magendie helps distinguish it from tumors that merely fill the fourth ventricle.

Question 32Pediatric Neuroradiology

A child with seizures has MRI showing a cleft extending from the ependymal surface of the lateral ventricle to the pial surface, lined entirely by gray matter. Which malformation is this?

  1. Polymicrogyria
  2. Porencephaly
  3. Holoprosencephaly
  4. Schizencephaly Correct answer.

Explanation

Schizencephaly is a developmental cleft that spans the cerebral hemisphere and is lined by gray matter, reflecting abnormal cortical formation. Porencephaly is a destructive lesion lined by gliotic white matter rather than gray matter.

Question 33Pediatric Neuroradiology

A 2-year-old with developmental delay and episodic hyperpnea has MRI showing thickened superior cerebellar peduncles and a deep interpeduncular fossa, creating a molar tooth appearance. Which diagnosis is most likely?

  1. Joubert syndrome Correct answer.
  2. Chiari II malformation
  3. Rhombencephalosynapsis
  4. Dandy-Walker malformation

Explanation

The molar tooth sign of Joubert syndrome reflects dysplastic superior cerebellar peduncles, vermian hypoplasia, and a deep interpeduncular fossa. It is associated with developmental delay and abnormal respiratory control.

Question 34Pediatric Neuroradiology

A 12-year-old with hearing loss and tinnitus has MRI demonstrating bilateral masses at the cerebellopontine angles extending into the internal acoustic canals. Which diagnosis should be suspected?

  1. Neurofibromatosis type 2 Correct answer.
  2. Neurofibromatosis type 1
  3. Tuberous sclerosis complex
  4. Sturge-Weber syndrome

Explanation

Bilateral vestibular schwannomas are the hallmark of neurofibromatosis type 2 and often present with hearing loss or tinnitus. NF1, tuberous sclerosis, and Sturge-Weber syndrome have different characteristic imaging findings.

Question 35Pediatric Neuroradiology

A child with seizures has MRI showing a well-defined lesion with a popcorn-like core and a complete hemosiderin rim on T2-weighted imaging. Which vascular malformation is most likely?

  1. Capillary telangiectasia
  2. Arteriovenous malformation
  3. Developmental venous anomaly
  4. Cavernous malformation Correct answer.

Explanation

A cavernous malformation has a lobulated core of mixed signal from blood products of different ages and a complete hemosiderin rim on T2-weighted images. It typically causes little mass effect and may present with seizures.

Question 36Pediatric Neuroradiology

A previously healthy 8-year-old presents with fever, confusion, and seizures. MRI shows asymmetric T2 hyperintensity and restricted diffusion in the medial temporal lobes, with sparing of the basal ganglia. Which diagnosis is most likely?

  1. Herpes simplex encephalitis Correct answer.
  2. Acute disseminated encephalomyelitis
  3. Brain abscess
  4. Acute ischemic stroke

Explanation

Herpes simplex encephalitis has a predilection for the limbic system, producing asymmetric medial temporal, insular, and inferior frontal involvement. Relative sparing of the basal ganglia helps distinguish it from a middle cerebral artery infarct.

Question 37Pediatric Neuroradiology

A newborn with microcephaly and hearing loss has CT showing scattered periventricular calcifications and MRI showing a simplified gyral pattern. Which congenital infection is most likely?

  1. Herpes simplex virus
  2. Toxoplasmosis
  3. Cytomegalovirus Correct answer.
  4. Rubella

Explanation

Congenital cytomegalovirus infection classically causes periventricular calcifications, ventriculomegaly, white matter injury, and cortical malformations such as polymicrogyria. Toxoplasmosis more often produces scattered parenchymal calcifications.

Question 38Pediatric Neuroradiology

A term neonate with severe jaundice and elevated unconjugated bilirubin develops choreoathetosis. MRI shows symmetric T1 hyperintensity in the globus pallidus. Which pattern of injury is most likely?

  1. Manganese accumulation
  2. Kernicterus Correct answer.
  3. Hypoxic-ischemic injury of the basal ganglia
  4. Normal myelination

Explanation

Unconjugated bilirubin crosses the immature blood-brain barrier and injures the globus pallidus, subthalamic nuclei, and hippocampus, producing kernicterus. Acute injury appears as T1 hyperintensity in the globus pallidus, later followed by T2 hyperintensity.

Question 39Pediatric Neuroradiology

A 9-year-old with medically refractory temporal lobe epilepsy has MRI showing a well-defined bubble-like cortical lesion in the anterior temporal lobe with a small pointed extension toward the ventricle. Which diagnosis is most likely?

  1. Pilocytic astrocytoma
  2. Dysembryoplastic neuroepithelial tumor Correct answer.
  3. Focal cortical dysplasia
  4. Ganglioglioma

Explanation

Dysembryoplastic neuroepithelial tumor is a benign, epilepsy-associated cortical tumor that classically has a multicystic or bubbly appearance, often in the temporal lobe. A pointed extension toward the ventricle can be seen and should not be mistaken for aggressive invasion.

Question 40Pediatric Neuroradiology

A 3-year-old with epilepsy has MRI showing multiple smooth nodules lining the lateral ventricles that follow gray matter signal on all sequences and do not calcify. Which diagnosis is most likely?

  1. Ependymoma
  2. Tuberous sclerosis complex
  3. Periventricular nodular heterotopia Correct answer.
  4. Subependymal giant cell astrocytoma

Explanation

Periventricular nodular heterotopia results from arrested neuronal migration, so the nodules are isointense to cortical gray matter on all MRI sequences and do not calcify. This distinguishes them from the subependymal nodules of tuberous sclerosis, which often calcify.

Question 41Pediatric Thoracic and Cardiovascular Imaging

In a premature neonate with respiratory distress syndrome, which chest radiographic pattern is most characteristic?

  1. Hyperinflation with coarse interstitial opacities
  2. Lobar consolidation with air bronchograms
  3. Low lung volumes with a reticulogranular pattern and air bronchograms Correct answer.
  4. Bilateral pleural effusions with cardiomegaly

Explanation

Surfactant deficiency causes diffuse alveolar collapse, so the lungs are underinflated and appear ground-glass or reticulogranular, with air bronchograms visible against opaque alveoli. Hyperinflation is more typical of meconium aspiration or transient tachypnea, and isolated lobar consolidation suggests pneumonia.

Question 42Pediatric Thoracic and Cardiovascular Imaging

A 2-month-old infant has a widened upper mediastinum on a frontal chest radiograph. The lateral radiograph shows the structure anteriorly, and it does not compress the trachea. Which structure most likely accounts for this finding?

  1. Thyroid gland
  2. Esophagus
  3. Thymus Correct answer.
  4. Aortic aneurysm

Explanation

The thymus is normally prominent in infants, and its anterior position plus lack of airway compression distinguishes it from pathologic mediastinal masses. On frontal views it may produce a sail sign or a wave sign where ribs indent its soft edges.

Question 43Pediatric Thoracic and Cardiovascular Imaging

A 4-year-old child with fever and cough has a well-circumscribed round opacity in the right lower lobe on chest radiograph. What is the most likely diagnosis?

  1. Round pneumonia Correct answer.
  2. Neuroblastoma
  3. Bronchogenic cyst
  4. Pulmonary sequestration

Explanation

Round pneumonia is a bacterial infection, most often due to Streptococcus pneumoniae, that appears as a spherical opacity in children because spread is limited by incompletely developed collateral airways. It typically resolves after antibiotic therapy, and persistent lesions require evaluation for a mass.

Question 44Pediatric Thoracic and Cardiovascular Imaging

A child with a barking cough and inspiratory stridor has a frontal radiograph showing symmetric narrowing of the subglottic airway. What is the most likely diagnosis?

  1. Epiglottitis
  2. Bacterial tracheitis
  3. Foreign body aspiration
  4. Croup Correct answer.

Explanation

Croup, or laryngotracheobronchitis, causes subglottic edema that narrows the airway symmetrically and produces the steeple sign on a frontal radiograph. Epiglottitis instead enlarges the epiglottis and is a medical emergency.

Question 45Pediatric Thoracic and Cardiovascular Imaging

A 3-year-old with drooling, fever, and tripod positioning has a lateral neck radiograph showing a thickened, rounded epiglottis. What is the most likely diagnosis?

  1. Laryngomalacia
  2. Croup
  3. Retropharyngeal abscess
  4. Epiglottitis Correct answer.

Explanation

An enlarged, rounded epiglottis on a lateral neck radiograph is the thumb sign of epiglottitis, a supraglottic airway emergency typically caused by Haemophilus influenzae type b. The history of drooling and tripod positioning supports this diagnosis, and airway management should not be delayed for imaging.

Question 46Pediatric Thoracic and Cardiovascular Imaging

A toddler has sudden coughing and wheezing after playing with small toys. Which finding most strongly suggests an aspirated radiolucent foreign body?

  1. Bilateral diffuse ground-glass opacities
  2. A large pleural effusion
  3. Mediastinal widening with a thymic sail sign
  4. Ipsilateral hyperinflation on an expiratory radiograph Correct answer.

Explanation

A radiolucent foreign body can act as a ball valve, letting air enter but not exit the affected lung, so the ipsilateral lung remains hyperinflated on expiration. Expiratory or decubitus radiographs increase the sensitivity for this asymmetric air trapping.

Question 47Pediatric Thoracic and Cardiovascular Imaging

A newborn with respiratory distress has bowel loops in the left hemithorax and rightward mediastinal shift. What is the most likely diagnosis?

  1. Pulmonary sequestration
  2. Congenital pulmonary airway malformation
  3. Bronchogenic cyst
  4. Congenital diaphragmatic hernia Correct answer.

Explanation

Congenital diaphragmatic hernia, usually through the left posterolateral Bochdalek foramen, allows abdominal viscera to enter the chest and shift the mediastinum. A nasogastric tube seen coiled in the thorax supports the diagnosis.

Question 48Pediatric Thoracic and Cardiovascular Imaging

Which congenital vascular anomaly most commonly causes a complete vascular ring around the trachea and esophagus?

  1. Pulmonary sling
  2. Aberrant right subclavian artery with a left aortic arch
  3. Left aortic arch with a normal branching pattern
  4. Double aortic arch Correct answer.

Explanation

A double aortic arch encircles the trachea and esophagus with both right and left arches, making it the most common complete vascular ring. An aberrant right subclavian artery with a left arch usually does not form a complete ring unless a right ligamentum arteriosum is present.

Question 49Pediatric Thoracic and Cardiovascular Imaging

A child has recurrent right lower lobe pneumonia. Chest radiograph shows a small right lung and a tubular opacity descending toward the right cardiophrenic angle. What is the most likely diagnosis?

  1. Scimitar syndrome Correct answer.
  2. Pulmonary sequestration
  3. Congenital pulmonary airway malformation
  4. Swyer-James syndrome

Explanation

Scimitar syndrome consists of partial anomalous pulmonary venous return from the right lung to the inferior vena cava, often with right lung hypoplasia and recurrent infection. The anomalous vein appears as a curved tubular opacity resembling a scimitar.

Question 50Pediatric Thoracic and Cardiovascular Imaging

An infant with cyanosis has a chest radiograph showing a boot-shaped heart and decreased pulmonary vascular markings. What is the most likely diagnosis?

  1. Transposition of the great arteries
  2. Tetralogy of Fallot Correct answer.
  3. Ebstein anomaly
  4. Total anomalous pulmonary venous return

Explanation

Tetralogy of Fallot combines right ventricular outflow tract obstruction, ventricular septal defect, overriding aorta, and right ventricular hypertrophy. The obstruction reduces pulmonary blood flow, producing oligemic lungs and a boot-shaped heart from right ventricular hypertrophy and a concave pulmonary bay.