Pediatric Radiology — MCQs

Pediatric Radiology Indian Medical PG Practice Questions and MCQs

Question 91: A child with lymphoma shows 'ivory vertebra' sign. Best imaging modality for evaluation?

A. Plain X-ray
B. MRI spine (Correct Answer)
C. CT spine
D. Bone scan

Explanation: ***MRI spine*** - **MRI** is the **most sensitive and specific** imaging modality for evaluating bone marrow infiltration in lymphoma, especially detecting the **'ivory vertebra' sign** (diffuse uniform sclerotic density). - It provides excellent soft tissue contrast, allowing for detailed visualization of **vertebral body involvement**, **bone marrow infiltration**, and **spinal cord compression**, which are critical in managing lymphoma. - MRI superior for assessing **extent of marrow replacement** and detecting **soft tissue masses** associated with lymphomatous involvement. *Plain X-ray* - While a plain X-ray might show the **'ivory vertebra' sign** as increased homogeneous bone density, it has **limited sensitivity** for early or subtle bone marrow changes. - It is often insufficient for comprehensive staging or assessing the full extent of **vertebral and paravertebral soft tissue involvement** in lymphoma. *CT spine* - **CT scans** excel at evaluating **cortical bone involvement** and detecting sclerotic changes but are less sensitive than MRI for detecting subtle **marrow infiltration** and soft tissue components. - While it can clearly depict the sclerotic density of **'ivory vertebra'**, it exposes the patient to **ionizing radiation** and offers inferior soft tissue resolution for bone marrow changes and epidural extension compared to MRI. *Bone scan* - **Bone scans** are sensitive for detecting **increased osteoblastic activity** and skeletal involvement but are **non-specific**, meaning they can indicate bone abnormalities without precisely defining the cause or extent. - While it can identify areas of **increased uptake** in lymphomatous bone involvement, it doesn't provide the detailed anatomical resolution needed to characterize the vertebral changes or assess **spinal cord compression** as effectively as MRI.

Question 92: The 'figure of eight' appearance on chest X-ray is commonly seen in which congenital heart defect?

A. Transposition of the great arteries
B. Ebstein's anomaly
C. Tetralogy of Fallot
D. Total anomalous pulmonary venous connection (TAPVC) (Correct Answer)

Explanation: ***Total anomalous pulmonary venous connection (TAPVC)*** - The "figure of eight" or "snowman" appearance on a chest X-ray is characteristic of **supracardiac TAPVC**. - This occurs due to the **dilated superior vena cava (SVC)** forming the "head" and the dilated right atrium and ventricle forming the "body" of the snowman. *Transposition of the great arteries* - The classic chest X-ray finding for this condition is a **"egg on a string"** appearance, where the narrow mediastinum gives the impression of an egg-shaped heart. - This is due to the **aorta** lying directly anterior to the **pulmonary artery**, obscuring their usual normal configuration. *Ebstein's anomaly* - Characterized by **apical displacement of the tricuspid valve leaflets**, leading to a large atrialized right ventricle. - Chest X-ray often shows a **markedly enlarged heart** (cardiomegaly) due to right atrial and right ventricular dilation, but not a "figure of eight" pattern. *Tetralogy of Fallot* - The classic chest X-ray finding for Tetralogy of Fallot is a **"boot-shaped" heart** (coeur en sabot). - This shape is due to **right ventricular hypertrophy** and an upturned apex, along with a concave pulmonary artery segment.

Question 93: What is indicated by the 'double bubble sign' on prenatal ultrasound?

A. Hirschsprung disease
B. Pyloric stenosis
C. Duodenal atresia (Correct Answer)
D. Esophageal atresia

Explanation: ***Duodenal atresia*** - The **double bubble sign** on prenatal ultrasound is pathognomonic for **duodenal atresia**, representing a dilated stomach and a dilated first part of the duodenum. - This congenital anomaly results from a failure of the **duodenal lumen** to recanalize during fetal development, leading to a complete obstruction. *Hirschsprung disease* - Characterized by the absence of **ganglion cells** in the distal colon, leading to functional obstruction, but it does not typically present as a **double bubble sign** on prenatal ultrasound. - While it can cause bowel dilation, it usually affects more distal portions of the bowel and presents with symptoms like **delayed meconium passage** postnatally. *Pyloric stenosis* - Involves hypertrophy of the **pyloric muscle**, leading to gastric outlet obstruction, but it typically presents in infancy with **non-bilious projectile vomiting** and an **olive-shaped mass**, not a double bubble sign antenatally. - The 'double bubble' is specific to obstructions *after* the pylorus, in the duodenum. *Esophageal atresia* - This condition involves a blind-ending esophagus and is often associated with a **tracheoesophageal fistula**, leading to symptoms like **frothing and bubbling at the mouth** and choking during feeds. - While it impacts feeding, it does not cause the characteristic appearance of a **dilated stomach** and duodenum seen in the double bubble sign.

Question 94: What is the most common cause of 'banana sign' in prenatal ultrasound?

A. Anencephaly
B. Dandy-Walker malformation
C. Spina bifida (Correct Answer)
D. Hydrocephalus

Explanation: ***Spina bifida*** - The **"banana sign"** is a characteristic ultrasound finding where the **cerebellum is compressed and flattened**, resembling a banana due to the caudal displacement of the posterior fossa contents into the spinal canal. - This compression is typically caused by the **Chiari II malformation**, which is almost always present with **myelomeningocele**, the most severe form of spina bifida. *Anencephaly* - Anencephaly results in the **absence of most of the brain and skull**, which is a distinctly different finding from the "banana sign." - The characteristic ultrasound finding for anencephaly is the **absence of the cranial vault and cerebral hemispheres** above the orbits. *Dandy-Walker malformation* - This malformation involves an **enlarged posterior fossa** with cystic dilation of the fourth ventricle and **agenesis/hypoplasia of the cerebellar vermis**. - It does not cause the cerebellar compression that creates the "banana sign." *Hydrocephalus* - Hydrocephalus involves the **enlargement of the ventricles** due to excessive cerebrospinal fluid (CSF) accumulation, leading to increased intracranial pressure. - While it can be associated with spina bifida and Chiari II malformation, **hydrocephalus itself doesn't directly cause the "banana sign"** as a primary feature.

Question 95: A child presents with injuries suggestive of physical abuse. Which radiological sign is most indicative of non-accidental trauma?

A. Single bone fracture
B. Multiple fractures in different stages of healing (Correct Answer)
C. Spiral fracture
D. Hairline fracture

Explanation: ***Multiple fractures in different stages of healing*** - This finding **strongly suggests repeated trauma** over time, which is **highly indicative of non-accidental injury (NAI)**. - The presence of both **acute and healing fractures** points to a pattern of abuse rather than a single accidental event. - This is considered one of the **classic radiological signs** of child abuse, along with metaphyseal corner fractures and posterior rib fractures. - Different stages of healing indicate injuries occurred at **different time points**, which is incompatible with a single traumatic event. *Single bone fracture* - While any fracture can be due to abuse, a **single bone fracture in isolation** is **less specific** for non-accidental trauma. - It might occur due to a single accidental event, and **further clinical correlation** is needed to determine its origin. - Additional factors like child's age, developmental stage, mechanism of injury, and presence of other injuries must be considered. *Spiral fracture* - **Spiral fractures** result from a **twisting force** applied to a long bone. - While they can occur accidentally (e.g., toddler's fracture), spiral fractures are **highly suspicious for abuse** in **non-ambulatory infants** who cannot walk or twist their own limbs. - In older ambulatory children, these are less specific as they can occur during play or sports. - Not as definitive as multiple fractures in different healing stages. *Hairline fracture* - A **hairline fracture** (or stress fracture) is a small crack in the bone from repetitive stress or minor trauma. - These are often **subtle** and can occur accidentally, making them **least specific** for abuse. - Common in normal childhood activities and sports.

Question 96: In a voiding cystourethrogram (VCUG), which condition is characterized by an adder head appearance?

A. Posterior urethral valve
B. Bladder tumour
C. Horse shoe kidney
D. Ureterocele (Correct Answer)

Explanation: ***Ureterocele*** - An **adder head appearance** on a VCUG is characteristic of a **ureterocele**, which is a cystic dilation of the distal intra-vesical ureter. - This appearance is due to the dilated ureterocele protruding into the bladder lumen, resembling the head of an adder. *Posterior urethral valve* - This condition presents as a **filling defect** or **narrowing of the posterior urethra** on VCUG, often with dilation of the prostatic urethra and reflux into the seminal vesicles. - It does not typically cause an "adder head" appearance. *Bladder tumour* - A bladder tumour typically appears as a **filling defect** within the bladder lumen or an **irregularity of the bladder wall** on a VCUG. - This morphology is distinctly different from the characteristic appearance of a ureterocele. *Horse shoe kidney* - Horseshoe kidney is a congenital anomaly where the **kidneys are fused**, usually at their lower poles, and is a finding on **renal imaging** (e.g., ultrasound, CT, IVP), not typically on a VCUG of the bladder and urethra alone. - It does not produce an "adder head" appearance as it relates to renal structure, not bladder or ureteral dilation.

Question 97: Which imaging modality is most commonly used to diagnose ectopic kidneys in children?

A. DTPA scan
B. Ultrasound (Correct Answer)
C. MAG3 scan
D. DMSA scan

Explanation: ***Ultrasound*** - **Ultrasound** is the initial and most commonly used imaging modality due to its non-invasive nature, accessibility, and ability to visualize renal anatomy and location without radiation exposure. - It can effectively identify the **presence and location of ectopic kidneys**, as well as associated anomalies like hydronephrosis. *DTPA scan* - A **DTPA (diethylenetriamine pentaacetic acid) scan** primarily evaluates **renal function and blood flow** and is less detailed for anatomical localization. - While it can show renal perfusion, it is not the primary diagnostic tool for initial anatomical diagnosis of an ectopic kidney. *DMSA scan* - A **DMSA (dimercaptosuccinic acid) scan** is used to assess **renal cortical scarring and function**, particularly in cases of pyelonephritis. - It provides functional information about the kidney but is not typically the first-line imaging for identifying the anatomical location of an ectopic kidney. *MAG3 scan* - A **MAG3 (mercaptoacetyltriglycine) scan** assesses **renal plasma flow and excretory function**, similar to DTPA but often preferred in cases of impaired renal function. - It is more functional than anatomical in nature and less suitable as a primary tool for diagnosing ectopic kidney location compared to ultrasound.

Question 98: A postnatal X-ray of the abdomen of a neonate shows a "double bubble sign". It is seen with:

A. Duodenal atresia (Correct Answer)
B. Ileal atresia
C. Pyloric stenosis
D. Esophageal atresia

Explanation: **Duodenal atresia** - The **"double bubble sign"** on an abdominal X-ray is classic for **duodenal atresia**, representing a dilated stomach and a dilated proximal duodenum separated by the pylorus. - This finding indicates a complete obstruction at the level of the duodenum, preventing the passage of gas distally. *Ileal atresia (may show distension throughout the bowel)* - In **ileal atresia**, the obstruction is further down the small bowel, leading to multiple dilated loops of bowel proximal to the atresia. - The X-ray would typically show more widespread **abdominal distension** with multiple air-fluid levels rather than the distinct double bubble. *Pyloric stenosis (typically presents with a single bubble sign)* - **Pyloric stenosis** involves narrowing of the pylorus but not an complete obstruction in the same way as duodenal atresia, leading to gastric outlet obstruction. - While it might show a **distended stomach (single bubble)**, it typically does not obstruct distally enough to create a second prominent bubble in the duodenum. *Esophageal atresia (associated with airless abdomen on X-ray)* - **Esophageal atresia** is an interruption in the continuity of the esophagus, preventing swallowed air from reaching the stomach and intestines. - An abdominal X-ray in this condition would typically show an **airless abdomen** because air cannot pass into the gastrointestinal tract.

Question 99: What is the investigation of choice for acute appendicitis in children?

A. USG (Correct Answer)
B. MRI
C. CT scan
D. X-ray

Explanation: ***USG*** - **Ultrasound** (USG) is the preferred initial imaging modality due to its **non-invasive nature** and **lack of radiation exposure**, which is particularly important in children. - It can effectively visualize the **appendix**, assess its compressibility, and identify signs of inflammation like wall thickening and pericecal fluid collection. *MRI* - **MRI** is a highly accurate imaging technique for appendicitis but is generally reserved for cases where USG is inconclusive, or when there is a need to avoid radiation, and USG is not sufficient. - It takes **longer to perform** and often requires **sedation** in younger children, making it less practical as a first-line investigation. *CT scan* - **CT scan** is very sensitive and specific for appendicitis but involves significant **ionizing radiation**, which is a concern in the pediatric population due to increased lifetime cancer risk. - While it provides detailed anatomical information, the **radiation exposure** makes it a second-line investigation for children, typically used when USG is inconclusive or appendicitis is strongly suspected despite negative USG. *X-ray* - A plain **abdominal X-ray** has **very limited utility** in diagnosing acute appendicitis as it cannot visualize the appendix directly. - It may show non-specific findings like a **fecalith** or **ileus**, but these are not diagnostic of appendicitis and can be found in other conditions.

Question 100: Egg on side appearance is seen in what condition?

A. Fallot's tetralogy
B. Ebstein's anomaly
C. Ventricular septal defect
D. Transposition of great vessels (Correct Answer)

Explanation: **Transposition of great vessels** - The "egg on side" or **egg-on-a-string** appearance is a classic radiographic sign of **transposition of the great vessels (TGV)**, where the heart appears ovoid and lying on its side. - This appearance is due to the **narrow mediastinum** as the great arteries (aorta and pulmonary artery) run parallel to each other. *Fallot's tetralogy* - The classic chest X-ray finding in Fallot's tetralogy is a **boot-shaped heart** (coeur en sabot), due to right ventricular hypertrophy and pulmonary artery hypoplasia. - The mediastinum is usually not narrowed, and the great arteries do not exhibit the same parallel arrangement. *Ebstein's anomaly* - Ebstein's anomaly typically shows marked **cardiomegaly** on chest X-ray due to right atrial enlargement and tricuspid regurgitation. - It does not produce the "egg on side" appearance; the heart size is usually significantly increased and not ovoid. *Ventricular septal defect* - A **ventricular septal defect (VSD)** often presents with **cardiomegaly** and **pulmonary plethora** (increased pulmonary vascular markings) due to left-to-right shunting. - The heart shape is not typically described as "egg on side" and the great arteries are not transposed.

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