Ultrasound — MCQs
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Which of the following diagnostic tests is most useful in confirming the presence of ascites?
Which finding is most indicative of a molar pregnancy on ultrasound?
What is the first-line imaging modality for the evaluation of pyloric stenosis in infants?
What is the first-line imaging modality for suspected appendicitis in a young adult?
Which of the following is the most appropriate initial imaging study for a child with suspected pyloric stenosis?
In which fetal anomalies are the 'banana sign' and 'lemon sign' observed?
What is the sonographic appearance of a hydatid cyst?
Which of the following is a soft tissue marker of Down syndrome on USG?
Which piezoelectric crystal is most widely used in ultrasonography probes?
Mercedes Benz sign is seen in:
Ultrasound Indian Medical PG Practice Questions and MCQs
Question 221: Which of the following diagnostic tests is most useful in confirming the presence of ascites?
- A. Ultrasound (Correct Answer)
- B. CT scan
- C. Liver function tests
- D. Abdominal X-ray
Explanation: ***Ultrasound*** - **Ultrasound** is highly sensitive and specific for detecting even small amounts of **ascitic fluid** and can differentiate it from other abdominal masses or fluid collections. - It also allows for assessment of underlying organ pathology (e.g., **liver cirrhosis**) that may be causing the ascites and can guide **paracentesis**. *CT scan* - While a **CT scan** can detect ascites, it exposes the patient to **ionizing radiation** and is generally more expensive than an ultrasound. - It is often reserved for complex cases or when additional information about solid organ pathology is needed, beyond what ultrasound can provide. *Liver function tests* - **Liver function tests (LFTs)** assess liver function and can indicate the presence of **liver disease**, which is a common cause of ascites. - However, LFTs do not directly confirm the presence of **ascitic fluid** in the abdominal cavity but rather point to an underlying cause. *Abdominal X-ray* - An **abdominal X-ray** is very insensitive for detecting small to moderate amounts of **ascites** and is not typically used for this purpose. - It may show a **ground-glass appearance** or flank bulging in cases of massive ascites, but it lacks the detail and specificity of ultrasound or CT.
Question 222: Which finding is most indicative of a molar pregnancy on ultrasound?
- A. Single gestational sac
- B. Snowstorm appearance (Correct Answer)
- C. Yolk sac
- D. Double decidual sign
Explanation: ***Snowstorm appearance*** - The **snowstorm appearance** (or "grape-like clusters") on ultrasound is highly characteristic of a **molar pregnancy**, representing numerous small anechoic vesicles. - This finding is due to the **swollen chorionic villi** and the absence of a normal fetus and amniotic fluid in a complete hydatidiform mole. *Single gestational sac* - A **single gestational sac** is a normal finding in most early pregnancies and does not indicate a molar pregnancy. - While a sac might be present, its presence alone is not diagnostic of molar disease; the internal contents are key. *Yolk sac* - A **yolk sac** is a normal structure seen in early fetal development, providing nourishment to the embryo. - Its presence usually indicates an **intrauterine pregnancy**, but its absence or abnormal appearance can be associated with failed pregnancies or certain molar gestations (e.g., partial mole with an anomalous fetus). *Double decidual sign* - The **double decidual sign** refers to the visualization of two concentric rings surrounding a gestational sac, indicating a true intrauterine pregnancy. - This sign helps differentiate an early intrauterine pregnancy from a **pseudogestational sac** seen in ectopic pregnancies but is not specific to molar pregnancies.
Question 223: What is the first-line imaging modality for the evaluation of pyloric stenosis in infants?
- A. X-ray
- B. CT scan
- C. MRI
- D. Ultrasound (Correct Answer)
Explanation: ***Ultrasound*** - **Ultrasound** is the preferred first-line imaging modality due to its **non-invasive nature**, lack of radiation, and high accuracy in diagnosing pyloric stenosis. - It allows direct visualization and measurement of the **pyloric muscle thickness** and length, which are key diagnostic criteria. *X-ray* - While an initial **X-ray** might be performed to rule out other causes of vomiting, it is generally **not definitive** for diagnosing pyloric stenosis. - It may show a **dilated stomach** but cannot visualize the pyloric muscle directly. *CT scan* - A **CT scan** is not the first-line imaging choice due to the **radiation exposure**, which should be minimized in infants. - It offers more detailed anatomical information but is **not necessary** for the diagnosis of pyloric stenosis, given the effectiveness of ultrasound. *MRI* - **MRI** is not routinely used for diagnosing pyloric stenosis because it is **time-consuming**, expensive, and often requires sedation in infants. - It provides excellent soft tissue contrast, but its benefits **do not outweigh the drawbacks** for this specific condition compared to ultrasound.
Question 224: What is the first-line imaging modality for suspected appendicitis in a young adult?
- A. X-ray abdomen
- B. Ultrasound of the abdomen (Correct Answer)
- C. CT scan of the abdomen
- D. MRI of the abdomen
Explanation: ***Ultrasound of the abdomen*** - **Ultrasound** is often the first-line imaging modality for suspected appendicitis, especially in young adults and children, due to its **non-invasive nature** and **lack of ionizing radiation**. - It can effectively visualize a **dilated, non-compressible appendix** with target sign, periappendiceal fluid, and increased vascularity. *X-ray abdomen* - **X-rays** are generally not useful for diagnosing appendicitis as they cannot visualize the appendix directly and offer **limited soft tissue detail**. - They may show secondary signs like a **fecalith** or localized ileus but are not diagnostic for appendicitis itself. *CT scan of the abdomen* - While highly sensitive and specific for appendicitis, **CT scans** involve significant **ionizing radiation**, making them a second-line option, especially for young adults where radiation exposure should be minimized. - CT is typically reserved for cases where ultrasound findings are inconclusive or when complications like **abscess formation** are suspected. *MRI of the abdomen* - **MRI** is an excellent modality for visualizing the appendix without radiation but is generally **less available**, more expensive, and **time-consuming** than ultrasound. - It is typically reserved for pregnant patients or those with **contraindications to CT contrast**, rather than as a first-line option in young adults.
Question 225: Which of the following is the most appropriate initial imaging study for a child with suspected pyloric stenosis?
- A. Barium swallow
- B. CT scan
- C. MRI
- D. Ultrasound (Correct Answer)
Explanation: ***Correct: Ultrasound*** **Ultrasound** is the preferred initial imaging modality for suspected **pyloric stenosis** due to its high diagnostic accuracy, non-invasive nature, and lack of radiation exposure. It allows for direct visualization and measurement of the **pyloric muscle thickness** (>3 mm diagnostic) and **length** (>15 mm diagnostic), which are key diagnostic criteria. Real-time assessment can also demonstrate the "pyloric muscle doughnut sign" and failure of gastric contents to pass through the pylorus. *Incorrect: Barium swallow* While a **barium swallow** can show a "string sign" or "double-track sign" indicative of pyloric stenosis, it is less preferred than ultrasound due to **radiation exposure** and potential for aspiration in infants with frequent vomiting. It is typically considered only if ultrasound results are equivocal or unavailable. *Incorrect: CT scan* A **CT scan** is generally not indicated for the diagnosis of pyloric stenosis due to significant **radiation exposure** (particularly concerning in infants) and its inability to provide real-time dynamic imaging of the pylorus. It offers no diagnostic advantage over ultrasound for this condition and involves unnecessary risks. *Incorrect: MRI* **MRI** provides excellent soft tissue contrast but is not the initial imaging choice for pyloric stenosis because it is more time-consuming, expensive, and often requires **sedation** in infants. The logistical challenges and lack of additional diagnostic benefit compared to ultrasound make it impractical as a first-line investigation.
Question 226: In which fetal anomalies are the 'banana sign' and 'lemon sign' observed?
- A. Neural tube defects (Correct Answer)
- B. Hydrops fetalis
- C. Multiple gestation
- D. Intrauterine death
Explanation: ***Neural tube defects*** - The **'banana sign'** describes the cerebellum appearing flattened and curved around the brainstem due to **posterior fossa effacement** in **Chiari II malformation**. - The **'lemon sign'** refers to the frontal bones of the fetal skull appearing indented, creating a **lemon-like shape**, also often associated with **Chiari II malformation**. *Hydrops fetalis* - This condition involves **excess fluid accumulation** in two or more fetal compartments (e.g., ascites, pleural effusion, skin edema) and is not characterized by the described cranial deformities. - It is often caused by various underlying conditions such as **anemia**, **chromosomal abnormalities**, or **infections**, but not primarily by changes in skull shape. *Multiple gestation* - Refers to the presence of **more than one fetus** in the uterus and is not directly associated with specific cranial ultrasound signs like the banana or lemon sign. - While anomalies can occur in multiple gestations, these signs are specific to certain brain abnormalities. *Intrauterine death* - The primary ultrasound findings for intrauterine death include the **absence of fetal heart activity**, as well as other signs such as **scalp edema**, **overlapping skull bones (Spalding sign)**, and fetal maceration. - It does not present with the characteristic banana and lemon signs, which indicate structural brain malformations.
Question 227: What is the sonographic appearance of a hydatid cyst?
- A. Hypoechoic lesion without septations
- B. Hyperechoic lesion with septations
- C. Hypoechoic lesion with septations (Correct Answer)
- D. Hyperechoic lesion without septations
Explanation: ***Hypoechoic lesion with septations*** - Hydatid cysts typically appear as **hypoechoic or anechoic lesions** on ultrasound, meaning they are fluid-filled and transmit sound well. - The presence of **septations** (daughter cysts or internal membranes) is a classic sonographic feature, often described as a "water lily sign" or "rosette sign." *Hypoechoic lesion without septations* - While hydatid cysts are usually **hypoechoic**, the absence of **septations** would be atypical, especially in a mature cyst. - A simple fluid-filled cyst without septations would be more indicative of other conditions, such as a **simple liver cyst**. *Hyperechoic lesion with septations* - A **hyperechoic lesion** indicates a solid or calcified structure that reflects sound strongly, which is not characteristic of the fluid-filled nature of a hydatid cyst. - While septations can be present, the overall echogenicity would rule out a typical hydatid cyst. *Hyperechoic lesion without septations* - This description suggests a **solid mass** or **calcified lesion** that strongly reflects ultrasound waves, which is inconsistent with the fluid-filled characteristic of a hydatid cyst. - The absence of septations further differentiates it from the typical appearance of a hydatid cyst.
Question 228: Which of the following is a soft tissue marker of Down syndrome on USG?
- A. Absent nasal bone
- B. Exomphalos
- C. Increased NT (Correct Answer)
- D. Normal fetal anatomy
Explanation: ***Increased NT*** - An **increased nuchal translucency (NT)** thickness, measured via ultrasound between 11 and 14 weeks of gestation, is a well-established **soft tissue marker** for **Down syndrome**. - NT represents **fluid accumulation in the subcutaneous tissue** at the nape of the fetal neck and is associated with a higher risk of chromosomal abnormalities, including **trisomy 21**. - As a true soft tissue finding (fluid in soft tissue), increased NT is one of the most important first-trimester screening markers. *Absent nasal bone* - An **absent or hypoplastic nasal bone** is an important marker for **Down syndrome**, but it is classified as a **skeletal/osseous marker**, NOT a soft tissue marker. - The nasal bone is a **bony structure**, and its assessment involves evaluation of ossification, not soft tissue or fluid characteristics. - While highly significant for Down syndrome screening, it does not fit the definition of a soft tissue marker as asked in the question. *Exomphalos* - **Exomphalos** (omphalocele) is an abdominal wall defect where abdominal organs protrude into the base of the umbilical cord, covered by a membrane. - While it can be associated with chromosomal abnormalities, including **Down syndrome**, it is classified as a **major structural anomaly** rather than a soft tissue marker. - Soft tissue markers are subtle findings used in aneuploidy screening, whereas exomphalos is a significant structural defect. *Normal fetal anatomy* - **Normal fetal anatomy** is not a marker but rather the absence of abnormal findings. - If all fetal anatomy appears normal, the likelihood of Down syndrome is reduced, but it does not completely rule out the condition as some affected fetuses may have no obvious ultrasound abnormalities.
Question 229: Which piezoelectric crystal is most widely used in ultrasonography probes?
- A. Lead zirconate titanate (Correct Answer)
- B. Quartz
- C. Molybdenum
- D. Titanium
Explanation: ***Lead zirconate titanate*** - **Lead zirconate titanate (PZT)** is the most widely used choice due to its superior **piezoelectric properties**, allowing efficient conversion of electrical energy into mechanical vibrations and vice versa. - It offers a good balance of **sensitivity**, **bandwidth**, and **coupling coefficient**, making it ideal for generating and detecting ultrasound waves in medical imaging. *Quartz* - While quartz exhibits **piezoelectric properties**, its electromechanical coupling coefficient is relatively low compared to PZT. - Its use is more common in **high-frequency applications** like crystal oscillators rather than medical ultrasound transducers, which require efficient energy conversion. *Molybdenum* - **Molybdenum** is a metal known for its strength and high melting point, but it does not possess **piezoelectric properties**. - It is often used in **X-ray tube anodes** and other high-temperature applications, not in ultrasonic transducers. *Titanium* - **Titanium** is a strong, corrosion-resistant metal commonly used in medical implants and aerospace applications due to its biocompatibility. - It is not a **piezoelectric material** and therefore cannot be used to generate or detect ultrasound waves in the same way as PZT.
Question 230: Mercedes Benz sign is seen in:
- A. Foreign body in bronchus
- B. Gallstone (Correct Answer)
- C. Bladder stone
- D. Renal stones
Explanation: ***Correct Option: Gallstone*** The **Mercedes Benz sign** is a classic radiologic finding specifically associated with **gallstones**, particularly cholesterol stones. - Appears as a **triradiate or stellate lucency** within the gallstone on plain radiographs, CT scans, or ultrasound - Named for its resemblance to the **Mercedes-Benz three-pointed star logo** - Caused by **nitrogen gas trapped within fissures or clefts** in the stone - Highly specific for gallstones when present *Incorrect Option: Bladder stone* - Bladder stones are calcifications in the **urinary bladder**, typically associated with urinary stasis, infection, or outlet obstruction - Appear as calcifications on imaging but **do not exhibit the Mercedes Benz sign** - This sign is unique to gallstones *Incorrect Option: Renal stones* - Renal stones (kidney stones) are found in the **kidneys or ureters** and are composed of various salts (calcium oxalate, uric acid, struvite, etc.) - Visible on imaging as calcifications or filling defects, but **do not show the Mercedes Benz sign** - This characteristic appearance is specific to certain types of gallstones *Incorrect Option: Foreign body in bronchus* - A foreign body in the bronchus presents as an **opaque or radiolucent object within the airway** on chest imaging - May cause complications like atelectasis, air trapping, or pneumonia - **No association** with the Mercedes Benz sign, which is specific to gallstones
Practice by Chapter
Physics of Ultrasound
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Instrumentation and Techniques
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Abdominal Ultrasonography
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Pelvic Ultrasonography
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Obstetric Ultrasonography
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Small Parts Ultrasonography
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Musculoskeletal Ultrasonography
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Vascular Ultrasonography
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Pediatric Ultrasonography
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Contrast-Enhanced Ultrasound
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Ultrasound-Guided Interventions
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Doppler Ultrasound Principles and Applications
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