Ultrasound — MCQs

Ultrasound Indian Medical PG Practice Questions and MCQs

Question 181: Best method to diagnose hydrocephalus in a fetus at 24 weeks gestation is:

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

Explanation: ***Ultrasound*** - **Fetal ultrasound** is the primary and most effective imaging modality for diagnosing hydrocephalus in a 6-month-old fetus due to its **safety**, accessibility, and ability to visualize the developing brain. - It allows for the measurement of **ventricular size** and observation of characteristic features of hydrocephalus, such as **ventriculomegaly** and **dangling choroid plexus**. *X-ray* - **X-rays** use ionizing radiation, which is generally avoided in pregnant women due to potential risks to the developing fetus. - They provide limited detail of **soft tissues** like the brain and would not be effective in diagnosing hydrocephalus. *CT scan* - **CT scans** also involve significant **radiation exposure**, posing risks to the fetus and limiting their use in prenatal diagnosis. - While capable of visualizing brain structures, the benefits do not outweigh the **radiation risk** when safer and equally effective alternatives like ultrasound are available. *MRI* - **Fetal MRI** can provide detailed imaging of the fetal brain but is typically reserved for **further characterization** of anomalies identified by ultrasound or when ultrasound findings are inconclusive. - It is more expensive and less readily available than ultrasound, making it a **secondary imaging tool** rather than the primary diagnostic method for initial screening.

Question 182: A 40-year-old female was sent to the Radiology department for thyroid USG scan. Which probe will you use for thyroid scan?

A. Linear (Correct Answer)
B. Curvilinear
C. Endocavitary
D. Phase array

Explanation: ***Linear*** - A **linear probe** is ideal for scanning superficial structures like the thyroid gland due to its high-frequency transducers, which provide excellent **spatial resolution** for structures close to the skin surface. - This probe type yields a **rectangular field of view**, allowing for detailed imaging of the thyroid's fine anatomy and any subtle nodules or abnormalities. *Curvilinear* - A **curvilinear probe** uses a lower frequency, which offers better **penetration depth** but at the cost of spatial resolution, making it suitable for deeper abdominal or pelvic organs. - Its **curved footprint** produces a wider, sector-shaped field of view, which is less optimal for the detailed assessment of a superficial organ like the thyroid. *Endocavitary* - An **endocavitary probe** is specifically designed for intracavitary examinations, such as transvaginal or transrectal ultrasound, providing high-resolution images of internal structures not accessible externally. - Its specialized shape and frequency are entirely unsuitable for surface scanning of the thyroid gland. *Phase array* - A **phase array probe** is characterized by a small footprint and the ability to electronically steer the ultrasound beam, making it ideal for cardiac imaging or transcranial doppler studies where a small acoustic window is present. - While it can achieve good depth penetration, its primary application and image quality profile are not optimized for superficial, high-resolution imaging of organs like the thyroid.

Question 183: Pulsatile Doppler signal (continuous flow) in the hepatic vein in the setting of Budd-Chiari syndrome indicates:

A. Congenital web in IVC
B. Renal vein thrombosis
C. Portal vein thrombosis
D. Partial IVC obstruction (Correct Answer)

Explanation: ***Partial IVC obstruction*** - A **pulsatile Doppler signal** (continuous flow) in the **hepatic vein** in the context of Budd-Chiari syndrome suggests **partial impedance** to hepatic venous outflow, often due to a **partial obstruction of the IVC**. - This pattern indicates that the normal triphasic flow in the hepatic veins, which is influenced by right atrial pressure, is maintained but with some degree of *dampening* or *modification* due to the obstruction. *Congenital web in IVC* - A **congenital web** in the IVC, while a cause of Budd-Chiari, would typically cause a more **complete obstruction** of hepatic venous outflow. - This would result in a **monophasic** or **absent flow** in the hepatic veins, rather than a pulsatile continuous pattern. *Renal vein thrombosis* - **Renal vein thrombosis** primarily affects the renal veins and would not directly cause a **pulsatile continuous flow** in the hepatic veins. - While it can be associated with hypercoagulable states that also lead to Budd-Chiari, it's not the direct cause of this specific hepatic vein Doppler finding. *Portal vein thrombosis* - **Portal vein thrombosis** affects inflow to the liver, leading to **portal hypertension**, but it does not directly impact the outflow dynamics of the hepatic veins in a way that would cause a **pulsatile continuous flow**. - Hepatic vein flow patterns are primarily determined by pressures within the **right atrium** and **hepatic venous outflow**.

Question 184: Precise FNAC can be obtained by using:

A. CT
B. MRI
C. Endoscopic USG
D. USG (Correct Answer)

Explanation: ***USG*** - **Ultrasound (USG)** guidance is the **most commonly used** modality for **fine needle aspiration cytology (FNAC)** due to its real-time imaging capabilities, allowing the operator to visualize the needle tip entering the lesion. - It is particularly useful for superficial lesions or those with a clear acoustic window, offering good **spatial resolution**, wide availability, no radiation exposure, and accessibility for most body regions. - USG provides excellent precision for routine FNAC procedures across various clinical settings. *CT* - **Computed tomography (CT)** provides excellent anatomical detail and is useful for guiding FNAC in deeper or more complex lesions within the body cavity (e.g., lungs, retroperitoneum). - However, it involves **ionizing radiation** and, unlike USG, does not offer real-time visualization of the needle path, requiring intermittent scanning. *MRI* - **Magnetic resonance imaging (MRI)** offers superior soft tissue contrast and is excellent for visualizing certain lesions, but it is less commonly used for routine FNAC guidance. - The high cost, long scan times, and challenges with MRI-compatible needles make it less practical for real-time guidance compared to USG or CT. *Endoscopic USG* - **Endoscopic ultrasound (EUS)** is highly effective for precise FNAC of lesions adjacent to the gastrointestinal tract (e.g., pancreas, mediastinum, submucosal lymph nodes) as it provides high-resolution imaging from within. - While very precise for its specific indications, it is an invasive procedure requiring endoscopy and is not suitable for all body regions like routine superficial or transthoracic biopsies where the question is generally referring to.

Question 185: An ultrasound examination shows dilated intrahepatic biliary channels with a small gallbladder. The most likely possibility is

A. Carcinoma of the head of the pancreas
B. Pancreatic calculus
C. Gallbladder stones
D. Common bile duct stone (Correct Answer)

Explanation: ***Common bile duct stone*** - A **common bile duct (CBD) stone** obstructing flow can cause **intrahepatic biliary dilation** as bile backs up into the liver. - A **small, non-distended gallbladder** suggests that the obstruction is distal to the cystic duct, preventing bile entry into the gallbladder or causing it to contract in response to a partial obstruction. *Carcinoma of the head of the pancreas* - Pancreatic head carcinoma typically causes **Courvoisier's sign**, characterized by a **palpable, non-tender, distended gallbladder** due to chronic, progressive obstruction of the distal CBD. - While it causes intrahepatic ductal dilation, the gallbladder usually appears distended, not small. *Pancreatic calculus* - A pancreatic calculus typically causes **pancreatitis** or **pain**, and may lead to **dilation of the pancreatic duct**, not primarily the biliary tree. - Unless directly causing CBD obstruction, it would not explain dilated intrahepatic biliary channels with a small gallbladder. *Gallbladder stones* - **Gallbladder stones** typically cause **cholecystitis** or **biliary colic**, and if they obstruct the cystic duct, they can cause a **distended gallbladder**. - They do not typically cause widespread intrahepatic biliary dilation unless they migrate into the common bile duct and cause obstruction there.

Question 186: The intensity of colour in Doppler is determined by-

A. Strength of returning echo
B. Velocity of flow (Correct Answer)
C. Direction of flow
D. None of the options

Explanation: ***Velocity of flow*** - The **intensity of color** in Doppler ultrasound is directly related to the **velocity of blood flow**; faster flow typically results in a brighter or more intense color display. - This is because the Doppler shift, which the ultrasound system uses to calculate velocity and assign color, is proportional to the speed of the moving blood cells. *Strength of returning echo* - The **strength of the returning echo** (amplitude) primarily determines the **brightness** of the B-mode image (grayscale), not the intensity of the color Doppler signal. - It relates to the density and acoustic properties of the tissue or blood, not its motion. *Direction flow* - The **direction of flow** relative to the ultrasound beam determines the **hue** of the color displayed (e.g., red for flow towards the transducer, blue for flow away). - It does not influence the intensity or brightness of that color.

Question 187: Which of the following liver metastases appear hypoechoic on ultrasound?

A. RCC
B. Colon cancer
C. Breast cancer (Correct Answer)
D. Mucinous adenocarcinoma

Explanation: **Breast cancer** - Liver metastases from **breast cancer** frequently present as **hypoechoic lesions** on ultrasound, due to the tumor's cellular composition and vascularity. - This appearance helps differentiate them from other more commonly echogenic or mixed metastatic patterns. *RCC* - **Renal cell carcinoma (RCC)** metastases to the liver often appear **hyperechoic** or **mixed echogenicity** on ultrasound due to their rich vascularity. - This is a distinct characteristic, different from the predominantly hypoechoic nature seen with breast cancer metastases. *Colon cancer* - Liver metastases from **colon cancer** are typically **echogenic** or **mixed echogenicity** on ultrasound, sometimes with a hypoechoic rim ("target sign"). - Their presentation is generally not purely hypoechoic, making them distinguishable from breast cancer metastases. *Mucinous adenocarcinoma* - Liver metastases from **mucinous adenocarcinoma** can be quite variable, but they often appear **complex**, possibly with **cystic components** or mixed echogenicity, rather than uniformly hypoechoic. - The mucin content can create a distinct internal architecture on ultrasound that differs from solid hypoechoic lesions.

Question 188: All correlates with USG findings of congenital pyloric stenosis except:

A. High gastric residues (Correct Answer)
B. Thickness >4mm
C. > 95% accuracy
D. Segment length >16mm

Explanation: ***High gastric residues*** - **High gastric residues** are a **clinical finding** in pyloric stenosis (due to impaired gastric emptying), NOT a direct **ultrasound measurement** of the pyloric muscle. - Ultrasound directly visualizes the **pyloric muscle dimensions and morphology**, not the volume of stomach contents. - While you may observe gastric contents on ultrasound, "high gastric residues" refers to the clinical assessment of retained stomach contents, typically assessed through aspiration or clinical examination. *Thickness >4mm* - A pyloric muscle wall **thickness greater than 4mm** is a **key diagnostic USG criterion** for congenital pyloric stenosis. - This measurement directly reflects the **hypertrophy** of the pyloric muscle visualized on ultrasound. *> 95% accuracy* - This refers to the **diagnostic accuracy of ultrasound** as the imaging modality for pyloric stenosis. - While this is a **test performance characteristic** rather than an anatomical finding, it describes how reliably USG **correlates with** the diagnosis of pyloric stenosis. - Ultrasound is the **imaging modality of choice** with very high sensitivity and specificity. *Segment length >16mm* - A pyloric channel **length greater than 16mm** is another **critical USG diagnostic criterion** for congenital pyloric stenosis. - This reflects the **elongation of the pyloric canal** due to muscle hypertrophy, directly measured on ultrasound.

Question 189: Which of the following is not assessed in FAST?

A. Sub-xiphoid area
B. Retroperitoneum (Correct Answer)
C. Left upper quadrant
D. Right upper quadrant

Explanation: ***Retroperitoneum*** - The **Focused Assessment with Sonography for Trauma (FAST)** is designed to rapidly detect free intraperitoneal fluid, not retroperitoneal pathology. - The **standard FAST exam** evaluates four key areas: the perihepatic space (right upper quadrant), perisplenic space (left upper quadrant), pelvic/suprapubic area, and pericardial space (subxiphoid view). - The **retroperitoneum** contains structures like the kidneys, pancreas, aorta, and IVC, but these are not routinely assessed in the standard FAST protocol, which focuses on detecting free fluid in dependent peritoneal and pericardial spaces. - Evaluation of retroperitoneal structures would require more detailed ultrasound examination beyond the scope of FAST. *Sub-xiphoid area* - This view assesses the **pericardial sac** for free fluid, which may indicate **cardiac tamponade**, a life-threatening condition in trauma patients. - It is a **standard component of FAST** and critical for detecting pericardial effusions. *Left upper quadrant* - This view examines the **perisplenic space** (between the spleen and diaphragm) and the **left paracolic gutter** for free fluid, suggesting splenic injury or intra-abdominal bleeding. - It is one of the **four standard FAST views** essential for trauma assessment. *Right upper quadrant* - This view assesses **Morrison's pouch** (hepatorenal recess) and the **right paracolic gutter**, which is the most sensitive area for detecting free intraperitoneal fluid. - It is typically the **first view obtained in FAST** and a crucial component of the examination.

Question 190: Ideal imaging method for diagnosis of hydrocephalus in infant is

A. X-Ray
B. MRI
C. CT Scan
D. USG (Correct Answer)

Explanation: ***USG*** - **Ultrasound (USG)** is the preferred initial imaging method for diagnosing hydrocephalus in infants due to their **open fontanelles**, which allow for excellent visualization of intracranial structures without radiation exposure. - It's **non-invasive**, portable, and can be performed at the bedside, making it ideal for critically ill or unstable infants. *X-Ray* - **X-rays** provide limited detail of soft tissues and are generally unable to directly visualize the ventricles or cerebrospinal fluid accumulation, making them unsuitable for diagnosing hydrocephalus. - While skull X-rays might show signs of increased intracranial pressure in chronic cases (e.g., **suture diastasis**), they are not a primary diagnostic tool for hydrocephalus. *MRI* - **MRI** offers superior soft tissue contrast and detailed anatomical information, making it excellent for characterizing hydrocephalus and its underlying causes in older children and adults. - However, it typically requires **sedation** in infants due to the need for prolonged immobility and is less readily available or rapid than ultrasound for initial diagnosis. *CT Scan* - **CT scans** provide good bony detail and can quickly identify ventricular enlargement, but they involve **ionizing radiation**, which is a significant concern in infants due to their radiosensitivity. - While useful in acute emergencies where rapid assessment is critical and USG is inconclusive, it's generally avoided as the first-line diagnostic tool for hydrocephalus in infants.

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Musculoskeletal Ultrasonography

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Ultrasound — MCQs

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