Radiological Anatomy — MCQs

Radiological Anatomy Indian Medical PG Practice Questions and MCQs

Question 211: To visualize vascular sling causing tracheal or external airway compression, which of the following would you best prefer?

A. MRI
B. CT (Correct Answer)
C. Catheter angiography of aorta and pulmonary artery
D. PET-CT

Explanation: ***Correct: CT (CT Angiography)*** - **CT angiography is the gold standard** for diagnosing vascular rings and slings causing airway compression - Provides **excellent spatial resolution** with multiplanar and 3D reconstruction capabilities to clearly demonstrate the anatomical relationship between anomalous vessels and the trachea/bronchi - **Fast acquisition time** minimizes motion artifacts, particularly important in pediatric patients who are the typical population affected by vascular slings - Superior for **surgical planning** due to detailed visualization of vascular anatomy and the exact site and degree of airway compression - More readily available and cost-effective compared to MRI for this specific indication *Incorrect: MRI* - While MRI provides excellent soft tissue contrast and avoids ionizing radiation, it has **longer acquisition times** leading to increased risk of motion artifacts, especially in children - Lower spatial resolution compared to CT for vascular structures - May be used as a **complementary modality** when radiation avoidance is critical or for follow-up imaging, but not the first-line preferred modality *Incorrect: Catheter angiography of aorta and pulmonary artery* - **Invasive procedure** with associated risks including vascular injury, bleeding, and contrast reactions - Provides excellent vascular detail but **no information about airway compression** or surrounding soft tissue structures - Reserved for cases requiring **intervention** (embolization, stent placement) or when non-invasive imaging is inconclusive - Has been largely replaced by non-invasive CTA for diagnostic purposes *Incorrect: PET-CT* - Primarily assesses **metabolic activity**, used for oncology staging, infection, and inflammatory conditions - **Not indicated** for structural vascular anomalies or their anatomical relationships to airways - Does not provide the necessary vascular or airway detail for evaluating vascular slings

Question 212: Which of the following can be detected radiographically?

A. Interproximal caries (Correct Answer)
B. Root caries
C. Deep caries
D. None of the options

Explanation: ***Interproximal caries*** - Radiography, particularly **bitewing radiographs**, is the **gold standard** for detecting interproximal caries that cannot be visualized clinically - Interproximal caries appears as a **radiolucent (dark) area** in the enamel and/or dentin between adjacent teeth - Radiographs can detect caries **before clinical examination** reveals cavitation, allowing for early intervention - The demineralization process reduces tissue density, making it appear darker on radiographs compared to healthy tooth structure *Root caries* - Root caries CAN be detected radiographically, appearing as **saucer-shaped radiolucencies** at the cervical region - However, root caries may be **easier to detect clinically** than interproximal caries since root surfaces are more accessible to direct visualization - Radiographic detection is still valuable, especially for subgingival root caries *Deep caries* - Deep caries CAN be detected radiographically as **extensive radiolucent areas** extending deep into dentin - However, the term "deep caries" refers to the **extent** rather than location, and can often be detected clinically - Radiographs help assess the **proximity to the pulp** and extent of involvement **Key Point:** While all three types of caries can be detected radiographically, **interproximal caries** is the type most dependent on radiographic detection since these areas cannot be directly visualized clinically between tooth contacts.

Question 213: The 'steeple sign' on X-ray neck (as shown in the image) is characteristically seen in which of the following diseases?

A. Epiglottitis
B. Croup (Correct Answer)
C. Laryngomalacia
D. Bronchiolitis

Explanation: ***Croup*** - The image suggests a **steeple sign** on the X-ray neck, which corresponds to the subglottic narrowing characteristic of croup. - Croup, primarily caused by **parainfluenza virus**, leads to inflammation and edema below the vocal cords reducing the airway. *Epiglottitis* - Epiglottitis is characterized by a **"thumb sign"** on lateral neck X-ray, indicating a swollen epiglottis. - Patients with epiglottitis typically present with rapidly progressing airway obstruction, high fever, and drooling, unlike the gradual onset and barking cough of croup. *Laryngomalacia* - Laryngomalacia involves the **collapse of supraglottic structures** during inspiration, causing inspiratory stridor. - It would not typically present with the subglottic narrowing seen in the image, but rather with dynamic airway changes visualized during endoscopy. *Bronchiolitis* - Bronchiolitis involves inflammation of the **small airways (bronchioles)** and is usually diagnosed clinically, with chest X-rays showing hyperinflation or peribronchial cuffing if at all. - It primarily affects the lower respiratory tract and would not produce findings like the steeple sign on a neck X-ray.

Question 214: The right border of the heart in a chest X-ray is formed by which of the following?

A. Right ventricle
B. Pulmonary artery
C. Right atrium (Correct Answer)
D. Superior vena cava

Explanation: ***Right atrium*** - The **right atrium** forms the major portion of the heart's **right cardiac border** on a standard posteroanterior (PA) chest X-ray. - Its position allows it to be the most lateral structure on the right side of the heart silhouette. *Right ventricle* - The **right ventricle** primarily forms the **anterior surface** of the heart. - While it contributes to the anterior cardiac outline, it rarely forms the right border on a PA chest X-ray unless there is significant enlargement. *Pulmonary artery* - The **pulmonary artery** typically forms the **left upper cardiac border** in the region below the aortic knob. - It does not contribute to the right border of the heart. *Superior vena cava* - The **superior vena cava (SVC)** lies superior and medial to the right atrium. - It forms part of the **right superior mediastinal border**, but not the actual right border of the heart itself.

Question 215: The 'water lily sign' is characteristic of which condition?

A. Hydatid cyst of lung (Correct Answer)
B. Aspergilloma lung
C. Tuberculosis
D. Silicosis

Explanation: ***Hydatid cyst of lung*** - The **'water lily sign'** in an **echinococcal cyst** (hydatid cyst) occurs when the **endocyst** ruptures and collapses, detaching from the pericyst. - This detached membrane floats within the cyst fluid, creating a characteristic appearance on imaging that resembles a water lily. *Aspergilloma lung* - An **aspergilloma (fungus ball)** is typically seen as a mobile mass within a pre-existing cavitary lesion, often associated with a **crescentic lucency (air crescent sign)**. - It does not present with the specific appearance of floating membranes seen in the 'water lily sign'. *Tuberculosis* - **Tuberculosis (TB)** in the lung can cause various imaging findings, including **cavitation**, consolidation, and nodules. - However, it does not typically produce the 'water lily sign', which is specific to parasitic cysts. *Silicosis* - **Silicosis** is a pneumoconiosis characterized by **multiple small nodules** in the upper lung fields and can lead to **progressive massive fibrosis**. - Its imaging findings are distinct and do not include the 'water lily sign'.

Question 216: The "raindrop skull" appearance is associated with which of the following conditions?

A. Hemophilia
B. Thalassemia
C. Hodgkin's lymphoma
D. Multiple Myeloma (Correct Answer)

Explanation: ***Multiple Myeloma*** - The **\"raindrop skull\"** appearance on X-ray is characteristic of multiple myeloma, resulting from numerous small, **punched-out lytic lesions** in the skull. - These lytic lesions are caused by the proliferation of **plasma cells** in the bone marrow, leading to localized bone destruction. *Hemophilia* - Hemophilia is a **bleeding disorder** caused by a deficiency in clotting factors and does not directly cause lytic bone lesions or a raindrop skull appearance. - While it can lead to **hemarthrosis** and other bleeding-related bone changes, these are distinct from the lytic lesions seen in myeloma. *Thalassemia* - Thalassemia is a **genetic blood disorder** characterized by abnormal hemoglobin production, leading to **anemia**. - Severe thalassemia can cause bone changes (e.g., **\"hair-on-end\" skull** due to marrow hyperplasia), but not the discrete lytic lesions of a raindrop skull. *Hodgkin's lymphoma* - Hodgkin's lymphoma is a **lymphatic system cancer** that can cause bone lesions, but these are typically **sclerotic** or mixed lytic/sclerotic, not the purely lytic, punched-out lesions characteristic of a raindrop skull. - Bone involvement in Hodgkin's is less common than in non-Hodgkin's lymphoma and usually presents differently.

Question 217: Which among the following has the least HU units?

A. Air (Correct Answer)
B. Acute hemorrhage
C. Iodinated contrast agents
D. Subcutaneous fat

Explanation: ***Air*** - **Air** has an HU value of **-1000**, which is the lowest possible value on the Hounsfield scale. - This low attenuation is due to the very low density of air, allowing almost all X-rays to pass through without significant interaction. *Acute hemorrhage* - **Acute hemorrhage** appears *hyperdense* on CT, with HU values typically ranging from **+40 to +90**. - This higher density is due to the protein content of blood and the hemoglobin within red blood cells. *Iodinated contrast agents* - **Iodinated contrast agents** are designed to significantly increase the attenuation of X-rays, leading to very high HU values, often in the range of **+100 to +300** or more, depending on concentration and location. - The high atomic number of iodine atoms results in strong X-ray absorption. *Subcutaneous fat* - **Subcutaneous fat** has HU values generally in the range of **-50 to -150**. - While lower than most soft tissues and acute hemorrhage, these values are still significantly higher than that of air.

Question 218: Apex of the lung is best assessed by

A. AP view
B. PA view
C. Lordotic view (Correct Answer)
D. Oblique view

Explanation: ***Lordotic view*** - The **lordotic view** is a specialized chest X-ray projection specifically designed to visualize the **lung apices** clearly by projecting the clavicles superiorly. - This view is achieved by leaning the patient backward (lordotic position) while the X-ray beam is angled, or by angling the X-ray tube itself superiorly. *AP view* - The **AP (Anteroposterior) view** often projects the **clavicles over the lung apices**, obscuring them and making thorough assessment difficult. - This general chest X-ray view is primarily used when the patient cannot stand or sits upright for a PA view. *PA view* - Similar to the AP view, the standard **PA (Posteroanterior) view** can also have the **clavicles superimpose the lung apices**, making subtle apical pathology hard to detect. - While a routine chest X-ray, it's not optimal for detailed evaluation of the uppermost lung regions. *Oblique view* - **Oblique views** are primarily used to separate superimposed structures or to better visualize specific areas that are obscured in standard AP or PA views, but they are not the best for the apices. - They are often employed to assess the pleura, hilum, or specific lung segments by rotating the patient.

Question 219: String of beads sign is seen in:

A. Gastroduodenal TB
B. Genital TB (Correct Answer)
C. Spinal tuberculosis
D. Ileocaecal TB

Explanation: ***Genital TB*** - The "string of beads sign" in **genital tuberculosis** refers to the characteristic appearance of multiple small, nodular lesions along the **fallopian tube** on **hysterosalpingography (HSG)**. - This results from **alternating areas of stricture and dilatation** due to chronic **tuberculous salpingitis** with granulomatous inflammation. - Among tuberculosis manifestations, this sign is specifically associated with female genital TB. - **Note:** The "string of beads" sign is also classically seen in **fibromuscular dysplasia of renal arteries**, but in the context of tuberculosis, it refers to genital TB. *Gastroduodenal TB* - Gastroduodenal TB typically manifests as ulcers, strictures, or mass lesions in the stomach or duodenum. - The "string of beads sign" is not a characteristic finding for tuberculosis in this location. *Spinal tuberculosis* - Spinal tuberculosis (Pott's disease) primarily affects the vertebrae, leading to vertebral collapse, kyphosis, and paraspinal abscesses. - Imaging shows vertebral destruction, disc space narrowing, and paravertebral soft tissue shadows. - The "string of beads sign" is not associated with spinal TB. *Ileocaecal TB* - Ileocaecal TB commonly presents with bowel wall thickening, ulcerations, strictures, and lymphadenopathy. - While strictures can occur, the specific "string of beads sign" is not a recognized feature of ileocaecal TB.

Question 220: Which structure is not visualized in a standard occipitomental (Water's) view?

A. Posterior ethmoid air cells (Correct Answer)
B. Sphenoid sinus
C. Maxillary sinus
D. Anterior ethmoid air cells

Explanation: ***Posterior ethmoid air cells*** - The **occipitomental (Water's) view** is designed to visualize the maxillary sinuses, frontal sinuses, and anterior ethmoid cells. - The **posterior ethmoid air cells** are consistently **not well-visualized** in this view due to their posterior location deep within the skull base and significant superimposition of overlying bony structures. - A **lateral skull view or CT scan** is required for proper evaluation of the posterior ethmoid cells. *Sphenoid sinus* - While the **sphenoid sinus** is also poorly visualized in a standard Water's view, portions of its anterior wall may sometimes be seen on well-positioned films. - However, it is generally considered inadequately assessed on Water's view and requires **lateral skull radiographs or CT** for proper evaluation. - Of the structures listed, the posterior ethmoid cells are the **least visualized** on this view. *Maxillary sinus* - The **maxillary sinuses** are the **primary target** of the Water's view, appearing as large radiolucent areas in the infraorbital region. - This view is excellent for detecting **fluid levels, mucosal thickening, or fractures** of the maxillary sinus. *Anterior ethmoid air cells* - The **anterior ethmoid air cells** are typically **well-visualized** in the Water's view, appearing medial to the medial orbital wall. - These cells can be assessed for opacification, mucosal disease, or orbital complications.

Practice by Chapter

Radiographic Anatomy of Skull and Face

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Radiographic Anatomy of Spine

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Radiographic Anatomy of Chest

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Radiographic Anatomy of Abdomen

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Radiographic Anatomy of Extremities

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Cross-sectional Anatomy: Brain and Head

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Cross-sectional Anatomy: Neck

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Cross-sectional Anatomy: Thorax

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Cross-sectional Anatomy: Abdomen and Pelvis

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Vascular Anatomy

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Developmental Anatomy Variations

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Anatomic Landmarks for Interventional Procedures

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