Chest Radiology — MCQs

Chest Radiology Indian Medical PG Practice Questions and MCQs

Question 161: What is the best investigation when there is clinical suspicion of pulmonary embolism?

A. D-Dimer Assay
B. Multidetector CT angiography (Correct Answer)
C. Doppler ultrasound
D. Catheter angiography

Explanation: **Explanation:** **Multidetector CT Angiography (MDCTA)** is currently the **gold standard and investigation of choice** for diagnosing pulmonary embolism (PE). Its high sensitivity and specificity allow for direct visualization of emboli within the pulmonary arteries down to the segmental and subsegmental levels. MDCTA is preferred because it is non-invasive, widely available, and can simultaneously evaluate alternative diagnoses (e.g., pneumonia, aortic dissection, or pneumothorax). **Why other options are incorrect:** * **D-Dimer Assay:** This is a screening tool with high negative predictive value. It is used to **rule out** PE in patients with low clinical probability (Wells’ Criteria), but it is not diagnostic because it can be elevated in various conditions like inflammation, pregnancy, or trauma. * **Doppler Ultrasound:** While useful for detecting Deep Vein Thrombosis (DVT) in the lower limbs (the source of most PEs), a negative scan does not exclude PE, as the clot may have already embolized. * **Catheter Angiography:** Historically the "gold standard," it is now rarely performed because it is invasive and carries higher risks. It is reserved for cases where catheter-directed thrombolysis is planned. **Clinical Pearls for NEET-PG:** * **Initial Investigation:** Chest X-ray (usually normal, but performed to rule out other causes). * **Classic CXR Signs:** Hampton’s Hump (wedge-shaped opacity) and Westermark sign (focal oligemia). * **ECG Finding:** Most common is sinus tachycardia; most specific is **S1Q3T3 pattern**. * **Pregnancy/Renal Failure:** Ventilation-Perfusion (V/Q) scan is often the preferred alternative when CT contrast is contraindicated.

Question 162: On barium swallow, which of the following causes a posterior impression?

A. Left atrium
B. Aortic knuckle
C. Pulmonary sling
D. Aberrant right subclavian artery (Correct Answer)

Explanation: **Explanation:** The correct answer is **Aberrant right subclavian artery (Arteria Lusoria)**. This is the most common congenital anomaly of the aortic arch. In this condition, the right subclavian artery arises as the last branch of the aortic arch (distal to the left subclavian) and crosses from left to right to reach the right arm. In 80% of cases, it passes **posterior to the esophagus**, creating a characteristic oblique indentation on the posterior wall during a barium swallow. Clinically, this can lead to "Dysphagia Lusoria." **Analysis of Incorrect Options:** * **Left Atrium:** Causes an **anterior** impression on the mid-to-lower esophagus when enlarged (Mitral Stenosis). * **Aortic Knuckle:** Causes a **left lateral** impression on the esophagus. * **Pulmonary Sling:** Occurs when the left pulmonary artery arises from the right pulmonary artery. It is the only vascular anomaly that passes **between the trachea and the esophagus**, causing an **anterior** impression on the esophagus and a posterior impression on the trachea. **High-Yield Clinical Pearls for NEET-PG:** * **Double Aortic Arch:** Causes a "vascular ring" that encircles both the trachea and esophagus, resulting in **bilateral and posterior** indentations. * **Right-sided Aortic Arch:** Causes a **right lateral** indentation. * **Key Distinction:** If a question mentions a posterior impression, think **Aberrant Right Subclavian** or **Double Aortic Arch**. If it mentions an impression *between* the trachea and esophagus, it is always a **Pulmonary Sling**.

Question 163: Unilateral hyperlucent hemithorax on chest X-ray is seen in which condition?

A. Bronchial asthma
B. Fallot's tetralogy
C. Pulmonary hypertension
D. Poliomyelitis (Correct Answer)

Explanation: **Explanation:** A **unilateral hyperlucent hemithorax** occurs when one side of the chest appears darker (more lucent) than the other on a radiograph. This is caused by either increased air (pneumothorax/emphysema), decreased blood flow (oligemia), or a **deficiency of the chest wall soft tissues**. **Why Poliomyelitis is correct:** Poliomyelitis can lead to asymmetric paralysis and profound **atrophy of the pectoralis major muscle** and other thoracic musculature. Since there is less soft tissue to attenuate the X-ray beams on the affected side, the underlying lung appears hyperlucent despite the lung parenchyma being normal. This is a "false" hyperlucency similar to what is seen in **Mastectomy** or **Poland Syndrome**. **Analysis of Incorrect Options:** * **Bronchial Asthma:** Typically presents with **bilateral** hyperinflation and increased lucency due to diffuse air trapping. Unilateral presentation is rare unless there is a localized foreign body. * **Fallot’s Tetralogy (TOF):** Characteristically shows a "boot-shaped heart" (coeur en sabot). While there is pulmonary oligemia, it is usually **bilateral** and symmetric. * **Pulmonary Hypertension:** Leads to enlargement of central pulmonary arteries with "peripheral pruning," but this vascular change is typically **bilateral**. **NEET-PG High-Yield Pearls:** * **Mnemonic for Unilateral Hyperlucent Hemithorax:** "M-C-P" (Mastectomy, Congenital absence of pectoralis/Poland Syndrome, Poliomyelitis). * **Swyer-James-MacLeod Syndrome:** A key differential involving unilateral hyperlucency due to post-infectious obliterative bronchiolitis (small lung with pruning of vessels). * **Technical Tip:** Always check for patient rotation; rotation can cause a false appearance of unilateral hyperlucency. * **Clinical Correlation:** If the lucency is due to chest wall issues (like Polio), the lung markings (vascularity) will still be visible and normal.

Question 164: A 44-year-old man presents with dyspnea, cough, and mild pyrexia. Which lobe of the lung is most likely involved?

A. Right upper lobe
B. Right middle lobe (Correct Answer)
C. Left lower lobe
D. Left upper lobe

Explanation: ***Right middle lobe*** - The **right middle lobe** is most commonly affected in pneumonia presenting with dyspnea, cough, and pyrexia, often showing **silhouette sign** with obliteration of the **right heart border** on chest X-ray. - On **lateral chest X-ray**, right middle lobe consolidation appears as opacity in the **anterior-inferior portion** of the thorax, helping differentiate from other lobes. *Right upper lobe* - Right upper lobe pneumonia typically shows consolidation **above the horizontal fissure** and would obliterate the **right paratracheal stripe**, not the heart border. - On lateral view, opacity would be located in the **anterior-superior** portion, distinctly different from middle lobe involvement. *Left lower lobe* - Left lower lobe consolidation would obliterate the **left hemidiaphragm** and **descending aorta** silhouette, not affecting the right heart border. - Symptoms would be similar, but radiological findings show **retrocardiac opacity** on PA view and **posterior-inferior** opacity on lateral view. *Left upper lobe* - Left upper lobe pneumonia would cause loss of the **left heart border** and **aortic knob** silhouette, with opacity in the **upper left thorax**. - On lateral chest X-ray, consolidation appears in the **anterior-superior** region, similar to right upper lobe but on the opposite side.

Question 165: Which of the following is FALSE about Kerley's A lines?

A. Lines are 2-6 cm in length
B. These are found in mid and upper zones
C. These are due to thickened interlobar septa
D. Transverse lines at the lung base perpendicular to the pleura (Correct Answer)

Explanation: ### Explanation This question tests the ability to differentiate between the various types of Kerley lines, which are radiological signs of pulmonary edema and interstitial lung disease. **Why Option D is the Correct (False) Statement:** Option D describes **Kerley B lines**, not Kerley A lines. Kerley B lines are short (1–2 cm), thin, horizontal lines located at the lung bases, perpendicular to the pleural surface. They represent thickened interlobular septa. In contrast, **Kerley A lines** are longer, radiate from the hila, and are found in the upper and mid-zones. **Analysis of Other Options:** * **Option A (2-6 cm in length):** This is **True**. Kerley A lines are significantly longer than Kerley B lines, typically measuring between 2 and 6 cm. * **Option B (Found in mid and upper zones):** This is **True**. Kerley A lines represent distended anastomotic channels between peripheral and central lymphatics and are characteristically seen radiating from the hila into the upper and middle lung fields. * **Option C (Due to thickened interlobar septa):** This is **True**. Both Kerley A and B lines are caused by the thickening of the pulmonary interstitium/septa due to fluid (edema), cellular infiltration, or fibrosis. **High-Yield NEET-PG Pearls:** * **Kerley A:** **A**way from the periphery (Central/Hilar), **A**bove (Upper zones), and longer. * **Kerley B:** **B**ase of the lung, **B**order (Peripheral/Pleural), and short. * **Kerley C:** Fine, reticular "spider-web" appearance over the entire lung (represents Kerley B lines seen end-on). * **Most Common Cause:** Congestive Heart Failure (Left-sided). * **Differential Diagnosis:** Mitral stenosis, Lymphangitic carcinomatosis, and Sarcoidosis.

Question 166: A 75-year-old lady with severe chronic obstructive pulmonary disease (COPD) presents with acute breathlessness. The chest X-ray shows no focal consolidation. She is afebrile, but D-dimers are markedly elevated. Which of the following is the best investigation to diagnose this condition?

A. MRI
B. Ventilation-perfusion (V/Q) scan
C. High-resolution CT thorax
D. CT pulmonary angiography (Correct Answer)

Explanation: **Explanation:** The clinical presentation of acute breathlessness, a clear chest X-ray (no consolidation), and markedly elevated D-dimers in an elderly patient strongly suggests **Acute Pulmonary Embolism (PE)**. **1. Why CT Pulmonary Angiography (CTPA) is the Correct Answer:** CTPA is currently the **gold standard and investigation of choice** for diagnosing pulmonary embolism. It allows direct visualization of emboli as filling defects within the pulmonary arteries. In this patient, the absence of focal consolidation on X-ray helps rule out pneumonia, making a vascular event more likely. CTPA is preferred due to its high sensitivity, specificity, and ability to provide alternative diagnoses if PE is absent. **2. Why Other Options are Incorrect:** * **MRI (A):** While it can detect PE, it is not the first-line investigation due to long acquisition times, lower resolution for peripheral vessels, and difficulty in monitoring unstable patients. * **Ventilation-Perfusion (V/Q) Scan (B):** Although used when CTPA is contraindicated (e.g., renal failure), it is **unreliable in COPD patients**. Underlying lung disease causes pre-existing ventilation defects, leading to "indeterminate" or "non-diagnostic" results. * **High-Resolution CT (HRCT) Thorax (C):** HRCT is used to evaluate interstitial lung disease and parenchyma (e.g., bronchiectasis, fibrosis). It is not designed to evaluate the pulmonary vasculature for clots. **Clinical Pearls for NEET-PG:** * **Gold Standard for PE:** CT Pulmonary Angiography. * **Best Initial Test for PE:** Chest X-ray (usually normal; done to rule out other causes). * **Westermark Sign:** Focal oligemia (hyperlucency) distal to an embolus on CXR. * **Hampton’s Hump:** Wedge-shaped opacity representing pulmonary infarction. * **Investigation of choice in Pregnancy/Renal Failure:** V/Q scan or Doppler Ultrasound of leg veins (to avoid radiation/contrast).

Question 167: The 'tree in bud' sign on HRCT is suggestive of which condition?

A. Sarcoidosis
B. Miliary tuberculosis
C. Endobronchial spread in tuberculosis (Correct Answer)
D. All the above

Explanation: ### Explanation The **'Tree-in-bud' appearance** on High-Resolution Computed Tomography (HRCT) represents an **impaction of the small airways** (bronchioles) with mucus, pus, or fluid, combined with peribronchial inflammation. This creates a pattern resembling a budding tree: the "stalk" is the fluid-filled terminal bronchiole, and the "buds" are the opacified centrilobular nodules. #### Why Option C is Correct: * **Endobronchial spread of Tuberculosis (TB):** This is the classic cause. When a TB cavity ruptures into the bronchial tree, infected material spreads distally into the bronchioles, causing an inflammatory response and impaction. It signifies **active disease**. #### Why Other Options are Incorrect: * **A. Sarcoidosis:** Characteristically shows a **perilymphatic distribution** of nodules. These nodules are typically found along the pleura, interlobular septa, and bronchovascular bundles, rather than a centrilobular tree-in-bud pattern. * **B. Miliary Tuberculosis:** This represents **hematogenous spread** (via blood). It presents as tiny, uniform (1–3 mm) nodules distributed randomly throughout both lungs, lacking the branching "budding" appearance of airway-related spread. #### High-Yield Clinical Pearls for NEET-PG: * **Differential Diagnosis for Tree-in-bud:** While TB is the most common cause in India, it is also seen in **Bronchiectasis** (especially Cystic Fibrosis), **Bacterial pneumonia** (Staphylococcus), and **Diffuse Panbronchiolitis**. * **Key Distinction:** Tree-in-bud = **Centrilobular** nodules. * **Golden Rule:** If you see "Tree-in-bud" in a clinical vignette involving fever, weight loss, and cough, it almost always points to **Active PTB**.

Question 168: What is the investigation of choice for pulmonary embolism?

A. CT scan
B. Contrast CT (Correct Answer)
C. Ventilation-Perfusion Scan
D. MRI

Explanation: **Explanation:** **Contrast-Enhanced Computed Tomography (CECT)**, specifically **CT Pulmonary Angiography (CTPA)**, is the investigation of choice (gold standard) for pulmonary embolism (PE). It allows direct visualization of the pulmonary arteries and can identify filling defects (clots) down to the segmental and sub-segmental levels. Its high sensitivity, specificity, and ability to provide alternative diagnoses (like pneumonia or aortic dissection) make it the first-line imaging modality. **Analysis of Options:** * **CT Scan (Plain):** A non-contrast CT is insufficient for PE because blood and thrombus have similar densities. Contrast is essential to create an "opacification" against which the clot appears as a dark filling defect. * **Ventilation-Perfusion (V/Q) Scan:** Previously the first-line test, it is now reserved for patients with **contraindications to CT contrast** (e.g., severe renal failure or contrast allergy) or in pregnancy. It provides a probability of PE rather than a definitive anatomical diagnosis. * **MRI:** While Magnetic Resonance Angiography (MRA) can detect PE, it is not the investigation of choice due to longer acquisition times, lower availability, and motion artifacts from breathing. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard (Historical/Definitive):** Invasive Catheter Pulmonary Angiography (rarely used now). * **Investigation of Choice:** CT Pulmonary Angiography (CTPA). * **Classic X-ray Signs:** **Hampton’s Hump** (wedge-shaped opacity) and **Westermark Sign** (focal oligemia). * **ECG Finding:** Most common is Sinus Tachycardia; most specific is **S1Q3T3**. * **Initial Screening Test:** D-Dimer (high negative predictive value).

Question 169: What is the most common lesion found in the middle mediastinum?

A. Lipoma
B. Aneurysm
C. Congenital cyst (Correct Answer)
D. Germ cell tumour

Explanation: **Explanation:** The mediastinum is traditionally divided into anterior, middle, and posterior compartments. The **middle mediastinum** contains the heart, pericardium, great vessels, trachea, and major bronchi. **Why "Congenital Cyst" is correct:** Congenital cysts are the most common primary lesions of the middle mediastinum. These include **bronchogenic cysts** (most common), pericardial cysts, and enteric cysts. They arise from abnormal budding of the primitive foregut during embryogenesis. On imaging, they typically appear as well-circumscribed, fluid-filled masses near the carina or paratracheal region. **Analysis of Incorrect Options:** * **Lipoma (A):** While lipomas can occur anywhere in the mediastinum, they are rare and most frequently found in the anterior mediastinum or cardiophrenic angles. * **Aneurysm (B):** Aortic aneurysms are common vascular pathologies of the middle mediastinum; however, they are categorized as vascular abnormalities rather than primary mediastinal "lesions" or tumors. * **Germ Cell Tumour (D):** These (along with the "4 Ts": Thymoma, Teratoma, Thyroid, and Terrible Lymphoma) are the hallmark lesions of the **Anterior Mediastinum**. **High-Yield Clinical Pearls for NEET-PG:** * **Anterior Mediastinum:** Most common site for mediastinal masses overall. Most common lesion: **Thymoma**. * **Middle Mediastinum:** Most common lesion: **Congenital/Bronchogenic Cyst**. Lymphadenopathy (sarcoid, lymphoma, or metastasis) is also frequently seen here. * **Posterior Mediastinum:** Most common lesion: **Neurogenic tumours** (e.g., Schwannoma, Neurofibroma). * **Imaging Gold Standard:** Contrast-Enhanced Computed Tomography (CECT) is the investigation of choice for characterizing mediastinal masses.

Question 170: What is the best radiographic view for demonstrating an interlobar pleural effusion?

A. Anteroposterior (AP) view
B. Posteroanterior (PA) view
C. Lateral view (Correct Answer)
D. Oblique view

Explanation: **Explanation:** **1. Why the Lateral View is Correct:** Interlobar pleural effusions (also known as "vanishing tumors" or "pseudotumors") occur when fluid collects within the pleural fissures (major or minor). On a standard frontal (PA) view, these collections often appear as ill-defined masses. However, the **Lateral View** is the gold standard for demonstration because it aligns the X-ray beam parallel to the orientation of the major and minor fissures. This allows the fluid to be clearly visualized as a characteristic **biconvex or spindle-shaped (lenticular) opacity** with well-defined margins, confirming its location within the fissure rather than the lung parenchyma. **2. Why Other Options are Incorrect:** * **PA and AP Views:** These are frontal projections. Because the fissures are oriented obliquely or horizontally in three-dimensional space, fluid within them appears "en face," leading to a hazy, rounded appearance that can be easily mistaken for a lung abscess or malignancy. * **Oblique View:** While sometimes used to clear overlying structures (like ribs or the heart), it does not consistently align with the anatomical plane of the fissures as effectively as the lateral view. **3. NEET-PG High-Yield Pearls:** * **Vanishing Tumor:** Interlobar effusions are most commonly associated with **Congestive Heart Failure (CHF)**. They are called "vanishing tumors" because they disappear rapidly with diuretic therapy. * **Shape:** Look for the "spindle shape" or "lemon shape" on the lateral film. * **Fissure Anatomy:** The minor (horizontal) fissure is only seen on the right side, while major (oblique) fissures are bilateral. * **Lateral Decubitus View:** This is the most sensitive view for detecting **small, free-flowing** pleural effusions (as little as 5-10ml), but it is not the best for *loculated* interlobar fluid.

Practice by Chapter

Normal Chest Radiographic Anatomy

Practice Questions

Radiographic Signs in Chest Imaging

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Pulmonary Infections

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Chronic Obstructive Pulmonary Disease

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Interstitial Lung Diseases

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Pulmonary Neoplasms

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Pleural Diseases

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Mediastinal Pathology

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Congenital and Developmental Chest Anomalies

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Pulmonary Vascular Diseases

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Chest Trauma Imaging

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Post-Surgical Chest Imaging

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