Emergency Radiology Practice Questions

Q: What is the imaging modality of choice in the setting of head trauma?

Helical CT scan without IV contrast. **Explanation:** In the acute setting of head trauma, **Non-Contrast Computed Tomography (NCCT) of the head** is the gold standard and the initial imaging modality of choice. **Why Option A is correct:** 1. **Speed and Accessibility:** Helical (spiral) CT is rapid, which is critical for unstable trauma patients. 2. **Acute Hemorrhage:** It is highly sensitive for detecting acute intracranial hemorrhage (which appears hyperdense/white). 3. **Bony Injuries:** It provides excellent visualization of skull fractures. 4. **No Contrast Needed:** IV contrast is avoided initially because it can extravasate or mimic the appearance of acute blood, making it difficult to differentiate a bleed from enhancement. **Why other options are incorrect:** * **Option B:** Contrast is generally avoided in trauma as it obscures acute blood and adds unnecessary time and risk of nephropathy/anaphylaxis. * **Option C:** While MRI is more sensitive for Diffuse Axonal Injury (DAI) and subacute changes, it is time-consuming, expensive, and difficult to monitor unstable patients inside the magnet. * **Option D:** Skull X-rays have a low sensitivity for intracranial pathology; a "normal" X-ray does not rule out a life-threatening intracranial bleed. **High-Yield Clinical Pearls for NEET-PG:** * **Epidural Hematoma (EDH):** Biconvex/Lens-shaped, does not cross sutures, usually involves the Middle Meningeal Artery. * **Subdural Hematoma (SDH):** Crescent-shaped, crosses sutures, involves tearing of cortical bridging veins. * **GCS Threshold:** Imaging is generally indicated if GCS <15 two hours after injury. * **Windowing:** Always evaluate the "Bone Window" to look for subtle fractures and the "Blood Window" to identify small hemorrhages.

Q: A patient presents to the emergency department with abdominal pain. What is the MOST significant diagnosis?

Superior mesenteric artery embolus. ***Superior mesenteric artery embolus*** - **Acute mesenteric ischemia** from SMA embolus requires **immediate surgical intervention** (within 6-8 hours) to prevent bowel necrosis and death. - **CT angiography** shows **filling defect** in the SMA with **decreased bowel wall enhancement** and potential **pneumatosis intestinalis**. *Superior mesenteric vein thrombosis* - Causes **venous congestion** rather than arterial ischemia, progressing more **slowly** than arterial embolus. - **CT shows thrombus** in the SMV with **bowel wall thickening** and **mesenteric edema**, but less immediately life-threatening. *Aortic dissection* - Presents with **tearing chest/back pain** radiating to the abdomen, not primarily abdominal pain. - **CT shows intimal flap** and **false lumen** in the aorta, but may not cause immediate bowel ischemia. *Leaking aortic aneurysm* - Typically presents with **hypotension** and **pulsatile abdominal mass** rather than isolated abdominal pain. - **CT shows retroperitoneal hematoma** and **aortic wall irregularity**, but bowel perfusion usually remains intact.

Q: The dependant viscera sign is seen in which of the following conditions?

Diaphragmatic rupture. ### Explanation **1. Why Diaphragmatic Rupture is Correct:** The **Dependent Viscera Sign** is a classic CT finding in **traumatic diaphragmatic rupture**. Under normal conditions, the diaphragm supports the abdominal organs (liver, spleen, and stomach), keeping them away from the posterior chest wall. When the diaphragm is ruptured, this support is lost. Consequently, the abdominal viscera "fall" posteriorly due to gravity and lie in direct contact with the posterior ribs or the posterior thoracic wall. This sign is highly specific (approx. 95%) for blunt diaphragmatic injury. **2. Analysis of Incorrect Options:** * **B. Fractured Bronchus:** This typically presents with the "Fallen Lung Sign" (the lung falls away from the hilum towards the dependent part of the hemithorax) and persistent pneumothorax despite chest tube drainage. * **C. Pneumoperitoneum:** This refers to free air in the peritoneal cavity. Key radiological signs include the Rigler sign (double wall sign), Cupola sign, or Football sign on an X-ray. * **D. Diaphragmatic Hernia:** While a rupture is a type of acquired hernia, the "Dependent Viscera Sign" specifically refers to the acute traumatic loss of diaphragmatic integrity where organs collapse against the posterior wall. Congenital hernias (like Bochdalek) usually have a well-defined hernial sac or defect edges that don't necessarily result in this specific "falling" appearance. **3. Clinical Pearls for NEET-PG:** * **Collar Sign:** Another specific sign for diaphragmatic rupture, representing a "waist-like" constriction of the herniated abdominal organs at the site of the diaphragmatic defect. * **Dangling Diaphragm Sign:** Seeing the free edge of the torn diaphragm. * **Most Common Side:** Diaphragmatic rupture is more common on the **left side** (the liver provides a protective cushioning effect on the right). * **Gold Standard Investigation:** Contrast-enhanced CT (CECT) of the chest and abdomen.

Q: What is the investigation of choice for the evaluation of upper abdominal trauma in a patient with stable vitals?

Computed Tomography (CT). **Explanation:** In the setting of blunt or penetrating upper abdominal trauma, the choice of investigation is primarily dictated by the patient's **hemodynamic stability**. **Why Computed Tomography (CT) is the Correct Answer:** For a **hemodynamically stable** patient, a **Contrast-Enhanced CT (CECT)** of the abdomen and pelvis is the gold standard and investigation of choice. It offers high sensitivity and specificity for identifying solid organ injuries (liver, spleen, kidneys), detecting active hemorrhage (contrast blush), and evaluating the retroperitoneum, which is poorly visualized on ultrasound. It also allows for the grading of injuries, which guides non-operative management. **Why the Other Options are Incorrect:** * **Ultrasound (USG/FAST):** While Focused Assessment with Sonography for Trauma (FAST) is the initial screening tool for *unstable* patients to detect free fluid (hemoperitoneum), it cannot reliably grade solid organ injuries or detect hollow viscus/retroperitoneal damage. * **Scintigraphy:** Nuclear medicine scans are too time-consuming and lack the anatomical detail required for acute trauma evaluation. * **MRI:** Although highly detailed, MRI is impractical in emergencies due to long acquisition times, difficulty in monitoring the patient inside the bore, and incompatibility with metallic resuscitation equipment. **Clinical Pearls for NEET-PG:** * **Hemodynamically Unstable + Positive FAST:** Proceed directly to **Laparotomy**. * **Hemodynamically Stable:** **CECT** is the investigation of choice regardless of FAST results if clinical suspicion is high. * **Seatbelt Sign:** Always look for bowel or mesenteric injuries on CT. * **Triple Contrast CT:** Occasionally used to rule out subtle distal esophageal or duodenal perforations.

Q: Which of the following appears hyperdense on CT?

Acute bleed. **Explanation:** In Computed Tomography (CT), the density of a tissue is measured in **Hounsfield Units (HU)**. This scale is based on the degree of X-ray attenuation. Substances that attenuate more X-rays appear whiter (**hyperdense**), while those that allow more X-rays to pass through appear darker (**hypodense**). **Why Acute Bleed is Correct:** An **acute hemorrhage** typically has a density of **+60 to +80 HU**. This hyperdensity is primarily due to the high concentration of **hemoglobin** and the formation of a fibrin clot, which increases the protein density within the blood. As the clot retracts and the hemoglobin breaks down over time (chronic stage), the density decreases, eventually becoming isodense and then hypodense. **Analysis of Incorrect Options:** * **A. Air:** This is the least dense substance on CT, appearing pitch black with a value of **-1000 HU**. * **B. Water:** Water is the reference point for the Hounsfield scale and is assigned a value of **0 HU**. * **C. Fat:** Fat is less dense than water and appears dark grey, typically ranging from **-50 to -100 HU**. **High-Yield Clinical Pearls for NEET-PG:** * **Hounsfield Unit (HU) Cheat Sheet:** * Air: -1000 * Fat: -50 to -100 * Water: 0 * Soft Tissue: +40 to +80 * **Acute Blood: +60 to +80** * Bone/Calcification: +400 to +1000 * **Evolution of Blood on CT:** Acute (Hyperdense) $\rightarrow$ Subacute (Isodense) $\rightarrow$ Chronic (Hypodense). * **Contrast Media:** Intravenous contrast (Iodine-based) also appears hyperdense on CT.

Q: Which radiographic view best visualizes zygoma fractures?

Occipitomental view. The **Occipitomental view (Water’s view)** is the gold standard radiographic projection for evaluating mid-facial fractures, particularly those involving the **zygoma** and the maxillary sinuses. ### Why Occipitomental View is Correct: In this projection, the patient’s chin is tilted up against the film, which displaces the dense petrous pyramids of the temporal bone downward, below the floor of the maxillary sinuses. This provides an unobstructed view of the **zygomatic bone, zygomatic arch, infraorbital rims, and the maxillary sinuses**. It is specifically used to diagnose the "Tripod fracture" (Zygomaticomaxillary complex fracture). ### Why Other Options are Incorrect: * **Lateral Oblique View:** Primarily used to visualize the body and ramus of the **mandible**, not the mid-face or zygoma. * **Towne’s View:** An AP axial projection used to visualize the **occipital bone** and the condylar processes of the mandible. It is the best view for mandibular condyle fractures. * **Lateral Skull View:** Useful for visualizing the sella turcica, paranasal sinuses (fluid levels), and calvarial fractures, but the superimposition of facial bones makes it poor for isolating zygomatic injuries. ### High-Yield Clinical Pearls for NEET-PG: * **Submentovertex View (Jug-handle view):** The best view for isolated fractures of the **zygomatic arch**. * **Black Line (Ames’ Line):** On a Water’s view, look for the "hanging drop" sign or disruption of the orbital floor (Blow-out fracture). * **Tripod Fracture:** Involves three points: the zygomaticofrontal suture, the infraorbital rim, and the zygomaticotemporal suture (arch). * **Caldwell View (Occipitofrontal):** Best for visualizing the frontal sinuses and superior orbital rims.

Q: Tear drop sign is seen in:

Fracture of floor of orbit. **Explanation:** The **Tear Drop Sign** is a classic radiological finding seen on a Water’s view (occipitomental projection) X-ray, indicating a **blow-out fracture of the orbital floor**. **Why it occurs:** When a blunt object (larger than the orbital rim, like a tennis ball or fist) strikes the eye, the intraorbital pressure increases suddenly. This pressure is transmitted to the weakest part of the orbit—the floor (maxillary bone). The fracture allows orbital fat and the **inferior rectus muscle** to herniate downward into the maxillary sinus. On imaging, this herniated soft tissue mass appears as a "tear drop" hanging from the roof of the maxillary sinus. **Analysis of Incorrect Options:** * **B. Fracture of lateral wall of nose:** Usually presents with epistaxis and localized deformity; it does not involve the maxillary sinus roof or orbital contents. * **C. Le Fort’s fracture:** These are complex midface fractures. While Le Fort II and III involve the orbit, they are characterized by specific patterns of craniofacial dissociation rather than the isolated "tear drop" herniation. * **D. Fracture of zygomatic arch:** Typically presents with a "V-shaped" deformity on a Submentovertex view (Jug-handle view) and does not involve the orbital floor. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site of orbital blow-out fracture:** Orbital floor (specifically medial to the infraorbital groove). * **Clinical Presentation:** Enophthalmos (sunken eye), diplopia (due to inferior rectus entrapment), and anesthesia in the distribution of the **infraorbital nerve**. * **Imaging Gold Standard:** Non-contrast CT (NCCT) of the Orbits (Coronal sections are best for visualizing the floor). * **Black Eyebrow Sign:** Another radiological sign of orbital fracture representing intraorbital air (orbital emphysema).

Question 1

What is the imaging modality of choice in the setting of head trauma?

Accepted Answer

Helical CT scan without IV contrast

Answer

Spiral CT scan with IV contrast

Answer

MRI

Answer

Digital skull radiographs

Question 2

A patient presents to the emergency department with abdominal pain. What is the MOST significant diagnosis?

Accepted Answer

Superior mesenteric artery embolus

Answer

Superior mesenteric vein thrombosis

Answer

Aortic dissection

Answer

Leaking aortic aneurysm

Question 3

Pneumatocele is seen in fracture of which sinus?

Accepted Answer

Frontal sinus

Answer

Maxillary sinus

Answer

Ethmoid sinus

Answer

Sphenoid sinus

Question 4

The dependant viscera sign is seen in which of the following conditions?

Accepted Answer

Diaphragmatic rupture

Answer

Fractured bronchus

Answer

Pneumoperitoneum

Answer

Diaphragmatic hernia

Question 5

Computed tomography (CT) is useful in the formulation of a treatment plan of blow-out fractures because:

Accepted Answer

CT can fairly accurately determine the size of the fracture and its relationship to the orbital soft tissues.

Answer

It is the only way to diagnose an orbital fracture.

Answer

Coexistent sinus disease can be evaluated.

Answer

Magnetic resonance imaging is superior to CT in the evaluation of orbital fractures.

Question 6

What is the investigation of choice for the evaluation of upper abdominal trauma in a patient with stable vitals?

Accepted Answer

Computed Tomography (CT)

Answer

Ultrasound (USG)

Answer

Scintigraphy

Answer

Magnetic Resonance Imaging (MRI)

Question 7

Which of the following appears hyperdense on CT?

Accepted Answer

Acute bleed

Answer

Air

Answer

Water

Answer

Fat

Question 8

Which radiographic view best visualizes zygoma fractures?

Accepted Answer

Occipitomental view

Answer

Lateral oblique view

Answer

Towne's view

Answer

Lateral skull view

Question 9

Pneumocephalus is most commonly seen with fractures of which anatomical structure?

Accepted Answer

Frontal sinus

Answer

Maxillary sinus

Answer

Sphenoid sinus

Answer

Mastoid antrum

Question 10

Tear drop sign is seen in:

Accepted Answer

Fracture of floor of orbit

Answer

Fracture of lateral wall of nose

Answer

Le Fort's fracture

Answer

Fracture of zygomatic arch

Emergency Radiology — MCQs

Emergency Radiology — MCQs

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