What is the investigation of choice for nasopharyngeal angiofibroma?
Tear drop sign is seen in?
What is the best imaging view for assessing the nasal bone in X-ray?
The most accurate investigation for assessing ventricular function is:
A chest X-ray shows bilateral lung infiltrates. What is the next best investigation?
On imaging, diffuse axonal injury is characterized by -
What is the investigation of choice for whole body imaging in metastatic breast cancer?
What is the maximum radiation dose (in Gray) that bone tissue can tolerate?
Which imaging modality is most effective in differentiating between epidermoid cyst and arachnoid cyst?
Radiological sign in case of Perthes disease?
NEET-PG 2013 - Radiology NEET-PG Practice Questions and MCQs
Question 11: What is the investigation of choice for nasopharyngeal angiofibroma?
- A. Contrast-enhanced CT (Correct Answer)
- B. Plain CT
- C. X-ray
- D. MRI
Explanation: ***Contrast-enhanced CT*** - A **contrast-enhanced CT** scan is the investigation of choice for **nasopharyngeal angiofibroma** due to its ability to clearly delineate the extent of the tumor, its vascularity, and its bony involvement. - The contrast highlights the **highly vascular nature** of the angiofibroma, which is crucial for surgical planning and embolization. *X-ray* - **X-rays** provide limited detail of soft tissue structures and mass lesions in the complex anatomy of the nasopharynx. - They are generally not sensitive enough to characterize a tumor like **angiofibroma** or determine its exact extent. *Plain CT* - A **plain CT** (non-contrast CT) can show soft tissue masses and bony erosion but lacks the ability to assess the **vascularity** of the tumor. - Without contrast, it's difficult to differentiate the tumor from surrounding tissues or identify its blood supply, which is critical for **angiofibroma** management. *MRI* - While **MRI** offers excellent soft tissue contrast and is valuable for assessing intracranial extension or perineural spread, **contrast-enhanced CT** is generally preferred as the primary imaging modality for angiofibroma. - **CT with contrast** is superior for demonstrating **bony erosion** and the characteristic **vascularity** of this tumor.
Question 12: Tear drop sign is seen in?
- A. Fracture zygomatic arch
- B. Fracture maxilla
- C. Fracture mandible
- D. Blow out fracture (Correct Answer)
Explanation: ***Blow out fracture*** - The **tear drop sign** on imaging (often CT scan) is characteristic of an **orbital blow-out fracture**, indicating herniation of orbital contents (fat, muscle) into the maxillary sinus. - This fracture typically involves the **orbital floor** or medial wall, often caused by a blunt force trauma to the eye. *Fracture zygomatic arch* - A fracture of the zygomatic arch is often associated with a **flattening of the malar prominence** rather than a "tear drop" sign. - It might lead to restricted jaw movement if the arch impinges on the coronoid process. *Fracture maxilla* - Maxillary fractures (e.g., Le Fort fractures) involve the midface bones and cause **facial deformity**, malocclusion, and mobility of the maxilla. - The tear drop sign is not a primary diagnostic feature of maxillary fractures. *Fracture mandible* - Mandibular fractures present with pain, swelling, and **malocclusion** of the teeth. - Imaging would reveal a break in the mandible, not a tear drop sign associated with orbital contents.
Question 13: What is the best imaging view for assessing the nasal bone in X-ray?
- A. Lateral (Correct Answer)
- B. Towne's
- C. Submentovertical
- D. Caldwell
Explanation: ***Lateral*** - The **lateral view** provides a clear profile of the nasal bones, allowing for the best assessment of fractures, displacement, and angulation. - It visualizes the nasal bone in relation to other facial structures, which is crucial for treatment planning. *Towne's* - The **Towne's view** is primarily used to visualize the **occipital bone** and the **foramen magnum**, not the nasal bones. - It projects the petrous pyramids inferiorly, which would obstruct the view of the nasal region. *Caldwell* - The **Caldwell view** is primarily used to assess the **frontal sinuses**, **ethmoid sinuses**, and **orbits**. - While it offers some visualization of the nasal region, it does not provide the detailed lateral projection needed for optimal nasal bone assessment. *Submentovertical* - The **submentovertical view** (also known as the **basal view**) is primarily used to visualize the **base of the skull**, **sphenoid sinuses**, and **zygomatic arches**. - This view does not offer a direct or clear projection of the nasal bones themselves.
Question 14: The most accurate investigation for assessing ventricular function is:
- A. Multislice CT
- B. Echocardiography
- C. MRI (Correct Answer)
- D. Nuclear scan
Explanation: ***MRI*** - Cardiac MRI is considered the **gold standard** for assessing ventricular function, providing highly accurate and reproducible measurements of **ventricular volumes**, **ejection fraction**, and **myocardial mass**. - It offers excellent tissue characterization, allowing for direct visualization of **fibrosis**, **inflammation**, and other myocardial pathologies that can affect function. *Multislice CT* - While useful for assessing cardiac anatomy, particularly **coronary arteries**, Multislice CT involves **ionizing radiation** and has limitations in accurately assessing subtle changes in myocardial function compared to MRI. - Its strength lies more in **anatomical evaluation** (e.g., calcium scoring, coronary angiography) rather than detailed functional assessment. *Echocardiography* - Echocardiography is a widely available and useful first-line imaging modality for ventricular function, but it can be limited by **acoustic windows**, **operator dependency**, and **spatial resolution** compared to MRI. - While it provides good estimates of ejection fraction, particularly in simple cases, its 3D capabilities and tissue characterization are generally inferior to MRI. *Nuclear scan* - Nuclear scans (e.g., MUGA scans, SPECT) can assess ventricular function and myocardial perfusion, but they involve **ionizing radiation** and primarily provide **functional information** based on tracer uptake, not detailed structural or tissue characterization. - They are often used for evaluating **perfusion defects** and overall ejection fraction, but are less precise for detailed chamber quantification and tissue characterization than MRI.
Question 15: A chest X-ray shows bilateral lung infiltrates. What is the next best investigation?
- A. Sputum examination
- B. CT (Correct Answer)
- C. Bronchoscopy
- D. Echocardiography
Explanation: ***CT*** - A **CT scan (preferably HRCT)** provides a more detailed view of the lung parenchyma, allowing for better characterization of the infiltrates (e.g., location, pattern, presence of nodules, ground-glass opacities, or consolidation). - This detailed imagery is crucial for narrowing down the differential diagnosis and guiding further diagnostic or therapeutic interventions. - **CT is the best next investigation** for characterizing bilateral lung infiltrates seen on chest X-ray. *Sputum examination* - While important for identifying infectious causes, **sputum examination** is often only productive in certain types of pneumonia or infections and might not directly clarify the morphology or distribution of the infiltrates as a CT scan would. - It might be a subsequent step once the nature of the infiltrate is better understood through imaging. *Bronchoscopy* - **Bronchoscopy** is an invasive procedure generally reserved for cases where less invasive methods have failed to yield a diagnosis or when specific findings from imaging (like a CT scan) suggest the need for direct visualization, lavage, or biopsy. - It's not typically the immediate next step after identifying bilateral infiltrates on a chest X-ray. *Echocardiography* - **Echocardiography** is useful for evaluating cardiac causes of bilateral infiltrates (such as pulmonary edema from heart failure). - However, it does not directly visualize or characterize the lung parenchymal infiltrates themselves, making CT more valuable as the next investigation.
Question 16: On imaging, diffuse axonal injury is characterized by -
- A. Patchy ill-defined low density lesion mixed with small hyperdensities of petechial hemorrhage
- B. Crescentic extra-axial hematoma
- C. White matter lucencies
- D. Multiple small petechial hemorrhages (Correct Answer)
Explanation: ***Multiple small petechial hemorrhages*** - Diffuse axonal injury (DAI) is characterized on imaging by numerous **small petechial hemorrhages** at the **gray-white matter junction**, **corpus callosum**, and **brainstem**. - These microhemorrhages are the **hallmark imaging finding** and are best visualized on MRI (GRE/SWI sequences), though they can be seen on CT as small hyperdensities. - This is the **most specific** and characteristic finding that defines DAI. *Patchy ill-defined low density lesion mixed with small hyperdensities of petechial hemorrhage* - While this description can be seen in DAI (combining edema with microhemorrhages), it is **less specific** and could represent other entities. - This mixed pattern is more commonly associated with **contusions** where there is more prominent parenchymal injury with larger areas of edema and hemorrhage. - DAI classically shows predominantly **small punctate hemorrhages** rather than larger patchy low-density lesions. *Crescentic extra-axial hematoma* - A crescentic extra-axial collection describes a **subdural hematoma**, which is an entirely separate entity from DAI. - Subdural hematomas are located between the dura and arachnoid membranes, whereas DAI involves direct **axonal shearing injury** within brain parenchyma. *White matter lucencies* - This is a **non-specific finding** that can occur in many conditions including ischemia, demyelination, and chronic small vessel disease. - While DAI can cause white matter edema leading to lucencies, this does not capture the **characteristic petechial hemorrhages** that define the condition on imaging.
Question 17: What is the investigation of choice for whole body imaging in metastatic breast cancer?
- A. Angiography
- B. Venography
- C. Magnetic Resonance Imaging
- D. CT Scan (Correct Answer)
Explanation: ***CT Scan (Correct answer for NEET 2013)*** - **Contrast-enhanced CT scan** was the standard imaging modality for **whole-body staging** in metastatic breast cancer at the time of this exam (2013). - CT offers **excellent spatial resolution** for detecting metastases in **bone, lung, liver, and lymph nodes**. - It is widely available, relatively quick, and provides comprehensive anatomical information. - **Modern Update:** While CT was the standard in 2013, **PET-CT (FDG-PET/CT) is now considered the gold standard** for whole-body staging in metastatic breast cancer due to its combined metabolic and anatomical imaging capabilities. However, PET-CT was not among the options in this historical question. *Magnetic Resonance Imaging* - **MRI** is highly sensitive for specific sites, particularly for **brain metastases** and **bone metastases (especially spine and bone marrow)**. - **Whole-body MRI** protocols are emerging but require longer acquisition times and specialized equipment. - Not ideal as a single first-line modality for comprehensive whole-body staging compared to CT (or modern PET-CT). *Angiography* - **Angiography** is an invasive vascular imaging procedure used to visualize **arterial blood flow**. - It has **no role in routine metastatic screening or staging** of breast cancer. - Reserved for specific indications like preoperative vascular mapping or interventional procedures. *Venography* - **Venography** specifically visualizes **venous structures** and is used to detect venous thrombosis or venous obstructions. - It is **not applicable** for detecting solid organ metastases, bone lesions, or lymph node involvement in cancer staging.
Question 18: What is the maximum radiation dose (in Gray) that bone tissue can tolerate?
- A. 50 Gray (Correct Answer)
- B. 30 Gray
- C. 20 Gray
- D. 40 Gray
Explanation: ***Correct Option: 50 Gray*** - The **maximum radiation tolerance dose** for bone tissue is approximately **50-60 Gray (Gy)** based on radiobiology literature and clinical practice. - Among the given options, **50 Gy** represents the most appropriate threshold for bone tolerance. - According to **Emami et al. tolerance doses** and **QUANTEC guidelines**, bone can typically tolerate up to 60 Gy without significant risk of complications. - Doses approaching or exceeding **60 Gy** carry increased risk of **osteoradionecrosis**, particularly in the **mandible and weight-bearing bones**. - **Clinical significance**: In radiation therapy planning, doses of 50-60 Gy to bone are commonly used therapeutically for tumors involving or adjacent to bone. *Incorrect Option: 40 Gray* - 40 Gy is **below the accepted tolerance threshold** for bone tissue. - This dose is generally **well-tolerated** by bone without significant risk of necrosis or fracture. - Commonly used in palliative and definitive radiation protocols without major bone complications. *Incorrect Option: 30 Gray* - 30 Gy is **considerably below** the tolerance limit for bone. - This dose level is **safe for bone tissue** and carries minimal risk of radiation-induced bone damage. - Often used in palliative treatments with excellent bone tolerance. *Incorrect Option: 20 Gray* - 20 Gy is a **low radiation dose** from the perspective of bone tolerance. - This dose is **highly unlikely** to cause any significant bone damage or complications. - Represents a conservative therapeutic dose well within safety margins.
Question 19: Which imaging modality is most effective in differentiating between epidermoid cyst and arachnoid cyst?
- A. Magnetic Resonance Imaging (MRI) (Correct Answer)
- B. Ultrasound (USG)
- C. Computed Tomography (CT) scan
- D. Positron Emission Tomography (PET) scan
Explanation: ***Magnetic Resonance Imaging (MRI)*** - **MRI** is superior for differentiating epidermoid and arachnoid cysts due to its excellent **soft tissue contrast** and ability to detect fluid signal characteristics. - **Diffusion-weighted imaging (DWI)**, a specific MRI sequence, is crucial; **epidermoid cysts** show high signal on DWI (diffusion restriction) due to their keratin content, while **arachnoid cysts** follow CSF signal on all sequences and do not restrict diffusion. *Ultrasound (USG)* - **Ultrasound** has limited utility for intracranial lesions in adults due to the bony skull, which prevents sound wave penetration. - It may be used in infants through the fontanelles but lacks the resolution and specific sequences needed to characterize these cysts. *Computed Tomography (CT) scan* - While a **CT scan** can identify these cysts as hypodense lesions, it lacks the detailed **tissue characterization** and signal patterns provided by MRI. - Both cysts would appear as **hypodense lesions**, making differentiation difficult based on density alone, especially after contrast administration. *Positron Emission Tomography (PET) scan* - A **PET scan** primarily assesses metabolic activity and would not effectively differentiate between benign **non-metabolic cysts** like epidermoid and arachnoid cysts. - It is more commonly used for detecting **malignancies** or assessing brain activity patterns, not for structural differentiation of fluid-filled lesions.
Question 20: Radiological sign in case of Perthes disease?
- A. Flattening of femoral head (Correct Answer)
- B. Fragmentation of femoral head epiphysis
- C. Lateral femoral head displacement
- D. Limited hip abduction
Explanation: ***Flattening of femoral head*** - **Flattening** and **fragmentation** of the femoral head are characteristic radiological findings in **early-stage** Perthes disease. - This flattening is a direct consequence of the **avascular necrosis** and subsequent **remodeling** of the femoral epiphysis. *Fragmentation of femoral head epiphysis* - While **fragmentation** is a key feature of Perthes disease, it's typically observed **after** the initial flattening and sclerosis in the avascular stage. - It represents the process of **resorption** and **revascularization** as the bone attempts to heal. *Lateral femoral head displacement* - **Lateral displacement** of the femoral head is a more common finding in conditions like **slipped capital femoral epiphysis (SCFE)**, where the epiphysis slips from the metaphysis. - In Perthes disease, the primary issue is the **necrosis and collapse** of the femoral head itself, rather than displacement from the neck. *Limited hip abduction* - **Limited hip abduction** is a clinical sign, not a radiological sign, and it is a common symptom in Perthes disease due to pain, inflammation, and deformity of the femoral head. - Radiological signs are visual abnormalities observed on imaging studies like X-rays.