NEET-PG 2013

1544 Questions — Page 128 of 155

Internal Medicine

2 questions

Q1271

In a patient with heart disease, which condition is most commonly associated with left atrial enlargement?

Q1272

Match stick test is positive in ?

NEET-PG 2013 - Internal Medicine NEET-PG Practice Questions and MCQs

Question 1271: In a patient with heart disease, which condition is most commonly associated with left atrial enlargement?

A. Mitral stenosis (Correct Answer)
B. Tricuspid regurgitation
C. AR
D. None of the options

Explanation: ***Mitral stenosis*** - **Mitral stenosis** leads to an obstruction of blood flow from the **left atrium to the left ventricle**, causing pressure buildup in the left atrium [1]. - This increased pressure over time results in **left atrial enlargement** as the chamber struggles to push blood through the narrowed valve [1]. *Tricuspid regurgitation* - **Tricuspid regurgitation** involves the backflow of blood from the **right ventricle to the right atrium**. - This condition primarily affects the **right side of the heart**, leading to **right atrial enlargement**, not left. *AR* - **Aortic regurgitation (AR)** is the backflow of blood from the **aorta into the left ventricle**. - While AR can cause **left ventricular enlargement** and eventually lead to left atrial dilation, it is not the most common direct cause of *primary* left atrial enlargement compared to mitral stenosis [2]. *None of the options* - **Mitral stenosis** is a well-established cause of significant left atrial enlargement due to the direct pressure overload it imposes on the left atrium [1].

Question 1272: Match stick test is positive in ?

A. Rhinophyma
B. P. versicolor
C. Leprosy (Correct Answer)
D. Rhinoscleroma

Explanation: ***Leprosy*** - The **matchstick test** is a simple neurological examination used to detect **nerve damage** in leprosy, specifically **sensory loss** [1]. - A positive test indicates the patient cannot perceive the touch or pain from a matchstick, commonly due to damage to superficial nerves caused by *Mycobacterium leprae* [1]. *Rhinophyma* - This condition is characterized by **sebaceous gland hypertrophy** and **fibrosis** of the nose, often associated with rosacea. - It does not involve nerve damage or sensory loss that would be assessed by a matchstick test. *Rhinoscleroma* - Rhinoscleroma is a **chronic granulomatous bacterial infection** of the upper respiratory tract. - While it causes significant tissue destruction and structural changes, it is not primarily associated with the sensory neuropathies that the matchstick test evaluates. *P. vesticolor* - *Pityriasis versicolor* is a **superficial fungal infection** of the skin, causing discolored patches. - This condition is a dermatological issue and does not involve nerve damage or sensory deficits, making the matchstick test irrelevant.

Physiology

1 questions

Q1271

The Doppler effect in medical ultrasound is caused by:

Radiology

7 questions

Q1271

Air bronchogram on chest X-ray denotes -

Q1272

In a patient with high clinical suspicion of pulmonary thromboembolism, best investigation would be?

Q1273

Which view is best for visualizing the collapse of the middle lobe of the lung?

Q1274

Which imaging modality delivers the highest dose of radiation?

Q1275

Gyromagnetic property of proton is seen in -

Q1276

Frequency of ultrasound waves in USG -

Q1277

What is an X-ray artifact?

NEET-PG 2013 - Radiology NEET-PG Practice Questions and MCQs

Question 1271: Air bronchogram on chest X-ray denotes -

A. Intrapulmonary lesion (Correct Answer)
B. Extrapulmonary lesion
C. Intrathoracic lesion
D. Extrathoracic lesion

Explanation: ***Intrapulmonary lesion*** - An **air bronchogram** indicates that the air-filled bronchi are surrounded by consolidated or fluid-filled alveoli, making the bronchi visible against the opacified lung parenchyma. - This pattern is a strong sign of a process **within the lung tissue itself**, such as pneumonia, pulmonary edema, or malignancy. *Extrapulmonary lesion* - **Extrapulmonary lesions**, such as pleural effusions or masses originating from the chest wall, typically displace or compress the lung and bronchi, rather than filling the alveoli around them. - They usually do **not produce an air bronchogram** because the air in the bronchi is not juxtaposed against diseased lung parenchyma. *Intrathoracic lesion* - This is a broad term that includes all lesions within the thoracic cavity, both intrapulmonary and extrapulmonary. - While an air bronchogram is an intrathoracic finding, it specifically points to an **intrapulmonary process**, not just any intrathoracic lesion. *Extrathoracic lesion* - **Extrathoracic lesions** are located outside the chest cavity and would not manifest as an air bronchogram on a chest X-ray. - This option is **completely unrelated** to the interpretation of an air bronchogram.

Question 1272: In a patient with high clinical suspicion of pulmonary thromboembolism, best investigation would be?

A. D-dimer
B. CT angiography (Correct Answer)
C. Catheter angiography
D. Color Doppler

Explanation: ***CT angiography*** - In a patient with **high clinical suspicion** of pulmonary embolism (PE), CT angiography of the pulmonary arteries is the preferred and often definitive diagnostic test. - It allows for direct visualization of thrombi within the pulmonary arterial tree with high sensitivity and specificity. *D-dimer* - While useful for **ruling out PE** in patients with low or intermediate pre-test probability, a positive D-dimer is non-specific and requires further investigation in high-suspicion cases. - It has a high **negative predictive value** but a low positive predictive value, meaning a normal D-dimer makes PE unlikely, but an elevated one does not confirm it. *Catheter angiography* - This is an **invasive procedure** that is typically reserved for cases where CT angiography is inconclusive or contraindicated, or when interventional treatment is contemplated. - It carries risks such as **bleeding** and **contrast-induced nephropathy**, making it less appropriate as a first-line diagnostic in most situations. *Color Doppler* - Color Doppler ultrasound is primarily used to diagnose **deep vein thrombosis (DVT)** in the lower extremities, which is a common source of PE. - It is **not used to directly diagnose PE** in the pulmonary arteries; however, finding a DVT can support the diagnosis of PE indirectly.

Question 1273: Which view is best for visualizing the collapse of the middle lobe of the lung?

A. Anteroposterior (AP)
B. Oblique
C. Lateral (Correct Answer)
D. Lordotic

Explanation: ***Lateral*** - A **lateral chest X-ray** is crucial for localizing abnormalities to specific lung lobes because it allows for a clear visualization of the **fissures** which define the lung lobes. - Collapse of the right middle lobe is particularly well-visualized on a lateral view as a **triangular opacity** that points towards the hilum, often obliterating the right heart border. *Anteroposterior (AP)* - While an AP or PA view can show collapse, it often appears as a **non-specific wedge or triangular opacity** and struggles with precise lobar localization due to superimposed structures. - The **heart shadow and mediastinum** can obscure parts of the middle lobe, making definitive diagnosis challenging from this view alone. *Oblique* - Oblique views are typically used for specific purposes, such as evaluating the **pleura** or **ribs**, and are not a standard view for initial assessment of lobar collapse. - They introduce **distortion and superimposition** that can make the identification and characterization of lobar collapse more difficult than a standard lateral projection. *Lordotic* - A lordotic view is primarily used to visualize the **lung apices** and to differentiate apical lesions from superimposed clavicular shadows. - It is not effective for visualizing the middle lobe, which is located more inferiorly, and would introduce significant distortion, making assessment of its collapse unreliable.

Question 1274: Which imaging modality delivers the highest dose of radiation?

A. Cardiac perfusion scan (Correct Answer)
B. CT scan of the chest
C. Mammogram
D. CT scan of the brain

Explanation: ***Cardiac perfusion scan*** - A **cardiac perfusion scan (nuclear cardiology)** involves the administration of a radioactive tracer, and the radiation dose can be significant due to the nature and energy of the isotopes used. - While varying, the effective dose for these scans can range from **10 to 30 mSv**, placing it among some of the highest radiation exposures from medical imaging. *CT scan of the chest* - A **CT scan of the chest** provides a relatively high radiation dose compared to plain X-rays, typically ranging from **5 to 7 mSv**. - This is generally lower than some nuclear medicine studies, particularly complex or prolonged cardiac perfusion scans. *Mammogram* - A **mammogram** involves a relatively low dose of radiation, typically in the range of **0.2 to 0.7 mSv**. - Its objective is to image the breast tissue with minimal exposure, making it one of the lower-dose imaging modalities available. *CT scan of the brain* - A **CT scan of the brain** usually delivers a moderate radiation dose, estimated to be around **1 to 2 mSv**. - This is often less than a chest CT due to the smaller volume and different shielding considerations, and significantly less than a cardiac perfusion scan.

Question 1275: Gyromagnetic property of proton is seen in -

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

Explanation: ***MRI*** - Magnetic Resonance Imaging (MRI) relies on the **gyromagnetic properties of protons**, primarily hydrogen nuclei in water and fat. - These protons align with a strong magnetic field and, when pulsed with radiofrequency waves, emit detectable signals that form the image. *CT* - Computed Tomography (CT) utilizes **X-rays** and their differential absorption by various tissues to create cross-sectional images. - It does not involve the gyromagnetic properties of protons. *PET scan* - Positron Emission Tomography (PET) scans detect **gamma rays** emitted from radiotracers, typically radionuclides like Fluorine-18, that accumulate in metabolically active tissues. - This imaging modality is based on radioactive decay, not proton spin. *USG* - Ultrasonography (USG) generates images by sending **high-frequency sound waves** into the body and detecting the echoes that bounce back from various tissues. - It relies on acoustic properties and tissue interfaces, not magnetic properties of protons.

Question 1276: Frequency of ultrasound waves in USG -

A. 2000 Hz
B. 5000 Hz
C. < 2 MHz
D. >2 MHz (Correct Answer)

Explanation: ***>2 MHz*** - Medical diagnostic ultrasound typically uses frequencies in the **range of 2-15 MHz**, with some applications extending from 1-20 MHz. - Frequencies **above 2 MHz** are considered the standard for diagnostic ultrasonography, providing adequate **spatial resolution** and tissue penetration for imaging internal structures. - **Frequency selection** depends on the application: - **2-5 MHz**: Deep structures (abdominal, obstetric imaging) - better penetration - **5-10 MHz**: Vascular studies, cardiac imaging - **7-15 MHz**: Superficial structures (thyroid, breast, musculoskeletal) - better resolution - Higher frequencies provide better resolution but less penetration; the choice represents a trade-off based on clinical needs. *2000 Hz* - This frequency (2 kHz) falls within the **audible range** for humans (20 Hz to 20 kHz). - Such low frequencies would not provide the necessary **spatial resolution** for diagnostic imaging and lack the characteristics needed for medical ultrasound. *5000 Hz* - At 5 kHz, this is still within the **audible frequency range**. - These frequencies are far too low for medical ultrasound imaging, which requires **megahertz frequencies** to generate diagnostically useful images with adequate detail. *< 2 MHz* - Frequencies below 2 MHz, while technically ultrasound (>20 kHz), are generally **below the diagnostic range** for most clinical applications. - Although lower frequencies offer better tissue penetration, frequencies below 2 MHz provide **insufficient spatial resolution** for standard diagnostic medical imaging.

Question 1277: What is an X-ray artifact?

A. A radiographic finding that indicates disease pathology
B. A normal anatomical structure visible on X-ray
C. An image distortion produced when the patient moves during the X-ray procedure
D. An unwanted image distortion that doesn't represent actual anatomy (Correct Answer)

Explanation: ***An unwanted image distortion that doesn't represent actual anatomy*** - An **X-ray artifact** is any feature or distortion on a radiographic image that is not present in the actual object being imaged. - These can arise from various sources such as patient movement, equipment malfunction, or improper technique, leading to **misinterpretation** of the image. - Artifacts are unwanted findings that can obscure true pathology or mimic disease. *A normal anatomical structure visible on X-ray* - This describes a **true anatomical finding**, which is the intended purpose of an X-ray. - Normal anatomical structures are expected and assist in diagnosis, unlike artifacts which obscure or mimic pathology. *An image distortion produced when the patient moves during the X-ray procedure* - While **patient motion** is a common cause of X-ray artifacts, this describes just one specific type (motion artifact), not a comprehensive definition of what an artifact is. - Other sources like metallic objects, scatter radiation, or detector issues can also cause artifacts. *A radiographic finding that indicates disease pathology* - This describes **true pathology** or disease findings, which is what radiologists aim to identify. - Artifacts are the opposite - they are false findings that do not represent actual anatomy or pathology.