Sectoral sign is positive in ?
**Core Concept**
The sectoral sign is a radiological finding related to the **pulmonary embolism (PE)**, specifically referring to a pattern seen on ventilation-perfusion scans. It is used to diagnose PE by identifying areas of the lung that are ventilated but not perfused, indicating a blockage of blood flow.
**Why the Correct Answer is Right**
The correct answer is related to the diagnosis of **pulmonary embolism**. In a ventilation-perfusion scan, a sectoral sign is positive when there is a wedge-shaped area of decreased perfusion, which corresponds to the distribution of a specific **pulmonary artery branch**. This pattern suggests a blockage of that artery, likely due to an embolus.
**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because it does not relate to the specific pattern of perfusion defect seen in pulmonary embolism.
**Option B:** Similarly, this option does not accurately describe the sectoral sign.
**Option D:** This choice is also incorrect as it does not correspond to the definition of the sectoral sign in the context of pulmonary embolism diagnosis.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the sectoral sign, when positive, is highly suggestive of **pulmonary embolism**, especially when correlated with clinical symptoms and other diagnostic findings. Recognizing this sign can aid in the timely diagnosis and management of PE.
**Correct Answer:** D. Pulmonary Embolism