UPSC-CMS 2016 — Radiology

Q: Endoluminal probe for transrectal ultrasonography operates at the frequency of:

7.5 MHz. ***7.5 MHz*** * **Transrectal ultrasonography (TRUS)** typically utilizes frequencies between **7 and 10 MHz** to achieve a good balance of penetration depth and resolution in the prostate and surrounding tissues. * A frequency of **7.5 MHz** is commonly employed for detailed imaging of the prostate, allowing for clear visualization of anatomical structures and detection of abnormalities like tumors or inflammation. *5.0 MHz* * A frequency of **5.0 MHz** provides greater penetration depth but offers lower resolution, which is generally not optimal for the detailed imaging required in TRUS of the prostate. * Lower frequencies are more often used for imaging deeper structures or in situations where tissue attenuation is high, which is less of a concern for the relatively superficial prostate. *2.5 MHz* * A frequency of **2.5 MHz** offers significantly higher penetration but at the cost of very low resolution, making it unsuitable for the precise diagnostic imaging of the prostate gland. * This lower frequency range is typically used for general abdominal imaging or structures requiring deep penetration, where fine detail is not the primary concern. *15.0 MHz* * A frequency of **15.0 MHz** provides excellent resolution but has very limited penetration depth, making it less practical for comprehensive transrectal imaging of the entire prostate gland. * While high frequencies can be used for very superficial structures or specific applications requiring extremely fine detail, they often cannot visualize the entire organ effectively due to rapid attenuation. [Practice more Radiology PYQs on OnCourse]

Q: A Seldinger needle is used for:

Arteriography. ***Arteriography*** - The **Seldinger technique** involves using a needle to puncture a blood vessel, typically an artery, after which a guidewire is threaded through the needle. - This method is fundamental for inserting catheters for procedures like **arteriography**, which visualizes arteries using contrast. *Breast biopsy* - Breast biopsies typically use specialized biopsy needles (e.g., **core needle biopsy** or vacuum-assisted biopsy needles) designed to extract tissue samples. - These are distinct from the Seldinger needle, which is primarily for accessing blood vessels. *Lymphangiography* - Lymphangiography involves injecting contrast into **lymphatic vessels**, which are typically very fine and superficial. - This procedure usually employs fine-gauge needles or direct cannulation of lymphatic vessels, not the Seldinger needle which is designed for larger vessels. *Liver biopsy* - Liver biopsies are usually performed with a **Menghini needle** or other types of cutting needles that can obtain a core sample from the liver parenchyma. - The Seldinger needle is not designed for obtaining solid tissue biopsies from organs like the liver. [Practice more Radiology PYQs on OnCourse]

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Endoluminal probe for transrectal ultrasonography operates at the frequency of:

A Seldinger needle is used for:

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