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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]

2 Previous Year Questions with Answers & Explanations

Questions

All Subjects Biochemistry (3)Community Medicine (33)Dermatology (1)Internal Medicine (14)Obstetrics and Gynecology (33)Orthopaedics (2)Pathology (2)Pediatrics (2)Pharmacology (4)Physiology (2)Psychiatry (1)Radiology (2)Surgery (15)

Endoluminal probe for transrectal ultrasonography operates at the frequency of:

A Seldinger needle is used for: