**Core Concept:** Diagnostic imaging techniques for detecting prostate cancer (Ca) involve various modalities that assess prostate gland characteristics. PSA (Prostate Specific Antigen) is a blood test used for screening and monitoring prostate cancer, but not for detection. MRI (Magnetic Resonance Imaging) and CT (Computed Tomography) scan are advanced imaging techniques used for diagnosis and staging, but they are not specific to prostate detection. DSA (Digital Subtraction Angiography) is an imaging technique primarily used for diagnosing vascular diseases, not prostate cancer. Transrectal Ultrasound (TRUS) is a targeted imaging technique that uses ultrasound waves to visualize the prostate gland and detect abnormalities.

**Why the Correct Answer is Right:** TRUS is the most suitable option among the given choices for detecting prostate cancer as it directly visualizes the prostate gland, enabling the identification of tumor size, location, and other morphological features. TRUS is a non-invasive, cost-effective, and readily available technique. It can assess the prostate gland and detect enlargement, nodules, or suspicious areas which can be further investigated.

**Why Each Wrong Option is Incorrect:**

A. PSA: A blood test that measures prostate-specific antigen levels, which can indicate prostate cancer but is not a direct imaging technique for detecting the tumor.

B. MRI and CT scan: While MRI and CT scans are powerful diagnostic tools, they are not specifically designed for prostate cancer detection. They may show prostate enlargement but lack the ability to directly visualize the prostate gland.

C. DSA: Digital Subtraction Angiography is an imaging technique used for diagnosing vascular diseases, not prostate cancer detection.

D. Transrectal Ultrasound (TRUS): TRUS is the most suitable option among the given choices for detecting prostate cancer as mentioned above. However, TRUS has limitations, such as reduced sensitivity in detecting early-stage cancers and its dependence on the skill and experience of the interpreter.

**Clinical Pearl:** In suspected prostate cancer cases, a combination of PSA testing and TRUS can be used for a comprehensive diagnostic approach. However, TRUS should be interpreted by experienced radiologists to optimize the accuracy of the results.

**Correct Answer:** TRUS (Transrectal Ultrasound) is the correct answer among the given options.