**Core Concept:** Transrectal ultrasound (TRUS) is a diagnostic imaging technique that uses high-frequency sound waves to create images of the prostate gland, bladder, and surrounding structures. In medical practice, TRUS is particularly useful for evaluating patients with suspected prostate cancer.

**Why the Correct Answer is Right:** In the context of patients with suspected prostate cancer, TRUS is most useful for:

1. **Option A:** Visualizing the prostate gland and its surrounding structures, including the seminal vesicles, urinary bladder, and rectum. TRUS allows for precise localization and staging of prostate cancer.
2. **Option B:** Differentiating between benign prostatic hyperplasia (BPH) and prostate cancer. TRUS can help identify the extent and location of the enlarged prostate, which is crucial for proper diagnosis and treatment planning.
3. **Option C:** Assessing the prostate volume and shape, which is essential for evaluating prostate cancer risk factors and guiding surgery or radiation therapy planning.
4. **Option D:** Differentiating between prostate cancer and other benign prostatic diseases, as mentioned above. TRUS can help differentiate between BPH, prostate cancer, and other benign prostatic conditions.

**Why Each Wrong Option is Incorrect:**

5. **Option D:** While TRUS can help differentiate between prostate cancer and other benign prostatic diseases, it cannot definitively diagnose prostate cancer. Additional tests, such as prostate-specific antigen (PSA) levels and digital rectal examination (DRE), are often necessary for accurate diagnosis.
6. **Option E:** TRUS is not specific enough to differentiate between prostate cancer and other malignant tumors, such as urethral or bladder tumors, that can present with similar symptoms and imaging findings.

**Clinical Pearl:** TRUS is a valuable tool in evaluating patients with suspected prostate cancer, as it helps in assessing prostate volume, shape, and identifying the presence and extent of prostatic lesions. However, TRUS alone is not enough to definitively diagnose prostate cancer, and a comprehensive approach involving PSA levels, DRE, and, if necessary, additional imaging modalities (e.g., MRI) is necessary for accurate diagnosis and treatment planning.