**Core Concept**
The investigation of choice for acoustic neuroma, a type of non-cancerous tumor that affects the eighth cranial nerve (vestibulocochlear nerve), is a critical diagnostic tool. **Magnetic Resonance Imaging (MRI)** of the internal auditory canal and cerebellopontine angle is essential for visualizing the tumor's size, location, and relationship to surrounding structures.

**Why the Correct Answer is Right**
MRI is preferred over computed tomography (CT) scans because it provides better soft-tissue resolution, allowing for more accurate tumor detection and assessment. **T2-weighted and T1-weighted images** with gadolinium enhancement are particularly useful in identifying the tumor and distinguishing it from other lesions. The **internal auditory canal and cerebellopontine angle** are the primary areas of interest for acoustic neuroma visualization.

**Why Each Wrong Option is Incorrect**
**Option A:** CT scans are less sensitive for detecting acoustic neuromas, especially in the early stages, due to limited soft-tissue resolution.
**Option B:** Positron emission tomography (PET) scans are not typically used for diagnosing acoustic neuromas, as they are more useful for detecting cancerous lesions.
**Option C:** Angiography may be used to evaluate the tumor's relationship to surrounding blood vessels but is not the primary investigation for acoustic neuroma diagnosis.

**Clinical Pearl / High-Yield Fact**
When considering the investigation of choice for acoustic neuroma, remember that **MRI is the preferred imaging modality** due to its superior soft-tissue resolution and ability to accurately visualize the tumor.

**Correct Answer: C. Angiography may be used to evaluate the tumor's relationship to surrounding blood vessels but is not the primary investigation for acoustic neuroma diagnosis.