Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which imaging technique is recommended for diagnosing an acoustic neuroma?

1. X-ray

2. CT scan

3. MRI

4. Ultrasound

The correct answer is: MRI

The recommended imaging technique for diagnosing an acoustic neuroma is MRI, or magnetic resonance imaging. This is due to several reasons. Firstly, MRI provides detailed images of the brain and surrounding structures, including the cranial nerves where an acoustic neuroma typically develops. Acoustic neuromas, which are benign tumors affecting the vestibulocochlear nerve (cranial nerve VIII), can be small and difficult to detect with less sensitive imaging techniques. Secondly, MRI is superior in differentiating soft tissue types and can show the location, size, and extent of the tumor more clearly than other modalities. It allows for a better evaluation of the relationship between the tumor and critical structures in the brain, which is essential for planning any potential surgical intervention. In contrast, while CT scans can be useful, they typically involve exposure to radiation and may not provide the same level of detail for soft tissue as MRI, especially for inner ear and cerebellopontine angle lesions where acoustic neuromas are commonly found. X-rays provide insufficient detail regarding soft tissue structures and are generally not useful for diagnosing tumors in the brain. Ultrasound tends to be more effective for evaluating superficial structures rather than deep-seated tumors like acoustic neuromas. These factors collectively highlight MRI as