Which of the following can not be evaluated with a tissue-equivalent phantom?

• A. Axial resolution
• B. Lateral resolution
• C. Contrast resolution
• D. Temporal resolution

Answer: (D)

Temporal resolution concerns how quickly the system can acquire and display frames, i.e., the frame rate determined by pulsing, data acquisition, processing, and display speed. A tissue-equivalent phantom is designed to mimic the acoustic properties of human tissue and provides static, reproducible targets to test spatial characteristics and contrast. You can use such a phantom to evaluate axial resolution by testing the system’s ability to separate echoes along the beam path, lateral resolution by examining side-to-side detail, and contrast resolution by different echogenicities. But because the phantom is static, it cannot simulate motion or rapid frame updates. Temporal resolution requires dynamic testing or measuring the scanner’s frame rate under operation, often with moving targets or dynamic phantoms. Therefore, temporal resolution cannot be evaluated with a tissue-equivalent phantom.