Which resolution is best evaluated with a phantom containing multiple rows of identical 5 mm spherical fluid-filled structures embedded in tissue-mimicking material?

Which resolution is best evaluated with a phantom containing multiple rows of identical 5 mm spherical fluid-filled structures embedded in tissue-mimicking material?

• A. Axial
• B. Lateral
• C. Contrast
• D. Elevation

Answer: (D)

Elevation resolution is the ability to distinguish two structures that are separated in the slice thickness direction of the ultrasound beam. In this phantom, the identical 5 mm spherical fluid-filled targets are arranged in multiple rows across the elevational (slice) dimension. If the transducer’s elevational resolution is good, those rows will be seen as separate, distinct lines; if it’s poor, the rows will blur together as one. The 5 mm size gives a clear target to judge how close two objects can be while still appearing separate in the elevational direction. This setup specifically probes the thickness dimension of the beam, rather than the axial (along the beam) or lateral (in-plane side-to-side) dimensions, or contrast resolution.

Elevation resolution is the ability to distinguish two structures that are separated in the slice thickness direction of the ultrasound beam. In this phantom, the identical 5 mm spherical fluid-filled targets are arranged in multiple rows across the elevational (slice) dimension. If the transducer’s elevational resolution is good, those rows will be seen as separate, distinct lines; if it’s poor, the rows will blur together as one. The 5 mm size gives a clear target to judge how close two objects can be while still appearing separate in the elevational direction. This setup specifically probes the thickness dimension of the beam, rather than the axial (along the beam) or lateral (in-plane side-to-side) dimensions, or contrast resolution.