Which statement is most accurate regarding resolution with a standard one-dimensional linear array transducer?

• A. A axial resolution is the worst measure with this type of transducer
• B. B lateral resolution is the worst measure with this type of transducer
• C. C elevational resolution is the worst measure of resolution with this type of transducer
• D. D isotropic spatial resolution is achieved

Answer: (C)

Resolution in ultrasound has three directions: axial, lateral, and elevational. A standard one-dimensional linear array forms a narrow beam within the imaging plane, so axial (along the beam) and lateral (across the beam in the plane) resolutions can be relatively good because they’re governed by pulse length and beam width within that plane. The elevational direction, which is perpendicular to the imaging plane and represents slice thickness, is determined by the physical height of the transducer elements and the amount of elevational focusing. This dimension is typically larger and less well controlled, so elevational resolution tends to be poorer. Because the elevational dimension limits the ability to distinguish structures out of the plane, isotropic spatial resolution—having the same detail in all directions—is not achieved with a standard 1D linear array.