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

• A. Axial resolution is the worst measure of resolution with this type of transducer
• B. Lateral resolution is the worst measure of resolution with this type of transducer
• C. Elevational resolution is the worst measure of resolution with this type of transducer
• D. Isotropic spatial resolution is achieved

Answer: (C)

Resolution in ultrasound has three relevant directions: axial (along the beam), lateral (across the beam in the imaging plane), and elevational (perpendicular to the imaging plane). A standard one-dimensional linear array forms the image by steering and focusing in the plane of the array, so axial and lateral resolution can be optimized with shorter pulses and beam focusing. The elevational dimension, however, is set largely by the physical height (thickness) of the transducer elements and is difficult to focus or modify after emission, resulting in a thicker slice and poorer elevational resolution. Isotropic spatial resolution, where all directions have equal detail, isn’t achieved with a 1D array because it cannot provide uniform focusing in the elevational direction. Therefore, elevational resolution is the weakest dimension for this type of transducer.