Axial resolution refers to the smallest distance that can exist between two objects along the direction of the ultrasound beam while still being displayed as separate structures on the image. It is determined primarily by the spatial pulse length, which is related to the frequency of the transducer: higher frequency transducers produce shorter pulses and therefore better axial resolution. For example, a 10 MHz transducer can distinguish structures that are closer together than a 3 MHz transducer can. Axial resolution is always better than lateral resolution in ultrasound, and understanding this relationship helps sonographers choose the appropriate transducer frequency for each examination to balance resolution with the depth of penetration needed.
Sonography Term