Which imaging technique is primarily used to evaluate heart motion?

M-mode is specifically designed for assessing cardiac motion, making it the most effective choice for evaluating the heart's movement. This technique uses ultrasound to produce a one-dimensional view that captures rapid changes in heart structure over time, offering a detailed time-motion graph of the moving structures within the heart. This allows practitioners to assess the motion of heart walls, chambers, and valves, which is critical in diagnosing various cardiac conditions.

Other options, like A-mode, primarily provide a single-dimensional view used mainly in various diagnostic ultrasound applications, and are not suited for evaluating motion. Endoscopy, while useful for visualizing internal organs, does not pertain to cardiac assessment, and Magnetic Resonance Imaging, although it can visualize cardiac function, is less specialized for direct assessment of heart motion compared to M-mode ultrasound.