A shoulder ultrasound is fast, cost-effective, and allows real-time dynamic imaging during movement, something MRI cannot provide. It is excellent for assessing tendons, bursae, and soft tissues. A shoulder MRI offers a more comprehensive view of all joint structures, including the labrum, cartilage, and bone marrow, and is better suited to complex pathology or where ultrasound findings are inconclusive. For most shoulder pain presentations, ultrasound is the recommended first-line investigation.