Fig. 1

a Diagram showing the left shoulder in external rotation. Using the anteroinferomedial approach, the target needle crosses the subscapularis (SubScp) muscle (yellow star) while the rotator cuff interval (green star) lies between supraspinatus (SSp) and subscapularis (SubScp) muscles. The long head of the biceps tendon (blue asterisks) courses in the bicipital groove and is displaced laterally away from target site for the needle. b Sagittal T1-weighted TSE fat-suppressed MR arthrography image showing rotator interval anatomy. Anatomic structures are overlaid by different transparent colors. Rotator interval (red) lies between subscapularis tendon anteriorly (green), and supraspinatus tendon posteriorly (orange). Long head of biceps brachii tendon (blue) traverses the rotator interval on its course from the bicipital-labral anchor to the bicipital groove. c Coronal T1-weighted TSE fat-suppressed MR arthrography image shows rotator interval (red transparent triangle), inferiorly limited by subscapularis tendon (asterisk), and superiorly by supraspinatus tendon (not shown). d Axial T1-weighted TSE fat-suppressed MR arthrography through rotator interval shows long head of biceps brachii tendon (arrow), and coracohumeral ligament (arrowhead)