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Figure 1a.  Patient positioning with MR and US imaging. (a) Oblique coronal proton-density–weighted MR image obtained with the arm at the side and in neutral position shows relatively limited exposure of the rotator cuff (arrows in a–d) lateral to the acromion (A in a–d). (b) US image obtained with the arm at the side, palm up, similarly demonstrates relatively limited exposure of the cuff lateral to the shadowing acromion. (c) Oblique coronal proton-density–weighted MR image obtained with the arm in external rotation shows greatly increased exposure of the cuff lateral to the acromion. (d) Extended-field-of-view US image obtained with the hand positioned behind the back demonstrates increased exposure of the cuff lateral to the shadowing acromion.