**1. Introduction**

Imaging modalities play a significant role in the evaluation of tendon pathology. Knowledge of anatomical landmarks of the tendons is of utmost importance in order to differentiate and accurately diagnose pathologic processes. Ultrasound (US) and Magnetic Resonance Imaging (MRI) are currently the imaging modalities of choice to evaluate tendon pathology, each with its own unique advantages as diagnostic tools. Tendons are characteristically seen as echogenic fibrillar structures on US and as homogeneous hypointense structures on MRI.

This chapter focuses on the key imaging features of tendons in US and MRI modalities, with emphasis on the shoulder, elbow, hand, hip, knee and foot joints. Each chapter section will provide a review of the anatomical landmarks, normal US and MRI appearance, imaging protocols, and discussion of common pathology affecting the tendons in each joint.

### **2. Shoulder**

### **2.1 MRI protocol**

The patient is positioned supine with the arm at the side in neutral position or slight external rotation in order to put some tension on the long head of the biceps tendon. A small field of view (approximately 14–16 cm) is obtained in three imaging planes: axial, coronal oblique, and sagittal oblique. The axial images are acquired from the top of the acromioclavicular joint through the proximal humeral shaft

including the insertion of the pectoralis muscle. The coronal oblique images are obtained with planes made parallel to the supraspinatus tendon or in a plane perpendicular to the articular surface of the glenoid, ranging from the coracoid process to the infraspinatus muscle. Finally, the sagittal oblique images are acquired with planes parallel to the articular surface of the glenoid, from the scapular neck through the lateral aspect of the humerus [1]. A standard shoulder MRI usually includes sagittal oblique T1-weighted image (T1WI), fast spin echo (FSE) T2-weighted image (T2WI) with fat suppression, coronal oblique FSE T2WI with fat suppression, and axial FSE T2WI and FSE proton density (PD) with fat suppression.
