Rotator cuff assessment on imaging

Abstract

The rotator cuff is a group of four muscles and tendons surrounding the shoulder joint providing it strength and stability. The rotator cuff consists of the subscapularis, supraspinatus, infraspinatus and teres minor. Many shoulder complaints are caused by rotator cuff pathology such as impingement syndrome, tendon tears and other diseases e.g. calcific tendonitis. Diagnosis starts with clinical history and physical examination, after which imaging is often used to help confirm clinical findings depending on the differential diagnosis. The aim of the article is to review the frequently used imaging modalities to assess the rotator cuff and cuff-related disease, specifically focusing on radiography, ultrasonography and magnetic resonance imaging. This article will outline the advantages and disadvantages for each modality and illustrate typical radiological findings of common rotator cuff pathologies.

Keywords: Imaging; MRI; Rotator cuff tendons; Shoulder pain; Ultrasound.

Fig. 1

AP radiograph of the right shoulder. This projection provides a general overview of the shoulder joint and hence is typically included in any standard shoulder radiograph. It is useful for evaluation of fractures or frank dislocation.

Fig. 2

Axillary view of a right shoulder. This projection is centered on the glenohumeral joint and is useful in detection of more subtle anterior or posterior dislocations.

Fig. 3

AP projection of the right shoulder take in external rotation. This projection is useful in detection of any glenohumeral joint arthritis or humeral head fractures.

Fig. 4

AP projection of the right shoulder taken in internal rotation. Note that the lesser tuberosity (yellow arrow) is seen en face. This projection allows evaluation for Hill-sachs deformity.

Fig. 5

AP radiograph. There is inferolateral tilt of the acromion (blue line) with osteophytes at the inferior surface of the ACJ (yellow arrow) causing reduction in subacromial space.

Fig. 6

(a) Axillary projection of a right shoulder demonstrating a zig-zag lucency between the acromion and main body of scapula (yellow arrow), this is an os acromiale and should not be confused as a fracture which is typically a straight non-corticated lucency. (b) Coronal CT of the same patient’s right shoulder confirming an os acromiale. Note the absence of any fat stranding which also makes this less likely to be secondary to an acute fracture.

Fig. 7

AP radiograph of a left shoulder with an avulsion fracture of the greater tuberosity at the site of the supraspinatus attachment (yellow arrow).

Fig. 8

AP radiograph of a right shoulder demonstrating superior migration of the humeral head with a reduction in the subacromial space (yellow arrow) in keeping with a ‘high riding’ shoulder.

Fig. 9

AP radiograph. Curvilinear, homogenous calcific deposit projected over the supraspinatus tendon (yellow arrow).

Fig. 10

Axillary radiograph. Calcific deposit projected anterior to the lesser tuberosity of the humeral head. This is a case of subscapularis calcific tendinosis (yellow arrow).

Fig. 11

AP radiograph of the left shoulder obtained for shoulder pain. Note the large soft tissue opacity projected over the left lung apex (yellow arrow) representing a pancoast tumour.

Fig. 12

AP radiograph. Subtle sclerotic lesion in the metaphysis of the proximal humerus (yellow arrow). Metastatic bone disease in a patient with known prostate carcinoma.

Fig. 13

Modified axillary radiograph. Significant reduction of the glenohumeral joint space with subchondral sclerosis (yellow arrows). Osteophyte formation is noted at the inferior articular margin of the humerus (green arrow).

Fig. 14

AP radiograph. Moderate reduction of the acromioclavicular space with subchondral sclerosis (yellow arrow) and cyst formation (green arrow).

Fig. 15

AP radiograph. Large, peri-articular erosions of the humeral head. Further erosion of the distal clavicle with widening at the ACJ. Advanced rheumatoid disease.

Fig. 16

AP radiograph. Cortical irregularity with erosion of the distal clavicle (yellow circle). Post-traumatic distal clavicle osteolysis. Note there is also lateral ‘down-sloping’ of the acromion.

Fig. 17

US image of a normal supraspinatus (SST) tendon which typically appears hyperechoic with fibrillar echo patterns. Note the curvilinear hypoechogenicity within the tendon secondary to anisotropy and should not be confused for a tear. The humeral head bony cortex appears echogenic with posterior acoustic shadowing (yellow arrowheads). The overlying hyaline cartilage appears uniformly hypoechoic (green arrow). The overlying deltoid muscle typically appears relatively hypoechoic to normal tendons.

Fig. 18

US image of a supraspinatus (SST) tendon with full-thickness tear at the footprint (yellow arrow) with retraction (blue arrow) to the level of the humeral head.

Fig. 19

US image of the humeral head in sagittal plane. No tendon is seen at the expected attachment site of supraspinatus (yellow arrow) and infraspinatus (green arrow) tendons. There is depression of the overlying deltoid muscle into the tendon defect (white arrows).

Fig. 20

US image of a supraspinatus tendon with partial thickness tear at its footprint (yellow arrow) extending to the articular surface. Note that the bursal surface remains intact (red arrowheads).

Fig. 21

US image of a thickened supraspinatus tendon with heterogenous echogenicity throughout consistent to moderate tendinosis. There is no tear within this tendon.

Fig. 22

US image demonstrating amorphous echogenicities (yellow arrows) with posterior acoustic shadowing within the supraspinatus tendon representing calcific deposit within the tendon.

Fig. 23

(a) US image of the long head of biceps tendon (blue arrow) in transverse axis demonstrating moderate biceps tendon sheath effusion (yellow). (b) US image of the long head of biceps tendon in longitudinal axis (blue arrow) with increased Doppler flow signal indicating acute tenosynovitis.

Fig. 24

(a) US image demonstrating a thickened subacromial bursa (blue arrow). (b) US-guided injection of the subacromial bursa. The needle appears as a linear hyperechoic structure (red arrows) with its tip within the subacromial bursa which is now distended with injectate fluid (yellow arrow) usually consisting of steroid and local anaesthetic mixture.

Fig. 25

Axial PD-FS plain MR of the right shoulder without intra-articular contrast administration at the level of the subscapularis tendon. Note that the structures are in close proximity to each other in the absence of any effusion or contrast administration to distend the joint.

Fig. 26

Fluoroscopic spot image of a right shoulder arthrogram. Note the iodine-based contrast has flown into the glenohumeral joint (yellow arrow) confirming correct intra-articular needle position.

Fig. 27

Axial T1-FS MR Arthrogram of the left shoulder of a different patient. Note that the joint capsule is distended with contrast which helps separate structures in the area to aid with interpretation.

Fig. 28

Plain shoulder MRI of different patients. (a) Coronal PD-FS MR a right shoulder demonstrating mild bursal thickening and excess fluid in the subacromial bursa (yellow arrows) representing subacromial bursitis. Note mild to moderate underlying supraspinatus tendinosis, no tear. (b) Sagittal T1 image of another shoulder demonstrating a prominent inferior acromial enthesophyte (red arrow) indenting onto the supraspinatus myotendinous junction (green curve line) leading to reduced subacromial space and impingement.

Fig. 29

Plain shoulder MR of different patients. (a) Coronal PD-FS MR a right shoulder demonstrating intermediate signal in the distal supraspinatus tendon (yellow circle) representing mild tendinosis without cuff tear. Note that the signal is not as high as seen in a rotator cuff tear. (b) Axial T2-FS of a left shoulder demonstrating a thickened subscapularis with intermediate signal in keeping with moderate tendinosis without tear (orange circle).

Fig. 30

(a). Coronal T2 FS plain MR of the right shoulder demonstrates curvilinear high signal at the articular side of the supraspinatus tendon medially involving between 25 and 50% of tendon thickness, in keeping with an articular-sided grade 2 partial thickness tear of the supraspinatus tendon. Fig. 30. (b) and (c) Coronal and Sagittal T2-FS plain MR of the left shoulder of a different patient demonstrates a curvilinear high signal at the bursal side of the mid-portion of the supraspinatus tendon (blue arrow) involving approximately 50% of tendon thickness, in keeping with a high grade bursal-sided partial thickness tear of the supraspinatus tendon.

Fig. 31

(a) and (b) Coronal and sagittal T2-FS MR of the right shoulder demonstrates high signal throughout the distal supraspinatus tendon without any appreciable tendon fibre representing a full-thickness tear (rupture) of the supraspinatus tendon. Note the tendon retraction (blue arrow) to the level of the humeral head. Note the loss of normal convex contour of the supraspinatus tendon representing full-thickness tear (green arrow). There is also high signal extending posteriorly into the infraspinatus tendon signifying tear extension into the infraspinatus tendon (yellow arrow).

Fig. 32

(a) and (b) Sagittal T1 MR of the shoulder through the medial border of the coracoid process (Y-shaped view) demonstrating a normal supraspinatus muscle belly bulk lying above the green line drawn between the superior border of the scapular spine and medial coracoid (negative tangent sign). The occupation ratio is calculated by dividing the surface area of the supraspinatus muscle belly (blue shaded area) by the supraspinatus fossa surface area (yellow shaded area). The occupation ratio here is normal (>0.6). Fig. 32. (c) and (d) Sagittal T1 MR of another patient’s shoulder demonstrating supraspinatus atrophy. The supraspinatus belly is below the green line drawn between the superior border of the scapular spine and medial coracoid (positive tangent sign). Note the amount of fatty replacement within the supraspinatus belly (green arrow) representing at least a Goutallier stage 3 fatty degeneration. The occupation ratio here is < 0.4 indicating stage 3 (severe) atrophy. Note that there is also mild infraspinatus atrophy and stage 2 fatty degeneration (yellow arrow).

Fig. 33

(a) and (b) Coronal and sagittal PD-FS MR of the left shoulder demonstrating a low signal body (yellow arrow) within the posterior supraspinatus tendon near the conjoint tendon. On MR alone, appearances are non-specific and can represent underlying tendinosis or calcification. (c) Corresponding AP radiograph of the left shoulder of the same patient confirming calcification within the supraspinatus tendon (blue arrow). This case highlights importance of correlating MR findings with radiographic features.