Detection of partial-thickness supraspinatus tendon tears: is a single direct MR arthrography series in ABER position as accurate as conventional MR arthrography?

Abstract

Purpose: The purpose of this study was to retrospectively evaluate sensitivity and specificity of a single magnetic resonance (MR) arthrography series in abduction external rotation (ABER) position compared with conventional MR arthrography for detection of supraspinatus tendon tears, with arthroscopy as gold standard, and to assess interobserver variability.

Materials and methods: Institutional review board approval was obtained; informed consent was waived. MR arthrograms of 250 patients (170 men and 80 women; mean age, 36 years) were retrospectively and independently evaluated by three observers. Oblique coronal T1-weighted fat-suppressed images, proton density, and T2-weighted images and axial T1-weighted images and oblique sagittal T1-weighted fat-suppressed images were analyzed to detect supraspinatus tendon tears. Separately, a single T1-weighted fat-suppressed oblique axial series in ABER position was evaluated. Both protocols were scored randomly without knowledge of patients' clinical history and arthroscopy results. Tears were subclassified, based on articular surface integrity and extension (Lee classification). Interobserver agreement was assessed by kappa statistics for all patients. Ninety-two of 250 patients underwent arthroscopy; sensitivity and specificity of ABER and conventional MR arthrography were calculated and compared using paired McNemar test.

Results: Weighted kappa values of ABER and conventional MR arthrography were 0.48-0.65 and 0.60-0.67, respectively. According to arthroscopy, 69 of 92 patients had an intact cuff, and 23 patients had a cuff tear (16 partial thickness and seven full thickness). There were no statistically significant differences between ABER and conventional MR arthrography regarding sensitivity (48-61% and 52-70%, respectively) and specificity (80-94% and 91-95%).

Conclusion: Sensitivity and specificity of a single T1-weighted series in ABER position and conventional MR arthrography are comparable for assessment of rotator cuff tears.

Fig. 1

Classification of the horizontal component of partial-thickness supraspinatus tendon tears according to Lee et al. [13], based on the ABER position. Schematic illustration of the anatomy of the glenohumeral joint in ABER position. 1 humeral head, 2 glenoid, 3 acromion. Detail illustrations (a–d) demonstrate: a intact supraspinatus tendon (arrows). b–d Classification of the horizontal component of partial-thickness tears of the supraspinatus tendon: b tear without articular surface abnormality (type A), c tear with irregularity of the articular surface (type B), and d tear with torn edge of the articular surface (type C)

Fig. 2

Arthroscopically proven partial-thickness supraspinatus tendon tear, type A. T1-weighted fat suppressed turbo spin echo (TSE) MR arthrography image in an oblique axial plane with the arm positioned in abduction and exorotation (ABER), obtained in a 40-year-old man, shows an example of a type A horizontal partial-thickness tear (arrow) without articular surface abnormality of the supraspinatus tendon

Fig. 3

Arthroscopically proven partial-thickness supraspinatus tendon tear, type B. Oblique axial T1-weighted FS TSE MR arthrography image in ABER position shows a type B horizontal partial-thickness tear with irregularity of the articular surface of the tendon near the insertion on the humerus (arrow)

Fig. 4

Arthroscopically proven partial-thickness supraspinatus tendon tear, type C Oblique axial T1-weighted FS TSE MR arthrography image in ABER position, obtained in a 57-year-old man, shows a type C partial-thickness tear (arrow) with a torn edge (asterisk) of the articular surface of the tendon

Fig. 5

Example of disagreement between ABER and conventional MR arthrography in the classification of an arthroscopically proven partial-thickness tear: a oblique coronal T1-weighted FS TSE MR arthrography image in neutral position shows subtle irregularity (arrow) of the articular surface of the supraspinatus tendon (type B). b oblique axial T1-weighted FS TSE MR arthrography image in ABER position of the same patient shows a significant partial-thickness tear of the supraspinatus tendon (arrow) with a torn edge of the articular surface (type C)