Table 1
Description of US procedures for capturing image and movie sequences of FD, NV, CAs and TT
| (1) FD: FD was defined as a clear collagen fascicle discontinuity or irregularity of fibrils in an otherwise regular parallel structuring of fibres in the tendon. A GS picture in the longitudinal axis of the supraspinatus was taken at the sight where FD was most apparent (FD picture). The FD static image was used for classifying the presence of FD. A GS PA dynamic movie sequence (PA movie) in the longitudinal plane of the supraspinatus tendon was captured by moving the transducer slowly in the PA direction. Further, a CC transversal GS dynamic movie sequence (CC movie) of the supraspinatus tendon was recorded by moving the transducer slowly in the CC direction. The static image and the movie sequence recordings were used as confirmation and assistance in assessing the grade of structural changes, and to secure identification of potential ambiguous GS features, such as anisotropy (erroneous signal caused when the transducer is angled obliquely to the tendon). FD was classified in relation to tendon thickness as: 0=normal, 1=mild, 2=moderate, 3=severe, 4=partial rupture (table 2). |  Grade 2 FD |
| (2) NV: NV was defined as a visualised PD signal with minimal artefactual noise. The supraspinatus tendon was evaluated for presence of NV by moving the transducer slowly in the PA direction, with the PD feature activated. In case NV was present, a 10 s dynamic movie sequence was recorded at the point with most NV signal (PD movie). When grading NV from the PD movie sequence, a static image of the location with the most visible NV was captured from the PD movie. A ROI (5×5 mm) was placed around the NV and used for grading NV. In participants with no NV, a movie sequence was recorded at a random location in the tendon to verify absence of NV. NV was classified in relation to ROI as 0=normal, 1=mild, 2=moderate, 3=severe, 4=extreme (table 2). |  Grade 2 NV |
| (3) CA: CA was defined as distinct white borders, imbedded in the length of the tendon, often with ‘shadows’ underneath. The PA movie was used to identify the number of CA in the tendon and to measure the length of each CA in the longitudinal axis of the supraspinatus. The length was measured between the most medial and lateral aspects of the distinct white boarder (in mm). The CC movie was used as confirmation and assistance in identifying CA. CA was counted and measured (mm). To obtain the total length of CA, the individual CA lengths were added up to one total per participant. |  CA length measure |
| (4) TT: TT was defined as the height, from the humeral head, at a point 20 mm from the supraspinatus tendon-snip (tendon insertion) in the longitudinal axis of the tendon, to the most superficial part of the tendon. In practice, an image was captured at a fixed point just laterally from the anterior-lateral corner of the acromion in the longitudinal plane of the supraspinatus. When measuring TT, a mark was placed 20 mm cranial from the supraspinatus tendon-snip (tendon insertion), on the edge of the cartilage of the humeral head. From that mark, the perpendicular thickness of the tendon was recorded.18 The TT picture was recorded bilaterally. TT was measured in mm. |  TT measure |
CA, calcification; CC, caudal–cranial; FD, fibrillar disruption; GS, grey-scale; NV, neovascularity; PA, posterior–anterior; PD, Power Doppler; ROI, Region of interest; TT, tendon thickness.