It is a case-control study, conducted between October 2018 to October 2019, and included 35 OA patients (27 females and eight males; median age, 60 years; age range, 43–69 years). The study group had primary OA (n = 15) and secondary OA (n = 20) in the glenohumeral joint; and we used 30 patients as a control group (25 females and five males; median age, 46 years; age range, 30–56 years).
The ethical committee of our institution approved the study. Inclusion criteria included any patient with osteoarthritis detected by X-ray and graded by the same two musculoskeletal radiologists who later evaluate MRI. The Samilson Prieto method used for the X-ray grading [11, 12]: grade 0, normal; grade I, inferior humeral and/or glenoid exostosis, both measuring < 3 mm in size; grade II, inferior humeral and/or glenoid exostosis, > 3 and < 7 mm in height, with slight glenohumeral joint irregularity; grade III, an inferior humeral and/or glenoid < 7 mm in height, with narrowing the glenohumeral joint and sclerosis. The inclusion criteria of the control group were normal X-ray findings of the shoulder joint; they conducted MRI for many reasons, as 20 individuals had distal soft tissue swelling because of minor trauma and 10 had bone tumors. The exclusion criteria of both the control group and the OA patients were fracture, acute arthritis, history of previous shoulder joint operation, and any contraindication for MRI.
We made an MRI using a 1.5 T MR scanner (Signa; 16channel, Excite, GE Healthcare, Milwaukee, WI, USA). Conventional MR sequences included coronal oblique T2-weighted (T2W) images (repetition time/echo time, 3220/70 ms), coronal oblique T2W images with fat suppression (3230–3245/70 ms), coronal oblique T1-weighted images (630/10 ms), sagittal oblique T2W images (3360/80 ms), axial proton density-weighted images (3500/20 ms), and axial T2W images with fat suppression (3130/60 ms) with a shoulder coil. Field of view (FOV) 22 × 18 mm; matrix, 310 × 620; slice thickness, 4 mm and slice gap, 0.4 mm. Three coronal oblique data sets were evaluated through the shoulder to get T2 mapping by using multi-echo spin-echo with a TR of 2630 and seven TEs (13 ms, 26 ms, 39 ms, 52 ms, 65 ms, 88 ms, and 10 ms) . FOV 22 × 18 mm; matrix, 159 × 318; slice thickness, 3 mm; slice gap, 1 mm. The total acquisition time for T2 mapping was 5 min. We pre-processed the images with an automatic motion correction to remove any motion artifact. Our MR technologist created a colored T2 map using the default functions and software setting. The T2 maps contained 16–22 color coronal oblique images with basic parameters of the T2 intensity with default parameters of 25–75 ms. The color scale ranged from red to blue. To standardize segmentation, we identified the central slice of coronal oblique where the total volume of the cartilage was observed and the partial volume effect markedly decreased. We extracted T2 values from a mono-exponential fit to the signal decay curve for each voxel using commercially available software (PRIDE; Philips Medical Systems). The slice position was the same as that of the conventional MRI. We chose three areas to evaluate the glenohumeral cartilage: humeral zone (the most superior-lateral portion), glenoid zone (the most inferior portion of the glenoid cavity), and central zone (the central part of cartilage) by manually drawn region of interest (ROI) visually inspected on the sequences. ROIs were drawn keeping a margin between 0.5 and 1.1 mm from the bone surface to avoid the inclusion of a nearby subchondral bone. T2 map and a corresponding standard MRI were placed side by side, and a multi-planar localization key used on the picture archiving and communication system (PACS). The total time of segmentation ranged from 20 to 25 min.
We assessed T2 values by two independent musculoskeletal radiologists (one with 4 years of experience and the other with 2 years of experience in reading T2 mapping of the knee joint). We collected and compared individually all the readings of both the control group and the OA patients (primary and secondary) in the three zones (humeral, mid, and glenoid zone) were collected and compared individually; we compared a control group with both primary and secondary OA patients, and primary OA with secondary OA. Also, different zones were compared together. We made the comparisons by using Mann-Whitney U tests as the got T2 values deviated from a normal distribution. We statistically described T2 values in terms of mean ± standard deviation (±SD). The inter-observer reliability of the T2 value measurements was assessed using intra-class correlation coefficients (ICC), with ICC values of < 0.40, 040–0.75, and > 0.75 showing poor, good, and excellent agreement, respectively . We performed All statistical analysis using the commercial software (SPSS, version 25, SPSS Inc., Chicago, IL, USA). P values < 0.05 were considered statistically significant.