Study group
This prospective study was approved by the local Ethics Committee of our institution.
Verbal and written informed consent was obtained from each patient.
- Twenty-two subjects (female,
13; male,
9; right,
12; left,
10; mean age,
37.9±16.6 years; body mass index (BMI),
23.5±3.7 kg/ m2) were classified as normal group upon clinical and ultrasound assessment.
- Twenty-six subjects (female,
20; right,
15; left,
11; male,
6; mean age,
49.31±14.66 years; BMI,
29.73±5.86 kg/ m2) were classified as patients goup with Achilles tendinosis.
For the normal group,
inclusion criteria were: no history of ankle injury,
no surgery,
no infection or chronic disease.
Exclusion criteria include a history of Achilles tears or major ankle trauma.
For patients group,
inclusion criteria were: chronic tendinopathy and mid-portion tendinosis of the Achilles tendon.
Exclusion criteria were peritendinitis,
rupture and traumatic Achilles pathology.
The general exclusion criteria for normal and patient group were claustrophobe subjects and pregnant women.
Clinical examination
The clinical and ultrasound assessment were performed by a musculoskeletal radiologist with 20 years of experience in musculoskeletal ultrasound.
Ultrasound was performed in longitudinal and transverse orientation using color Doppler mode.
Morphological MR protocol of AT includes sagittal Turbo Spin Echo Protons Density Fat-Sat sequence (TSE PD FS) and axial TSE PD FS sequence. For relaxation times quantification,
we used a sagittal 3D FLASH variable flip angle gradient echo UTE sequence (3D VFA-GE UTE) and a sagittal multi-echo gradient echo sequence (MEGE) for T1 and T2* mapping,
respectively. Table 1 shows the scanning parameters.
Data analysis
Morphologic evaluation of tendons was performed on sagittal and axial TSE PD FS images by a radiologist expert in musculoskeletal MRI (20 years of experience) to classify AT diseases and to confirm the inclusion and exclusion criteria for all subjects.
The evaluation was done using Siemens workstation with syngo software.
T1 and T2* values were measured on three regions of interest (ROI) (insertion tendon (INS),
mid-portion (MID),
and musculotendinous junction (MJT)) drawn within each AT (Figure 1).
The length of each region is defined as a third of the total AT length,
measured from the most proximal to the most distal [4].
T1 and T2* relaxation times values were quantified using two self-developed algorithms written in MATLAB (MATLAB 2014).
The analysis algorithm is executed offline on sagittal images obtained with our quantitative T1 and T2* protocol.
T1 and T2* maps are calculated on a voxel-by-voxel basis.
Statistical analysis
A paired sample T-test was realized to calculate mean and SD of T1 and T2* relaxation times values and to compare the difference between groups.
Person correlation analysis was performed to compare T1 and T2* values of AT for the normal and patients group.
Correlation coefficients r indicates very strong correlation (r = 0.80 to 1.00),
strong correlation (r =0.60 to 0.79),
moderate correlation (r = 0.40 to 0.59),
weak correlation (r = 0.20 to 0.39) or no correlation (r<0.20).
We have drawn T1 and T2* curves and we performed linear regression on each of these plots.
The slope of each regression line was used as an indicator of the dynamic range for each parameter.
Then,
we calculated the coefficient of determination (R²) where R² equal to 1 related to very high correlation.
Statistical evaluation was performed with SPSS 15.0 (SPSS,
Chicago,
Illinois,
USA).
P value of less than 0.05 was considered to be statistically significant.