UTE T2* mapping of tendinopathic patellar tendons: an MRI reproducibility study

Abstract

Background There is currently a lack of imaging modalities that can be used as a sensitive measure in tendinopathy. Recent findings suggest the applicability of ultra-short echo time (UTE) magnetic resonance imaging (MRI) T2* mapping in tendons, but the reproducibility remains unknown. Purpose To evaluate test–retest reproducibility of UTE MRI T2* mapping of tendinopathic patellar tendons and to evaluate the intra- and inter-observer reproducibility of the measurement. Material and Methods Fifteen patients with chronic patellar tendinopathy were evaluated with UTE MRI twice in a 3.0-T scanner on the same day. Manual segmentation of the patellar tendon was performed by two blinded investigators and automated T2*map reconstruction was performed in custom-made software. Results There was a significant and numerically small difference in test–retest T2* values (T2*meandiff = 0.06 ± 0.07 ms ≈ 3.7%; P = 0.006) with an ICC = 0.91 (95% confidence interval [CI] 0.58–0.98; typical error of 3.0%). The intra- and inter-observer reproducibility showed no significant bias ( P = 0.493 and P = 0.052), and generally substantial reproducibility was demonstrated for T2* (intra-observer ICC = 0.99; 95% CI 0.98–1.00 and inter-observer ICC = 0.99; 95% CI 0.96–1.00, and typical error 1.3% and 1.3%, respectively). Conclusion These data demonstrate a small bias between repeated measurements for UTE T2*, but with a very low associated mean difference (3.7%) between the two tests. The high ICC values and low typical error % demonstrate reproducibility of repeated T2*-mapping sessions. Further, the method showed substantial intra- and inter-observer reproducibility for T2* values proving feasibility for use of UTE T2* mapping in research and clinical practice.

Magnetic Resonance T2* Is Increased in Patients With Early‐Stage Achilles and Patellar Tendinopathy

“…This was, however, expected since this patient group represents less severe disease. When comparing values obtained from protocols with similar TE range and spacing, and comparable fitting algorithms, a general pattern suggests higher values in tendinopathic compared to healthy tendons 16, 23 . Few studies have directly compared T 2 * in healthy and chronic tendinopathic tendons in vivo.…”

“…The UTE scans were analyzed according to a previously described protocol 16 . In brief, UTE recordings with varying TEs were automatically loaded into a custom‐made program, and all TEs were combined, and signal intensity was plotted against TE on a voxel‐by‐voxel basis.…”

Mechanical properties and UTE‐T2* in Patellar tendinopathy: The effect of load magnitude in exercise‐based treatment

“…Tendon biopsies can provide useful structural and biochemical information, however, its invasive nature precludes repeated measurements 20 . Alternatively, non‐invasive MRI ultra‐short time to echo (UTE) imaging with T2* mapping of tendon is a reproducible method, 21 which has been proposed to correlate with collagen structure and water content in tendons 22,23 . The method is based on UTE recordings with varying short echo times (TE), which can be used to calculate the T2* by plotting the signal intensity against the TE 21 .…”

“…Alternatively, non‐invasive MRI ultra‐short time to echo (UTE) imaging with T2* mapping of tendon is a reproducible method, 21 which has been proposed to correlate with collagen structure and water content in tendons 22,23 . The method is based on UTE recordings with varying short echo times (TE), which can be used to calculate the T2* by plotting the signal intensity against the TE 21 . However, it is unknown if MRI UTE T2* mapping can be a suitable non‐invasive methodology to evaluate subtle changes in tendon over time, which need to be explored.…”

No Additive Clinical or Physiological Effects of Short-term Anti-inflammatory Treatment to Physical Rehabilitation in the Early Phase of Human Achilles Tendinopathy: A Randomized Controlled Trial

“…3,12,14 The UTE scans were analyzed according to a previously described protocol. 1 In short, UTE recordings with varying TE were automatically loaded into a custom-made program. TE was plotted against signal intensity on a voxel-by-voxel basis, and a mono-exponential fitting incorporating noise reduction was applied to reconstruct T2* and goodness-offit maps used for analyses.…”