Zero and ultra-short echo time and contrast-medium injection at 3-T to detect Achilles enthesitis and distinguish rheumatismal vs mechanical etiologies.

AIM: To evaluate ultra-short echo time (UTE) and zero echo time (ZTE) sequences vs conventional imaging, with/without contrast enhancement, for detecting abnormal signal intensities of the Achilles enthesis organ and distal tendon, discriminating spondyloarthropathy (SpA) from mechanical aetiologies, and detecting preclinical findings in asymptomatic SpA (asSpA) patients.

MATERIALS AND

METHODS

In this prospective single-centre study, 52 patients with asSpA or with hindfoot pains related to SpA or mechanical origins underwent 3-Tesla hindfoot magnetic resonance imaging (MRI) with fat-suppressed proton density-weighted imaging (PD-WI), UTE and ZTE between 2018 and 2023. Contrast-enhanced (CE) sequences comprised fat-suppressed CE-T1-WI, CE-UTE, and CE-ZTE. Four radiologists assessed, alone then in consensus pathological findings at the periost-fibrocartilage (PCa), sesamoid-fibrocartilage (SCa), enthesis-fibrocartilage (ECa), posterior side of the enthesis and Achilles tendon. Statistical analyses comprised McNemar's and Chi-squared tests, and Benjamini-Hochberg adjustments.

RESULTS

median age was 48.5 years (51.9% women). There were 16/52 (30.8%) asSpA patients, 19/52 (36.5%) symptomatic SpA (sySpA) patients and 17/52 (32.7%) 'mechanical' patients. The ZTE and CE-ZTE provided the highest detection rates for fibrocartilage abnormalities in SpA patients, outperforming PD-WI, particularly at the ECa (all SpA: 25.7% for ZTE vs 0% for PD-WI, P = 0.0383; all SpA: 42.4% for CE-ZTE vs 14.3% for CE-T1-WI, P = 0.0221). A total of 31.2% of asSpA patients showed abnormalities at the ECa on CE-ZTE, unseen on PD-WI, suggesting early enthesitis before symptom onset. Mechanical patients had more Achilles tendon involvement compared with SpA (P value range: 0.0348-0.0420), which was similarly detected with conventional MRI and UTE/ZTE (P > 0.05).

CONCLUSION

At 3-Tesla, ZTE, especially CE-ZTE, improve the detection of SpA-related Achilles enthesitis and may identify early, asymptomatic disease.