Assessment of Sacroiliitis Using Zero Echo Time Magnetic Resonance Imaging: A Comprehensive Evaluation

Abstract

Objective The aim of this study was to assess the effectiveness of zero echo time (ZTE) MRI in identifying structural lesions in patients with enthesitis-related arthritis (ERA), a subset of juvenile idiopathic arthritis (JIA) known for frequent sacroiliac (SI) joint involvement. Conventional MRI pulse sequences often struggle to adequately visualize osseous and calcified tissues. Methods All MRI examinations were conducted using a 1.5 T scanner. The MRI protocol included standard sequences such as fat-suppressed axial T2-weighted, axial T1-weighted, coronal short tau inversion recovery (STIR), and axial T2-weighted sequences. In addition to conventional MRI, a ZTE sequence was employed. Low-dose CT (ldCT) served as the reference standard and was performed using a 640-multislice CT device. Structural lesions, including erosions, sclerosis, and changes in joint space, were compared between imaging modalities. Results A total of 20 patients were included in the study (12 boys, 8 girls), with a median age at diagnosis of 14.1 years. ZTE-MRI demonstrated similar sensitivity to ldCT in detecting erosion (7 vs 8, p = 0.707). The interclass correlation coefficient (ICC) between ldCT and ZTE-MRI was 0.993 (p < 0.001), indicating excellent agreement. Moreover, ZTE-MRI showed strong agreement with ldCT in detecting sclerosis (ICC = 0.954, p < 0.001) and changes in joint space (ICC = 0.998, p < 0.001). Conclusions ZTE imaging shows promise in providing sacroiliac joint visualization comparable to ldCT scans, thereby improving the detection of subtle erosion and sclerosis in these joints.