Assessment of sacroiliitis using zero echo time magnetic resonance imaging: a comprehensive evaluation

Enthesitis-related arthritis (ERA), a subset of juvenile idiopathic arthritis (JIA), is characterized by frequent involvement of the sacroiliac (SI) joints.

The aim of this study was to assess the effectiveness of zero echo time (ZTE) magnetic resonance imaging (MRI) in identifying structural lesions in patients with ERA. Conventional MRI pulse sequences often struggle to adequately visualize osseous and calcified tissues.

All MRI examinations were conducted using a 1.5-T (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 computed tomography (CT) 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.

A total of 20 patients were included in the study (12 boys, 8 girls), with a median age at diagnosis of 14 years. ZTE-MRI demonstrated similar sensitivity to low-dose CT in detecting erosion (7 vs 8, P = 0.707). The interclass correlation coefficient (ICC) between low-dose CT and ZTE-MRI was 0.993 (P < 0.001), indicating excellent agreement. Moreover, ZTE-MRI showed strong agreement with low-dose CT in detecting sclerosis (ICC = 0.954, P < 0.001) and changes in joint space (ICC = 0.998, P < 0.001).

Zero echo time imaging shows promise in providing sacroiliac joint visualization comparable to low-dose CT scans, thereby improving the detection of subtle erosion and sclerosis in these joints.