Zero-echo time MRI: an alternative method for the diagnosis of urinary stones in children.

Objectives: To evaluate the potential of zero-echo time-magnetic resonance imaging (ZTE-MRI) in the assessment of urolithiasis and compare ZTE-MRI with computed tomography (CT) in pediatric patients.

Materials and methods: This was a single-center, prospective cross-sectional study conducted between April 2023 and December 2023. 23 patients (12 girls, 11 boys; mean age: 12.3, range 1-18) with urinary tract stones detected on non-enhanced abdominal CT were enrolled. The images were evaluated independently by two radiologists for the presence, and number of stones in the kidneys, ureters, and bladder. In the second session, two radiologists evaluated whether urinary tract stones could be detected by MRI compared to CT, and the maximum diameter of the stones was measured. The CT and MRI results were compared with the Wilcoxon test. The agreement between the results of the observers was examined using Spearman's rho correlation coefficient and the intraclass correlation coefficient.

Results: A total of 58 urinary tract stones were detected by CT and 39 of these were detected by MRI. Most of the stones that MRI could not detect were < 5 mm and the detection sensitivity of MRI increased in correlation with stone size (p < 0.001). There was poor intermodality agreement for stones < 5 mm, substantial agreement for stones 5-10 mm, and almost perfect agreement for stones > 10 mm. Interobserver agreement for stone detection on MRI was almost perfect for stones > 10 mm and 5-10 mm and was substantial for stones < 5 mm.

Conclusion: ZTE-MRI is a promising modality for detecting urinary stones without radiation exposure in children.

Clinical relevance statement: Zero-echo time-magnetic resonance imaging is a potential method for identifying urinary stones in children and other populations who are particularly sensitive to radiation.

Key points: Urinary system stone disease in children is increasing and imaging is needed for managing urolithiasis. Zero-echo time-magnetic resonance imaging (ZTE-MRI) had an accuracy of 81.8% and 93.7% for stones larger than 5 mm and 10 mm, respectively. ZTE-MRI is a potential non-irradiating method for the diagnosis and management of urolithiasis.