Improved grading method of 99m Tc-dimercaptosuccinic acid static renal imaging helps predict the prognosis of urinary tract infection in children.

Objective: This study aimed to refine the 99m Tc-dimercaptosuccinic acid (Tc-99m DMSA) renal static imaging (DMSA) rating method and evaluate its prognostic value in children with urinary tract infections (UTIs) associated with vesicoureteral reflux (VUR).

Methods: Retrospective analysis was conducted on DMSA data (DMSA1 at the initial visit and DMSA2 at follow-up; imaging interval ≥ 6 months) and clinical data from 117 children. Each kidney was divided into three regions: upper, middle, and lower. Lesions were graded in a blinded manner based on the distribution of the imaging agent and whether the defect area exceeded 50% of the region. Lesion grades were classified as 0 (normal) to 5 (complete defect). DMSA2 ratings were categorized as complete recovery, improvement, similar, or deterioration, and clinical factors influencing each group were analyzed.

Results: A total of 160 diseased kidneys were identified in 117 children. The DMSA1 and DMSA2 image ratings were highly consistent (kappa coefficients: 0.806, 0.839, 0.813, 0.820 for left and right kidneys, respectively). A statistically significant difference in image ratings was observed between DMSA1 and DMSA2 when DMSA1 rating was ≥3b. Changes in DMSA2 ratings were associated only with the initial DMSA1 rating and the presence of breakthrough urinary sensation at follow-up.

Conclusion: Image changes were related solely to breakthrough urinary sensation. When the initial DMSA lesion grade exceeds 3b, improvement in the lesion is unlikely, regardless of subsequent breakthrough urinary sensation. The modified DMSA rating method is effective and can predict prognosis in children with UTIs.