The study investigates the relationship between renal medullary pyramidal thickness (PT), parenchymal thickness, and differential renal function (DRF) in children with unilateral hydronephrosis, particularly focusing on cases with a PT of 3 mm or less, which is often linked to increased risk for ureteropelvic junction (UPJ) obstruction and pyeloplasty. Conducted as a retrospective review of ultrasound and nuclear renal scans (MAG3) in 98 children with grade 3 and 4 unilateral hydronephrosis, the research aimed to evaluate how these ultrasound measurements correlate with the renal function as determined by the MAG3 scan. The results indicate that no kidneys with a PT greater than 3 mm or a parenchymal thickness above 5 mm exhibited a DRF below 40%, with significant findings highlighting that 17% of kidneys with a PT of 3 mm or less and 18% with a parenchymal thickness of 5 mm or less demonstrated a DRF <40%. Additionally, a weak positive correlation was identified between the ratio of PT in the hydronephrotic kidney compared to the non-hydronephrotic kidney and its corresponding DRF, suggesting that these ultrasound metrics could be beneficial in selecting patients for further renal scanning. The study concludes that maintaining a PT above 3 mm and a parenchymal thickness above 5 mm is associated with preserving a relative renal function greater than 40%, thus supporting the utility of ultrasound assessments in pediatric patients with hydronephrosis while minimizing unnecessary radiation exposure from nuclear imaging.
November 4, 2024
