Background: Interstitial nephritis is a common cause of renal failure. Gallium-67 scintigraphy is reportedly useful for diagnosing interstitial nephritis; however, its ability to assess disease activity remains unknown. We aimed to analyze the relationship between the renal uptake of gallium-67 and the disease activity in interstitial nephritis.
Methods: We retrospectively analyzed the data of patients who underwent gallium-67 scintigraphy at a hospital in Tokyo. The renal uptake adjusted for the soft tissues beneath the kidneys was semi-quantitatively evaluated. We compared the renal uptake levels between patients clinically diagnosed with and without interstitial nephritis. Among those undergoing renal biopsy, we evaluated the predictive ability of gallium-67 scintigraphy and analyzed the renal uptake levels regarding the disease activity through a histopathological analysis.
Results: We included 143 patients; among them, 30, 17, and 96 patients were clinically diagnosed with interstitial nephritis, other kidney diseases, and non-kidney diseases, respectively. The renal uptake of gallium-67 was the highest among patients with interstitial nephritis. Among the 25 patients who underwent renal biopsy, 15 were pathologically diagnosed with interstitial nephritis. The renal uptake levels showed a high discriminative ability (C-statistic: 0.83). Furthermore, net reclassification improvement with the addition of gallium-67 scintigraphy to N-acetyl-β-D-glucosaminidase for the prediction of interstitial nephritis was 1.14. Histopathological analysis revealed a positive correlation between renal uptake and inflammation in the cortex and peritubular capillaries.
Conclusions: This study confirmed the diagnostic value and potential usefulness of gallium-67 scintigraphy for evaluating interstitial nephritis.
Keywords: Biopsy; Clinical epidemiology; Gallium-67 scintigraphy; Interstitial nephritis; Radionuclide imaging.
© 2022. The Author(s), under exclusive licence to The Japanese Society of Nephrology.