title: The use of gallium-67 scintigraphy in the diagnosis of acute interstitial nephritis.
abstract: BACKGROUND
  Gallium-67 scintigraphy has been suggested as a noninvasive method to diagnose acute interstitial nephritis (AIN). However, its diagnostic performance and usefulness remain controversial.
  
  
  METHODS
  We retrospectively reviewed the charts of 76 patients who underwent gallium-67 scintigraphy for a suspicion of AIN. Patients were classified based on kidney biopsy and/or clinical probability of AIN. Gallium-67 scintigraphy results were reinterpreted blindly using both posterior planar and single photon emission computed tomography (SPECT) imaging. Intensity of radioisotope uptake in the kidney was graded from 0 to 5.
  
  
  RESULTS
  The diagnosis of AIN was confirmed in 23 patients and excluded in 44. Nine patients with an uncertain diagnosis were excluded from subsequent analysis. A gallium-67 kidney uptake cutoff of 1 gave a negative predictive value of 100%, whereas a cutoff of 5 had an excellent specificity and positive predictive value for the diagnosis of AIN. When using a cutoff of 3, which had previously been used in the literature, we obtained a sensitivity of 61% and a specificity of 75% with posterior planar imaging. The results of both SPECT and posterior planar imaging modalities were comparable.
  
  
  CONCLUSIONS
  Gallium-67 scintigraphy may be of interest in patients with a clinical suspicion of AIN, especially in those who are unable to undergo kidney biopsy. However, results need to be interpreted with caution and depend on the intensity of gallium-67 kidney uptake.
authors.affiliation: Department of Allergy and Immunology, Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada; Department of Nephrology, Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montreal, QC, Canada.
authors.forename: François
authors.initials: F
authors.lastname: Graham
authors.affiliation: Department of Nuclear Medicine , Centre Hospitalier de l'Université de Montréal , Montreal, QC , Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Lord
authors.affiliation: Department of Nephrology , Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame , Montreal, QC , Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Froment
authors.affiliation: Department of Nephrology , Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame , Montreal, QC , Canada.
authors.forename: Héloise
authors.initials: H
authors.lastname: Cardinal
authors.affiliation: Department of Nephrology , Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame , Montreal, QC , Canada.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bollée
keywords: gallium scintigraphy; interstitial nephritis