title: Excretory urography and renal scintigraphy for chronic obstructed kidney: does nonopacity mean nonsalvageability?
abstract: BACKGROUND
  This study aimed to ascertain whether nonopacified kidney on excretory urography (also known as intravenous urography [IVU]) indicates nonsalvageability.
  
  
  METHODS
  We retrospectively reviewed 45 adult patients with chronic unilateral urinary tract obstruction, in whom IVU revealed nonopacified kidney on one side but normal excretion on the contralateral side. Affected kidneys with split glomerular filtration rate (GFR) < 10 mL/min/1.73 m2 on 99mTc-diethylenetriaminepentaacetic acid diuretic renal scintigraphy were considered nonsalvageable. Non-function was defined based on cutoff points (< 15% and < 20%) to determine the sensitivity and specificity of differential renal function. Differences in IVU and renal scintigraphy findings, with respect to the duration of delayed filming on IVU, were analysed for significance.
  
  
  RESULTS
  The results of IVU and renal scintigraphy findings for 34 (75.6%) nonopacified kidneys matched, representing nonsalvageable kidneys. Sensitivity and specificity of differential renal function were 76% and 100%, respectively, when the cutoff point for non-function was set at < 15%. Sensitivity and specificity were 97% and 82%, respectively, when the cutoff point was < 20%. There was no significant difference between renal scintigraphy findings and IVU with 2-hour and > 2-hour delayed films (p = 0.96).
  
  
  CONCLUSIONS
  Although most nonopacified kidneys on IVU were nonsalvageable, a quarter of them were found to be salvageable on renal scintigraphy. Besides split GFR, differential function at cutoff point < 15% could be used to determine non-function of a chronic obstructed kidney when the contralateral kidney is normal. Delayed filming beyond two hours appears unnecessary in ensuring non-excretion on IVU.
authors.affiliation: Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand. aklaipet@med.cmu.ac.th
authors.forename: Alisa
authors.initials: A
authors.lastname: Klaipetch
authors.forename: Sirianong
authors.initials: S
authors.lastname: Namwongprom
authors.forename: Molrudee
authors.initials: M
authors.lastname: Ekmahachai
authors.forename: Bannakij
authors.initials: B
authors.lastname: Lojanapiwat
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging; D007674:Kidney Diseases / Q000000981:diagnostic imaging / Q000628:therapy*; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D004369:Pentetic Acid; D011866:Radioisotope Renography / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013667:Technetium; D016896:Treatment Outcome; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging / Q000628:therapy*; D014567:Urography / Q000379:methods*
chemical_list: D013667:Technetium; D004369:Pentetic Acid