title: Quantitative residual cortical activity measurement: appropriate test for diagnosis of renal artery stenosis?
abstract: OBJECTIVE
  To evaluate the diagnostic validity of quantitative measurement of residual cortical activity (RCA) in renal artery stenosis (RAS).
  
  
  METHODS
  In 45 patients with a high clinical likelihood of renovascular hypertension (RVH) and unimpaired renal function, dynamic imaging was performed after an intravenous bolus injection of 148 MBq (99m)Tc MAG3 for both baseline renoscintigraphy and captopril renography following oral application of 50 mg captopril. RCA was measured according to the Sfakianakis method: RCA = cortical counts at 20 min/counts at peak x100%. An increase in RCA of >/=5% from baseline was considered indicative of RAS. After renography, all patients underwent selective transfemoral angiography with the digital subtraction technique. A luminal reduction of >/=50% was considered as proof of RAS.
  
  
  RESULTS
  The number of kidneys that had a change of >/=5% in RCA values was 12 (27.2%) in normal kidneys, 7 (58.3%) in the patients with bilateral RAS, 14 (82.3%) in the patients with unilateral RAS, and 21 (72.4%) in overall kidneys with RAS. The positive test ratio in pathologic groups was significantly higher than normal (p < 0.05). The sensitivity and specificity of the RCA test were 72.4 and 72.7%, respectively; the positive and negative predictive values were 63.6 and 80%, respectively.
  
  
  CONCLUSIONS
  Quantitative measurements of RCA can be used as a diagnostic parameter of renal artery stenosis and may contribute of the diagnostic accuracy of visual interpretation and other renographic diagnostic criteria.
authors.affiliation: Department of Nuclear Medicine, University Hospital, Maastricht, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Gezici
authors.forename: A
authors.initials: A
authors.lastname: Ersay
authors.forename: E
authors.initials: E
authors.lastname: Antevska
authors.forename: G K
authors.initials: GK
authors.lastname: Heidental
authors.forename: G
authors.initials: G
authors.lastname: Schreij
authors.forename: O C
authors.initials: OC
authors.lastname: Demirtas
mesh_terms: D000792:Angiography; D000806:Angiotensin-Converting Enzyme Inhibitors; D002216:Captopril; D005260:Female; D006801:Humans; D006978:Hypertension, Renovascular / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D007275:Injections, Intravenous; D007672:Kidney Cortex / Q000098:blood supply / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011866:Radioisotope Renography; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D012077:Renal Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D012078:Renal Artery Obstruction / Q000150:complications / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017263:Technetium Tc 99m Mertiatide / Q000008:administration & dosage; D014661:Vasoconstriction / Q000187:drug effects
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D019275:Radiopharmaceuticals; D017263:Technetium Tc 99m Mertiatide; D002216:Captopril