title: Determination of glomerular filtration rate per unit renal volume using computerized tomography: correlation with conventional measures of total and divided renal function.
abstract: OBJECTIVE
  Previous studies suggest that functional computerized tomography (CT) can measure glomerular filtration rate (GFR) per unit renal volume. We compared this index with conventionally determined GFR measurements.
  
  
  METHODS
  A total of 16 men and 8 women 63.3 +/- 14.9 years old (range 31 to 88) were studied using with contrast enhanced CT. A single slice of kidney was scanned sequentially after bolus injection (0.5 to 1.0 ml. per second(-1)) of 20 ml. iopamidol (300 mg. iodine per ml.(-1)). GFR per volume of kidney was calculated using a Patlak graphical analysis, and this index was multiplied by renal volume on CT to yield global GFR (ml. per minute(-1)). Divided function was also calculated. GFR and divided renal function were calculated in all cases from radioisotope renography with 99m diethylenetetraminepentaacetic acid. In 12 subjects in whom 24-hour urine collection was possible GFR was also calculated from creatinine clearance.
  
  
  RESULTS
  A strong correlation was observed between divided renal function, expressed with respect to the right kidney calculated from CT (52.7 +/- 14.8%, range 19.9% to 97.4%) and by radioisotope renography (51.7 +/- 14.6%, range 18.9% to 92.6%, r = 0.97, p <0.0001). A strong correlation (r = 0.92, p <0.0001) was also seen between global GFR determined by CT (80.1 +/- 43.9 ml. per minute(-1), range 38.2 to 197.9) and creatinine clearance (72.4 +/- 47.5, range 14.6 to 168.5), and was stronger than the correlation between the radioisotope and creatinine clearance method (r = 0.67, p = 0.02) in the same patients.
  
  
  CONCLUSIONS
  Functional CT using nonionic contrast material can measure GFR normalized to renal volume and is an accurate alternative to conventional methods of renal function evaluation.
authors.affiliation: Departments of Radiology and Urology, Motojima General Hospital and Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Hospital, Gunma, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tsushima
authors.forename: M J
authors.initials: MJ
authors.lastname: Blomley
authors.forename: K
authors.initials: K
authors.lastname: Okabe
authors.forename: K
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: J
authors.initials: J
authors.lastname: Aoki
authors.forename: K
authors.initials: K
authors.lastname: Endo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000502:physiology*; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D011866:Radioisotope Renography; D014057:Tomography, X-Ray Computed