Determination of glomerular filtration rate (GFR) from fractional renal accumulation of iodinated contrast material: a convenient and rapid single-kidney CT-GFR technique
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To develop a convenient and rapid single-kidney CT-GFR technique.
One hundred and twelve patients referred for multiphasic renal CT and 99mTc-DTPA renal dynamic imaging Gates-GFR measurement were prospectively included and randomly divided into two groups of 56 patients each: the training group and the validation group. On the basis of the nephrographic phase images, the fractional renal accumulation (FRA) was calculated and correlated with the Gates-GFR in the training group. From this correlation a formula was derived for single-kidney CT-GFR calculation, which was validated by a paired t test and linear regression analysis with the single-kidney Gates-GFR in the validation group.
In the training group, the FRA (x-axis) correlated well (r = 0.95, p < 0.001) with single-kidney Gates-GFR (y-axis), producing a regression equation of y = 1665x + 1.5 for single-kidney CT-GFR calculation. In the validation group, the difference between the methods of single-kidney GFR measurements was 0.38 ± 5.57 mL/min (p = 0.471); the regression line is identical to the diagonal (intercept = 0 and slope = 1) (p = 0.727 and p = 0.473, respectively), with a standard deviation of residuals of 5.56 mL/min.
A convenient and rapid single-kidney CT-GFR technique was presented and validated in this investigation.
• The new CT-GFR method takes about 2.5 min of patient time.
• The CT-GFR method demonstrated identical results to the Gates-GFR method.
• The CT-GFR method is based on the fractional renal accumulation of iodinated CM.
• The CT-GFR method is achieved without additional radiation dose to the patient.
KeywordsTomography, X-ray computed Glomerular filtration rate Radioisotope renography Prospective studies Humans
Amount of CM accumulated in the kidney (in units of mgI)
Total amount of CM injected (in units of mgI)
GFR determined by the CT method
Conversion factor between iodine concentration and CT number enhancement
Fractional renal accumulation = CMk/CMtotal
GFR determined by the Gates method
Glomerular filtration rate
99mTc diethylenetriaminepentaacetic acid
We thank Mr. Kolo from Toshiba Medical Systems Corporation for English language editing.
Compliance with ethical standards
The scientific guarantor of this publication is Yuan XiaoDong.
Conflict of interest
The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
Statistics and biometry
One of the authors (Yuan XiaoDong) has significant statistical expertise.
Institutional review board approval was obtained.
Written informed consent was obtained from all subjects (patients) in this study.
• performed at one institution
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