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Quantitative Evaluation of Renal Function Using Dynamic MRI

  • Mri
  • Gd-Dtpa
  • レノグラム
  • Gfr
  • Ndc:492.4
  • Mathematics
  • Physics


A study of quantitative analysis of renal function using dynamic-enhanced MR Imaging was performed on a 1.5T superconducting MR system. To determine the best suitable pulse sequence and dose of Gd-DTPA to injection, preliminary study using phantom was done before clinical application. As the aim of this study was quantitative evaluation, S/N ratio and contrast resolution were most important factors to decide pulse sequence. Consequently, spin echo technique (TR/TE=200/15, INEX, 128×128) was adopted without respiratory suspension. Eleven patients with slightly impaired renal function and 12 patients with grafted kidney were included in this clinical study. Time-intensity curve of renal parenchyma obtained by dynamic MRI (=MRI renogram) was intended to mathematical analysis. First, 2 compartment model was established for washout of Gd-DTPA Then a formula as below can be formed for expressing theoretical time-intensity curve. X(t)=A・ex exp (-k1・t)+B・exp(-k2・t)-C・exp(-k3・t) The parameters of A, B, C and k1, k2, k3 can be figure out by calculation of measured data by means of nonlinear least squares method. A new parameter (named MRI-GFR), expressed in formula as below, was settled for representing GFR. MRI-GFR=k1・k2/A・k1+B・k2 The MRI-GFR was correlated well with GFR obtained by renogram using ^<99m>Tc-DTPA (correlation coefficient: r=0.901). As a conclusion, MRI renogram was useful to calculate GFR by using of mathematical analysis.

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