AI Article Synopsis
- A new method to calculate contrast agent concentration from MR signal intensity in T(1)-weighted MR renography studies was developed and validated using a Gd-DTPA-doped water phantom.
- The method demonstrated no bias for concentrations between 0 and 1 mM and showed better accuracy compared to traditional relative signal calculations.
- It successfully measured contrast concentrations in kidney tissues of patients, showing similar behaviors for Gd-DTPA and (99m)Tc-DTPA, with minimal errors in concentration due to signal noise.
Article Abstract
A method for calculating contrast agent concentration from MR signal intensity (SI) was developed and validated for T(1)-weighted MR renography (MRR) studies. This method is based on reference measurements of SI and relaxation time T(1) in a Gd-DTPA-doped water phantom. The same form of SI vs. T(1) dependence was observed in human tissues. Contrast concentrations calculated by the proposed method showed no bias between 0 and 1 mM, and agreed better with the reference values derived from direct T(1) measurements than the concentrations calculated using the relative signal method. Phantom-based conversion was used to determine the contrast concentrations in kidney tissues of nine patients who underwent dynamic Gd-DTPA-enhanced 3D MRR at 1.5T and (99m)Tc-DTPA radionuclide renography (RR). The concentrations of both contrast agents were found to be close in magnitude and showed similar uptake and washout behavior. As shown by Monte Carlo simulations, errors in concentration due to SI noise were below 10% for SNR = 20, while a 10% error in precontrast T(1) values resulted in a 12-17% error for concentrations between 0.1 and 1 mM. The proposed method is expected to be particularly useful for assessing regions with highly concentrated contrast.
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