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Korean J Radiol. 2017 Jul-Aug;18(4):585-596. doi: 10.3348/kjr.2017.18.4.585. Epub 2017 May 19.

Influence of B1-Inhomogeneity on Pharmacokinetic Modeling of Dynamic Contrast-Enhanced MRI: A Simulation Study.

Park B1,2, Choi BS3, Sung YS1,2, Woo DC1,2, Shim WH1,2, Kim KW1,2, Choi YS1,2, Pae SJ4, Suh JY1,2, Cho H5, Kim JK1,2.

Author information

1
Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea.
2
Center for Bioimaging of New Drug Development, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea.
3
Department of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Korea.
4
Department of Surgery, National Health Insurance Service Ilsan Hospital, Goyang 10444, Korea.
5
Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea.

Abstract

OBJECTIVE:

To simulate the B1-inhomogeneity-induced variation of pharmacokinetic parameters on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

MATERIALS AND METHODS:

B1-inhomogeneity-induced flip angle (FA) variation was estimated in a phantom study. Monte Carlo simulation was performed to assess the FA-deviation-induced measurement error of the pre-contrast R1, contrast-enhancement ratio, Gd-concentration, and two-compartment pharmacokinetic parameters (Ktrans, ve, and vp).

RESULTS:

B1-inhomogeneity resulted in -23-5% fluctuations (95% confidence interval [CI] of % error) of FA. The 95% CIs of FA-dependent % errors in the gray matter and blood were as follows: -16.7-61.8% and -16.7-61.8% for the pre-contrast R1, -1.0-0.3% and -5.2-1.3% for the contrast-enhancement ratio, and -14.2-58.1% and -14.1-57.8% for the Gd-concentration, respectively. These resulted in -43.1-48.4% error for Ktrans, -32.3-48.6% error for the ve, and -43.2-48.6% error for vp. The pre-contrast R1 was more vulnerable to FA error than the contrast-enhancement ratio, and was therefore a significant cause of the Gd-concentration error. For example, a -10% FA error led to a 23.6% deviation in the pre-contrast R1, -0.4% in the contrast-enhancement ratio, and 23.6% in the Gd-concentration. In a simulated condition with a 3% FA error in a target lesion and a -10% FA error in a feeding vessel, the % errors of the pharmacokinetic parameters were -23.7% for Ktrans, -23.7% for ve, and -23.7% for vp.

CONCLUSION:

Even a small degree of B1-inhomogeneity can cause a significant error in the measurement of pharmacokinetic parameters on DCE-MRI, while the vulnerability of the pre-contrast R1 calculations to FA deviations is a significant cause of the miscalculation.

KEYWORDS:

Brain; Dynamic contrast enhancement; Magnetic resonance imaging; Monte Carlo method; Phantoms, imaging

PMID:
28670153
PMCID:
PMC5447634
DOI:
10.3348/kjr.2017.18.4.585
[Indexed for MEDLINE]
Free PMC Article

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