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Intravoxel incoherent motion diffusion-weighted MR imaging of the liver: effect of triggering methods on regional
Yedaun Lee1, Seung Soo Lee, Namkug Kim
1From the Department of Radiology and Research Institute of Radiology (Y.L., S.S.L., N.K., E.K., Y.J.K., S.H.P., S.Y.K., M.G.L.) and Department of Clinical Epidemiology and Biostatistics (S.C.Y.), University of Ulsan College of Medicine, Asan Medical Center, 86 Asanbyeongwon-Gil, Songpa-Gu, Seoul 138-736, South Korea; Siemens AG, Healthcare, Oncology Applications Development, Erlangen, Germany (B.K.); and Siemens Healthcare Korea, Seoul, South Korea (I.S.K.).
Purpose:
To compare the influence of triggering methods for diffusion-weighted imaging (DWI) on apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) parameters in the liver, as well as regional variability and measurement repeatability.
Materials And Methods:
In this institutional review board-approved prospective study, 12 healthy volunteers (six women, six men; mean age, 30 years) underwent 1.5-T DWI of the liver by using nine b values twice with free breathing (FB) without triggering (mean acquisition time ± standard deviation, 3.7 minutes ± 0), respiratory triggering (RT) (mean acquisition time, 6.8 minutes ± 1.4), and echocardiography triggering (ET) (mean acquisition time, 8.3 minutes ± 2.0) after providing written informed consent. ADC and IVIM parameters, including pure diffusion coefficient (D), perfusion fraction (f), and perfusion-related diffusion coefficient (D*), were measured by using 15 regions of interest (ROIs). Regional variability of ADC and IVIM parameters and measurement repeatability were evaluated by using the coefficient of variation (CV) across ROIs and within-subject CV, respectively.
Results:
ET DWI (range of CV across ROIs, 6.69%-20.0%) resulted in significantly decreased regional variability of ADC, D, and f, compared with FB DWI (13.86%-35.8%) and RT DWI (15.15%-35.91%, P ≤. 049). ET DWI showed better repeatability of ADC measurement (within-subject CV range, 3.17%-4.12% for ET DWI; 4.15%-4.74% for FB DWI; and 2.33%-6.96% for RT DWI), D (4.05%-5.34% for ET DWI, 4.11%-12.51% for FB DWI, and 3.19%-16.17% for RT DWI), and f (7.6%-9.86% for ET DWI, 13.83%-16.81% for FB DWI, and 10.05%-12.10% for RT DWI), compared with FB DWI and RT DWI, with significant differences in within-subject CV for D in the left hepatic lobe compared with RT DWI (P = .023) and for f compared with FB DWI (P ≤ .032). For all three imaging techniques, D* showed the worst repeatability (within-subject CV, 57.05%-156.61%) among ADC and IVIM parameters.
Conclusion:
ET DWI is more effective for decreasing regional variability of ADC and IVIM parameters than FB DWI or RT DWI; it may improve measurement repeatability by reducing cardiac motion-induced measurement error.
Insights
Echocardiography triggering (ET) for diffusion-weighted imaging (DWI) significantly reduces liver parameter variability and improves measurement repeatability compared to free breathing (FB) or respiratory triggering (RT). This technique enhances apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) analysis.
Area of Science:
- Medical Imaging
- Radiology
- Biophysics
Background:
- Diffusion-weighted imaging (DWI) is crucial for liver assessment.
- Apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) parameters provide insights into liver tissue microstructure and function.
- Respiratory motion artifacts can impact the accuracy and repeatability of liver DWI measurements.
Purpose of the Study:
- To compare the effectiveness of different triggering methods—free breathing (FB), respiratory triggering (RT), and echocardiography triggering (ET)—on liver DWI.
- To evaluate the influence of these triggering methods on ADC and IVIM parameters (D, f, D*).
- To assess regional variability and measurement repeatability of liver DWI parameters across different triggering techniques.
Main Methods:
- Prospective study involving 12 healthy volunteers undergoing 1.5-T liver DWI.
- DWI was performed twice using nine b values under FB, RT, and ET conditions.
- ADC and IVIM parameters were measured in 15 regions of interest (ROIs); regional variability and repeatability were assessed using coefficient of variation (CV).
Main Results:
- ET DWI significantly reduced regional variability of ADC, D, and f compared to FB and RT DWI (P ≤ .049).
- ET DWI demonstrated superior repeatability for ADC, D, and f measurements compared to FB and RT DWI.
- D* exhibited the poorest repeatability across all triggering methods (within-subject CV, 57.05%-156.61%).
Conclusions:
- Echocardiography triggering (ET) is more effective in reducing regional variability of liver ADC and IVIM parameters than FB or RT DWI.
- ET DWI may enhance measurement repeatability by mitigating cardiac motion-induced errors.
- These findings suggest ET DWI as a valuable technique for more accurate liver microstructural and functional assessment.
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