Reproducibility of spatial penalty-based methodologies for intravoxel incoherent motion analysis with diffusion MRI

Area of Science:

• Medical Imaging
• Radiology
• Oncology

Background:

• Intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) is a valuable technique for assessing tissue microenvironment.
• Conventional bi-exponential (BE) IVIM models face challenges in precision and reproducibility, particularly in dynamic studies like chemotherapy response assessment.
• Spatial penalty-based methods offer potential improvements in IVIM parameter estimation.

Purpose of the Study:

• To compare the precision and reproducibility of spatial penalty-based IVIM methods (BE+TV, BE+HPF) against conventional BE models.
• To evaluate IVIM parameter estimation (D, D*, f) in osteosarcoma patients undergoing neoadjuvant chemotherapy.
• To determine the efficacy of different IVIM fitting methodologies in clinical settings.

Main Methods:

• IVIM MRI was performed on 40 osteosarcoma patients at baseline, after 1 cycle, and after 3 cycles of chemotherapy using 11 b-values (0-800 s/mm²).
• Diffusion coefficient (D), perfusion coefficient (D*), and perfusion fraction (f) were estimated using five methods: BE, BESeg-2, BESeg-1, BE+TV, and BE+HPF.
• Within-subject (wCV) and between-subject (bCV) coefficients of variation were calculated for healthy muscle and tumor tissues to assess precision and reproducibility.

Main Results:

• BE+TV and BE+HPF methods demonstrated significantly lower wCV and bCV for D, D*, and f compared to conventional BE, BESeg-2, and BESeg-1 methods (p < 10⁻³).
• These improvements in precision and reproducibility were observed across all three time-points in both healthy muscle and tumor tissues.
• Spatial penalty-based methods showed substantially reduced variability in IVIM parameter estimation.

Conclusions:

• Spatial penalty-based IVIM analysis methods (BE+TV and BE+HPF) offer superior precision and reproducibility over conventional methods.
• These advanced IVIM techniques are well-suited for clinical applications, including monitoring treatment response in osteosarcoma.
• The improved reliability of BE+TV and BE+HPF enhances their utility in quantitative MRI studies.