Science and Research

Assessment of intravoxel incoherent motion MRI with an artificial capillary network: analysis of biexponential and phase-distribution models

PURPOSE: To systematically analyze intravoxel incoherent motion (IVIM) MRI in a perfusable capillary phantom closely matching the geometry of capillary beds in vivo and to compare the validity of the biexponential pseudo-diffusion and the recently introduced phase-distribution IVIM model. METHODS: IVIM-MRI was performed at 12 different flow rates ( 0.2 cdots, three dots, centered 2.4 m L / min ) in a capillary phantom using 4 different DW-MRI sequences (2 with monopolar and 2 with flow-compensated diffusion-gradient schemes, with up to 16 b values between 0 and 800 s / mm 2 ). Resulting parameters from the assessed IVIM models were compared to results from optical microscopy. RESULTS: The acquired data were best described by a static and a flowing compartment modeled by the phase-distribution approach. The estimated signal fraction f of the flowing compartment stayed approximately constant over the applied flow rates, with an average of f = 0.451 +/- 0.023 in excellent agreement with optical microscopy ( f = 0.454 +/- 0.002 ). The estimated average particle flow speeds v = 0.25 cdots, three dots, centered 2.7 mm / s showed a highly significant linear correlation to the applied flow. The estimated capillary segment length of approximately 189 u m agreed well with optical microscopy measurements. Using the biexponential model, the signal fraction f was substantially underestimated and displayed a strong dependence on the applied flow rate. CONCLUSION: The constructed phantom facilitated the detailed investigation of IVIM-MRI methods. The results demonstrate that the phase-distribution method is capable of accurately characterizing fluid flow inside a capillary network. Parameters estimated using the biexponential model, specifically the perfusion fraction f , showed a substantial bias because the model assumptions were not met by the underlying flow pattern.

  • Schneider, M. J.
  • Gaass, T.
  • Ricke, J.
  • Dinkel, J.
  • Dietrich, O.

Keywords

  • *dw-mri
  • *ivim
  • *capillary phantom
  • *flow-compensated IVIM
  • *intravoxel incoherent motion
  • *perfusion
Publication details
DOI: 10.1002/mrm.27816
Journal: Magn Reson Med
Pages: 1373-1384 
Number: 4
Work Type: Original
Location: CPC-M
Disease Area: PLI
Partner / Member: LMU
Access-Number: 31131482
See publication on PubMed

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