Spatially-constrained probability distribution model of incoherent motion (SPIM) for abdominal diffusion-weighted MRI.
Quantitative diffusion-weighted MR imaging (DW-MRI) of the body enables characterization of the tissue microenvironment by measuring variations in the mobility of water molecules. The diffusion signal decay model parameters are increasingly used to evaluate various diseases of abdominal organs such as the liver and spleen. However, previous signal decay models (i.e., mono-exponential, bi-exponential intra-voxel incoherent motion (IVIM) and stretched exponential models) only provide insight into the average of the distribution of the signal decay rather than explicitly describe the entire range of diffusion scales. In this work, we propose a probability distribution model of incoherent motion that uses a mixture of Gamma distributions to fully characterize the multi-scale nature of diffusion within a voxel. Further, we improve the robustness of the distribution parameter estimates by integrating spatial homogeneity prior into the probability distribution model of incoherent motion (SPIM) and by using the fusion bootstrap solver (FBM) to estimate the model parameters. We evaluated the improvement in quantitative DW-MRI analysis achieved with the SPIM model in terms of accuracy, precision and reproducibility of parameter estimation in both simulated data and in 68 abdominal in-vivo DW-MRIs. Our results show that the SPIM model not only substantially reduced parameter estimation errors by up to 26%; it also significantly improved the robustness of the parameter estimates (paired Student's t-test, p < 0.0001) by reducing the coefficient of variation (CV) of estimated parameters compared to those produced by previous models. In addition, the SPIM model improves the parameter estimates reproducibility for both intra- (up to 47%) and inter-session (up to 30%) estimates compared to those generated by previous models. Thus, the SPIM model has the potential to improve accuracy, precision and robustness of quantitative abdominal DW-MRI analysis for clinical applications.
Computational Radiology Laboratory; Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States. Electronic address: sila.kurugol@childrens.harvard.edu.
Sila
S
Kurugol
Computational Radiology Laboratory; Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States.
Moti
M
Freiman
Computational Radiology Laboratory; Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States.
Onur
O
Afacan
Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States.
Jeannette M
JM
Perez-Rossello
Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States.
Michael J
MJ
Callahan
Computational Radiology Laboratory; Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States.
Simon K
SK
Warfield
D000005:Abdomen / Q000000981:diagnostic imaging*; D000293:Adolescent; D000465:Algorithms; D002648:Child; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008099:Liver / Q000000981:diagnostic imaging; D008297:Male; D008390:Markov Chains; D009038:Motion; D009068:Movement; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013154:Spleen / Q000000981:diagnostic imaging; D055815:Young Adult
Abdomen; Diffusion-weighted MRI; Liver; Markov random field; Model fitting; Probability distribution model; Spatial homogeneity prior; Spleen