In vivo assessment of optimal b-value range for perfusion-insensitive apparent diffusion coefficient imaging

• Published in: Medical physics (Lancaster) Vol. 39; no. 8; pp. 4832 - 4839
• Main Authors: Freiman, Moti, Voss, Stephan D., Mulkern, Robert V., Perez-Rossello, Jeannette M., Callahan, Michael J., Warfield, Simon K.
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01.08.2012
• Subjects: Abdomen - pathology; Adolescent; Adult; Algorithms; Analysis of motion; Anatomy; apparent diffusion coefficient; biodiffusion; biomedical MRI; b‐value optimization; Child; Computer Simulation; Diagnostic Imaging - methods; Diffusion; Diffusion Magnetic Resonance Imaging - methods; diffusion‐weighted imaging; Digital computing or data processing equipment or methods, specially adapted for specific applications; Female; Fluid mechanics and rheology; General statistical methods; haemorheology; Humans; Image analysis; Image data processing or generation, in general; image motion analysis; Image Processing, Computer-Assisted; intravoxel incoherent motion; Involving electronic [emr] or nuclear [nmr] magnetic resonance, e.g. magnetic resonance imaging; Kidneys; least squares approximations; Least-Squares Analysis; Likelihood Functions; Liver; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Magnetic Resonance Physics; Male; mean square error methods; Medical image artifacts; Medical image noise; Medical image quality; Medical imaging; Models, Statistical; Numerical approximation and analysis; Pathology; Perfusion; Reproducibility of Results; apparent diffusion coefficient; b-value optimization; diffusion-weighted imaging; intravoxel incoherent motion
• ISSN: 0094-2405; 2473-4209; 0094-2405
• DOI: 10.1118/1.4736516

Purpose: To assess the optimalb-values range for perfusion-insensitive apparent diffusion coefficient (ADC) imaging of abdominal organs using short-duration DW-MRI acquisitions with currently available ADC estimation methods. Methods: DW-MRI data of 15 subjects were acquired with eightb-values in the range of 5–800 s/mm2. The reference-standard, a perfusion insensitive, ADC value (ADCIVIM), was computed using an intravoxel incoherent motion (IVIM) model with all acquired diffusion-weighted images. Simulated DW-MRI data was generated using an IVIM model with b-values in the range of 0–1200 s/mm2. Monoexponential ADC estimates were calculated using: (1) Two-point estimator (ADC2); (2) least squares three-point (ADC3) estimator and; (3) Rician noise model estimator (ADCR). The authors found the optimal b-values for perfusion-insensitive ADC calculations by minimizing the relative root mean square error (RRMS) between the ADCIVIM and the monoexponential ADC values for each estimation method and organ. Results: Lowb-value = 300 s/mm2 and high b-value = 1200 s/mm2 minimized the RRMS between the estimated ADC and the reference-standard ADCIVIM to less than 5% using the ADC3 estimator. By considering only the in vivo DW-MRI data, the combination of low b-value = 270 s/mm2 and high b-value of 800 s/mm2 minimized the RRMS between the estimated ADC and the reference-standard ADCIVIM to <7% using the ADC3 estimator. For all estimators, the RRMS between the estimated ADC and the reference standard ADC correlated strongly with the perfusion-fraction parameter of the IVIM model (r = [0.78–0.83], p ≤ 0.003). Conclusions: The perfusion compartment in DW-MRI signal decay correlates strongly with the RRMS in ADC estimates from short-duration DW-MRI. The impact of the perfusion compartment on ADC estimations depends, however, on the choice ofb-values and estimation method utilized. Likewise, perfusion-related errors can be reduced to <7% by carefully selecting the b-values used for ADC calculations and method of estimation.