Measurement reproducibility of perfusion fraction and pseudodiffusion coefficient derived by intravoxel incoherent motion diffusion-weighted MR imaging in normal liver and metastases

Objective

To determine the measurement reproducibility of perfusion fraction f, pseudodiffusion coefficient D ^* and diffusion coefficient D in colorectal liver metastases and normal liver.

Methods

Fourteen patients with known colorectal liver metastases were examined twice using respiratory-triggered echo-planar DW-MRI with eight b values (0 to 900 s/mm²) 1 h apart. Regions of interests were drawn around target metastasis and normal liver in each patient to derive ADC (all b values), ADC_high (b values ≥100 s/mm²) and intravoxel incoherent motion (IVIM) parameters f, D ^* and D by least squares data fitting. Short-term measurement reproducibility of median ADC, ADC_high, f, D ^* and D values were derived from Bland–Altman analysis.

Results

The measurement reproducibility for ADC, ADC_high and D was worst in colorectal liver metastases (?21 % to +25 %) compared with liver parenchyma (?6 % to +8 %). Poor measurement reproducibility was observed for the perfusion-sensitive parameters of f (?75 % to +241 %) and D ^* (?89 % to +2,120 %) in metastases, and to a lesser extent the f (?24 % to +25 %) and D* (?31 % to +59 %) of liver.

Conclusions

Estimates of f and D ^* derived from the widely used least squares IVIM fitting showed poor measurement reproducibility. Efforts should be made to improve the measurement reproducibility of perfusion-sensitive IVIM parameters.

Key Points

? Quantitative diffusion-weighted MRI parameters are increasingly used for clinical management decisions. ? However perfusion-sensitive intravoxel incoherent motion (IVIM) parameters showed poor measurement reproducibility. ? Measurement reproducibility of IVIM parameters was worse in metastases than normal liver. ? Efforts to improve measurement reproducibility of IVIM parameters should be explored.