Fig. 8: Relationship between all MRI metrics and histological indices obtained in cancer patients scanned in vivo.
Metrics from Histo-μSim are indicated by subscript MC, for “Monte Carlo simulation-informed''; metrics from the analytical signal models are indicated by subscript AN, for “analytical''; metrics from histology are indicated by subscript histo. MRI metrics are: IC fraction fin; volume-weighted characteristic CS indices (vCS); intrinsic IC and EC diffusivities (D0∣in and D0∣ex); EC ADC (ADCex); cell membrane permeability κ. Panels to the left: results for Histo-μSim; panels to the right: results for the analytical two-compartment model. Top row: correlation matrices ((a) for Histo-μSim; (b) for the analytical model). p < 0.05 is flagged by yellow squares (sample size n = 26 biopsies). Histological metrics were obtained by automatic image processing in QuPath. Middle row: Bland-Altman plots, with biases and upper/lower limit-of-agreement (LOA) comparing MRI and histological fin ((c) for Histo-μSim; (d) for the analytical model). Bottom row: Bland-Altman plots, with biases and LOAs comparing MRI and histological vCS ((e): vCScyl for Histo-μSim; (f) vCSsph for the analytical model). To aid the visual comparison of the results of each model, the same limits have been used for the axes related to fin and related to vCS in both models. This leads to an abrupt cut-off of the contours, and to the presence of empty white space, since the two models provide fin and vCS estimates in slightly different numerical ranges.
