Figure 1
Calculation of vascular hysteresis loops and VAM biomarker maps for a 63-year-old female patient suffering from a recurrent glioblastoma. The presented data were obtained from an examination which was performed before onset of bevacizumab treatment (baseline examination). (a) Conventional MRI (cMRI) included contrast-enhanced T1-weighted (CE T1w), FLAIR, GE-EPI DSC perfusion evaluated as maps of cerebral blood flow (CBV), and DWI evaluated as apparent diffusion coefficient (ADC), respectively. (b) The ΔR(t)2,GE and \({{\rm{\Delta }}{\rm{R}}(t)}_{2,\text{SE}}^{3/2}\,\,\) curves for the first bolus of the GE- and SE-EPI DSC data, respectively, were fitted to a gamma-variate function (left) and used for calculation of the vascular hysteresis loops (VHLs, i.e. the \({{\rm{\Delta }}{\rm{R}}}_{2,\text{GE}}\) versus \({{\rm{\Delta }}{\rm{R}}}_{2,\text{SE}}^{3/2}\) diagram, right). The red-framed part shows bolus curves and VHLs for a voxel position (red squares in a) with arterial-dominated microvasculature, and the blue-framed the analogue for a voxel position (blue squares in a) with venule/capillary-dominated microvasculature. The arrows indicate the rotational direction of the VHLs. (c) The maps of the microvessel type indicator (MTI), the upper limit for microvessel density (NU) and radius (RU) adapted to the temporal shift phenomenon, and the curvature (Curv) of the VHL (top-down). The color codes are depicted at the right image margins.
