Table 2. The linear relationship and corresponding coefficients as calculated between specialist and non-specialist observers using semi-automated software to identify the first pixel lying within a vessel and that representing the maximum relative cerebral blood volume (rCBV_max) non-vessel tumour value.

Analysis	Slope	Intercept	Correlation coefficient (r)
Raw vessel with smallest pixel value	0.98	0.40	0.993
Normalised vessel with smallest pixel value	0.97	0.41	0.959
Raw rCBVmax	0.98	0.43	0.997
Normalised nrCBVmax	0.96	0.62	0.997

Data from both raw (unaltered) glioblastoma multiforme tumour series and tumour series normalised by the averaged rCBV in a region of contralateral white matter (nrCBV_max) are shown. A correlation coefficient of 1 with a gradient of 1 and intercept of 0 would correspond to absolute correlation. Values measured by the specialist can be predicted using the formula: specialist values=(slope)×(non-specialist values)+intercept.