FIGURE 1. Scatterplot and regression line of correlation coefficients (R) between individual PET and SPECT z maps on dementia severity (MMSE). Correspondence between PET and SPECT tended to be closer in patients with more severe dementia (1 extreme additional point at MMSE = 11, r = 0.75, not included in plot; the 2 boxed points represent 2 cases each). Regression was significant (Pearson coefficient for correlation between imagewise correlation coefficients and MMSE = -0.57, r2 = 0.33, P = 0.002; corresponding Spearman rank correlation coefficient = -0.50, P = 0.01).
