Fig. 5
A and B Boxplots of WRSS obtained from the weighted square difference between measured and fitted curves obtained with the MDIFs (white-) and IDIFs (grey-filled rectangles). Results are shown for GM and WM TACs (n = 18). WRSS values are shown for A the first 3 min and B the complete 60 min of data. Logarithmic scale (base 10) was used for the y-axis. C Total GM (circles) and WM (squares) TACs together with the respective best-fit curves obtained with the MDIF (dashed black) and IDIF (grey) for the representative subject shown in Fig. 4. Fitted curves obtained with the MDIF presented a WRSS of 4.6 × 10−3 and 6.9 × 10−2 kBq2/mL2 for the GM and WM TACs, respectively. Respective fitted curves using the IDIF presented WRSS of 4.8 × 10−1 and 2.0 × 10−1 kBq2/mL2. D First 3 min of the TACs to visualize the initial pass of [18F]FDG. Similar graphs are shown in E and F for two randomly chosen voxels (one for each tissue type). Fitted curves obtained with the MDIF presented a WRSS of 7.2 and 2.8 kBq2/mL2 for the GM and WM voxel TACs, respectively. Respective fitted curves using the IDIF presented WRSS of 7.0 and 2.9 kBq2/mL2. [18F]FDG: 2-deoxy-2-[18F]fluoro-D-glucose; GM: grey matter; IDIF: Image-derived input function; MDIF: Model-derived input function; TAC: Time-activity curve; VOI: Volume-of-interest; WM: White matter; WRSS: weighted residual sum of squares