Figure 3: DCE-MRI region of interest (ROI) analysis in the centrum semiovale (CSO) of a 73-year-old healthy female. (a) Axial 𝑇 1 -weighted (turboFLASH) images were collected on a Siemens 7 T system with 8-channel phased array transmit/receive head coil; selected ROI shown in white. (b) Plot of pre-post contrast 𝑅 1 𝑡 ( Δ 𝑅 1 𝑡 ) versus time. Images were collected immediately preceding two 0.05 mmol/kg bolus injections of gadoteridol and every 2.5 seconds over the next 175 sec. 𝑅 1 𝑡 values were calculated at each time point by fitting the signal intensity curves to a standard two-parameter single exponential inversion recovery equation [77]. (c) Δ 𝑅 1 𝑡 plotted as a function of Δ 𝑅 1 𝑏 . Changes in the blood signal, Δ 𝑅 1 𝑏 , were determined from an ROI placed entirely in the sagittal sinus. The solid line represents the best fit of the data to (3). Resultant estimates of 𝑣 𝑏 , 𝜏 𝑏 1 , and 𝑃 𝑤 𝑆 are also shown.