Figure 2. Schematic diagram of four-processor computational server with respect to interactive functional MR imaging system. P1–P4 represent processor numbers. For a blood-oxygenation-level–dependent study, the statistics and display steps take 20 seconds after the completion of the raw data acquisition. For a dynamic contrast-enhanced study, the statistics step takes about 29 seconds, during which the changes in signal intensity for each voxel in the brain are fitted with a gamma variate function to determine the relative cerebral blood volume. The maximum change in signal intensity over time is used to determine the map of time to peak intensity. A search is performed for the arterial input function, and the deconvolution is performed with the singular-value decomposition algorithm to determine the relative cerebral blood flow (29,30). It takes another 17 seconds to display the maps, for a total time of 49 seconds after the completion of the raw data acquisition. DEC = Digital Equipment Corp (computational server), SUN = Sparc 20 Unix workstation.