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The rCBF (Autorad) model is intended for the quantitative assessment of the regional cerebral blood flow. The required measurements are a static PET after the injection of a H215O bolus and external blood sampling from the start of injection. An autoradiographic solution of the 1-tissue compartment model for the exchange of an inert tracer is applied [1]. The solution is based on the convolution of the blood activity with an exponential which contains the flow and the partition coefficient in the exponent. The convolved function is integrated over the acquisition time and compared with the integrated PET value. Given a specified value for the partition coefficient, the perfusion can be estimated by a table lookup approach.
Acquisition and Data Requirements
Image Data |
A static PET data set representing the average brain activity after injection of a H215O bolus. If a dynamic data set is loaded, the average pixel activity over the acquisition period will automatically be calculated during pixel-wise processing. The acquisition duration should only cover the uptake phase. |
Blood Data |
Blood activity sampled at a peripheral artery from the time of injection until the end of the PET acquisition. |
Blood Preprocessing
Because autoradiographic data is usually static, the 1-tissue compartment fit for estimating the delay and dispersion can not be applied. Therefore the only available blood preprocessing option is decay correction.
Note: The loaded blood data should have been corrected for delay and dispersion beforehand. This processing can be done on the Blood panel of in PKIN.
Model Preprocessing
ntab |
Number of pre-calculated values in the lookup table. Should be an even number. |
f |
Perfusion in [ml/min/100ml]. Please specify the range within which the tabulation is performed. |
p |
Partition coefficient or distribution volume of water in brain. This input parameter must be specified by the user. |
Model Configuration
f |
Regional perfusion in [ml/min/100ml]. It is calculated for each pixel by a table look-up procedure. Reasonable values are about 30 (white matter) and 60 (gray matter) ml/min/100ml [11] Note: The results are accurate only for voxels with the partition coefficient equal to that entered in the p-field. |
Reference
1. Herscovitch P, Markham J, Raichle ME: Brain blood flow measured with intravenous H2(15)O. I. Theory and error analysis. J Nucl Med 1983, 24(9):782-789.