Accuracy of Non-invasive Arterial Input Functions and Error in Quantitative Images in the Cerebellar Reference Method

PURPOSE: We developed and validated the accuracy of a method to calculate the arterial input function (AIF) from PET images only, without the need for the arterial blood sampling, in the absolute quantitation of functional parametric values in 15O- gas PET examinations.METHODS: We extended the method reported by Iguchi et al. (2013) to derive the arterial input function, thus absolute quantitative functional parametric images of cerebral perfusion and oxygen metabolism by a reference tissue approach. We compared shapes of the AIF and reproducibility of the absolute functional values. Existing test data that were carried out with the continuous arterial blood sampling were used for this study.RESULTS: The estimated AIF shapes agreed well with those estimated from the continuous arterial blood sampling. The error range of the absolute quantitative values was approximately ±20%, with a fairly well reproducibility in the relative values being less than 3%.CONCLUSION: The AIFs by this method were reproducible. Although the absolute quantitative values varied depending on the assumed functional values in the reference region in individual cases, the relative images showed fairly good agreement with the results from the standard technique that employed the arterial blood sampling. The present technique may provide significant contribution to clinical examination.