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Image-derived input function for assessment of F-18-FDG uptake by the inflamed lung
Journal article   Open access   Peer reviewed

Image-derived input function for assessment of F-18-FDG uptake by the inflamed lung

Tobias Schroeder, Marcos F. Vidal Melo, Guido Musch, R. Scott Harris, Jose G. Venegas and Tilo Winkler
The Journal of nuclear medicine (1978), Vol.48(11), pp.1889-1896
11/01/2007
DOI: 10.2967/jnumed.107.041079
PMCID: PMC3172049
PMID: 17942803
url
https://doi.org/10.2967/jnumed.107.041079View
Published (Version of record) Open Access

Abstract

Pulmonary uptake of F-18-FDG assessed with PET has been used to quantify the metabolic activity of inflammatory cells in the lung. This assessment involves modeling of tracer kinetics and knowledge of a time-activity curve in pulmonary artery plasma as an input function, usually acquired by manual blood sampling. This paper presents and validates a method to accurately derive an input function from a blood-pool region of interest (ROI) defined in dynamic PET images. Methods: The method is based on a 2-parameter model describing the activity of blood and that from spillover into the time-activity curve for the ROL The model parameters are determined using an iterative algorithm, with 2 blood samples used to calibrate the raw PET-derived activity data. We validated both the 2-parameter model and the method to derive a quantitative input function from ROIs defined for the cavities of the right and left heart and for the descending aorta by comparing them against the time-activity curve obtained by manual blood sampling from the pulmonary artery in lungs with acute inflammation. Results: The model accurately described the time-activity curve from sampled blood. The 2-sample calibration method provided an efficient algorithm to derive input functions that were virtually identical to those sampled manually, including the fast kinetics of the early phase. The F-18-FDG uptake rates in acutely injured lungs obtained using this method correlated well with those obtained exclusively using manual blood sampling (R-2 > 0.993). Within some bounds, the model was found quite insensitive to the timing of calibration blood samples or the exact definition of the blood-pool ROIs. Conclusion: Using 2 mixed venous blood samples, the method accurately assesses the entire time course of the pulmonary F-18-FDG input function and does not require the precise geometry of a specific blood-pool ROI or a population-based input function. This method may substantially facilitate studies involving modeling of pulmonary F-18-FDG in patients with viral or bacterial infections, pulmonary fibrosis, and chronic obstructive pulmonary disease.
 Life Sciences & Biomedicine Radiology, Nuclear Medicine & Medical Imaging Science & Technology

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