Arterial input function
Arterial input function (AIF), also known as plasma input function, referees to the concentration of blood-plasma measured over time in an artery. The oldest record on pubmed shows that AIF was used by Harvey et al.[1] in 1962 to measure exchange of materials between red blood cells and blood plasma, and for positron emission tomography (PET) studies in 1983.[2][3] Now a days, kinetic analysis in various medical imaging techniques requires an AIF as one of the inputs to the mathematical model, for example, in dynamic PET imaging, or dynamic contrast-enhanced magnetic resonance imaging (dce-MRI).[4][5]
AIF can be obtained in several different ways, for example, using the invasive method of continuous arterial sampling using an online blood monitor, using the invasive method of arterial blood samples obtained at discrete time points post-injection[6], using a minimally invasive method using a population based AIF where an input function in a subject is estimated partly from the prior information obtained from a previous population and partly from the blood information from the subject itself obtained at the time of scanning[7], or using an image derived arterial input function (IDAIF) obtained by placing a region of interest (ROI) over an artery and calibrating the resulting curves against venous blood samples obtained during the later phases (30 to 60 minutes) of the dynamic scan[8] when venous and arterial tracer concentrations become equal[6].
An IDAIF obtained by measuring the tracer counts over the aorta offers an alternative to invasive arterial blood sampling. An IDAIF at the aorta can be determined by measuring the tracer counts over the left ventricle, ascending aorta, and abdominal aorta and this has been previously validated by various researchers[8][6]. The arterial activity from the image data requires corrections for differences between whole blood and plasma activity, which are not constant over time and are also subject to partial volume errors (PVE). These are corrected using late venous blood samples,[6][8] spill-over errors due to activity from neighbouring tissues outside the ROI[9], error due to patient movement and noise introduced due to the limited number of counts acquired in each time frame because of the small size of an ROI.
References
- ^ HARVEY, RB (1962). "Renal extraction of para-aminohippurate and creatinine measured by continuous in vivo sampling of arterial and renal-vein blood". Ann N Y Acad Sci. 102: 46–54.
- ^ Herscovitch, P (1983). "Brain blood flow measured with intravenous H2(15)O. I. Theory and error analysis". J Nucl Med. 24(9): 782–9.
- ^ "Measurements of regional tissue and blood-pool radiotracer concentrations from serial tomographic images of the heart". J Nucl Med. 24(11): 987–96. 1983 Nov.
{{cite journal}}: Check date values in:|date=(help) - ^ Schabel, Matthias C. (2012-01-31). "A unified impulse response model for DCE-MRI". Magnetic Resonance in Medicine. 68 (5): 1632–1646. doi:10.1002/mrm.24162. ISSN 0740-3194.
- ^ Tanuj Puri, Sarah Wiscombe, Sally Marshall, John Simpson, Josephine Naish, Pete Thelwall. Changes in pulmonary vascular properties in a human model of acute lung injury measured using DCE-MRI, In 20th Annual Scientific Meeting of the British Chapter of International Society for Magnetic Resonance in Medicine (ISMRM), Edinburgh, UK, September 2014
- ^ a b c d Cook, Gary J. R.; Lodge, Martin A.; Marsden, Paul K.; Dynes, Angela; Fogelman, Ignac (1999-10-27). "Non-invasive assessment of skeletal kinetics using fluorine-18 fluoride positron emission tomography: evaluation of image and population-derived arterial input functions". European Journal of Nuclear Medicine and Molecular Imaging. 26 (11): 1424–1429. doi:10.1007/s002590050474. ISSN 1619-7070.
- ^ Blake, Glen Mervyn; Siddique, Musib; Puri, Tanuj; Frost, Michelle Lorraine; Moore, Amelia Elizabeth; Cook, Gary James R.; Fogelman, Ignac (2012-08). "A semipopulation input function for quantifying static and dynamic 18F-fluoride PET scans:". Nuclear Medicine Communications. 33 (8): 881–888. doi:10.1097/MNM.0b013e3283550275. ISSN 0143-3636.
{{cite journal}}: Check date values in:|date=(help) - ^ a b c Puri, Tanuj; Blake, Glen M.; Siddique, Musib; Frost, Michelle L.; Cook, Gary J.R.; Marsden, Paul K.; Fogelman, Ignac; Curran, Kathleen M. (2011-06). "Validation of new image-derived arterial input functions at the aorta using 18F-fluoride positron emission tomography:". Nuclear Medicine Communications. 32 (6): 486–495. doi:10.1097/MNM.0b013e3283452918. ISSN 0143-3636.
{{cite journal}}: Check date values in:|date=(help) - ^ Nuyts, J (1996). "Three-Dimensional Correction for Spillover and Recovery of Myocardial PET Images". Journal of Nuclear Medicine. 37(5): 767–74.