Correction of arterial input-function saturation for extraction fraction estimation in retinal fluorescein videoangiography
6 affiliations
- 1Biomedical Engineering, Illinois Institute of Technology, Chicago, IL 60616, United States of America
- 2Department of Medical Biophysics, Western University, London, ON N6A 5C1, Canada
- 3Lawson Research Institute, St. Joseph’s Health Care, London, ON N6A 4V2, Canada
- 4Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, United States of America
- 5Department of Ophthalmology and Visual Sciences, Illinois Eye and Ear Infirmary, University of Illinois at Chicago, Chicago, IL 60607, United States of America
- 6Department of Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, United States of America
Abstract
Objective. Quantitative retinal fluorescein videoangiography (FVA) can estimate extraction fraction (E), but the 8-bit intensity resolution of clinical systems creates a dynamic-range tradeoff: preserving arterial input function (AIF) linearity can restrict tissue signal, particularly for pixel-level analysis. We developed a single-bolus correction method to broaden the usable acquisition range while maintaining E estimation accuracy. Approach. The method combined truncated-mean reconstruction when sufficient unsaturated arterial pixels remained with gamma-variate interpolation when saturation dominated the first-pass peak. Development simulations used four human-derived AIF templates, empirically characterized signal-dependent noise, and 20 paired realizations evaluated over arterial scaling factors f = 0.1–2.25. Tissue curves were generated using a distributed-transit-time AATH model and fitted using a plug-flow AATH model. The locked correction threshold was then evaluated by artificially clipping raw arterial-pixel time curves from 10 originally undersaturated FVAs without adding synthetic noise. Performance was compared with the clipped arterial mean, piecewise cubic Hermite interpolation, and gamma-variate interpolation alone. Main results. The combined method completed all 60 patient-by-clipping analyses and produced lower first-pass peak, normalized mean squared error (NMSE), and area-under-the-curve errors than the comparator methods under moderate-to-strong clipping. In kinetic simulations, mean absolute relative ROI E error with the uncorrected AIF increased from 17 ± 9% at f = 1.25–60 ± 20% at f = 2.25, whereas corrected-AIF error remained approximately 10%–20%. Single-pixel E error decreased as signal approached the detector ceiling, reached 17 ± 11% at f = 1.75, and remained statistically similar across f = 0.8–2.0. No single-pixel fits failed at f ⩾ 1.0. Significance. The correction framework converts modest AIF saturation from a restrictive acquisition limit into a manageable analytical condition. This broader operating range is valuable for 8-bit FVA, supporting acquisition near the detector ceiling to improve tissue signal and enable high-resolution E mapping without dual-bolus acquisition.
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BibTeX
@article{vavrek2026correction,
title = {{Correction of arterial input-function saturation for extraction fraction estimation in retinal fluorescein videoangiography}},
author = {Sarah R Vavrek and Elif Kayaalp Nalbant and Nicholas Konopek and Nicole L Decker and Amani A Fawzi and William F Mieler and Jennifer J Kang-Mieler and Kenneth M Tichauer},
journal = {Physics in Medicine and Biology},
year = {2026},
month = oct,
doi = {10.1088/1361-6560/aeb793},
url = {https://doi.org/10.1088/1361-6560/aeb793},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Correction of arterial input-function saturation for extraction fraction estimation in retinal fluorescein videoangiography
AU - Sarah R Vavrek
AU - Elif Kayaalp Nalbant
AU - Nicholas Konopek
AU - Nicole L Decker
AU - Amani A Fawzi
AU - William F Mieler
AU - Jennifer J Kang-Mieler
AU - Kenneth M Tichauer
PY - 2026
DA - 2026/10/30
JO - Physics in Medicine and Biology
DO - 10.1088/1361-6560/aeb793
UR - https://doi.org/10.1088/1361-6560/aeb793
AB - Objective. Quantitative retinal fluorescein videoangiography (FVA) can estimate extraction fraction (E), but the 8-bit intensity resolution of clinical systems creates a dynamic-range tradeoff: preserving arterial input function (AIF) linearity can restrict tissue signal, particularly for pixel-level analysis. We developed a single-bolus correction method to broaden the usable acquisition range while maintaining E estimation accuracy. Approach. The method combined truncated-mean reconstruction when sufficient unsaturated arterial pixels remained with gamma-variate interpolation when saturation dominated the first-pass peak. Development simulations used four human-derived AIF templates, empirically characterized signal-dependent noise, and 20 paired realizations evaluated over arterial scaling factors f = 0.1–2.25. Tissue curves were generated using a distributed-transit-time AATH model and fitted using a plug-flow AATH model. The locked correction threshold was then evaluated by artificially clipping raw arterial-pixel time curves from 10 originally undersaturated FVAs without adding synthetic noise. Performance was compared with the clipped arterial mean, piecewise cubic Hermite interpolation, and gamma-variate interpolation alone. Main results. The combined method completed all 60 patient-by-clipping analyses and produced lower first-pass peak, normalized mean squared error (NMSE), and area-under-the-curve errors than the comparator methods under moderate-to-strong clipping. In kinetic simulations, mean absolute relative ROI E error with the uncorrected AIF increased from 17 ± 9% at f = 1.25–60 ± 20% at f = 2.25, whereas corrected-AIF error remained approximately 10%–20%. Single-pixel E error decreased as signal approached the detector ceiling, reached 17 ± 11% at f = 1.75, and remained statistically similar across f = 0.8–2.0. No single-pixel fits failed at f ⩾ 1.0. Significance. The correction framework converts modest AIF saturation from a restrictive acquisition limit into a manageable analytical condition. This broader operating range is valuable for 8-bit FVA, supporting acquisition near the detector ceiling to improve tissue signal and enable high-resolution E mapping without dual-bolus acquisition.
SN - 0031-9155
SN - 1361-6560
ER -