Dual energy window imaging for optimisation of P/V ratios in VP SPECT
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
SpringerOpen
Abstract
Purpose: Ventilation–perfusion single-photon emission computed tomography (VP SPECT) plays an important role in pulmonary embolism diagnosis. Rapid results may
be obtained using same-day ventilation followed by perfusion imaging, but generally
requires careful attention to achieving an optimal count rate ratio (P/V ratio) of ≥ 3:1.
This study investigated whether the ratio of counts simultaneously acquired in adjacent
primary and Compton scatter energy windows (Eratio) on V SPECT was predictive
of final normalised perfusion count rate (
PCRnorm) on P SPECT using [
99mTc]Tc-macroaggregated
albumin (MAA), thus allowing for optimisation of P/V ratios.
Methods: Same-day VP SPECT studies acquired using standard protocols in adult
patients during a 2-year period (training dataset) were assessed. Studies were included
provided they were acquired with correct imaging parameters, and injection site imaging
and laboratory records were available for quality control and normalised count rate
corrections. Extraction of DICOM information, and linear regression were performed
using custom Python and R scripts. A predictive tool was developed in Microsoft Excel.
This tool was then validated using a second (validation) dataset of same-day studies
acquired over a subsequent 7-month period. Accuracy of the prediction tool was
assessed by calculating the mean absolute percentage error (MAPE).
Results: Of 643 studies performed, the scans of 342 participants (median age
30.4 years, 318 female) were included in the training dataset, the analysis of which
yielded a significant regression equation (F(1,340) = 1057.3, p < 0.0001), with an
adjusted R2 of 0.756 and MSE of 0.001089. A prediction tool designed for routine clinical
use was developed for predicting final P/V ratio. Of an additional 285 studies, 198
were included in the second (validation) dataset (median age 29.7 years, 188 female).
The Excel-based tool was shown to be 91% accurate (MAPE: 9%) in predicting P/V ratio.
Conclusion: The relationship between the ratio of simultaneously acquired counts
in adjacent energy windows on V SPECT and perfusion count rate after administration
of a known activity of [
99mTc]Tc-MAA can be linearly approximated. A predictive
tool based on this work may assist in optimising the dose and timing of [
99mTc]Tc-MAA
administration in same-day studies to the benefit of patients and workflows.
Description
CITATION: Doruyter, A. G. G. & Holness, J. L. 2021. Dual energy window imaging for optimisation of P/V ratios in VP SPECT. EJNMMI Physics, 8:69, doi:10.1186/s40658-021-00417-z.
The original publication is available at https://ejnmmiphys.springeropen.com
Publication of this article was funded by the Stellenbosch University Open Access Fund
The original publication is available at https://ejnmmiphys.springeropen.com
Publication of this article was funded by the Stellenbosch University Open Access Fund
Keywords
Artificial respiration -- Complications -- Diagnosis, Dual energy CT (Tomography), Pulmonary embolism -- Diagnosis, Ventilation-perfusion ratio
Citation
Doruyter, A. G. G. & Holness, J. L. 2021. Dual energy window imaging for optimisation of P/V ratios in VP SPECT. EJNMMI Physics, 8:69, doi:10.1186/s40658-021-00417-z