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Impact of residual subtraction on myocardial blood flow and reserve estimates from rapid dynamic PET protocols
Alexis Poitrasson-Rivière1, Jonathan B Moody2, Jennifer M Renaud2
1INVIA Medical Imaging Solutions, 3025 Boardwalk Drive, Suite 200, Ann Arbor, MI, 48108, USA. apoitrasson@inviasolutions.com.
Background:
13N-ammonia and 18F-flurpiridaz require longer delays between rest and stress studies to allow for decay, lowering clinical throughput. In this study, we investigated the impact of residual subtraction on MBF and MFR estimates, as well as its effects on diagnostic accuracy.
Methods:
We retrospectively analyzed 63 patients who underwent a dynamic ammonia rest/stress study and 231 patients from the flurpiridaz 301 trial. Residual subtraction was performed by subtracting the mean pre-injection activity in each sampled region from that region's time activity curve. Corrected and uncorrected MBF and MFR were analyzed. Diagnostic accuracy was compared to quantitative coronary angiograms (QCA) for the flurpiridaz population.
Results:
With delays between injections above 3 half-lives, and a doubled stress dose, residual activity did not meaningfully increase ammonia MBF (< 5%). For shorter injection delays, stress MBF was overestimated by 13.6% ± 5.0% (P < .001). Residual activity had a large effect on flurpiridaz stress MBF, overestimating it by 37.9% ± 23.2% (P < .001). Comparison to QCA showed a significant improvement in AUC with residual subtraction (from 0.748 to 0.831, P = .001). MFR yielded similar results.
Conclusions:
Accounting for residual activity has a marked impact on stress MBF and MFR and improves diagnostic accuracy relative to QCA.
Insights
Residual activity significantly impacts myocardial blood flow (MBF) and flow reserve (MFR) estimates, particularly for 18F-flurpiridaz. Accounting for this residual activity improves diagnostic accuracy in cardiac imaging studies.
Area of Science:
- Nuclear cardiology
- Radiopharmaceutical imaging
- Cardiovascular diagnostics
Background:
- 13N-ammonia and 18F-flurpiridaz require extended delays for radiotracer decay, reducing clinical efficiency.
- Residual activity from previous injections can affect myocardial blood flow (MBF) and myocardial flow reserve (MFR) measurements.
Purpose of the Study:
- To investigate the impact of residual activity subtraction on MBF and MFR estimates.
- To evaluate the effect of residual subtraction on diagnostic accuracy compared to quantitative coronary angiography (QCA).
Main Methods:
- Retrospective analysis of 63 patients (13N-ammonia) and 231 patients (18F-flurpiridaz).
- Residual subtraction performed by removing mean pre-injection activity from time-activity curves.
- Comparison of corrected and uncorrected MBF/MFR; diagnostic accuracy assessed against QCA for flurpiridaz.
Main Results:
- Residual activity had minimal impact on 13N-ammonia MBF with delays >3 half-lives.
- Shorter delays led to overestimation of 13N-ammonia stress MBF by 13.6%.
- Residual activity overestimated 18F-flurpiridaz stress MBF by 37.9%, significantly improving AUC (0.748 to 0.831) post-subtraction.
Conclusions:
- Accounting for residual activity significantly impacts stress MBF and MFR calculations.
- Residual subtraction enhances diagnostic accuracy, especially for 18F-flurpiridaz imaging when compared to QCA.
