Prolonged Venous Stasis: Invisible Intravenous FDG Infiltrations and Potential Negative Implications in PET/CT Examination

Objectives: Venous stasis, the temporary sequestration of blood from the general circulation, can produce spurious and clinically meaningful measurement bias ^1-2 that lead to scan misinterpretation³. Similarly, F-18 FDG infiltrations (published rates 9-21%^4-7) impact dose and uptake time⁸ and are well known to affect image quality and quantification. The aim of this study was to determine if time activity curves (TACs) produced by a novel Quality Assurance and Quality Control (QA/QC) device corresponded to dynamic PET images taken during the tracer uptake period.

Methods: Patients undergoing routine F-18 FDG PET/CT imaging are eligible for this IRB-approved study had QA/QC scintillation sensors (Lucerno Dynamics, LLC, Morrisville, NC, USA) topically placed on their arms during standard 60 minutes uptake phase to create TACs. After injection, patients’ arms were dynamically scanned, arms down and compressed to torso, for 45 minutes (90 frames). Sensors were removed and routine clinical PET/CT imaging followed. Standard and dynamic images were evaluated by the reading physician for the presence of abnormal FDG accumulation at the injection site. Dynamic images were then compared to independently reviewed TACs.

Results: Dynamic images were acquired in 16 patients and agreed with TACs in 100% of cases. 15 indicated abnormal radiotracer presence and 1 case showed no abnormal presence. A comparison of standard and dynamic images revealed a difference in radiotracer presence and classification. Standard image reviews found 10 patients with no evidence of abnormal tracer presence and 6 (5 mild and 1 moderate) with evidence. Dynamic images found 1 patient with no evidence and 15 (8 mild, 6 moderate, 1 severe) with evidence during 45 minutes of dynamic imaging. 9 of the 15 dynamic images showed radiotracer stasis that resolved so completely there was no evidence of abnormal radiotracer presence at the injection site in standard clinical images.

Conclusion: Dynamic images support sensor TACs as a means to identify presence of radiotracer at the injection site. Both dynamic images and TACs captured venous stasis that resolved during the standard uptake period. Since a standard PET image cannot routinely assess the quality of the injection⁹, and long-lasting stasis impacts studies in the same manner as infiltrations, the device provides important QC by identifying and characterizing all invisible and visible infiltration and stasis cases. This may prove valuable by improving the injection process, quantification, and patient safety during PET/CT examination. Research Support: