Partial injection technique for real time infiltration assessment

Introduction: Injection monitoring systems have been a major topic of discussion. The advantages to using this type of system is to detect if an infiltration has occurred during injection. Knowledge of the injection quality can aid physicians by providing additional information about the confidence of quantitative values and image quality observed. Infiltrations currently can only be determined to be significant after the patient study has been performed and an analysis of the resulting images completed. If an infiltration is noted and significant enough, then the patient must be rescanned resulting in additional patient inconvenience, radiation exposure, increased cost to the hospital and lost revenues.

During a typical PET-CT injection, the entire dose is typically given as a bolus. In this work we use a new test injection technique to first inject a small amount of the radioactive tracer then use real-time monitoring to assess the IV placement and injection quality. This study examines the use of a real-time display of injection information to perform an initial assessment of the quality of the IV placement prior to administering the entire radiopharmaceutical dose.

Methods: Five patients were monitored using the LARA injection monitoring device (Lucerno Dynamics) with real-time feedback of countrate underneath the detector. Each patient had an injection sensor (sensor#1) placed right above the injection site and a control sensor (sensor#2) placed on the opposite arm at the same location. The test injection technique involved the initial injection of approximately 10% of the full dose followed by completion of the dose push if the real-time analysis indicated a quality IV placement. In order to ensure only 10% of the dose was given in the first push, saline was added so that the total volume of the dose was 2ml and 0.2ml was administered for the first push. Approximately 10% of the dose was administered in a bolus while watching the real time counts increase. Then, flushed with 10ml of saline while watching the numbers lower to match the control sensor. If this was achieved, then the remaining 90% of the dose was given in a bolus injection and flushed with 10ml of saline. If during the first "test push" the real counts increased but did not return to background this would suggest an infiltration. That IV would be discontinued, and a better one would be started and used for the remaining 90% of the dose.

Results: All five patients test injection of 10% real count displays indicated no infiltration so the remaining 90% of the injection was given in a bolus. The count curve that is generated by the Lara device after the data is uploaded also indicated that the 10% injections were not infiltrated, and the injection curve did return to background. As seen in figure 1 under test injection technique. Figure 1 also shows an example of an infiltrated injection showing how the injection plot does not return to the control level.

Conclusions: Our facility determined that by only pushing 10% of the dose, we could decide whether the injection would be infiltrated or not. At that point, the decision could be made to either continue pushing the dose or to adjust the IV. This type of test injection technique could also be used when administering therapeutic agents as well. Use of this injection technique could prevent infiltrations or limit their impact with reduced patient exposure from rescans, prevent lost revenue from rescheduling and wasted radiopharmaceutical doses.

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