Patterns and Prevalence of FDG Extravasation in PET/CT Scans

PET (Positron Emission Tomography) images are used to help make patient management decisions in staging and treatment assessment, often after a cancer diagnosis.

Improper injections of PET tracers (dye) may occur approximately 15% of the time. This is known as extravasation or infiltration, and it compromises the doctor's ability to read the PET image. Often, the site where the tracer is injected into the vein (usually in the inside of the elbow) are not in the images taken, so reading physicians are unaware that an extravasation or infiltration has occurred.

Technology exists to capture time activity curves (amount of tracer in a location over a period of time) during the PET tracer uptake period (usually once the tracer is injected, the tracer circulates for 60 minutes prior to images), which can enable physicians to accurately detect extravasations. This information is currently unavailable to physicians reading routine PET/CT scans.

Time activity curves information gathered from these sensors during the circulation period appear to match the brief pictures taken approximately 70 minutes after the tracer injection.

This study will determine if these time activity curves correspond to PET images of the injection site taken during the tracer uptake period. If time activity curves correspond to PET images, they can be used to determine if the tracer was properly injected. If there was an improper injection, clinicians can be alerted to this fact and interpret the image with this additional information.

In oncology, whole-body PET/CT is typically performed from the head to the pelvic floor (eyes to thighs). The use of the term whole-body is misleading because the most commonly used field of view (FOV) for arms-up whole-body PET/CT protocols includes only the base of skull to the upper thighs and does not include the brain, skull, and large portions of both upper and lower extremities. In such FOV, the most commonly used site of injection, namely the antecubital fossa (inside of the elbow), is frequently not included in the imaging field. In the Frontiers in Oncology article, Osman also determined that based on the commonly used FOV at most PET/CT centers, that when infiltration is present, it may be unnoticed by clinicians in approximately 31% of the cases.

Lucerno Dynamics, a privately held company in North Carolina, has also discovered that the static image may be incapable of reporting on the quality of FDG administration during the ~60 minute uptake period. Lucerno's system has been used in two investigational studies at two centers. At one center, the system was used with 8 patients for a total of 15 scans. At the other center, the system was used with 40 patients for a total of 85 scans. Similar rates of infiltrations were found to those described in the published articles. Based on this experience, Lucerno has found that infiltrations can partially resolve during the uptake period, so that even if they are visible in the PET image, the image may not reveal the extent of the infiltration. This could severely and negatively impact research and therapy decisions and thus patient outcomes.

The Lucerno devices (Lucerno ID) are nonsignificant risk devices that add only 2-3 minutes to the current standard of care PET/CT scanning process. Lucerno ID sensors are applied to the patient's skin before the injection of the radiotracer and are removed after the FDG uptake period and prior to the PET/CT imaging process. The Lucerno ID has the ability to identify infiltrations, whether they are within or outside the FOV of reviewing clinicians, and can alert clinicians before their patient undergoes a compromised PET/CT scan due to the infiltration. This technology can prevent patients from receiving the additional CT radiation exposure of a compromised scan, can save cost, and can improve patient outcomes by ensuring more accurate PET scan interpretation.