In a study published in the November/December 2009 issue of JCAT, Tom Lombardi, M.D. found the research showed high sensitivity while maintaining high specificity in the subcutaneous detection of contrast extravasation using radiofrequency (RF) permittivity sensitivity.¹ Sensitivity was found to be 98.8% whereas the specificity was found to be 99.97%.¹ Extravasations occur when fluids, drugs, or solutions leak from the vein into the surrounding tissue. This can occur during hand or power injection.
RF technology uniquely exploits the differences in electrical permittivity values between fluids and subcutaneous tissue. The technology, therefore, lends high sensitivity in detecting extravasations early in the injection as well as at various depths within adipose tissue.¹ The patented RF technology used in the study, the MEDRAD XDS®, detects an extravasation and stops the injection before the extravasation becomes severe.
Extravasated contrast media are toxic to skin and tissues, and can lead to acute and chronic inflammation, ulceration, tissue necrosis, or “compartment” syndrome.² Low-osmolality contrast media is better tolerated than high-osmolality contrast media.²
Although increasing use of nonionic contrast media allows for less morbidity following extravasations, large volume extravasations or extravasations of ionic contrast can lead to significant morbidity. Early extravasation detection and injection cessation may, therefore, reduce the morbidity associated with extravasations.
Upon activation, MEDRAD’s extravasation detector establishes the patient’s baseline measurement. During the injection, it safely passes an RF signal through the injection site tissue. The signal passes freely through the tissue when there is no extravasated fluid. If an extravasation occurs, the signal change is detected and the injection is stopped. An added benefit to RF technology is that the scan can be started more quickly after the contrast injection has begun – allowing for higher injection rates and, thereby, leading to higher quality images.¹
1Bouton, Chad E., Experimental Detection of Subcutaneous Contrast Extravasation Using Radio Frequency Permittivity Sensing.” Computer Assist Tomography; Volume 33 – Number 6; November/December 2009.
2“Injection of Contrast Media" American College of Radiology. Accessed 14 October 2009. http://www.acr.org/SecondaryMainMenuCategories/quality_safety/contrast_manual.aspx
*Note: In the JCAT article, Dr. Bouton expresses his assessment of the cause of an increase in extravasations. This assessment does not correlate to other published studies and should be substantiated by additional research.