Attenuation correction is a process that identifies and corrects for soft tissue artifacts in SPECT images. Ultimately, the goal is to minimize the visual impact of attenuation in order to provide images that more accurately portray the distribution of imaging agent in the patient. This results in higher reading confidence, improves diagnostic accuracy, and lowers the incidence of false positive studies thereby reducing the number of unnecessary diagnostic cardiac catheterizations.
Traditional attenuation correction methods
Historically, there were two primary methods of attenuation correction, line source, and CT. While line source attenuation correction is a valid method and is still currently used, its biggest disadvantages include the challenging number of mechanical failures, the difficulty of use, line source decay yields imaging quality issues as a function of time and has expensive replacement cost. For these reasons, users often opt for an alternative method when it’s time to consider replacing or upgrading equipment.
CT attenuation correction is a popular method primarily used in the radiology and oncology fields where the CT can be used for diagnostic purposes. However, for a dedicated cardiac environment, the high cost of a SPECT-CT system is unsustainable. Additionally, the costs of constructing a shielded room can be greater than the scanner itself.
The lack of viable options for Cardiologists has resulted in patients being without the benefit of attenuation correction. However, Cardiologists who want to offer attenuation correction are leveraging a new, third method – Fluorescence Attenuation Correction.
Fluorescence Attenuation Correction – Low dose and low cost
Fluorescence attenuation correction utilizes a fluorescence X-ray thus allowing for a lower dose and less radiation exposure to the patient. The method is a unique combination of hardware and software technology that allows for the delivery of superior image quality at the lowest possible radiation burden (less than 5 microsieverts).
From a cost standpoint, FAC does not require room shielding and uses the same detectors as the SPECT system. The homogenous pattern of the fluorescence X-ray also contributes significantly to a better, cleaner image and substantially increases diagnostic confidence.
Currently, fluorescence attenuation correction is only available in conjunction with the Digirad X-ACT+ camera. Although attenuation correction is not new to the industry, Digirad’s methodology is able to offer a significant improvement from a reliability, exposure and cost standpoint. The X-ACT+ uses an optimized design to bring benefits of attenuation correction to the cardiac patient, physician, technologist, and facility. The end result is more accurate results, less false positives, and less needless additional testing which means less radiation burden for patients and lower costs to the payer systems.