The first thing that comes to mind when opening a nuclear medicine department is the equipment.
There are many types of different gamma cameras available on the market today, each with various features, and it can be challenging to sort through the noise to determine what you need. Extraordinary advancements in imaging technology have given facilities a wide variety of cameras and different levels and types of technology in the field.
In this post, we will explore the cameras options and the different types of technology available on the market today.
What Options Are Available for SPECT Cameras for Cardiology
SPECT (single photon emission computed tomography) cameras are the most popular gamma cameras. These cameras typically have two or more detectors (camera heads) that allow the technologist to acquire images to create the reconstructed SPECT studies.
Several manufactures sell and service nuclear medicine cameras specifically developed for cardiac imaging needs. As such, there is no need to investigate or purchase a general purpose nuclear medicine camera that happens to also perform cardiac SPECT.
The main purpose of a SPECT camera is to create a 3D image of the patient. Images are acquired by rotating the detectors or patient, stopping every few degrees creating a tomographic image. From here, the image is processed into clinically diagnostic images that can be displayed in multiple 2 and 3-dimensional views.
There are three main types of SPECT cameras currently available on the market today: SPECT, SPECT/CT, and SPECT/FAC. The table below provides a high-level overview of each option:
SPECT Camera Technology Quick Reference Chart
A SPECT only camera is the most common technology for nuclear cardiology studies. While it does have the ability to create adequate 3D images of the heart, most do not offer attenuation correction (AC) capabilities. SPECT MPI studies without AC have lower sensitivity and specificity when compared to SPECT MPI studies with AC.
Historically, the attenuation correction is performed by a radioactive rod source that travels the length of the system detectors while the patient acquisition is occurring. This step adds time to the acquisition and can come with complications. The radiation from the rod source travels through the patient and is detected by the detector heads. While this does get the job done for creating a rudimentary attenuation correction map, it is the least advanced of the technology available today.
Having a rod source can also lead to headaches and complicated issues; one of the most common issues with a rod source is the device getting stuck during image acquisition. This necessitates rebooting of the system and acquiring the patient images again. Rod sources are also expensive and require replacement every year.
A SPECT/CT camera may be used to create attenuation correction maps of patients undergoing SPECT MPI imaging. While utilizing CT for attenuation correction purposes does work, the radiation exposure levels can vary widely, depending on manufacturer protocols and operator preferences.
These systems are often found in hospitals and large imaging centers, as SPECT/CT is commonly used for oncology imaging purposes. Most find that a SPECT/CT system is an excessive spend for cardiology studies given their physical size and overall expense, including repair and maintenance, post warranty.
A SPECT/FAC system may be the ideal fit for an office or facility that focuses on cardiac imaging. While many users might be unfamiliar with the FAC acronym, it is quickly becoming mainstream in the nuclear cardiology imaging community. FAC stands for fluoresce attenuation correction.
In a sense, it’s like a fluoro x-ray procedure where the x-ray source is turned on, and then a rapid, extremely low radiation dose scan is performed immediately prior to acquiring the SPECT portion of the study. These images create the attenuation correction map that is applied and overlayed onto the SPECT images.
It is important to note that cameras that utilize this technology, like the Digirad X-ACT+, produce clear images with the lowest radiation dose available on the market. Pairing FAC technology with advanced solid-state detectors provides a fast, high-quality, and efficient cardiac imaging system.
SPECT Camera Detector Heads
One additional item to consider when evaluating SPECT cameras is the number of detectors or camera heads. While most systems have two detectors, there are systems available that have one or even three camera heads. So, what’s the difference between all of these systems? It’s the speed and ability to provide you with more detail.
Here’s a quick look at the pros and cons of each: