From the Guidelines
Single Photon Emission Computed Tomography (SPECT) offers significant advantages in medical imaging, particularly in its ability to assess physiological processes and metabolic activity, allowing for the evaluation of organ function and blood flow, as noted in a study from 1. The primary benefits of SPECT include its ease and quickness of performance, requiring only an intravenous injection, and its widespread availability in most radiology departments, as highlighted in 1. Some of the key advantages of SPECT are:
- It provides three-dimensional functional information about organs and tissues.
- It is valuable in cardiac imaging for detecting coronary artery disease by showing areas of reduced blood flow to the heart muscle during stress tests.
- It helps identify abnormal brain perfusion patterns in neurological conditions like dementia, epilepsy, and stroke.
- It uses gamma-emitting radiopharmaceuticals, which pose minimal radiation risk to patients.
- It is more widely available and less expensive than other functional imaging modalities like PET, making it accessible in many clinical settings, as compared in 1 and 1. However, it's also important to consider the limitations of SPECT, such as attenuation, motion, and soft tissue artifacts, which may underestimate the extent of disease, and exposure to radiation, as mentioned in 1. Despite these limitations, SPECT remains a valuable diagnostic tool, especially when combined with CT (SPECT/CT), which enhances its diagnostic capability by providing simultaneous functional and anatomical information, improving localization of abnormalities and diagnostic accuracy, as supported by the most recent guidelines and studies, including 1 and 1.
From the Research
Advantages of SPECT
- The main advantage of SPECT/CT is the increased specificity achieved through a more precise localization and characterization of functional findings 2.
- SPECT provides comprehensive functional data across the spectrum of coronary artery disease (CAD) and a cost-effective strategy in patients with intermediate pre-test probability of CAD or with a history of ischemic cardiomyopathy 3.
- SPECT myocardial perfusion scintigraphy (MPS) is a non-invasive technique that allows the presence, location, and extent of ischemia to be determined, which is important from a prognostic and therapeutic point of view 4.
- SPECT MPS variables yield both independent and incremental value to combinations of clinical, exercise tolerance testing (ETT), and angiographic variables in predicting cardiac death or non-fatal MI 4.
Clinical Applications
- SPECT/CT should be a routine imaging technique, fully integrated into the clinical decision-making process, including oncology, endocrinology, orthopedics, pediatrics, and cardiology 2.
- Myocardial perfusion SPECT is widely used in assessing coronary artery disease (CAD) owing to its proven efficacy in extensive clinical experience 3.
- SPECT MPS provides important additional information to that from ETT and/or coronary angiography (CA) that helps to risk-stratify patients with suspected or known CAD or following myocardial infarction (MI), enabling them to be managed more appropriately 4.
Comparison with Other Imaging Modalities
- PET MPI offers better quality images, higher diagnostic accuracy, along with shorter protocols and lower radiation dose to the patient compared to SPECT MPI 5.
- PET MPI addresses most of the limitations of SPECT, including soft-tissue attenuation artifacts, underestimation of ischemia, and longer protocols with higher radiation dose 5.
- Cardiac dedicated SPECT scanners can also perform dynamic imaging and have stimulated research into myocardial blood flow (MBF) quantification using SPECT tracers 6.