A Single Photon Emission Computed Tomography (SPECT) scan is a sophisticated nuclear imaging test that provides invaluable insights into the blood flow within our organs and tissues. 

At its core, a SPECT scan combines the capabilities of a CT scan (Computed Tomography) with a radioactive tracer to visualize blood flow through various tissues and organs. This procedure is particularly prominent in neurological examinations to assess blood circulation within the brain and post-traumatic incidents.

Before undergoing a SPECT scan, patients receive an injection of a radioactive chemical, emitting gamma rays crucial for detection by the scanner. The CT scanner’s computer interprets the signals emitted by the radioactive tracer, rendering two-dimensional cross-sectional images of the body. These cross-sections can subsequently be assembled to construct a three-dimensional brain representation. Commonly employed radioisotopes for SPECT scans include iodine-123, xenon-133, fluorine-18, and thallium-201. These isotopes are chosen for their rapid and safe elimination from the body post-examination. In some instances, diverse chemicals and medications can be tagged with these elemental isotopes to serve specific diagnostic purposes.

The choice of tracer depends on the medical practitioner’s objectives. For instance, when investigating a tumor, glucose may be labeled with radioactivity to monitor the tumor’s metabolic activity. It is important to note that a SPECT scan differs from a Positron Emission Tomography (PET) scan, as in the former, the tracer remains in the bloodstream and is not absorbed by tissues. While this limits the detection area of the SPECT scanner, it is a more cost-effective and widely available option than the higher-resolution PET scan.

SPECT scans predominantly examine blood flow within the brain, specifically the arteries and veins. Some medical professionals assert that SPECT scans possess greater sensitivity in detecting brain injuries compared to CT or MRI scans, as they can identify reduced blood flow in injured brain regions.

Moreover, SPECT scans serve as a valuable pre-surgical assessment for individuals experiencing uncontrolled seizures despite medication. By conducting tests during both seizure and non-seizure periods, medical practitioners gain insights into how blood flow in the brain is affected at the seizure’s onset.

Additionally, SPECT scanning can detect stress fractures of the spine, medically termed spondylolysis. This imaging technique is also instrumental in identifying the regions of the brain impacted by strokes and pinpointing the presence of tumors. Highly trained technologists specializing in nuclear medicine conduct SPECT scans.

SPECT scans are typically performed at hospitals or outpatient imaging centers within the nuclear medicine department. Patients preparing for the examination need only wear comfortable attire and should anticipate 1-2 hours for the procedure.

During the test, a technologist will insert an intravenous (IV) line and administer a small amount of radioactive tracer. After a brief waiting period of ten to twenty minutes, the tracer will have circulated to the brain, and the CT scanner will capture the necessary images. Patients are required to lie still throughout this process. Following the scan, it is advisable to drink plenty of water to aid in flushing the radioactive tracer from the system.

^{Editor’s Note: updated 11.2.23 Photo by Accuray on Unsplash}