SPECTscans

SPECT scans refer to imaging studies that use single photon emission computed tomography to visualize the distribution of radiopharmaceuticals in the body. The technique combines a gamma-emitting tracer with a rotating gamma camera to acquire multiple projections from different angles, which are reconstructed into three-dimensional images. SPECT provides functional information about tissue perfusion, metabolism, and receptor activity, complementing anatomic imaging.

Common uses include cardiology, neurology, oncology, and infection imaging. In cardiology, SPECT assesses myocardial perfusion and viability to help diagnose coronary artery disease and guide treatment. In neurology, it evaluates cerebral blood flow in conditions such as epilepsy, dementia, stroke, and traumatic brain injury. In oncology, SPECT helps with tumor characterization, staging, and monitoring response to therapy, sometimes using targeted radiopharmaceuticals. For infection or inflammation, radiolabeled white blood cells or other tracers can localize active sites.

Procedure and interpretation: after intravenous injection of the radiotracer, uptake is allowed to occur, followed by image acquisition with a gamma camera that rotates around the patient. The data are reconstructed into cross-sectional images and, in many cases, fused with computed tomography (SPECT/CT) to provide anatomical reference. Tracers commonly used include technetium-99m compounds (for example, sestamibi or tetrofosmin in cardiac imaging) and agents such as Tc-99m HMPAO for brain imaging.

Safety and limitations: SPECT uses ionizing radiation; dose depends on the tracer and protocol. Advantages include functional insight and relative availability; limitations include lower spatial resolution and, historically, longer imaging times compared with newer modalities like PET. Advances in detectors and hybrid systems continue to improve accuracy and localization.