SPECTCT

SPECT-CT is a hybrid medical imaging modality that combines single-photon emission computed tomography (SPECT) with computed tomography (CT) in a single imaging session. By fusing functional information from radiotracer uptake with detailed anatomical structure, SPECT-CT provides precise localization of physiologic or pathologic processes.

In a typical SPECT-CT exam, a radionuclide is administered and SPECT acquires functional data, while CT provides anatomical reference and, often, attenuation correction for the SPECT data. Modern scanners integrate gamma cameras and CT in one gantry, enabling sequential or simultaneous acquisition and software fusion to create co-registered images.

Common applications include oncology for tumor staging and assessment, sentinel lymph node mapping, and monitoring response to therapy; cardiology for myocardial perfusion imaging with CT attenuation correction; neurology for localization of seizures or brain tumors; and infectious or inflammatory conditions such as osteomyelitis, fever of unknown origin, and bone infections.

SPECT-CT offers improved lesion localization and diagnostic confidence compared with SPECT or CT alone, but it adds radiation exposure from the CT component. Dose can be minimized with low-dose CT protocols. Limitations include equipment cost, availability, potential fusion artifacts, and the need for multidisciplinary interpretation.