Clinical applications of SPECT/CT

Author(s): Dr Malavika Nathan

Hospital: Royal Free London NHS Foundation Trust

Reference: RAD Magazine, 45, 532, 11-12


SPECT/CT has established itself as a powerful diagnostic tool in nuclear medicine. The combined advantages of high sensitivity SPECT imaging with high specificity CT imaging has been shown to be superior to planar and SPECT imaging for many clinical indications. The CT component of SPECT/CT improves image quality through attenuation correction (AC), precise anatomical localisation of radio-pharmaceutical uptake and lesion characterisation.

The benefit of improved diagnostic accuracy with SPECT/CT potentially outweighs the risk from additional CT radiation exposure. Factors affecting CT radiation dose include x-ray tube current and voltage, acquisition slice thickness, pitch and body area imaged (less radiation dose to the extremities compared to the torso due to differences in tissue volume and radiosensitivity). CT protocols should be optimised to adhere to the principles of ALARA (as low as reasonably achievable) for each clinical indication.

Current SPECT/CT cameras on the market include conventional Anger detector configuration with integrated two to 16-slice multidetector helical CT capabilities and solid state cameras with cadmium-zinc-telluride detectors that have shown a slightly higher sensitivity and specificity compared with conventional SPECT/CT for certain indications. This article will focus on the use of SPECT/CT for select non-oncological indications, as its role in oncology will be discussed elsewhere in this issue.

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