PET/CT

PET/CT > Normal Activity > Thorax > Lungs

Lungs

Normal lung

There should be very low level activity within the lungs on attenuation corrected images. Conversely, activity will appear diffusely more intense on non attenuation-corrected images. Any activity that appears focally more intense than other lung activity should be viewed with suspicion and the CT data scrutinized for evidence of pathology.

Normal lung parenchyma demonstrates relatively low level FDG activity diffusely on attenuation-corrected images (top row). In contrast, there appears to be diffusely increased activity throughout the lungs compared to other tissues on non-attenuation-corrected images (bottom row) because of the relatively little attenuation of the photons originating in the lungs by the surrounding lung parenchyma through which they have to pass to reach the detectors. The difference between these two data sets highlights the necessity of attenuation correction for accurate results in PET imaging.