Non-Target Activity Detection By Post-Radioembolization Yttrium-90 Pet/Ct: Image Assessment Technique And Case Examples

High resolution yttrium-90 (Y-90) imaging of post-radioembolization microsphere biodistribution may be achieved by conventional positron emission tomography with integrated computed tomography (PET/CT) scanners that have time-of-flight capability. However, reconstructed Y-90 PET/CT images have high background noise, making non-target activity detection technically challenging. This educational article describes our image assessment technique for non-target activity detection by Y-90 PET/CT, which qualitatively overcomes the problem of background noise. We present selected case examples of non-target activity in untargeted liver, stomach, gallbladder, chest wall, and kidney, supported by angiography and Y-90 bremsstrahlung single-photon emission computed tomography with integrated computed tomography (SPECT/CT) or technetium-99m macroaggregated albumin SPECT/CT.