A 78-year-old male with hepatocellular carcinoma and no prior radioembolization
was injected with 99mTc-MAA via right groin access into the right
hepatic artery and was imaged 109 minutes after injection. Calculated lung shunt
fraction was 16%. He did not undergo 90Y-radioembolization
because of extensive portal venous thrombus identified during angiography.
Axial, coronal, and MIP SPECT (Row A), axial and coronal fused SPECT/CT (Row B),
axial and coronal CT (Row C), and anterior planar (D) images demonstrate
radiotracer uptake within the gastric mucosa and not the serosa, as well as in
the thyroid and salivary glands, consistent with a pertechnetate distribution.
This case also demonstrates radiotracer uptake in the spleen, which, similar to
but less commonly seen than the renal cortex, is hypothesized to relate to
proteolytic breakdown of MAA into smaller aggregates, which may be subsequently
cleared by the reticuloendotheliar system.