Spectrum of findings in 99mTc-MAA SPECT/CT and their significance in treatment planning for Yttrium 90-microsphere radioembolization for hepatocellular carcinoma

The primary utility of 99mTc-MAA SPECT/CT is to quantify lung shunt fractions and identify additional sites of extra-hepatic uptake in the pre-therapy evaluation for Yttrium-90-microsphere (Y90) radioembolization of the liver.After a review of 99mTc-MAA intra-arterial injection and SPECT/CT imaging technique, the evaluation of lung shunt fraction and it significance will be discussed.The potential morbidities from extra-hepatic distribution including radiation pneumonitis, gastrointestinal tract ulceration / bleeding and cholecystitis will be reviewed.Findings on 99mTc-MAA SPECT/CT that may preclude the patient from receiving radioembolization will be identified.Multiple examples of extra-hepatic 99mTc-MAA distribution involving gallbladder, duodenum, stomach, and portal vein tumor thrombus will be displayed with correlative fused and diagnostic CT imaging.The impact of extra-hepatic 99mTc-MAA identified by the nuclear physician on the treatment plan will be reviewed.This will include the role of prophylactic arterial bland arterial embolization / coiling with correlative arteriograms.Examples of pitfalls in extra-hepatic uptake including 99mTc-MAA breakdown products in thyroid, stomach and kidneys will be shown and potential technique changes to ameliorate these pitfalls will be discussed.