The effectiveness of SPECT/CT in hepatic arterial Tc-99m MAA scan (MAAS) planning prior to hepatic Y-90 microsphere therapy (YT)

Objectives MAAS is utilized to assess proper infusion catheter positioning & absence of abdominal extrahepatic shunting (ES) prior to YT. To this end, accuracy & certainty of planar & SPECT were compared with SPECT/CT MAAS findings on same patients.

Methods 133 MAAS were performed with planar & SPECT/CT prior to YT. Planar, SPECT, & SPECT/CT were separately reviewed by 2 observers for hepatic regional distribution (HRD) pattern (right, left lobes, segmental or all), & presence/location of ES. The confidence in each assessment was categorized as certain or uncertain. Most patients had prior liver therapy (36 partial resection, 74 chemoembolization, & 16 radiation).

Results Of 133 SPECT/CT studies, the recognized HRD was less accurate (P< 0.001) in SPECT alone (118) & planar (109). Certainty of HRD was decreased (p< 0.001) in planar (69) & SPECT (102) than SPECT/CT (133). ES was seen in 18 MAAS by SPECT/CT (stomach, duodenum, pancreas, spleen or combinations), of which significantly less correct ES was observed in planar (9) & SPECT alone (13). Certainty of ES was notably less (p< 0.001) in planar (56) & SPECT (76) than SPECT/CT (132).

Conclusions SPECT/CT imaging allows correct anatomic identification of intra & extrahepatic MAA distribution & if possible should always be obtained during MAAS performed for YT planning. The markedly higher accuracy & certainty of SPECT/CT findings over planar or SPECT alone in our study may have been magnified by unusual liver configuration due to underlying pathology, tumor &/or prior therapy/resection.