Significance of MIBG liver uptake in children with neuroblastoma

Objectives I-123 MIBG assessment of metastatic liver disease in children with neuroblastoma is difficult due to normal background activity. We investigated patterns of MIBG uptake in the liver with correlation to radiological and clinical data.

Methods 53 consecutive MIBG studies of 27 children with neuroblastoma were reviewed. All studies included SPECT/CT of the abdomen. Sites of diffuse or focally increased uptake in the liver were recorded. Focal uptake intensity was expressed as a ratio between the counts in regions of interest placed over the focus and segment 7. MIBG findings were compared to CT, MR, US and to the clinical course. Further comparison was made to another group of 4 selected children with proven metastatic liver disease.

Results Heterogeneous liver uptake, due to sites with focal or diffuse increase in MIBG localization, was noted in 64% of the studies. Sites with diffuse uptake in the left lobe were present in 30 studies, in both lobes in 4 studies and none in the right lobe only. Diffuse uptake, anteriorly in the left lobe, was seen in 11/30 studies. 44 sites of focal uptake were detected in 30 studies predominantly in segments 4 and 2 of the left lobe. Focal uptake ratios ranged from 1.4 to 4.6. Correlative imaging and clinical follow up detected liver metastases in only one child. His MIBG study showed diffuse and focal sites in both lobes. The highest focal uptake ratio was 1.6. Selected studies of 4 children with known liver metastases showed focal uptake in 6/7 studies and diffuse uptake in 3/7. Some foci appeared intense. Ratios were not calculated because disease was present in the reference segment. The right lobe was involved in 6/7 and the left in 7/7 studies.

Conclusions Diffuse and focally increased MIBG uptake is often seen in livers of children with neuroblastoma, predominantly in the left lobe, reflecting, in most cases normal tracer biodistribution. MIBG findings in the right liver lobe are more likely to suggest liver disease. MIBG is limited in detecting liver disease. Correlation with radiologic modalities is essential