Different concentrations of I-123 MIBG and In-111 pentetreotide in the two main liver lobes in children - Persisting regional functional differences after birth?

Purpose: At examinations in children with I-123 metaiodobenzylguanidine or with In-111 pentetreotide using SPECT, we have observed a different distribution of the radiopharmaceuticals between the left and right main liver lobes. This phenomenon was studied in retrospect from clinical examinations. Patients and Methods: Seventeen children (mean age, 51 months; range, 11-150 months) with neuroblastoma or ganglioneuroma examined with both radiopharmaceuticals within I week using SPECT were assessed. There was no history of liver disease and all liver lobes showed uniform activity distribution. Simultaneous radiologic examinations were all normal with regard to the liver. No child with a pathologic liver chemistry test was included. The activity ratios between the left and right main liver lobes were calculated from transverse tomographic sections. Results: The mean left:right lobar activity ratio for I-123 metaiodobenzylguanidine was 1.26 +/- 0.12 (null hypothesis = 1.00; P < 0.001) and for In-111 pentetreotide 0.88 +/- 0.06 (null hypothesis = 1.00; P < 0.001). There was no age-dependent distribution of the tracers. The correlation between the tracer uptake of the different liver lobes was very weak. Conclusion: A functional difference between the 2 main liver lobes in utero is believed to reflect differences of the vascular supply. The current findings indicate a persisting functional heterogeneity of the liver after birth not caused by perfusion differences. A relatively higher uptake of I-123 NHBG and a lower uptake of In-111 pentetreotide of the left liver lobe are normal findings.