Different concentrations of various radiopharmaceuticals in the two main liver lobes: A preliminary study in clinical patients

Background. At clinical scintigraphic examinations of the abdomen using single photon emission computed tomography (SPECT), we have observed a different distribution between the left and right main liver lobes of various radiopharmaceuticals. This was studied retrospectively in clinical patients. Methods. Examinations with [123I]-metaiod obenzylguanidine MIBG; (n = 19), a 99mTc-labelled monoclonal antibody against granulocytes (n = 18), and 111In-pentetreotide (n = 26) were assessed. There was no known history of, or risk factor for liver disease, and all lobes showed a uniform activity distribution. Twenty healthy volunteers underwent consecutive examinations with 99mTc-dimethyliminodiacetic acid (HIDA). The activity ratios between the left and right main liver lobes were calculated from the transverse tomographic (SPECT) sections. Results. The left: right lobar activity ratio for [123 I]-MIBG was (mean plusmn; SD) 1.25 ± 0.21 (null hypothesis = 1.00; P < 0.001); for the antibody, acquisition after 3-5 h was 0.98 plusmn; 0.06 (NS) and after 20-24 h, 0.99 plusmn; 0.11 (NS); for 111In-pentetreotide, 0.90 plusmn; 0.09 (P < 0.001); for 99mTc-HIDA, immediate acquisition, 0.68 plusmn;0.12 (P < 0.001) and acquisition at 7 min, 0.66 plusmn; 0.12 (P < 0.001). Conclusions. The differences in tracer uptake between the liver lobes cannot be caused only by differences in blood flow. One explanation of the higher uptake of [123I]-MIBG by the left lobe may be a greater presence of catecholamines and a higher sympathetic nerve density in this liver portion. Consequently, there may be a functional difference between the two main liver lobes. © Springer-Verlag Tokyo 2005.