Till Alexander Heusner MD, Presenter: Nothing to Disclose

Christian Boy MD, Abstract Co-Author: Nothing to Disclose

Stefan Petersenn, Abstract Co-Author: Nothing to Disclose

Steffen Hahn MD, Abstract Co-Author: Nothing to Disclose

Andreas Bockisch, Abstract Co-Author: Nothing to Disclose

Gerald Antoch MD, Abstract Co-Author: Nothing to Disclose

To provide an atlas of physiological SUVmax values on 68Ga-DOTATOC-PET/CT-scans and to correlate the results with the regional mRNA expression of the somatostatin (sst) receptors 1-5.

SUVmax values were obtained from 100 oncological patients (mean age: 54 y, 19-83 y, SD: 13.5 y, 46 men, 54 women) who underwent whole-body 68Ga- DOTATOC-PET/CT. Normal SUVmax values were documented for different physiological tissues not affected by tumor spread or inflammation. SUVmax values were correlated with mRNA expression of sst receptors 1-5 measured independently in pooled normal tissue by real time polymerase chain reaction (RT-PCR). Results were correlated by using the Spearman´s rank correlation coefficient.

SUVmax values (mean±SD) for normal tissues were heterogenous [e.g., spleen 30.3±10.3; kidney 16.8±5.0; liver 12.6±3.5; pancreas 8.7±3.8; stomach 6.9±3.0; small bowel 4.7±1.8; bone 3.9±1.4; muscle 2.1±0.5; lung 0.7±0.3; parotid gland 1.9±0.6]. SUVmax values correlated significantly with the mRNA expression of sst receptor 2 in physiological tissues (r=0.846, p<0.001), whereas there was no correlation with the expression of the other four subtypes.

Physiological SUVmax values show a wide range on 68Ga-DOTATOC-PET/CT scans. Parenchymal organs not affected by tumor may have high SUVs on image assessment. In vivo, the molecular target of 68Ga-DOTATOC is limited to only one sst receptor subtype, the sst receptor 2.

The knowledge of 68Ga-DOTATOC tracer binding to sst receptor 2 may improve the diagnostic work-up and molecular therapy of sst receptor expressing neuroendocrine tumors in vivo.

Heusner, T, Boy, C, Petersenn, S, Hahn, S, Bockisch, A, Antoch, G, 68Ga-DOTATOC-PET/CT Imaging and Somatostatin (SST) Receptor-Fingerprints in Physiological Human Tissues: SUVmax Meets mRNA-expression.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8002393.html