PET-CT with <sup>68</sup>Ga-DOTA-peptides in non gastro-entero-pancreatic (nonGEP) neuroendocrine tumors (NET). Initial experience — ASN Events
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  3. PET-CT with 68Ga-DOTA-peptides in non gastro-entero-pancreatic (nonGEP) neuroendocrine tumors (NET). Initial experience

PET-CT with 68Ga-DOTA-peptides in non gastro-entero-pancreatic (nonGEP) neuroendocrine tumors (NET). Initial experience (#59)

Daniel Valenzuela 1 , Pilar Orellana 1 , Juan Carlos Quintana 1 , Vicentini Daniel 1 , Rodrigo Pinillla 1
  1. Pontificia Universidad Católica de Chile, Santiago, METROPOLITANA, Chile

Background

68Ga-DOTA-peptide currently is the imaging of choice in the evaluation of tumors that overexpress somatostatin receptors (SSTR) such as gastroenteropancreatic neuroendocrine tumors (GEP-NETs). There are other pathological entities that show SSTR overexpression. 68Ga-DOTA-peptide can be useful in the evaluation of these tumors.

We show our experience in use of 68Ga-DOTA-peptide in the evaluation of non GEP-NETs.

Methodology

We retrospectively reviewed clinical data and PET-CT in patients suspected to have a non GEP-NET.  Final diagnosis was confirmed by histology, laboratory tests and clinical outcome.

Results

Thirty out of 259 (11.6%) PET-CT studies with 68Ga-DOTA-peptides were included; corresponding to twenty five patients with non GEP-NETs; 13 females, between 15 days and 74 years old. Ten patients had medullary thyroid cancer, 6 had pheochromocytoma, 3 had congenital hyperinsulinism, 3 had oncogenical osteomalacia, 2 had ectopic ACTH syndrome and 2 had thymoma. Others diagnoses were suspected in four patients. Results of PET-CT according diagnosis are shown in Figure N°1. Study showed the presence of a mesenchymal phosphaturic tumor in two patients with oncogenic osteomalacia. In 2 out of 3 neonates with congenital hyperinsulinism, study shows hyperplasia of Langerhans cells. SSTR density was different among tumors. Two patients underwent further Peptide Receptor Radionuclide Therapy (PRRT) with 177Lu-DOTATATE, one with malignant pheochromocytoma and one with dedifferentiated papillary thyroid cancer.

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Figure 1: 68Ga-DOTA-peptides in non GEP-NETs. MTC: medullary thyroid cancer.  PHEO: pheocromocitoma. CHI: congenital hyperinsulinism. OO: oncogenial osteomalacia. EAS: ectopic ACTH syndrome.  THY: thymoma.

Conclusions

68Ga-DOTA-peptides PET-CT appears to be a valuable imaging modality in a broad clinical spectrum of non GEP-NETs that overexpress SST receptors, with potential utility for initial diagnosis, follow-up and selection of candidates for PRRT. Expression of various SST receptor subtypes and their density on abnormal cell surface may contribute to variability on radiotracer uptake that was observed in this small series.