Value of the ⁶⁸Ga-DOTATATE PET-CT in the diagnosis of endometriosis. A pilot study

Objective: The non-invasive diagnosis of endometriosis remains challenging. Recent data suggested that somatostatin might be involved in its pathogenesis. High sensitive visualization of somatostatin receptors expression is possible using PET-CT imaging after the administration of a ⁶⁸Ga-labeled somatostatin analog (DOTATATE) that will bind to the somatostatin receptor sub-types 2 and 5. The aim of the present study was to assess the usefulness of ⁶⁸Ga-DOTATATE PET-CT in the diagnosis of endometriosis.

Study design: This is a prospective, single center pilot study. A pre operative ⁶⁸Ga-DOTATATE PET-CT was performed in all of the patients who presented with suspected endometriosis and who were scheduled for a laparoscopy. Surgical endometriosis staging and histopathological analysis, including somatostatin receptors SST1, 2 and 5 immunohistochemistry (IHC) of removed specimens, were confronted to the results of the ⁶⁸Ga-DOTATATE PET-CT.

Results: 12 patients were included in this study. ⁶⁸Ga-DOTATATE PET-CT performed pre operatively showed increased pathologic uptake in four patients with a deep infiltrating endometriosis (DIE) recto-vaginal lesion and in another patient with an adenomyoma. Expression of SST1, 2 and 5 receptors in surgical specimens was confirmed by IHC in these five lesions. Neither superficial peritoneal endometriosis, nor ovarian endometrioma were found to show an increased pathologic uptake on ⁶⁸Ga-DOTATATE PET-CT. IHC analysis confirmed that SST1, 2, and 5 receptors were not present in these lesions.

Conclusion: The results observed in this small size series of patients seem to confirm expression of somatostatin receptors only in recto-vaginal DIE and focal adenomyosis lesions. The usefulness of ⁶⁸Ga-DOTATATE PET-CT in the diagnosis of this entity is uncertain. Future research should concentrate on studying the role of somatostatin in the pathogenesis of DIE.