Role of ⁶⁸Ga-DOTATOC in the management of neuroendocrine tumors

^99mTc-Octreoscan and Gallium ⁶⁸Ga-DOTATOC are used respectively with SPECT/CT and with PET/CT imaging for localization of somatostatin receptor positive neuroendocrine tumors (NETs). Both techniques have showed a potential in the management of neuroendocrine tumors even if PET DOTATOC demonstrated higher sensitivity and better specificity in several publications. In this study, we have compared the results of both investigations in 36 patients who have been enrolled for diagnosis or assessment of neuro endocrine tumors. ^99mTc-Octreotide SPECT/CT was performed following intravenous administration of approximately 925 MBq (^25m Ci) ^99mTc-Octreotide, considering maximum 10% error in administered activity. Planar acquisition started 3 hours after injection. Subsequently, after voiding and SPECT/CT for thoracic, abdominal and cervical regions. Whole-body scan, from skull-base to mid-thigh, was performed 60 minutes after approximately 185 MBq (^5m Ci) ⁶⁸Ga-DOTATOC bolus IV injection using a Discovery PET/CT scanner. ^99mTc-Octreotide SPECT/CT was positive in 24/36 of the patients showing a total number of 77 lesions detected by this method. ⁶⁸Ga-DOTATOC PET/CT detected NET in (26/36) of the patients representing a total number of 135 lesions while ⁶⁸Ga-DOTATOC PET/CT detected all lesions in the neck and thoracic regions (sensitivity = 100%). The lowest sensitivity for PET/CT was attributed to liver and pancreas. Regarding the limitation of global availability, ⁶⁸Ga-DOTATOC PET/CT can be particularly recommended in patients with negative ^99mTc-Octreotide scan and when alternative therapeutic protocol is evaluated. (author)