Comparison of 68Ga-DOTATOC PET and 111In-DTPAOC (Octreoscan) SPECT in patients with neuroendocrine tumours

Purpose Neuroendocrine tumours (NETs) can be imaged with scintigraphy using radiolabelled somatostatin analogues. The aim of our study was to compare the value of Ga-68-DOTATOC PET and In-111-DTPAOC SPECT (Octreoscan) in the detection of NET manifestations. Methods Twenty-seven NET patients were prospectively examined. Ga-68-DOTATOC PET and In-111-DTPAOC SPECT were performed using standard techniques. Treatment was not applied in between. Mean and maximum standardised uptake values (SUVs) were calculated for PET findings. Tumour/non-tumour ratios were calculated for SPECT findings. Findings were compared by a region-by-region analysis and verified with histopathology, CT and MRI within 21 days. Results SUVs of positive lesions on Ga-68-DOTATOC PET ranged from 0.7 to 29.3 (mean SUV) and from 0.9 to 34.4 (maximum SUV). Tumour/non-tumour ratios on In-111-DTPAOC SPECT ranged from 1.8 to 7.3. In imaging lung and skeletal manifestations, Ga-68-DOTATOC PET was more efficient than In-111-DTPAOC SPECT. All discrepant lung findings and 77.8% of discrepant osseous findings were verified as true positive PET interpretations. In regional comparison of liver and brain, Ga-68-DOTATOC PET and In-111-DTPAOC SPECT were identical. In lymph nodes, the pancreas and the gastro-intestinal system, different values of the two techniques were not indicated in regional analyses. In a single patient, surgical interventions were changed on the basis of Ga-68-DOTATOC PET findings. Conclusion Ga-68-DOTATOC PET is superior to In-111-DTPAOC SPECT in the detection of NET manifestations in the lung and skeleton and similar for the detection of NET manifestations in the liver and brain. Ga-68-DOTATOC PET is advantageous in guiding the clinical management.