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

Abstract

Purpose: Neuroendocrine tumours (NETs) can be imaged with scintigraphy using radiolabelled somatostatin analogues. The aim of our study was to compare the value of (68)Ga-DOTATOC PET and (111)In-DTPAOC SPECT (Octreoscan) in the detection of NET manifestations.

Methods: Twenty-seven NET patients were prospectively examined. (68)Ga-DOTATOC PET and (111)In-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 (68)Ga-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 (111)In-DTPAOC SPECT ranged from 1.8 to 7.3. In imaging lung and skeletal manifestations, (68)Ga-DOTATOC PET was more efficient than (111)In-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, (68)Ga-DOTATOC PET and (111)In-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 (68)Ga-DOTATOC PET findings.

Conclusion: (68)Ga-DOTATOC PET is superior to (111)In-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. (68)Ga-DOTATOC PET is advantageous in guiding the clinical management.