Purpose: Somatostatin receptor scintigraphy with (111)In-DOTA-D: Phe(1)-Tyr(3)-octreotide ((111)In-DOTA-TOC) and (111)In-DOTA-lanreotide ((111)In-DOTA-LAN) has been used for staging of neuroendocrine tumours (NETs). However, the comparative diagnostic value of these radioligands on a lesion basis has not yet been established. The aim of this study was to compare the diagnostic capacity of (111)In-DOTA-TOC and (111)In-DOTA-LAN scintigraphy in patients with NETs, evaluating whether significant differences exist in lesion imaging with these radioligands. Furthermore, dosimetric data were compared.
Methods: Forty-five patients with NETs were investigated with (111)In-DOTA-TOC and (111)In-DOTA-LAN scintigraphy. Scintigraphic results were compared with those of conventional imaging and/or surgery in each patient, and also (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) in 20 patients.
Results: (111)In-DOTA-TOC and (111)In-DOTA-LAN scintigraphy were true positive in 42/45 (93%) and 39/45 (87%) patients, and imaged 74/91 (81%) and 73/91 (80%) tumour lesions, respectively. (111)In-DOTA-TOC and (111)In-DOTA-LAN detected liver metastases in 21 and 14 patients, mediastinal metastases in seven and 11 patients, and bone metastases in two and seven patients, respectively. These radioligands revealed lesions not seen by conventional imaging in seven and eight patients, respectively, or by (18)F-FDG-PET in eight and seven patients, respectively. The estimated tumour absorbed doses for (90)Y-DOTA-TOC were higher than those for (90)Y-DOTA-LAN in 14 patients, whereas the opposite was true in 12 patients.
Conclusion: Both (111)In-DOTA-TOC and (111)In-DOTA-LAN are suitable for imaging tumour lesions in patients with NETs and can detect lesions that may not be seen by conventional imaging and (18)F-FDG-PET. Compared with (111)In-DOTA-LAN, (111)In-DOTA-TOC has a superior diagnostic capacity for liver metastases, but a lower diagnostic capacity for metastatic lesions in mediastinum and bone.