Added value of 111-Indium octreotide SPECT/CT in the imaging of neuroendocrine tumours

Objectives Background: Neuroendocrine Tumours (NET) constitute a heterogeneous group of neoplasms which originate from neuroendocrine cells,and may frequently present with hypersecretory syndromes. SPECT/CT provides the functional information of 111Indium Octreotide study and the structural information provided by the CT study in a single study. This helps overcome the limitations of the individual studies by providing accurate localisation and characterisation of the pathology. It is also useful in the identification of coexistent pathologies. Aim: To evaluate the benefit of SPECT/CT imaging over traditional planar and SPECT 111Indium octreotide imaging.

Methods We retrospectively assessed planar, SPECT and SPECT /CT imaging in 30 patients (8 females, 22 males) with neuroendocrine tumours referred for 111Indium Octreotide imaging. Two nuclear medicine physicians evaluated the studies independently. Planar and SPECT 111In Octreotide images were initially assessed for the presence and extent of the disease. This was followed by evaluation of the SPECT/CT images. Note was made of any additional information provided by the SPECT/CT images regarding accurate localisation and characterisation of the areas of uptake noted on the 111Indium Octreotide study. Also note was made of any clinically significant incidental findings.

Results There was improved localisation and characterisation of the areas of uptake seen in 50% of the patients (15/30).The most common sites where additional localisation information proved beneficial was noted in the abdomen and pelvis and to a lesser extent within the thorax. Clinically significant new information was seen in 36% patients (11/30).This included identification of non tracer avid disease, pleural effusions and adrenal nodules on the CT study.

Conclusions SPECT/CT provides valuable additional information regarding localisation and characterisation of the tracer avid disease. The identification of incidental clinically significant non avid disease has important implications in further management of the patients