Role of 123-Iodine MIBG SPECT/CT in patients with clinically suspected or histological confirmed neuroendocrine tumours

Objectives Introduction: Neuroendocrine tumours (NET’s) are rare, slowly growing and possess distinct biological and clinical characteristics. Several radiolabelled SPECTand PET tracers are used in the diagnosis of NET’s. 123I-MIBG plays a complimentary role in imaging NET’s as they not only express somatostatin receptors, but often express active amine precursor uptake-1 mechanisms also. Aim: To assess the additional benefits of 123-Iodine MIBG SPECT/CT over planar/SPECT images in patients with clinically suspected or histological confirmed NET’s.

Methods 53 patients with clinically/biochemical suspicion or histological proven neuroendocrine tumours (28 females and 25 males) were referred for 123-Iodine MIBG scan. The tumour types include carcinoid tumours, VHL syndrome, paraganliomas, medullary thyroid cancer and metastatic. Patients underwent whole body 123I-MIBG scan followed by SPECT/CT. SPECT/CT imaging was performed using a dual head gamma camera SPECT/CT system (Philips Precedence 16; Philips, Milpitas, CA). The scans were retrospectively reviewed for (a) accurate localisation, and (b) for any clinically relevant additional findings.

Results 29/53 patients the planar and SPECT/CT were normal (no evidence of MIBG avid lesions). In 24/53 patients MIBG scan was positive and MIBG avid disease were identified in both planar and SPECT images. However, SPECT/CT improved localisation and characterisation in 45% of the patients (11/24). Liver metastases in 3 patients were localised to specific segments of the liver. In 8 Patients SPECT/CT localised extrahepatic MIBG avid lesions (precarinal and para aortic lymph nodes, mesentery, lung nodules, subcutaneous metastasis and pharyngeal lesion). In addition, 123I-MIBG SPECT/CT identified clinical relevant findings such as non-avid disease, lung nodules, lymph nodes and adrenal adenoma in 41% (10/24).

Conclusions 123I-MIBG SPECT/CT is useful in accurate localisation and characterisation of NET’s. Incidental findings may have a significant impact on patient’s further management