validation of the tricistronic vector hNET.2A.FLuc.2A.RQR8 via (a) BLI and (b-e) SPECT/CT. 5 × 106 SupT1/hNET.2A.FLuc.2A.RQR8 were inoculated into the right flank of immunocompromised mice. Regions of interest were drawn around the right flanks and mean luminescence signal intensity was measured (n = 3). (b-d) Maximum intensity projection (MIP) SPECT images and (e) SPECT/CT illustrate 123I-MIBG clearance via renal excretion, with increasing signal in the adrenals, thyroid, salivary glands and tumour (d, e). Percent injected dose (n = 3) of 123I-MIBG within the tumours was determined by drawing 3D regions of interest. Colour bars represent counts per minute with maximum and minimum threshold levels indicated.