FIGURE 1.

Tyr3-octreotide (TOC) variant VMT-α-NET is a novel and ideal ligand for ²⁰³Pb/²¹²Pb that shows lower renal excretion, higher neuroendocrine tumor uptake, and high chelation properties for retention of daughter α-particle emitting radionuclide ²¹²Bi. In an end-stage midgut neuroendocrine tumor patient with carcinoid heart disease, right ventricular dysfunction, mildly reduced renal function, and refractory to 6 cycles of ¹⁷⁷Lu-HA-DOTATATE therapy, planar, and 22 hours ²⁰³Pb-VMT-α-NET SPECT/CT (low dose) images were acquired after injection of 224 MBq of ²⁰³Pb-VMT-α-NET to assess the feasibility of performing ²¹²Pb-VMT-α-NET therapy. The patient tolerated the injection without any significant alteration in the vital parameters. There was rapid renal clearance of the tracer within the first hour itself as was evident from tracer excretion in the urinary bladder and in the renal pelvicalyceal system. Because of known right ventricular dysfunction, there was evidence of blood pool activity in the heart, which however decreased significantly after 21 hours. A comparison of the 1.5 and 22 hours SPECT/CT images with ⁶⁸Ga-HA-DOTATATE PET/CT images (contrast-enhanced diagnostic CT) showed high uptake of ²⁰³Pb-VMT-α-NET in liver metastases matching with the results of the PET/CT. A, Anterior and posterior planar images acquired at 1 and 22 hours. B, Fused ⁶⁸Ga-HA-DOTATATE PET/CT transverse slice. C, Transverse contrast-enhanced CT image. D and E, SPECT/CT (low-dose) fused transverse slice. Arrows are showing the liver metastases.^1–8