Hot Embolus Artifact Mimicking Disease Progression in Post-therapy ¹⁷⁷Lu-DOTATATE Scan: Incremental Value of SPECT/CT

Peptide receptor radionuclide therapy (PRRT) has become an established treatment for patients with inoperable and/or metastatic, well-differentiated neuroendocrine tumors with overexpression of somatostatin receptor type 2 (SSTR-2). The post-therapy ¹⁷⁷Lu-DOTATATE whole-body scan not only assesses the biodistribution of the lesions seen on pre-therapy ⁶⁸ Ga-SSTR PET/CT scan but also provides a quick assessment of disease status and dosimetry during treatment. Like any other radionuclide scan, the whole-body ¹⁷⁷Lu-DOTATATE scan may also show abnormal radiotracer uptake, which may require further imaging to establish its exact etiology. Though radiotracer emboli mimicking focal pulmonary lesions have been described with ¹⁸F-FDG and ⁶⁸ Ga-DOTANOC PET/CT scans, similar artifacts with post-therapy ¹⁷⁷Lu-DOTATATE scans have not been described. Herein, we report two cases of hot emboli in the post-therapy ¹⁷⁷Lu-DOTATATE scans.