Rare Documentation & Theranostic Approach of Renal Metastases from Pancreatic Neuroendocrine Tumour with ¹⁸F-NOTANOC PET/CT and ¹⁷⁷Lu-DOTATATE SPECT/CT

Gastrointestinal-pancreatic neuroendocrine tumours (GEP-NETs) most frequently metastasise to the liver, lymph nodes, and bones.^[1] Primary renal neuroendocrine tumours are extremely rare, accounting for 0.05 to 0.4% of NETs, as enterochromaffin cells are typically absent in the adult kidney under normal conditions. These tumours usually present as solitary, unilateral, slow-growing masses larger than 4 cm and are often advanced at the time of diagnosis.^[2,3] Renal metastases originating from NETs are even more rare, with only four cases being documented in the literature, including three instances of rectal NET and one case of bronchial carcinoid.^{[4-7] 68}Ga labelled somatostatin analogues are the most widely used positron emission tomography (PET) radiopharmaceuticals for positron emission tomography/computed tomography. imaging of NETs.^{[8] 18}F labelled somatostatin analogues such as Fluorine-18 Aluminum Fluoride 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) -Octreotide (¹⁸F NOTANOC) have shown better tumourto-background ratio and better sensitivity for smaller lesions, which can be attributed to shorter positron energy and range of ¹⁸F positrons.^[9] Lesions that are positive on somatostatin receptor (SSTR) PET/CT can be treated with ¹⁷⁷Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) in a theranostic approach, which has demonstrated significantly longer progression-free survival and a higher response rate compared to high-dose octreotide LAR alone in the landmark NETTER trial.^[10] For solitary operable metastases, surgical resection or ablative therapy may be considered.^[11] However, in patients with widespread metastases, systemic treatments like PRRT or chemotherapy are more appropriate. Renal metastases from GEP-NET are extremely rare but can occur, often presenting as secondary renal lesions with SSTR-targeted imaging playing a vital role, both for diagnosis and treatment with PRRT, usually in widespread metastatic disease burden, as shown in this case [Fig 1].

Close

Fig 1: A 62-year-old female presented with abdominal pain, loss of appetite, and an abdominal lump, biopsy of which revealed a well-differentiated pancreatic neuroendocrine tumour of WHO grade 2 with Mib-1 index 18-20%. (a) ¹⁸F-NOTANOC PET/CT MIP (maximum intensity projection) image showing a large SSTR-expressing pancreatic mass (white arrow), hepatic metastases (black arrow), pulmonary metastases (blue arrow), and right renal metastasis (red arrow); (b and c) Post-therapy scan after 6.99 GBq ¹⁷⁷Lu-DOTATATE PRRT showing radiopharmaceutical uptake in primary and metastatic lesions (arrows); (d) Contrast-enhanced CT scan showing right renal lesion (arrow); (e) Fused transaxial 18F-NOTANOC PET/CT showing SSTR-expressing right renal metastasis (arrow). (f) Post-therapy SPECT/CT fused transaxial image showing radiopharmaceutical localisation in right renal metastasis (arrow). WHO: World health organization MIP: Maximum intensity projection; SSTR: Somatostatin receptor; PET/CT: Positron emission tomography/computed tomography; PRRT: Peptide receptor radionuclide therapy; SPECT: Single photon emission computed tomography

Export to PPT