# An Unusual Observation in Metastatic Neuroendocrine Neoplasm: Diffuse Pattern Hepatic [ 68 Ga]Ga-DOTATATE Uptake Related to Micro-metastatic Disease and Discordance between Dual-Tracer PET-CT Findings and MIB-1 Labelling Index

## TL;DR

A patient with a neuroendocrine tumor showed unusual PET scan results that highlighted the complexity of tumor imaging and the need for multiple diagnostic tools.

## Contribution

This case highlights discordance between PET-CT findings and Ki-67 index, emphasizing the need for multimodal imaging in neuroendocrine tumor management.

## Key findings

- Dual-tracer PET-CT showed diffuse hepatic uptake with skeletal metastases but no FDG uptake.
- Liver biopsy revealed high Ki-67 (55–60%) despite low MIB-1 index (15%).
- The case illustrates the complexity of NEN imaging and the importance of multimodal assessment.

## Abstract

Neuroendocrine neoplasms (NENs) are a rare and diverse group of neoplasms that can originate from neuroendocrine cells in any organ. We herein present a patient with Grade II neuroendocrine tumor (NET) of the pancreas with bilobar liver metastasis and a MIB-1 labelling index of 15%, who underwent various systemic and targeted therapies. On follow-up, dual-tracer PET-CT imaging with [
68
Ga]Ga-DOTATATE PET/CT showed new onset skeletal metastases and diffuse pattern SSTR (somatostatin receptor) expression in the left lobe of the liver (Krenning score 3), contrasted by absent uptake on [
18
F]FDG. Magnetic resonance imaging of the liver confirmed sub-centimetric left liver lobe lesions, further biopsy of which suggested Grade-III NET exhibiting high Ki-67 (55–60%). Thus, a discordance was observed between Ki-67 and the dual-tracer PET-CT findings, emphasizing the complexity of NEN imaging (with possibility of differentiation even in a relatively high Ki-67) and the importance of using multiple tracers for accurate assessment in guiding evidence-based management strategy.