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Background
The fusion of PET with CT allowed for significant advancements in spatial resolution and sensitivity. However, there are still some limitations due to scanner design, some of which are due to differences in acquisition timing between PET and CT. Respiratory motion can cause tumor blurring and misregistration, limiting SUV calculation, and leading to difficulty in localization of small radiotracer avid lesions. This is especially applicable for DOTATATE imaging of neuroendocrine tumors.

Educational Goals / Teaching Points
Lesions near the dome of the liver, a common site of metastases, or bowel in close proximity to the diaphragm may be difficult to differentiate from nodal or intrathoracic lesions. While DOTATATE imaging allows greater sensitivity in lesion detection, localization is sometimes still challenging. Correction for respiratory motion can help localize lesions more accurately, which is important for staging and treatment. Emerging techniques in PET imaging allow for motion correction without the use of additional devices and minimal change in radiation dose.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Liver and lung metastases are commonly seen in patients with malignant neuroendocrine tumors (NETs). And, in some cases, the primary lesions are difficult to identify or locate on 68Ga-DOTATATE PET/CT. Furthermore, respiratory motion can cause tumor blurring and misregistration, limiting SUV calculation and leading to difficulty in localization of small radiotracer avid lesions. We have applied our newly developed automated data-driven gating (DDG) PET/CT technique to our routine DOTATATE PET/CT practice.

Conclusion
This presentation demonstrates the use of DDG 68Ga-DOTATE PET/CT to decrease artifact associated with respiratory motion without the use of external respiratory gating devices and increase diagnosis confidence and accuracy.