Endocrine Abstracts

DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)−peptide (DOTA peptide) seen on positron emission tomography combined with computed tomography (⁶⁸Ga-DOTA PETCT) has been proven to be one of the most accurate methods of imaging NETs. The first stage in the accurate reporting and utilising DOTA PETCT is a clear understanding of the normal patterns. PNETs can present with focal DOTA peptide uptake on imaging. We present preliminary data of a retrospective study of consecutive ⁶⁸GaDOTA PET/CT scans carried out at Queen Elisabeth Hospital Birmingham between 2017 and 2018 for staging and restaging non-pancreatic NET. We defined the pattern seen in regions of the uncinate process, head, neck, body and tail of the pancreas. We recorded the pattern seen (focal/diffuse/homogenous/inhomogenous) in these regions and the SUVmax. Other normal imaging including contrast enhanced CT, pancreatic MRI and normal pattern on CT component of the PETCT were used to define absence of focal pathology. We present initial data on 55 ⁶⁸Ga-DOTA PETCTs. 34/54 (63%) scans had focal uptake in the head/uncinate. 1/54 (2%) had uptake in neck. 12/54 (22%) uptake in body. 10/54 (19%) in tail. 18/54 (33%) scans presented with benign multifocal uptake in more than 2 anatomical areas; 11/54 (20%) had two focal regions. 3/54 (6%) had three focal regions. 1/54 (2%) had four focal regions. 1/54 had whole diffuse homogenous pancreas DOTA uptake with normal structural imaging. Focal uptake in the head and uncinate process of the pancreas had already been described and our study confirms this in 63% of initial patients. In this study we show a more complex normal pattern that, to our knowledge, has not been formally described before. Many of these benign patterns of uptake are diffuse (25%) rather than focal. Our preliminary data shows that benign ⁶⁸Ga-DOTA uptake is not limited to the head and uncinate process and that both focal and diffuse uptake in the body and tail can also be benign. We therefore also hypothesise that ⁶⁸GaDOTA PET/CT may not be an accurate imaging modality for assessment of presence or absence of PNETs without structural imaging.